Localization of neurotensin NTS2 receptors in rat brain, using

The brain localization of the neurotensin receptor NTS2 was studied with [3H]levocabastine, using an autoradiographic procedure. This study suggests that NTS2 receptors are mainly intracellular. High densities of binding sites were observed in the cingulate, insular, temporal, occipital, enthorhinal cortex, amygdaloid complex, septohippocampal nuclei, medial thalamus, mammillary bodies and superior colliculi; a moderate labelling was observed in the anterior and medial hippocampus, olfactory tubercle, hypothalamus, periaqueductal gray matter, caudate putamen, nucleus accumbens, septum, lateral thalamus, dorsal raphe nucleus and cerebellum; finally, a low labelling was apparent in the ventral tegmentum area and substantia nigra. Thus it appears that NTS2 receptors are particularly abundant in the cerebral cortex, the limbic areas and some areas involved in pain perception.     

Efferent projections of the infralimbic (area 25) region of the medial prefrontal cortex in the rat: an anterograde tracer PHA-L study

The efferent projections of the infralimbic region (IL) of the medial prefrontal cortex of the rat were examined by using the anterograde transport of Phaseolus vulgaris leucoagglutinin (PHA-L). Major targets of the IL were found to include the agranular insular cortex, olfactory tubercle, perirhinal cortex, the whole amygdaloid complex, caudate putamen, accumbens nucleus, bed nucleus of the stria terminalis, midline thalamic nuclei, the lateral preoptic nucleus, paraventricular nucleus, supramammillary nucleus, medial mammillary nucleus, dorsal and posterior areas of the hypothalamus, ventral tegmental area, central gray, interpeduncular nucleus, dorsal raphe, lateral parabrachial nucleus and locus coeruleus. Previously unreported projections of the IL to the anterior olfactory nucleus, piriform cortex, anterior hypothalamic area and lateroanterior hypothalamic nucleus were observed. The density of labeled terminals was especially high in the agranular insular cortex, olfactory tubercle, medial division of the mediodorsal nucleus of the thalamus, dorsal hypothalamic area and the lateral division of the central amygdaloid nucleus. Several physiological and pharmacological studies have suggested that the IL functions as the 'visceral motor' cortex, involved in autonomic integration with behavioral and emotional events. The present investigation is the first comprehensive study of the IL efferent projections to support this concept.     

Efferent connections of the lateral cortex of the lizard gekko gecko: Evidence for separate origins of medial and lateral pathways from the lateral cortex to the hypothalamus

The lateral cortex of the lizard Gekko gecko is composed of three parts: a dorsal and ventral part located rostrally and a posterior part located caudally. In order to obtain detailed information about the efferent connections of these lateral cortex subdivisions, iontophoretic injections of the anterograde tracers Phaseolus vulgaris leucoagglutinin and biotinylated dextran were made in the various parts. The main projection from the dorsal part terminates in the caudal part of the medial cortex. Other cortical projections were noted to the ipsi- and contralateral lateral cortex, the large-celled part of the medial cortex, and the dorsal cortex. Additional fibers were found bilaterally in the anterior olfactory nucleus and the external amygdaloid nucleus. The ventral part of the lateral cortex projects mainly to the ipsilateral, posterior part of the dorsal ventricular ridge and the external amygdaloid nucleus. Minor contralateral projections to these nuclei were also found. Other projections were observed to travel to the caudal part of the medial cortex, to the nucleus sphericus, and bilaterally to the lateral cortex and the anterior olfactory nucleus. The posterior part of the lateral cortex has similar efferent connections as the dorsal part and should be regarded as the caudal continuation of the dorsal part. Because previous studies have shown that the medial cortex and the amygdaloid complex project to different hypothalamic areas, we conclude that the dorsal and ventral parts of the lateral cortex transmit olfactory information to separate hypothalamic areas that are probably involved with different types of behavior. © 1995 Wiley-Liss, Inc.     

Afferent connections of septal nuclei of the domestic chick (Gallus domesticus): a retrograde pathway tracing study

The afferents to the septum of the domestic chicken were studied using retrograde tracers, rhodamine conjugated latex bead or Fast Blue, placed in different septal subregions. The results were verified by anterograde tracer injections deposited to selected areas. The main telencephalic afferents to the septum arise ipsilaterally from the hippocampal formation, dorsolateral corticoid area, piriform cortex, amygdaloid pallium, and the ventral pallidum. Contralateral afferents originate from the lateral septum and the amygdaloid pallium. A massive bilateral projection arises from the lateral hypothalamus. Other hypothalamic afferents arise from the periventricular, paraventricular and anterior medial nuclei, and the premammillary and mammillary areas. The dorsal thalamic nuclei (dorsal medial anterior and posterior) and the reticular dorsal nuclei also contribute septal afferents. Brainstem afferents arise bilaterally from the ventral tegmental area, substantia nigra, central gray, A8, locus coeruleus, ventral subcoeruleus nucleus, and raphe nuclei. The main terminal fields for septal afferents lie in the lateral septal nucleus and the belt of medial septal nucleus. The core of the latter is invaded mainly by fibers from the brainstem, presumably belonging to the ascending activating system. The septal afferents of the chicken are largely similar to those of other avian and nonavian species. The most prominent differences with previous pigeon data were found in the subregional selectivity of the hippocampal formation, dorsolateral corticoid area, mammillary nuclei, some dorsal thalamic nuclei, substantia nigra, and subcoeruleus nuclei in their projections to defined septal nuclei.     

