Distribution of alpha-neoendorphin immunoreactivity in the diencephalon and the brainstem of the dog.

Alpha-neoendorphin (alpha-NE) is an opiate decapeptide derived from the prodynorphin protein. Its anatomical distribution in the brain of mammals other than the rat, particularly in carnivores, is less well known than for other opiate peptides. In the present work, we have charted the distribution of alpha-NE immunoreactive fibers and perikarya in the diencephalon and the brainstem of the dog. The highest densities of labeled fibers were found in the substantia nigra and in patches within the nucleus of the solitary tract. Moderate densities appeared in the arcuate nucleus (Ar), median eminence, entopeduncular nucleus, ventral tegmental area, retrorubral area, periaqueductal central gray, interpeduncular nucleus and lateral parabrachial nucleus. Groups of numerous labeled perikarya were localized in the magnocellular hypothalamic nuclei, Ar and in the central superior and incertus nuclei in the metencephalon. Moreover, less densely packed fibers and cells appeared widely distributed throughout many nuclei in the region studied. These results are discussed with regard to the pattern described in other species. In addition, the present results were compared with the distribution of met-enkephalin immunoreactivity in the diencephalon and the brainstem of the dog that we have recently described. Although the distributions of these two peptides overlap in many areas, the existence of numerous differences suggest that they form separate opiate systems in the dog.     

Distribution of somatostatin-28 (1–12) immunoreactivity in the diencephalon and the brainstem of the dog

The term somatostatin refers to a family of peptides, mainly somatostatin-14, somatostatin-28 and somatostatin-28 (1–12), which are the cleavage products of a single 116 amino acid-long preprosomatostain molecule. The production of antibodies to these peptides allows their localization in a number of neuronal populations throughout the entire neuroaxis in many mammals. The dog has been pointed out as an extremely useful animal model for studying age-related cognitive dysfunction and other neuronal changes associated with aging in which somatostatin appears to be involved. However, only very scanty information is available with regard to the distribution of somatostatin in the brain of the dog. In the present work we have determined the pattern of the distribution of somatostatin-28 (1–12) immunoreactivity in the diencephalon and the brainstem of the dog. High to moderate densities of labeled perikarya were found in the anterior periventricular and arcuate hypothalamic nuclei, the reticular thalamic nucleus, in delimited parts of the nucleus of the brachium inferior colliculus, the retrorubral area, the dorsal raphe nucleus, the myelencephalic reticular formation and the dorsal motor nucleus of the vagus. Less dense population of somatostatin cells were localized in other diencephalic and brainstem nuclei. The distribution of labeled fibers was even broader as in addition to those above mentioned there were a number of areas that appeared devoid of labeled perikarya. Many of the findings were similar to those reported in earlier works while others underlined the existence of inconsistencies in the distribution pattern of this peptide in the brain of mammals.     

Distribution of somatostatin-28 (1-12) immunoreactivity in the diencephalon and the brainstem of the dog

The term somatostatin refers to a family of peptides, mainly somatostatin-14, somatostatin-28 and somatostatin-28 (1-12), which are the cleavage products of a single 116 amino acid-long preprosomatostain molecule. The production of antibodies to these peptides allows their localization in a number of neuronal populations throughout the entire neuroaxis in many mammals. The dog has been pointed out as an extremely useful animal model for studying age-related cognitive dysfunction and other neuronal changes associated with aging in which somatostatin appears to be involved. However, only very scanty information is available with regard to the distribution of somatostatin in the brain of the dog. In the present work we have determined the pattern of the distribution of somatostatin-28 (1-12) immunoreactivity in the diencephalon and the brainstem of the dog. High to moderate densities of labeled perikarya were found in the anterior periventricular and arcuate hypothalamic nuclei, the reticular thalamic nucleus, in delimited parts of the nucleus of the brachium inferior colliculus, the retrorubral area, the dorsal raphe nucleus, the myelencephalic reticular formation and the dorsal motor nucleus of the vagus. Less dense population of somatostatin cells were localized in other diencephalic and brainstem nuclei. The distribution of labeled fibers was even broader as in addition to those above mentioned there were a number of areas that appeared devoid of labeled perikarya. Many of the findings were similar to those reported in earlier works while others underlined the existence of inconsistencies in the distribution pattern of this peptide in the brain of mammals.     

Distribution of met-enkephalin immunoreactivity in the diencephalon and the brainstem of the dog

The endogenous opioid system, in particular the enkephalins, has been implicated in a vast array of neurological functions. The dog could be a suitable model for the study of complex interactions between behavioral state and regulatory physiology in which the opioid system appeared to be implicated. Moreover, opiate derivatives are currently used in veterinary clinic and sometimes pharmacologically tested in the dog. However, there are no anatomical data regarding the organization of the opioid system in this species. The present work represents the first attempt to map the distribution of Met⁵-enkephalin-like-immunoreactive (Met-enk-li) cell bodies and fibers in the diencephalon and the brainstem of the dog. In the diencephalon, labeled cells were present in all the mid-line and intralaminar thalamic nuclei; the lateral posterior, pulvinar and suprageniculate nuclei; the ventral nucleus of the lateral geniculate body and the medial geniculate body. Additionally, Met-enk-li cells were seen in every hypothalamic nucleus except in the supraoptic. Variable densities of labeled fibers were also seen in all these nuclei except in the medial geniculate body and in most areas of the lateral posterior and pulvinar nuclei. In the mesencephalon, positive cells were found in the periaqueductal gray, the Edinger–Westphal and interpeduncular nuclei, delimited areas of the superior and inferior colliculi and the ventral tegmental area. In the rhombencephalon, labeled cells were seen in the majority of the nuclei in the latero-dorsal pontine tegmentum, the nuclei of the lateral lemniscus, the trapezoid, vestibular medial, vestibular inferior and cochlear nuclei, the prepositus hypoglossal, the nucleus of the solitary tract and the dorsal motor nucleus of the vagus, the infratrigeminal nucleus and the caudal part of the spinal trigeminal nucleus and in the rhombencephalic reticular formation. The distribution of fibers included additionally the substantia nigra, all the trigeminal nerve nuclei, the facial nucleus and a restricted portion of the inferior olive. These results are discussed with regard to previous reports on the distribution of Met-enk in other species.     

