Neuronal projections to the lateral retrochiasmatic area of sheep with special reference to catecholaminergic afferents: immunohistochemical and retrograde tract-tracing studies

The retrochiasmatic area contains the A15 catecholaminergic group and numerous monoaminergic afferents whose discrete cell origins are unknown in sheep. Using tract-tracing methods with a specific retrograde fluorescent tracer, fluorogold, we examined the cells of origin of afferents to the retrochiasmatic area in sheep. The retrogradely labeled cells were seen by observation of the tracer by direct fluorescence or by immunohistochemistry with specific antibodies raised in rabbits or horses. Among the retrogradely labeled neurons, double immunohistochemistry for tyrosine hydroxylase, dopamine-beta-hydroxylase, and serotonin were used to characterize catecholamine and serotonin FG labeled neurons. The retrochiasmatic area, which included the A15 dopaminergic group and the accessory supraoptic nucleus (SON), received major inputs from the lateral septum (LS), the bed nucleus of the stria terminalis (BNST), the thalamic paraventricular nucleus, hypothalamic paraventricular and supraoptic nuclei, the perimamillary area, the amygdala, the ventral part of the hippocampus and the parabrachial nucleus (PBN). Further, numerous scattered retrogradely labeled neurons were observed in the preoptic area, the ventromedial part of the hypothalamus. the periventricular area, the periaqueductal central gray (CG), the ventrolateral medulla and the dorsal vagal complex. Most of the noradrenergic afferents came from the ventro-lateral medulla (Al group), and only a few from the locus coeruleus complex (A6/A7 groups). A few dopaminergic neurons retrogradely labeled with flurogold were observed in the periventricular area of the hypothalamus. Rare serotoninergic fluorogold labeled neurons belonged to the dorsal raphe nucleus. Most of these afferents came from both sides of the brain, except for hypothalamic supraoptic and paraventricular nuclei. In the light of these anatomical data, we compared our results with data obtained from rats, and we discussed the putative role of these afferents in sheep in the regulation of several specific functions in which the retrochiasmatic area may be involved, such as reproduction.     

猫蓝斑核向嗅球、嗅前核的投射——HRP逆轴突传递法研究

本研究用HRP逆轴突传递法观察了28只猫蓝斑核(LC)向嗅球(OB)、嗅前核(AON)的投射,结果如下: 1.于OB注射例中,LC内出现少到中等量的标记细胞,其分布状况在各例大致相同:全长分布,中间居多,两端渐少;各亚核的细胞数为蓝班主核多于蓝班α核外侧部,后者又多于其内侧部,即pLC>ILCa>mLCa。细胞以中型为主,少量小及大型细胞,多为卵圆、三角和梭形。同侧LC中的标记细胞明显多于对侧。 2.于AON注射例中,LC内出现不等量的标记细胞,其分布特点、细胞大小及形态与OB例基本相同,LC中出现的标记细胞数平均多于OB例。 3.注HRP于OB和AON例中,LC中出现的标记细胞显著多于OB或AON注射例。     

Projections from the ventral tegmental area and mesencephalic raphe to the dorsal raphe nucleus in the rat

Summary The origins of the dopaminergic innervation of the rat dorsal raphe nucleus (NRD) have been investigated using a combination of fluorescent retrograde tracing and fluorescence histochemistry. Stereotaxic microinjections of True Blue were placed in the central, caudal and lateral portions of the NRD, and after 6–12 days survival the brains were processed for fluorescence histochemical detection of catecholamines. Retrogradely labeled neurons were searched for in the diencephalic A11 and A13 dopaminergic cell groups, substantia nigra, ventral tegmental area (VTA) and the linear, central superior and dorsal raphe nuclei. The various NRD injections consistently resulted in retrograde labeling of a small number of catecholamine-containing, presumed dopaminergic cell bodies, confined mainly to three regions: the VTA, the linear and central superior raphe nuclei and the NRD itself. The present findings indicate that not only dopaminergic neurons in the VTA but also the system of catecholamine-containing cells, extending dorsally and caudally from the VTA within the midline raphe area, project to the NRD. Although often similar in size, shape and distribution to the catecholaminergic neurons the majority of retrogradely labeled cells in these regions were, however, found to be non-catecholaminergic.Abbreviations 3 Principal oculomotor nucleus - 4 Trochlear nucleus - Aq Cerebral aqueduct - cp cerebral peduncle - cst cortico-spinal tract - dscp decussation of the superior cerebellar peduncle - DTg Dorsal tegmental nucleus - fr fasciculus retroflexus - IF Interfascicular nucleus - IP Interpeduncular nucleus - LL nucleus of the lateral lemniscus - ml medial lemniscus - mlf medial longitudinal fasciculus - mNV mesencephalic trigeminal nucleus - NLC Nucleus linearis caudalis - NLR Nucleus linearis rostralis - NRD Dorsal raphe nucleus - PAG Periaqueductal grey - PN Pontine nucleus - PRN Pontine raphe nucleus - R Red nucleus - RCS Nucleus raphe centralis superior - SN Substantia nigra - VTA Ventral tegmental area - VTg Ventral tegmental nucleus     