The amygdala of the box turtle, Terrapene c. carolina

The amygdala of the box turtle lies beneath the posterior hypopallial ridge. Three nuclear groups may be distinguished in it: (1) the anterior amygdaloid area, (2) the basolateral group and (3) the corticomedial group. The anterior amygdaloid area shows no subdivisions; its location ventral and ventromedial to the caudal part of the small-celled portion of the piriform area is evident. The basolateral group is subdivided into lateral and basal amygdaloid nuclei. The interconnections of this group through the anterior commissure with the comparable area in the opposite amygdala and with the corticomedial group indicate that it is functionally a vicarious cortex. The corticomedial group is divisible into medial and cortical amygdaloid nuclei. The medial nucleus is poorly defined. The cortical nucleus is bounded by the medial amygdaloid nucleus on the medial side and the ventral border of the piriform cortex laterally, and is comparable to the cortical amygdaloid nucleus of higher vertebrates. The lateral olfactory tract arises from mitral cells of the olfactory bulb and accessory olfactory bulb and neurons of the anterior olfactory nucleus. The lateral part of the anterior olfactory nucleus, the lateral and the intermediate parts of the tuberculum olfactorium and the small-celled part of the piriform cortex contribute to and receive fibers from the lateral olfactory tract. The lateral olfactory tract sends fibers to the anterior amygdaloid area and the corticomedial group. The lateral corticohabenular tract has an anterior and a posterior division. The anterior division arises from cells of the nucleus of the lateral olfactory tract and the lateroventral portion of the piriform cortex. It is joined by those fascicles arising in the corticomedial group and designated as the amygdalohabenular tract. This tract crosses in the habenular commissure and retraces its course to enter the corticomedial amygdaloid nuclear group on the side opposite its origin. The basolateral group is interconnected through the anterior commissure. The stria terminalis contains three components which interconnect the corticomedial amygdaloid nuclear group with the septum, the preoptic area and the hypothalamus. The supracommissural and the intracommissural components relate the cortical and the medial nuclei to the septum, the preoptic area and the hypothalamus of the same side. The infracommissural component interconnects the cortical and the medial amygdaloid nuclei with the septum, the preoptic area and the hypothalamus of the same and the opposite side. The dorsal and the ventral olfactory projection tracts arise from the corticomedial amygdaloid nuclear group. They terminate in the preoptic area and anterior hypothalamus.     

Opioid receptor-like (ORL1) receptor distribution in the rat central nervous system: comparison of ORL1 receptor mRNA expression with (125)I-[(14)Tyr]-orphanin FQ binding.

The recently discovered neuropeptide orphanin FQ (OFQ), and its opioid receptor-like (ORL1) receptor, exhibit structural features suggestive of the micro, kappa, and delta opioid systems. The anatomic distribution of OFQ immunoreactivity and mRNA expression has been reported recently. In the present analysis, we compare the distribution of orphanin receptor mRNA expression with that of orphanin FQ binding at the ORL1 receptor in the adult rat central nervous system (CNS). By using in vitro receptor autoradiography with (125)I-[(14)Tyr]-OFQ as the radioligand, orphanin receptor binding was analyzed throughout the rat CNS. Orphanin binding sites were densest in several cortical regions, the anterior olfactory nucleus, lateral septum, ventral forebrain, several hypothalamic nuclei, hippocampal formation, basolateral and medial amygdala, central gray, pontine nuclei, interpeduncular nucleus, substantia nigra, raphe complex, locus coeruleus, vestibular nuclear complex, and the spinal cord. By using in situ hybridization, cells expressing ORL1 mRNA were most numerous throughout multiple cortical regions, the anterior olfactory nucleus, lateral septum, endopiriform nucleus, ventral forebrain, multiple hypothalamic nuclei, nucleus of the lateral olfactory tract, medial amygdala, hippocampal formation, substantia nigra, ventral tegmental area, central gray, raphe complex, locus coeruleus, multiple brainstem motor nuclei, inferior olive, deep cerebellar nuclei, vestibular nuclear complex, nucleus of the solitary tract, reticular formation, dorsal root ganglia, and spinal cord. The diffuse distribution of ORL1 mRNA and binding supports an extensive role for orphanin FQ in a multitude of CNS functions, including motor and balance control, reinforcement and reward, nociception, the stress response, sexual behavior, aggression, and autonomic control of physiologic processes.     

Afferent connections to the lateral hypothalamus: A horseradish peroxidase study in the rat

Horseradish peroxidase, 13% Sigma Type VI, was administered iontophoretically to the mid lateral hypothalamus (LH) of male hooded rats. Animals were perfused intracardially on the following day and brains were removed and sliced in the coronal or sagittal planes into 30–50 μm sections. Sections were processed with DAB and BDH for the brown and blue reaction products and later examined by bright and dark field microscopy for the presence and location of retrogradely labeled neurons. Results indicate that a significant number of afferent connections to the LH originate in the olfactory and accumbens nuclei, pyriform cortex, olfactory tracts, magnocellular and medial preoptic and anterior hypothalamic regions, stria terminalis, stria hypothalamic tract, diagonal tract of Broca, caudate-putamen and globus pallidus, internal capsule, lateral septal nuclei, lateral preoptic area and anterior medial forebrain bundle, the various amygdaloid nuclei, zona incerta, perifornical region, dorsal and ventral medial hypothalamic areas, supraoptic, paraventricular and periventricular nuclei, posterior hypothalamus and medial forebrain bundle, ventral thalamic nuclei, the fields of Forel, arcuate and mammillary nuclei, adjacent to the fasciculus retroflexus, in the ventral tegmental area of Tsai, interpeduncular nucleus, substantia nigra, mesencephalic reticular formation, periaqueductal gray, locus coeruleus and parabrachial region. Results are discussed in terms of previous anatomical and neurophysiological data, probable pathways, and the function of LH neurons.     

Efferents and centrifugal afferents of the main and accessory olfactory bulbs in the hamster

The efferents and centrifugal afferents of the hamster olfactory bulbs were studied using orthograde and retrograde tracing techniques. Following injections of tritiated amino acids which were restricted to the main olfactory bulb (MOB), autoradiographic grains were observed ipsilaterally over layer IA of the entire anterior olfactory nucleus (AON), the ventral portion of the hippocampal rudiment (HR), the entire prepyriform cortex and olfactory tubercle, the anterior and posterolateral cortical amygdaloid nuclei and the lateral entorhinal cortex. An ipsilateral projection to the nucleus of the lateral olfactory tract (nLOT) was also indicated. No subcortical or contralateral projections were observed. Amino acid injections into the accessory olfactory bulb (AOB) revealed ipsilateral projections to the superficial plexiform layer of the medial and posteromedial cortical amygdaloid nuclei and to the bed nucleus of the accessory olfactory tract (nAOT) and the bed nucleus of the stria terminalis (nST). Following injections of HRP which were restricted to the MOB, contralateral HRP-positive neurons were found predominantly in pars externa and to a lesser extent in the other subdivisions of the AON. Centrifugal projections to the MOB were identified ipsilaterally from the entire AON, the ventral portion of the HR, the anterior portion of the prepyriform cortex, and the nLOT. No labelled neurons were found in the olfactory tubercle, the anterior and posterolateral cortical amygdaloid nuclei or the entorhinal cortex. Centrifugal projections to the MOB were also identified from subcortical structures of the ipsilateral basal forebrain and from midline structures of the midbrain. Labelling occurred in the fusiform neurons of the diagonal band near the medial base of the forebrain at the level of caudal olfactory tubercle. Heavy labelling was seen in a distinct group of large, predominantly multipolar neurons (magnocellular preoptic area) that continued from the level of caudal olfactory tubercle to the level of the nLOT. This band of HRP-positive neurons could be followed more caudally to a position dorsal and medial to the nLOT near the lateral margin of the lateral anterior hypothalamic area. The midbrain projections to the MOB originated in the dorsal and median raphe nuclei. After injections of HRP into the AOB, centrifugal projections were identified from the nAOT and the posteromedial cortical amygdaloid nucleus. In addition, isolated neurons were labelled in the medial cortical amygdaloid nucleus but no labelled neurons were found in the nST. These results support the notion of two anatomically distinct olfactory systems and demonstrate two previously unreported pathways through which the limbic system may modulate sensory processing in the olfactory bulb.     