一氧化氮合成酶阳性神经元在大鼠前脑的分布

用NADPH—d组织化学方法观察一氧化氮合成酶阳性神经元在大鼠前脑结构的分布和形态,结果显示在大脑皮质、纹状体、嗅球、杏仁核、基底前脑和下丘脑有较多一氧化氮合成酶神经元分布,这些神经元大多显示了Golgi样染色外观,它们尚不能与任何已知的神经递质类型神经元单一相对应.皮质、嗅球、纹状体和Calleja氏岛分别含有中等密度和密集的一氧化氮合成酶阳性纤维,一氧化氮合成酶阳性纤维较细,带有小的或中等大小的膨体,相互编织成疏密不等的纤维网.     

Brain afferents to the lateral caudal ventrolateral medulla: a retrograde and anterograde tracing study in the rat

The ventrolateral medulla (VLM) modulates autonomic functions, motor reactions and pain responses. The lateralmost part of the caudal VLM (VLMlat) was recently shown to be the VLM area responsible for pain modulation. In the present study, the brain sources of VLMlat afferent fibers were determined by tract-tracing techniques. Following injection of cholera toxin subunit B into the VLMlat, retrogradely labeled neurons in the forebrain occurred at the somatosensory, insular, motor, limbic and infralimbic cortices, and at the central amygdaloid nucleus. Retrogradely labeled neurons in diencephalic regions were observed in the lateral hypothalamus, posterior hypothalamus and paraventricular nucleus. In the brainstem, retrograde labeling occurred at the periaqueductal gray, red nucleus, parabrachial area, nucleus raphe magnus, nucleus tractus solitarii, lateral reticular nucleus and dorsal and ventral medullary reticular formation. In the cerebellum, retrogradely labeled neurons occurred at the lateral nucleus. Following injections of the anterograde tracer biotinylated dextran amine (BDA) into the lateral hypothalamus or paraventricular nucleus, anterogradely labeled fibers were mainly observed in the VLMlat. Injections of BDA into the periaqueductal gray, red nucleus or lateral nucleus of the cerebellum resulted in anterograde labeling in the VLMlat and lateral reticular nucleus.The present study gives an account of the brain regions putatively involved in triggering the modulatory actions elicited from the VLMlat. These include areas committed to somatosensory processing, autonomic control, somatic and visceral motor activity and affective reactions. The findings suggest that the VLMlat may play a major homeostatic role in the integration of nociception with other brain functions.     

Atrial natriuretic polypeptide: topographical distribution in the rat brain by radioimmunoassay and immunohistochemistry

The widespread distribution of neurons containing alpha-atrial natriuretic polypeptide-like immunoreactivity in the rat brain was demonstrated using radioimmunoassay and immunohistochemistry in conjunction with specific antisera. The highest concentrations of alpha-atrial natriuretic polypeptide-like immunoreactivity were in the hypothalamus and septum, with low but still appreciable concentrations in the mesencephalon, cerebral cortex, olfactory bulb and thalamus by radioimmunoassay. Immunohistochemical studies clearly showed that the perikarya of immunoreactive neurons are most prevalent in the ventral part of the lateral septal nucleus, periventricular preoptic nucleus, bed nucleus of the stria terminalis, periventricular and dorsal parts of the paraventricular hypothalamic nucleus, ventromedial nucleus, dorsomedial nucleus, arcuate nucleus, median mamillary nucleus, supramamillary nucleus, zona incerta, medial habenular nucleus and the periaqueductal grey matter. Scattered neurons were seen in the cingulate cortex, endopiriform nucleus, lateral hypothalamic area, and pretectal and dorsal thalamic areas. In addition to the areas mentioned above, high concentrations of immunoreactive varicose fibers were seen in the glomerular layer of the olfactory bulb, external layer of the median eminence, central to paramedian parts of the interpeduncular nucleus and the paraventricular hypothalamic nucleus. The globus pallidus, medial and central amygdaloid nuclei, dorsal raphe, dorsal parabrachial nucleus, locus coeruleus, vagal dorsal motor nucleus, solitary nucleus and some circumventricular organs, including the subfornical organ and organum vasculosum laminae terminalis, contained considerable numbers of immunoreactive varicose fibers. In dehydrated rats and homozygous Brattleboro rats, the pattern of alpha-atrial natriuretic polypeptide-immunoreactive neurons and varicose fibers was qualitatively similar to that seen in normal conditioned rats. This study gives an atlas of the distribution of the alpha-atrial natriuretic polypeptide-containing neuronal system in the rat brain and provides the groundwork for studying the influence of this new peptide on various brain functions.     