Afferent and efferent connections of the medial preoptic area in the rat: A WGA-HRP study

Afferent and efferent connections of the medial preoptic area including medial preoptic nucleus (MP) and periventricular area at the MP level were examined using WGA-HRP as a marker. Injections were performed by insertion of micropipette containing (1) small amount of HRP powder or (2) dryed HRP solution for 24 to 48 hr until the fixation or for 5 min respectively. Dorsal and ventral approaches of injection micropipettes were performed and the results were compared. Previously reported reciprocal connections with lateral septum, bed nucleus of the stria terminalis, medial amygdaloid nucleus, lateral hypothalamic nucleus, paraventricular hypothalamic nucleus, ventromedial hypothalamic nucleus, arcuate nucleus, supramammillary nucleus, central gray at the mesencephalon, raphe dorsalis, raphe medianus, and lateral parabrachial nucleus have been confirmed. In addition, we found reciprocal connections with septo-hypothalamic nucleus, amygdalo-hipocampal nucleus, subiculum, parafascicular thalamic nucleus, posterior thalamic nucleus at the caudo-ventral subdivision, median preoptic nucleus, lateral preoptic nucleus, anterior hypothalamic nucleus, periventricular area at the caudal hypothalamic level, dorsomedial hypothalamic nucleus, posterior hypothalamic nucleus, dorsal and ventral premammillary nucleus, lateral mammillary nucleus, peripeduncular nucleus, periventricular gray, ventral tegmental area, interpeduncular nucleus, nucleus raphe pontis, nucleus raphe magnus, pedunculo-pontine tegmental nucleus, gigantocellular reticular nucleus and solitary tract nucleus. The areas which had only efferent connections from MP were accumbens, caudate putamen, ventral pallidum, substantia innominata, lateral habenular nucleus, paratenial thalamic nucleus, paraventricular thalamic nucleus, mediodorsal thalamic nucleus, reuniens thalamic nucleus, median eminence, medial mammillary nucleus, subthalamic nucleus, pars compacta of substantia nigra, oculomotor nucleus, red nucleus, laterodorsal tegmental nucleus, reticular tegmental nucleus, cuneiform nucleus, nucleus locus coeruleus, and dorsal motor nucleus of vagus among which substantia innominata and median eminence were previously reported. Efferent connections to the nucleus of Darkschewitsch, interstitial nucleus of Cajal, dorsal tegmental nucleus, ventral tegmental nucleus, vestibular nuclei, nucleus raphe obsculus were very weak or abscent in the ventral approach while they were observed in dorsal approach. Previously reported afferent connections from dorsal tegmental nucleus, cuneiform nucleus, and nucleus locus ceruleus were not detected in this study.(ABSTRACT TRUNCATED AT 400 WORDS)     

Organization of the pallium in the fire-bellied toad Bombina orientalis. I: Morphology and axonal projection pattern of neurons revealed by intracellular biocytin labeling

The cytoarchitecture and axonal projection pattern of pallial areas was studied in the fire-bellied toad Bombina orientalis by intracellular injection of biocytin into a total of 326 neurons forming 204 clusters. Five pallial regions were identified, differing in morphology and projection pattern of neurons. The rostral pallium receiving the bulk of dorsal thalamic afferents has reciprocal connections with all other pallial areas and projects to the septum, nucleus accumbens, and anterior dorsal striatum. The medial pallium projects bilaterally to the medial pallium, septum, nucleus accumbens, mediocentral amygdala, and hypothalamus and ipsilaterally to the rostral, dorsal, and lateral pallium. The ventral part of the medial pallium is distinguished by efferents to the eminentia thalami and the absence of contralateral projections. The dorsal pallium has only ipsilateral projections running to the rostral, medial, and lateral pallium; septum; nucleus accumbens; and eminentia thalami. The lateral pallium has ipsilateral projections to the olfactory bulbs and to the rostral, medial, dorsal, and ventral pallium. The ventral pallium including the striatopallial transition area (SPTA) has ipsilateral projections to the olfactory bulbs, rostral and lateral pallium, dorsal striatopallidum, vomeronasal amygdala, and hypothalamus. The medial pallium can be tentatively homologized with the mammalian hippocampal formation, the dorsal pallium with allocortical areas, the lateral pallium rostrally with the piriform and caudally with the entorhinal cortex, the ventral pallium with the accessory olfactory amygdala. The rostral pallium, with its projections to the dorsal and ventral striatopallidum, resembles the mammalian frontal cortex.     

Efferent projections of infralimbic and prelimbic areas of the medial prefrontal cortex in the Japanese monkey, Macaca fuscata