New data on the immunocytochemical localization of thyrotropin-releasing hormone in the rat central nervous system

An antiserum raised against the synthetic tripeptide pyroglutamyl-histidyl-proline (free acid) was used to localize thyrotropin-releasing hormone (TRH) in the rat central nervous system (CNS) by immunocytochemistry. The distribution of TRH-immunoreactive structures was similar to that reported earlier; i.e., most of the TRH-containing perikarya were located in the parvicellular part of the hypothalamic paraventricular nucleus, the suprachiasmatic portion of the preoptic nucleus, the dorsomedial nucleus, the lateral basal hypothalamus, and the raphe nuclei. Several new locations for TRH-immunoreactive neurons were also observed, including the glomerular layer of the olfactory bulb, the anterior olfactory nuclei, the diagonal band of Broca, the septal nuclei, the sexually dimorphic nucleus of the preoptic area, the reticular thalamic nucleus, the lateral reticular nucleus of the medulla oblongata, and the central gray matter of the mesencephalon. Immunoreactive fibers were seen in the median eminence, the organum vasculosum of the lamina terminalis, the lateral septal nucleus, the medial habenula, the dorsal and ventral parabrachial nuclei, the nucleus of the solitary tract, around the motor nuclei of the cranial nerves, the dorsal vagal complex, and in the reticular formation of the brainstem. In the spinal cord, no immunoreactive perikarya were observed. Immunoreactive processes were present in the lateral funiculus of the white matter and in laminae V-X in the gray matter. Dense terminal-like structures were seen around spinal motor neurons. The distribution of TRH-immunoreactive structures in the CNS suggests that TRH functions both as a neuroendocrine regulator in the hypothalamus and as a neurotransmitter or neuromodulator throughout the CNS.     

Transneuronal transport of peroxidase-conjugated wheat germ agglutinin (WGA-HRP) from the olfactory epithelium to the brain of the adult rat

Summary The sensory neurons of the olfactory epithelium, as a consequence of their odor detection function, contact both the external environment and the central nervous system. The possibility that substances applied to the epithelium might reach the central nervous system was investigated by the intranasal application of peroxidase-conjugated wheat germ agglutinin (WGA-HRP). WGA-HRP was transported through olfactory receptor axons to the glomerulus of the olfactory bulb. Reaction product was localized electron microscopically to tubulovesicular profiles and dense bodies in sensory axons. Evidence of transneuronal transport was indicated by reaction product localized in dense bodies in dendrites postsynaptic to receptor cell axons. Periglomerular, tufted and mitral cells in the olfactory bulb also were transneuronally labeled. Anterograde transneuronal labeling occured in the olfactory tubercle, piriform cortex and surrounding the lateral olfactory tract. Retrograde transneuronal label was found in neurons of the basal forebrain with the largest number of perikarya in the lateral nucleus of the horizontal limb of the diagonal band, a major source of cholinergic afferents to the olfactory bulb. These data suggest that substances, specifically those which bind to receptors, are transported from the olfactory receptor neurons in the nasal epithelium to the brain. Thus, the olfactory system may provide a route of entry for exogenous substances to the basal forebrain.Abbreviations AC anterior commissure - CC corpus callosum - CI internal capsule - CP caudate putamen - DBB diagonal band of Broca - FX fornix - GP globus pallidus - IC island of Callelae - LV lateral ventricle - MS medial septum - OC optic chiasm - PIR piriform cortex - RF rhinal fissure - SON supraoptic nucleus - SCN suprachiasmatic nucleus - SM stria medullaris - ST stria terminalis - TOL lateral olfactory tract - TUO olfactory tubercle - III third ventricle     

Origin of projections from the midbrain raphe nuclei to the hypothalamic paraventricular nucleus in the rat: A combined retrograde and anterograde tracing study