The infralimbic area (IL) and prelimbic area (PL) have been postulated as an autonomic motor region in the medial prefrontal cortex. The present study was conducted to reveal the projection sites of IL and PL of the monkey, Macaca fuscata, using biotinylated dextran amine as an anterograde tracer. IL and PL projected densely to the ventromedial caudate nucleus, the core and shell of the nucleus accumbens (Acb), parvicellular lateral basal and magnocellular accessory basal nuclei of the amygdala, lateral preoptic area, ventromedial hypothalamic nucleus, tubero-mammillary nucleus (TM), medial part of the magnocellular and dorsal part of the parvicellular (MDpc) dorsomedial thalamic nuclei, reunience and medial part of the medial pulvinar nucleus, and dorso-lateral part of the periaqueductal gray (PAGdl) in the mesencephalon. Moderately to weakly projected areas were the intermediate and lateral parts of the agranular insular cortex, orbital part of area 12, agranular and dysgranular part of the temporal pole cortex (TPa-g), auditory temporal cortex, lateral and medial (MS) septal nuclei, bed nucleus of the stria terminalis, diagonal band of Broca, substantia innominata, and medial preoptic area, dorsomedial, lateral, and posterior hypothalamic nuclei, magnocellular lateral basal and lateral amygdaloid nuclei, paratenial, paraventricular (PV), inter-antero-medial (IAM), reticular, central medial (CeM), parafascicular (PF) and limitans nuclei of the thalamus, lateral habenular nucleus, pedunculo-pontine nucleus, dorsal part of the lateral lemniscal nucleus, ventral tegmental area (VTA), dorsal raphe, superior central nucleus, medial and lateral parabrachial nuclei (PBl) and nucleus locus coeruleus (LC). A few scattered terminals were observed in the perifornical nucleus of the hypothalamus and substantia nigra pars compacta. PL and area 24 were characterized by projections to the entorhinal (Ent) and piriform (Pir) cortex as well as to the magnocellular part of the ventral anterior thalamic nucleus (VAmc). The morphology of the terminal arborization in each nuclei was different in appearance, perhaps reflecting the synaptic interaction between the nerve terminals and postsynaptic dendrites. PL projected uniquely to Ent, Pir and VAmc and IL projected uniquely to TPa-g, MS, IAM, CeM, MDpc, PF, PBl and LC. IL projected more strongly than PL to the shell of Acb, amygdaloid nuclei, PV, TM, VTA and PAGdl. The present results support the hypothesis that IL is a major cortical autonomic motor area and PL integrates limbic and autonomic inputs in the primate.     

Compartmental organization of the thalamostriatal connection in the cat.

The compartmental organization of the thalamostriatal connection in the cat was studied by labelling thalamic fibers in anterograde axonal transport experiments and comparing their striatal distributions with the arrangement of striosomes and matrix tissue identified by histochemical staining methods. When analyzed according to their principal compartmental targets in dorsal striatum, the thalamic deposits indicated the existence of medial and lateral divisions within the thalamostriatal projection. Nuclei of the medial division, which includes parts of the thalamic midline, projected primarily to striosomes. The lateral division, which embraces the anterior and posterior intralaminar groups, the rostral ventral tier nuclei, and parts of the posterior lateral nuclear complex, predominantly innervated matrix tissue. In the dorsal division of the nucleus accumbens, the medial system preferentially terminated in zones that stain heavily in butyrylcholinesterase and substance P preparations, but fibers from both the medial and the lateral systems largely avoided the histochemically marked compartments such as the border islands of the nucleus accumbens that are seen elsewhere in the ventral striatum. Medial division: Thalamic deposits involving the paraventricular and rhomboid nuclei of the thalamic midline elicited labelling of striosomes and, invariably, ventral extrastriosomal matrix, the nucleus accumbens, and the amygdala. This projection was topographically organized: rostral thalamic deposits elicited labelling in the medial caudate nucleus and the medial nucleus accumbens. More caudal injections produced more lateral labelling. Lateral division: The lateral division is composed of at least three projection systems distinguished by their patterns of matrix innervation. Deposits involving the anterior intralaminar nuclei and the striatally projecting cells located lateral to the stria medullaris (anterior intralaminar complex) produced an even, diffuse labelling of the matrix tissue and weak labelling of the striosomes. Injections placed in the ventroanterior, ventrolateral, and ventromedial nuclei (rostral ventral complex) elicited fibrous labelling of matrix tissue that often showed nonstriosomal inhomogeneities. Deposits involving the centromedian and parafascicular nuclei (posterior intralaminar complex) produced a highly variable pattern of matrix labelling that included both homogeneous and decidedly patchy innervations of the extrastriosomal matrix. Each of these lateral thalamostriatal systems showed a similar spatial organization, whereby dorsoventral and mediolateral thalamic axes were roughly preserved in the projection to striatum.     