A number of neuronal functions governed by the hypothalamic paraventricular nucleus are influenced by serotonin, and it is generally believed that the moderate density of serotonin-immunoreactive fibres and terminals within the paraventricular nucleus originates from the midbrain dorsal and median raphe nuclei. To further evaluate the intricate anatomy of projections from brain stem raphe nuclei of the rat, a combination of retrograde and anterograde tracing experiments were conducted to determine the medullary raphe nuclei projection to the paraventricular nucleus. Rhodamine-labelled latex microspheres, Cholera toxin subunit B and FluoroGold we used as retrograde tracers. Intracerebroventricular injections into the third ventricle of all retrograde tracers labelled a distinct population of neurons in the dorsal raphe situated in the subependymal stratum adjacent to the cerebral aqueduct indicating that these cells take up the tracer from the cerebrospinal fluid. Very few retrogradely labelled neurons were seen in the median raphe after i.c.v. administration of the tracers. Retrograde tracers delivered into the medial part of the paraventricular nucleus labelled no further cells in the midbrain dorsal and median raphe nuclei, whereas a substantial number of retrogradely labelled cells emerged in the pontine raphe magnus. However, when the retrograde tracers were delivered into the lateral part of the paraventricular nucleus, avoiding leakage of the tracer into the ventricle, very few labelled neurons were seen in the dorsal and median raphe, whereas the prominent labelling of raphe magnus neurons persisted. The anatomical organization of nerve fibres terminating in the area of paraventricular nucleus originating from midbrain raphe nuclei was studied in a series of anterograde tracing experiments using the plant lectin Phaseolus vulgaris leucoagglutinin. Injections delivered into the dorsal raphe or median raphe labelled but a few fibres in the paraventricular nucleus proper. A high number of fine calibered nerve fibres overlying the ependyma adjacent to the paraventricular nucleus was, however, seen after the injections into the subependymal rostral part of the dorsal raphe. Injections delivered into the raphe magnus gave rise to a dense plexus of terminating fibres in the parvicellular parts of the paraventricular nucleus and moderately innervated the posterior magnocellular part of the paraventricular nucleus as well as the magnocellular supraoptic nucleus. Concomitant visualization of serotonin-immunoreactive neurons and retrograde FluoroGold-tracing from the paraventricular nucleus revealed that none of the serotonergic neurons of the raphe magnus projects to this nucleus, while a few of the neurons putatively projecting to the paraventricular nucleus from the median raphe are serotonergic.

The current observations suggest that the raphe magnus constitute by far the largest raphe input to the paraventricular nucleus and strongly questions the earlier held view that most raphe fibres innervating the paraventricular nucleus are derived from the midbrain dorsal and median raphe. However, the source of serotonergic innervation of the paraventricular nucleus remains elusive.     

Collateralization of periaqueductal gray neurons to forebrain or diencephalon and to the medullary nucleus raphe magnus in the rat.

Antinociceptive effects elicited from the midbrain may involve both ascending and descending projections from the periaqueductal gray and dorsal raphe nucleus. To investigate the relationship between these different efferent pathways in the rat, we performed a double-labeling study using two retrograde tracers, colloidal gold-coupled wheatgerm agglutinin-apo horseradish peroxidase and a fluorescent dye. One tracer was microinjected in the medullary nucleus raphe magnus; the second was injected into one of several regions rostral to the periaqueductal gray that have been implicated in nociceptive and antinociceptive processes. The results can be grouped into two categories. First, injections into the ventrobasal thalamus, lateral hypothalamus, amygdala, and cerebral cortex labeled neurons in the dorsal raphe nucleus but not in the periaqueductal gray. Up to 90% of these projection neurons were serotonin immunoreactive, and up to 17% were also retrogradely labeled from the nucleus raphe magnus. Second, only injections into the ventrobasal hypothalamus (which included the beta-endorphin-containing arcuate neurons) or into the medial thalamus labeled neurons in the periaqueductal gray itself. Injections into the medial thalamus, but not into the ventrobasal hypothalamus, also labeled neurons in the dorsal raphe nucleus. Up to 20% of the neurons retrogradely labeled from these regions were also retrogradely labeled from nucleus raphe magnus. The presence of large populations of rostrally projecting periaqueductal gray neurons that collateralize to the nucleus raphe magnus implies that activity in ascending projections necessarily accompanies any activation of the periaqueductal gray-nucleus raphe magnus pathway. Possibly, projections from the medial thalamus and medial hypothalamus mediate antinociceptive effects that complement descending inhibition. Finally, possible antidromic activation of these pathways must be considered when interpreting the results of electrical brain stimulation studies.     