Efferent projections of infralimbic and prelimbic areas of the medial prefrontal cortex in the Japanese monkey, Macaca fuscata

The infralimbic area (IL) and prelimbic area (PL) have been postulated as an autonomic motor region in the medial prefrontal cortex. The present study was conducted to reveal the projection sites of IL and PL of the monkey, Macaca fuscata, using biotinylated dextran amine as an anterograde tracer. IL and PL projected densely to the ventromedial caudate nucleus, the core and shell of the nucleus accumbens (Acb), parvicellular lateral basal and magnocellular accessory basal nuclei of the amygdala, lateral preoptic area, ventromedial hypothalamic nucleus, tubero-mammillary nucleus (TM), medial part of the magnocellular and dorsal part of the parvicellular (MDpc) dorsomedial thalamic nuclei, reunience and medial part of the medial pulvinar nucleus, and dorso-lateral part of the periaqueductal gray (PAGdl) in the mesencephalon. Moderately to weakly projected areas were the intermediate and lateral parts of the agranular insular cortex, orbital part of area 12, agranular and dysgranular part of the temporal pole cortex (TPa-g), auditory temporal cortex, lateral and medial (MS) septal nuclei, bed nucleus of the stria terminalis, diagonal band of Broca, substantia innominata, and medial preoptic area, dorsomedial, lateral, and posterior hypothalamic nuclei, magnocellular lateral basal and lateral amygdaloid nuclei, paratenial, paraventricular (PV), inter-antero-medial (IAM), reticular, central medial (CeM), parafascicular (PF) and limitans nuclei of the thalamus, lateral habenular nucleus, pedunculo-pontine nucleus, dorsal part of the lateral lemniscal nucleus, ventral tegmental area (VTA), dorsal raphe, superior central nucleus, medial and lateral parabrachial nuclei (PBl) and nucleus locus coeruleus (LC). A few scattered terminals were observed in the perifornical nucleus of the hypothalamus and substantia nigra pars compacta. PL and area 24 were characterized by projections to the entorhinal (Ent) and piriform (Pir) cortex as well as to the magnocellular part of the ventral anterior thalamic nucleus (VAmc). The morphology of the terminal arborization in each nuclei was different in appearance, perhaps reflecting the synaptic interaction between the nerve terminals and postsynaptic dendrites. PL projected uniquely to Ent, Pir and VAmc and IL projected uniquely to TPa-g, MS, IAM, CeM, MDpc, PF, PBl and LC. IL projected more strongly than PL to the shell of Acb, amygdaloid nuclei, PV, TM, VTA and PAGdl. The present results support the hypothesis that IL is a major cortical autonomic motor area and PL integrates limbic and autonomic inputs in the primate.     

The projection field of the stria terminalis in the rat brain. An experimental study

The problem of the stria terminalis projection field has been examined by use of two versions of the cupric-silver technique as well as variations of the Fink-Heimer and Nauta-Gygax techniques applied to material fixed under different conditions using brains from very young rats surviving 30 hours to four days after production of lesions at different levels of the course of the stria terminalis and related structures. The findings are as follows:

• (1) A dorsal subventricular portion of the stria terminalis divides into retrocommissural and supracommissural contingents which together account for degenerating terminals seen in the ipsilateral bed nuclei of the stria terminalis and of the anterior commissure, and in the medial preoptic-hypothalamic junction area. The supracommissural bundle also disseminates into the laterobasal septum, nucleus accumbens, olfactory tubercle, the posterior and medial divisions of the anterior olfactory nucleus, and the granular layer of the accessory olfactory bulb. Additional fibers end in the paucicellular capsule of the ventromedial hypothalamic nucleus, also in a small lateral parvocellular tuberal nuclear area, and throughout the premammillary nuclei. A small truly commissural division of the dorsal component was traced to the contralateral cortical amygdaloid nucleus and to small clusters of medial amygdaloid cells.
• (2) A ventral juxtacapsular portion of the stria terminalis was traced to the ipsilateral strial bed nucleus, medial preoptic-hypothalamic junction area, the entire ventromedial hypothalamic nucleus, the lateral tuberal area and the premammillary nuclei. The lateralmost fibers of the dorsal strial component as well as those of the ventral component which lie lateral to the “commissural bundle” appear to terminate exclusively in the lateral portions of the bed nucleus of the stria.
• (3) A “commissural bundle” or component, after crossing the midline in the anterior commissure, ends in the bed nucleus of the posterior limb of the latter, in the olfactory tubercle, prepiriform cortex, lateral amygdaloid nucleus and the strial bed nucleus. It is thus a decussation rather than a commissure. No contribution from stria terminalis to stria medullaris could be identified.