Localization of glutamatergic/aspartatergic neurons projecting to the hypothalamic paraventricular nucleus studied by retrograde transport of [3H]D-aspartate autoradiography

Morphological and functional data indicate that glutamatergic innervation of the hypothalamic paraventricular nucleus plays an important role in the control of this prominent cell group. Sources of this neural input are unknown. The present investigations were aimed at studying this question. The retrograde tracer [3H]D-aspartate, which is selectively taken up by the terminals of neurons that use glutamate or aspartate as a neurotransmitter, and is retrogradely transported to their perikarya, was injected into the paraventricular nucleus. The brain was examined for labelled neurons visualized by autoradiography. Labelled neurons were detected in the paraventricular nucleus itself, in several hypothalamic areas including medial and lateral preoptic area, suprachiasmatic nucleus, anterior hypothalamic area, ventromedial nucleus, dorsomedial nucleus, lateral hypothalamic area, posterior part of arcuate nucleus, ventral premammillary nucleus and supramammillary nucleus. Outside the hypothalamus labelled neurons were found in the thalamic paraventricular nucleus and in certain telencephalic regions including lateral septum, bed nucleus of the stria terminalis and amygdala. All of them are known to project to the hypothalamic paraventricular nucleus. We failed to detect labelled neurons in the lower brainstem.From these findings we conclude that firstly, there are glutamatergic/aspartatergic interneurons in the paraventricular nucleus; secondly, all intrahypothalamic and telencephalic, but not lower brainstem afferents to this nucleus contain glutamatergic/aspartatergic fibres; and thirdly, the glutamatergic/aspartatergic innervation of this heterogeneous cell group is extremely complex.     

Participation of the olfactory system in the regulation of food intake

Evoked potentials in the olfactory bulb (OB), lateral hypothalamus (HL) and rostral portion of the nucleus of the tractus solitarius (NTS), were recorded after cervical vagus nerve stimulation. The slow component in the OB only was recorded in the periglomerular layer. Electrolytic lesion of the NTS, abolished the evoked potentials in the OB by vagus nerve stimulation. The results of the present experiments indicate that the pathway from the vagus nerve to OB go into the NTS but probably not into the LH.     

Efferent connections of the rostral linear nucleus of the ventral tegmental area in the rat

The ventral tegmental area (VTA) is crucially involved in brain reward, motivated behaviors, and drug addiction. This district is functionally heterogeneous, and studying the connections of its different parts may contribute to clarify the structural basis of intra-VTA functional specializations. Here, the efferents of the rostral linear nucleus (RLi), a midline VTA component, were traced in rats with the Phaseolus vulgaris leucoagglutinin (PHA-L) technique. The results show that the RLi heavily innervates the olfactory tubercle (mainly the polymorph layer) and the ventrolateral part of the ventral pallidum, but largely avoids the accumbens. The RLi also sends substantial projections to the magnocellular preoptic nucleus, lateral hypothalamus, central division of the mediodorsal thalamic nucleus, lateral part of the lateral habenula and supraoculomotor region, and light projections to the prefrontal cortex, basolateral amygdala, and dorsal raphe nucleus. A similar set of projections was observed after injections in rostromedial VTA districts adjacent to RLi, but these districts also send major outputs to the lateral ventral striatum. Overall, the data suggest that the RLi is a distinct VTA component in that it projects primarily to pallidal regions of the olfactory tubercle and to their diencephalic targets, the central division of the mediodorsal thalamic nucleus and the lateral part of the lateral habenula. Because the rat RLi reportedly contains a lower density of dopaminergic neurons as compared with most of the VTA, its unusual projections may reflect a non-dopaminergic, putative GABAergic, phenotype, and this distinctive cell population seemingly extends beyond RLi boundaries into the laterally adjacent VTA. By being connected to the central division of the mediodorsal thalamic nucleus (directly and via ventral striatopallidal system) and to the magnocellular preoptic nucleus, the RLi and its surroundings may play a role in olfactory-guided behaviors, which are part of the approach responses associated with appetitive motivational states.     