     

Distribution of immunoreactive metorphamide (adrenorphin) in discrete regions of the rat brain: Comparison with met-enkephalin-Arg-Gly-Leu

The distribution of immunoreactive (ir)-metorphamide (adrenorphin) in 101 microdissected rat brain and spinal cord regions was determined using a highly specific radioimmunoassay. The highest concentration of metorphamide in brain was found in globus pallidus (280.1 fmol/mg protein). High concentrations of ir-metorphamide (>120 fmol/mg protein) were found in 9 nuclei, including central amygdaloid nucleus, lateral preoptic area, anterior hypothalamic nucleus, hypothalamic paraventricular nucleus, interpeduncular nucleus, periaqueductal grey matter and nucleus of the solitary tract. Moderate concentrations of the peptide (between 60 and 120 fmol/mg protein) were found in 47 brain nuclei such as nucleus accumbens, bed nucleus of stria terminalis, several septal and amygdaloid nuclei, most of the hypothalamic nuclei, ventral tegmental area, red nucleus, raphe nuclei, lateral reticular nucleus, area postrema and others. Low concentrations or ir-metorphamide (<60 fmol/mg protein) were measured in 41 nuclei, e.g., cortical structures, hippocampus, caudate nucleus, thalamic nuclei, supraoptic nucleus, substantia nigra, vestibular nuclei, cerebellum (nuclei and cortex). The olfactory bulb has the lowest metorphamide concentration (5.8 fmol/mg protein). Spinal cord segments exhibit very low peptide concentrations.     

An HRP study of the afferent connections to rat lateral hypothalamic region

Afferent connections to the lateral hypothalamic region in the rat were studied using horseradish peroxidase (HRP). HRP was injected iontophoretically by a parapharyngeal approach. After HRP injections into the lateral hypothalamic area, labeled cells were found mainly in the medial prefrontal and infralimbic cortices, lateral and dorsal septal nuclei, nucleus accumbens, bed nucleus of the stria terminalis, medial and lateral amygdaloid nuclei, lateral habenular nucleus, peripeduncular nucleus, ventral tegmental area, mesencephalic and pontine central gray, ventral nucleus of the lateral lemniscus, lateral parabrachial area, raphe nuclei and the nucleus locus coeruleus. Labeled cells following HRP injections into the lateral preoptic area were found mainly in the lateral and dorsal septal nuclei, nucleus accumbens, diagonal band, ventral part of the globus pallidus, bed nucleus of the stria terminalis, central amygdaloid nucleus, mesencephalic and pontine central gray, dorsal raphe nucleus, parabrachial area and the nucleus locus coeruleus. The intrahypothalamic connections were also discussed.     

Distribution of immunoreactive metorphamide (adrenorphin) in discrete regions of the rat brain: comparison with Met-enkephalin-Arg6-Gly7-Leu8

The distribution of immunoreactive (ir)-metorphamide (adrenorphin) in 101 microdissected rat brain and spinal cord regions was determined using a highly specific radioimmunoassay. The highest concentration of metorphamide in brain was found in globus pallidus (280.1 fmol/mg protein). High concentrations of ir-metorphamide (greater than 120 fmol/mg protein) were found in 9 nuclei, including central amygdaloid nucleus, lateral preoptic area, anterior hypothalamic nucleus, hypothalamic paraventricular nucleus, interpeduncular nucleus, periaqueductal grey matter and nucleus of the solitary tract. Moderate concentrations of the peptide (between 60 and 120 fmol/mg protein) were found in 47 brain nuclei such as nucleus accumbens, bed nucleus of stria terminalis, several septal and amygdaloid nuclei, most of the hypothalamic nuclei, ventral tegmental area, red nucleus, raphe nuclei, lateral reticular nucleus, area postrema and others. Low concentrations or ir-metorphamide (less than 60 fmol/mg protein) were measured in 41 nuclei, e.g., cortical structures, hippocampus, caudate nucleus, thalamic nuclei, supraoptic nucleus, substantia nigra, vestibular nuclei, cerebellum (nuclei and cortex). The olfactory bulb has the lowest metorphamide concentration (5.8 fmol/mg protein). Spinal cord segments exhibit very low peptide concentrations.     

Amygdaloid projections to subcortical structures within the basal forebrain and brainstem in the rat and cat

The efferent fiber connections of the nuclei of the amygdaloid complex with subcortical structures in the basal telencephalon, hypothalamus, midbrain, and pons have been studied in the rat and cat, using the autoradiographic method for tracing axonal connections. The cortical and thalamic projections of these nuclei have been described in previous papers (Krettek and Price, ′77b,c). Although the subcortical connections of the amygdaloid nuclei are widespread within the basal forebrain and brain stem, the projections of each nucleus have been found to be well defined, and distinct from those of the other amygdaloid nuclei. The basolateral amygdaloid nucleus projects heavily to the lateral division of the bed nucleus of the stria terminalis (BNST), to the caudal part of the substantia innominata, and to the ventral part of the corpus striatum (nucleus accumbens and ventral putamen) and the olfactory tubercle; it projects more lightly to the lateral hypothalamus. The central nucleus also projects to the lateral division of the BNST and the lateral hypothalamus, but in addition it sends fibers to the lateral part of the substantia nigra and the marginal nucleus of the brachium conjunctivum. The basomedial nucleus has projections to the ventral striatum and olfactory tubercle which are similar to those of the basolateral nucleus, but it also projects to the core of the ventromedial hypothalamic nucleus and the premammillary nucleus, and to a central zone of the BNST which overlaps the medial and lateral divisions. The medial nucleus also projects to the core of the ventromedial nucleus and the premammillary nucleus, but sends fibers to the medial division of the BNST and does not project to the ventral striatum. The posterior cortical nucleus projects to the premammillary nucleus and to the medial division of the BNST, but a projection from this nucleus to the ventromedial nucleus has not been demonstrated. Projections to the “shell” of the ventromedial nucleus have been found only from the ventral part of the subiculum and from a structure at the junction of the amygdala and the hippocampal formation, which has been termed the amygdalo-hippocampal area (AHA). The AHA also sends fibers to the medial part of the BNST and the premammillary nucleus. Virtually no subcortical projections outside the amygdala itself have been demonstrated from the lateral nucleus, or from the olfactory cortical areas around the amygdala (the anterior cortical nucleus, the periamygdaloid cortex, and the posterior prepiriform cortex). However, portions of the endopiriform nucleus deep to the prepiriform cortex project to the ventral putamen, and to the lateral hypothalamus.     

Afferent connections of the striatum and the nucleus accumbens in the lizard Gekko gecko

The afferent connections of the striatum and the nucleus accumbens of the lizard Gekko gecko were studied with retrograde tracing by means of horseradish peroxidase and Fluoro-Gold and with anterograde tracing by means of Phaseolus vulgaris leukoagglutinin. The striatum receives projections from the cortex, the dorsal ventricular ridge, the lateral amygdaloid nucleus, the globus pallidus, the anterior peduncular nucleus, the ventral tegmental area and substantia nigra, the area ventral to the substantia nigra, and the dorsal thalamus. The nucleus accumbens is projected upon by the cortex, the diagonal band, the ventral pallidum, the lateral preoptic area, the ventral tegmental area, and the dorsal thalamus. The source of the cortical projection to the striatum and the nucleus accumbens is a longitudinal zone in the dorsal cortex that, rostrally in the hemisphere, is located medially and, more caudally, in its middle one third. The medial and rostrolateral areas of the dorsal ventricular ridge each project to the striatum in a vertical zone. The fibers from the caudolateral area of the ridge end in two oblique bands located parallel to the border between the dorsal ventricular ridge and the striatum. The pathways from the mesencephalic tegmentum to the striatum and the nucleus accumbens show a medial to lateral topography. This is similar to the situation in birds, but contrary to that in mammals in which these pathways are extensively interconnected. The specific sensory nuclei of the dorsal thalamus were found to project not only to the dorsal ventricular ridge, but also, and in a topographical fashion, to the striatum. The dorsomedial thalamic nucleus, which innervates the dorsal ventricular ridge, has additional projections to the striatum and the nucleus accumbens. This projection pattern is similar to that of the intralaminar thalamic nuclei of birds and mammals.     

Afferent and efferent connections of the olfactory bulbs in the lizard Podarcis hispanica.

The connections of the olfactory bulbs of Podarcis hispanica were studied by tract-tracing of injected horseradish peroxidase. Restricted injections into the main olfactory bulb (MOB) resulted in bilateral terminallike labeling in the medial part of the anterior olfactory nucleus (AON) and in the rostral septum, lateral cortex, nucleus of the lateral olfactory tract, and ventrolateral amygdaloid nucleus. Bilateral retrograde labeling was found in the rostral lateral cortex and in the medial and dorsolateral AON. Ipsilaterally the dorsal cortex, nucleus of the diagonal band, lateral preoptic area, and dorsolateral amygdala showed labeled cell bodies. Retrogradely labeled cells were also found in the midbrain raphe nucleus. Results from injections into the rostral lateral cortex and lateral olfactory tract indicate that the mitral cells are the origin of the centripetal projections of the MOB. Injections in the accessory olfactory bulb (AOB) produced ipsilateral terminallike labeling of the ventral AON, bed nucleus of the accessory olfactory tract, central and ventromedial amygdaloid nuclei, medial part of the bed nucleus of the stria terminalis, and nucleus sphericus. Retrograde labeling of neurons was observed ipsilaterally in the bed nucleus of the accessory olfactory tract and stria terminalis, in the central amygdaloid nucleus, dorsal cortex, and nucleus of the diagonal band. Bilateral labeling of somata was found in the ventral AON, the nucleus sphericus (hilus), and in the mesencephalic raphe nucleus and locus coeruleus. Injections into the dorsal amygdala showed that the mitral neurons are the cells of origin of the AOB centripetal projections. Reciprocal connections are present between AOB and MOB. To our knowledge, this is the first study to address the afferent connections of the olfactory bulbs in a reptile. On the basis of the available data, a discussion is provided of the similarities and differences between the reptilian and mammalian olfactory systems, as well as of the possible functional role of the main olfactory connections in reptiles.