Enkephalin innervation of the paraventricular nucleus of the hypothalamus: distribution of fibers and origins of input

The opioid peptide enkephalin emerges as a major neuromodulator in the regulation and integration of the physiologic response in stressful conditions. The paraventricular nucleus of the hypothalamus is a coordinating center of neuroendocrine and autonomic functions. However, the detailed distribution of the enkephalin fibers and terminals in the paraventricular nucleus and the sources of enkephalinergic innervation are not well defined. In the present study, we used immunocytochemistry for the proenkephalin-derived octapeptide met-arg⁶-gly⁷-leu⁸ enkephalin to determine the distribution of enkephalin-immunoreactive fibers and somata within paraventricular nucleus. Without colchicine pretreatment, enkephalinergic fibers were prominent mainly in the ventromedial part of the parvicellular subdivision of the paraventricular nucleus, appearing in coronal sections as a dense collection of short segments of enkephalin-immunoreactive fibers. In the periventricular portion of the paraventricular nucleus, enkephalin-immunoreactive fibers produced a moderate plexus of short enkephalin-immunoreactive fibers dorsoventrally oriented. With colchicine treatment, a dense cluster of enkephalin-immunoreactive cell bodies was located in the dorsomedial and the dorsal parts of the parvicellular subdivisions. These enkephalin-immunoreactive neurons were small (< 10 μm) to medium sized (10–15 μm), with round and elongated shapes. Retrograde transport of wheat germ-conjugated gold particles. WGA-apoHRP-Au, from the paraventricular nucleus, combined with immunocytochemistry for enkephalin revealed that the major sources of extrahypothalamic enkephalin afferents to the paraventricular nucleus are provided by enkephalin neurons neurons in the lateral reticular nucleus and the paragigantocellularis reticular nucleus of the medulla (20% of retrogradely labeled neurons within this nucleus were double labeled) and in the nucleus solitary tract (10% of retrogradely labeled neurons within thisnucleus were double labeled). Retrogradely labeled enkephalin neurons were also observed in the medial preoptic area, median preoptic nucleus, dorsomedial hypothalamic nucleus, lateral septum and hypothalamic arcuate nucleus. These enkephalinergic pathways from the medulla and the forebrain could represent an anatomical substrate underlying the opioid effects on paraventricular neurons during physiological processes, such as a cardiovascular regulation, feeding or stress responses.     

Distribution of dopamine-immunoreactive neuronal perikarya and fibres in the brain of a teleost, Gasterosteus aculeatus L. comparison with tyrosine hydroxylase- and dopamine-beta-hydroxylase-immunoreactive neurons

The distribution of dopamine in the brain of the teleost Gasterosteus aculeatus L. was demonstrated with the indirect peroxidase-antiperoxidase immunohistochemical method using highly specific antibodies against a dopamine-glutaraldehyde-thyroglobulin conjugate. Dopamine-immunoreactive (DAir) neuronal somata were observed in all main brain regions. In the forebrain, DAir neurons were located in a continuous cell column extending from the caudal part of the olfactory bulbs to the preoptic area. The neurons lie lateral to the dorsal (and caudally to the subcommissural) portion of the ventral telencephalic area, and ventromedial to the central nuclei of the dorsal area. In the diencephalon, cerebrospinal fluid-contacting neurons were located in the paraventricular organ and in the subependymal layers of the dorsal and caudal zones of the periventricular hypothalamus. Small DAir neurons were observed in the suprachiasmatic nucleus, in the parvocellular preoptic nucleus and in the ventromedial thalamic nucleus, while large perikarya were observed dorsolateral to the dorsal zone of the periventricular hypothalamus ('PVO-accompanying cells'), in the posterior tuberal nucleus and in the most rostral portion of the mammillary bodies. Numerous small DAir neurons were located in the periventricular pretectal nucleus. In the brainstem, DAir neurons were observed in the isthmus region, in the dorsal raphe nucleus and in the lateral parts of the nucleus of the solitary tract. DAir perikarya were also observed in the area postrema. Direct comparison with the distribution of tyrosine hydroxylase- and dopamine-beta-hydroxylase-immunoreactivity (THir and DBHir) gave the following results: THir neurons were found in all areas where DAir neurons were located, except for the paraventricular organ and the dorsal and caudal zones of the periventricular hypothalamus, which were devoid of THir. DBHir (putatively noradrenergic or adrenergic) neurons were observed in the lateral parts of the nucleus of the solitary tract, and in the isthmus region. The DBHir neurons in the isthmus region, which have previously been shown to be noradrenergic, appeared to be identical with the THir and DAir neurons of the same area. DAir axons were found in high numbers in most parts of the brain. Especially dense innervation was found in the ventrolateral and posterior parts of the dorsal telencephalic area, the region surrounding the lateral recesses of the third ventricle, the interpeduncular nucleus, the dorsal and median raphe nuclei (the rostral raphe nuclei), and in the nucleus of the solitary tract.(ABSTRACT TRUNCATED AT 400 WORDS)     

Sources of subcortical afferents to the macaque's dorsal lateral geniculate nucleus

Background: The dorsal lateral geniculate nucleus (dLGN) is the thalamic region responsible for transmitting retina signals to cortex. Brainstem pathways to this nucleus have been described in several species and are believed to control the retinocortical pathway depending on the state of the animal (awake, asleep, drowsy, etc.). The purpose of this study was to determine all of the subcortical sources of afferents to the dLGN in a higher primate, the macaque monkey, whose visual system is similar to that of humans. Methods: Injections of horseradish peroxidase (HRP), with or without conjugation to wheat germ agglutinin, were made into the dLGNs of seven macaque monkeys, followed by perfusion, brain sectioning, and analyses of neurons in the brainstem, thalamus, and hypothalamus that contained the retrogradely transported marker. Results: The reticular nucleus of the thalamus, pedunculopontine nucleus, parabigeminal nucleus, pretectal nucleus of the optic tract, superior colliculus, dorsal raphe nucleus, and tuberomammillary region of the hypothalamus contained many retrogradely labeled neurons ipsilateral to the injections. In the contralateral brainstem, HRP-labeled cells were found only in the pedunculopontine nucleus, nucleus of the optic tract, and dorsal raphe nucleus. The number of labeled neurons on the contralateral side was about one-half of that in corresponding ipsilateral nuclei. The locus coeruleus contained no labeled neurons in four of the macaques that had injections limited to the dLGN. Conclusion: There are seven subcortical regions that send afferents to the dLGNs of macaque monkeys. Except for the locus coeruleus, these are the same as observed for other species, such as the cat and rat, and indicate the possible sources of subcortical control over the dLGNs of humans. © 1995 Wiley-Liss, Inc.     

Afferents to the median raphe nucleus of the rat: retrograde cholera toxin and wheat germ conjugated horseradish peroxidase tracing, and selective D-[3H]aspartate labelling of possible excitatory amino acid inputs

Afferents to the median-paramedian raphe nuclear complex, which contains the B8 serotonergic cell group, were investigated in the rat with neuroanatomical and transmitter-selective retrograde labelling techniques. Injection of sensitive retrograde tracers, cholera toxin genoid or wheat germ agglutinin conjugated horseradish peroxidase into the median raphe resulted in labelling of neurons in a large number of brain regions. Projections from 26 of these regions are supported by available orthograde tracing data; the cingulate cortex, bed nucleus of stria terminalis, medial septum and diagonal band of Broca, ventral pallidum, medial and lateral preoptic areas, lateral hypothalamus, dorsomedial nucleus of hypothalamus, lateral habenula, interpeduncular nucleus, substantia nigra, central (periaqueductal) gray, and laterodorsal tegmental nucleus seem to represent major sources of afferents to the median-paramedian raphe complex. Retrogradely labelled cells were also observed in a number of regions for which anterograde tracing data are not available, including the perifornical hypothalamic nucleus, ventral premammillary nucleus, supramammillary and submammillothalamic nuclei and the B9 area. Possible excitatory amino acid afferents were identified with retrograde D-[3H]aspartate labelling. Microinjection of D-[3H]aspartate at a low concentration, 10(-4) M in 50 nl, resulted in retrograde labelling of a limited number of median raphe afferents. The most prominent labelling was observed in the lateral habenula and the interpeduncular nucleus, but retrogradely labelled cells were also noted in the medial and lateral preoptic areas, lateral and dorsal hypothalamus, ventral tegmental area, laterodorsal tegmental nucleus, medial parabrachial nucleus, and the pontine tegmentum. After injections of 10(-3) M D-[3H]aspartate selective labelling also appeared in more distant afferent regions, including cells in cingulate cortex, and in some regions located at shorter distances, such as the supramammillary nucleus. Injections of D-[3H]aspartate at high concentration, 10(-2) M, resulted in the appearance of weakly to moderately labelled cells in most afferent areas which were devoid of labelled cells after injections of lower concentrations, suggesting that this labelling may be non-specific. It was concluded that the median-paramedian raphe receives afferents from a large number of forebrain and hypothalamic regions, while relatively few brain stem regions project to this nuclear complex. The selectivity of retrograde labelling with D-[3H]aspartate was found to be concentration dependent, and it is suggested that the connections showing high affinity for D-[3H]aspartate may use excitatory amino acids as transmitters. Excitatory amino acid inputs from lateral habenula and interpeduncular nucleus may play predominant roles in the control of ascending serotonergic and non-serotonergic projections originating in the median and paramedian raphe nuclei.     

大鼠神经系统内5-羟色胺2A受体亚型的免疫组织化学定位

目的：观察大鼠神经系统内5－羟色胺受体2A亚型（5－HT2AR）免疫组织化学染色阳性结构的分布。方法：5－HT2AR特异性抗体的免疫组织化学染色。结果：5－HT2AR阳性细胞体主要分布于嗅球的小球层和僧帽细胞层、海马始层、外侧缰核、丘脑背外侧核、下丘脑室旁核、中脑中央灰质、小脑浦肯野细胞、脑干运动核和感觉神经节等；5－HT2AR阳性纤维和终末主要分面于嗅球的小球层和内丛层、大脑皮质、外侧隔核、杏仁外侧核、丘脑网状核、腹侧顶盖区、桥核、下橄榄及脑干运动核等。结论：5－HT2AR亚型阳性结构广泛分布于大鼠神经系统，它们可能介导5－HT在神经系统中的多种生理功能。     

CNS inputs to the suprachiasmatic nucleus of the rat

The neural circuits that modulate the suprachiasmatic nucleus (SCN) of the rat were studied with the retrograde transneuronal tracer--pseudorabies virus. First-order afferents were also identified using cholera toxin beta subunit. Olfactory processing regions (viz., main olfactory bulb, anterior olfactory nucleus, taenia tecta, endopiriform nucleus, medial amygdaloid nucleus, piriform cortex, and posteriomedial cortical amygdaloid nucleus) were virally labeled. The subfornical organ directly innervates SCN; two other circumventricular organs: organum vasculosum of the lamina terminalis and area postrema provide multisynaptic inputs. Direct limbic afferents arise from lateral septum, bed nucleus of the stria terminalis, amygdalohippocampal zone, and ventral subiculum; multineuronal connections come from the basolateral and basomedial amygdaloid nuclei, ventral hippocampus, amygdalopiriform area, as well as lateral entorhinal, perirhinal, and ectorhinal cortices. Most preoptic regions project directly to SCN. Multisynaptic inputs come from the lateral preoptic region. Hypothalamic inputs originate from the anterior, arcuate, dorsal, dorsomedial, lateral, paraventricular, posterior, periventricular posterior, retrochiasmatic, subparaventricular, ventromedial and tuberomammillary nuclei. Paraventricular thalamic nucleus, intergeniculate leaflet and zona incerta directly innervate SCN. Polyneuronal inputs arise from the subparafascicular parvicellular thalamic nucleus. Brainstem afferents originate from the pretectum, superior colliculus, periaqueductal gray matter, parabrachial nucleus, pedunculopontine nucleus, raphe system, locus coeruleus, nucleus incertus and reticular formation. Nucleus tractus solitarius, C3 catecholamine region, rostral ventrolateral medulla and spinal trigeminal nucleus provide indirect inputs.We propose that the SCN receives feedback primarily from interoceptive systems such as the circumventricular, autonomic, and neuroendocrine systems that are important in the central regulation of glucose metabolism (e.g., insulin and glucocorticoids).     

Age-related change of neuropeptide Y-immunoreactive neurons in the rat anterior olfactory nucleus

Neuropeptide Y (NPY) is located in the olfactory system, including the olfactory bulb, and is thought to be one of the main neurotransmitters for olfaction. Thus, we examined age-related changes of NPY-immunoreactive (IR) neurons in the rat anterior olfactory nucleus (AON) at various aging stages over a period of 2 years; postnatal months 1 (PM 1), PM 6, PM 12 and PM 24. NPY-IR neurons in the AON were present in the lateral and medial subdivisions at PM 1 and at PM 6 were distributed in all subdivisions of the AON. Prior to PM 12, the NPY-IR neurons showed a tendency to change from bipolar cells with short processes into multipolar cells with long processes. Moreover, the population of NPY-IR neurons and nerve fibers in the AON increased in proportion to age. In particular, the number of NPY-IR neurons increased about 6-fold between PM 1 and PM 3. At PM 24, the number of NPY-IR neurons was much smaller than that at PM 12 and somal size had decreased. It is therefore suggested that the dramatic increase in the number and size of the NPY-IR neurons between PM 1 and PM 3 may be associated with sexual maturation and that the decrease in the number and cell size of the NPY-IR neurons at PM 24 may underlie age-related changes in the olfactory process.