Distribution of ACTH immunoreactivity in the diencephalon and the brainstem of the dog

The present work describes for the first time the anatomical distribution of adrenocorticotropic hormone (ACTH) in the diencephalon and the brainstem of the dog by means of the indirect immunoperoxidase technique. The distribution found in this species agrees well with the pattern found in other mammals and particularly confirms much of the findings reported in the cat. An exception to that concordance is the presence of ACTH perikarya in the nucleus of the solitary tract of the dog, a population that has been described in the rat but not in the cat, and in the ventral mesencephalon. This last population spread across the ventral tegmental area from the raphe to the cerebral peduncle and appeared to be a specific feature of the canine brain. On the other hand, we can not see ACTH fibers in the substantia nigra of the dog which could be a characteristic of the domestic carnivores, opposite to rodents, since these fibers appeared to be also lacking in the cat. Nevertheless, the widespread distribution of ACTH fibers in the brain of the dog included many other nuclei containing monoaminergic neurons which supported a possible role for ACTH in the regulation of these neurotransmitter systems.     

The distribution of vasotocin and mesotocin immunoreactivity in the brain of the snake,Bothrops jararaca

Polyclonal antibodies against vasotocin (AVT) and mesotocin (MST) were used to explore the distribution of these peptides in the brain of the snake Bothrops jararaca. Magnocellular AVT- and MST-immunoreactive (ir) perikarya were observed in the supraoptic nucleus (SON), being AVT-ir neurons more numerous. A portion of the SON, in the lateroventral margin of the diencephalon ventrally to optic tract, showed only AVT-ir perikarya and fibers. However, the caudal most portion displayed only mesotocinergic perikarya. Parvocellular and magnocellular AVT- and MST-ir perikarya were present in the paraventricular nucleus (PVN) being AVT-ir fibers more abundant than MST-ir. Vasotocinergic perikarya were also found in a dorsolateral aggregation (DLA) far from the PVN. Mesotocinergic perikarya were also present in the recessus infundibular nucleus and ependyma near to paraventricular organ. Nerve fibers emerging from supraoptic and paraventricular nuclei run along the diencephalic floor, internal zone of the median eminence (ME) to end in the neural lobe. Also a dense network of AVT- and MST-ir fibers was present in the external zone of the ME, close to the vessels of the hypophysial portal system. As a rule, all regions having vasotocinergic and mesotocinergic perikarya also showed immunoreactive fibers. Vasotocinergic and mesotocinergic fibers but not perikarya were found in the lamina terminalis (LT). Moreover AVT-ir fibers were present in the nucleus accumbens and MST-ir fibers in the septum. In mesencephalon and rhombencephalon MST-ir fibers were more numerous than AVT-ir fibers. Vasotocinergic and mesotocinergic fibers in extrahypothalamic areas suggest that these peptides could function as neurotransmitters and/or neuromodulators in the snake B. jararaca.     

Immunohistochemical mapping of pro-opiomelanocortin- and pro-dynorphin-derived peptides in the alpaca (Lama pacos) diencephalon

Using an indirect immunoperoxidase technique, we studied the distribution of cell bodies and fibres containing non-opioid peptides (adrenocorticotropin hormone (ACTH), alpha-melanocyte-stimulating hormone) and opioid peptides (beta-endorphin (1–27), alpha-neo-endorphin, leucine-enkephalin) in the alpaca diencephalon. No immunoreactive cell bodies containing ACTH were found. Perikarya containing the other four peptides were observed exclusively in the hypothalamus and their distribution was restricted. Perikarya containing alpha-melanocyte-stimulating hormone or alpha-neo-endorphin showed a more widespread distribution than those containing leucine-enkephalin or beta-endorphin (1–27). Cell bodies containing pro-opiomelanocortin-derived peptides were observed in the arcuate nucleus, anterior and lateral hypothalamic areas and in the ventromedial and supraoptic hypothalamic nuclei, whereas perikarya containing alpha-neo-endorphin (a pro-dynorphin-derived peptide) were found in the arcuate nucleus, dorsal and lateral hypothalamic areas, and in the paraventricular, ventromedial and supraoptic hypothalamic nuclei. Immunoreactive cell bodies containing leucine-enkephalin were found in the lateral hypothalamic area and in the paraventricular hypothalamic nucleus. Immunoreactive fibres expressing pro-opiomelanocortin-derived peptides were more numerous than those expressing pro-dynorphin-derived peptides. A close anatomical relationship was observed: in all the diencephalic nuclei in which beta-endorphin (1–27)-immunoreactive fibres were found, fibres containing alpha-melanocyte-stimulating hormone or alpha-neo-endorphin were also observed. Fibres containing beta-endorphin (1–27), alpha-melanocyte-stimulating hormone or alpha-neo-endorphin were widely distributed throughout the diencephalon, but fibres containing ACTH or leucine-enkephalin showed a moderate distribution. The distribution of the five peptides studied here is also compared with that reported previously in other mammalian species. The widespread distribution observed indicates that both the pro-dynorphin and the pro-opiomelanocortin systems are involved in multiple physiological actions (e.g., food intake, thermoregulation, neuroendocrine and reproductive mechanisms) in the alpaca diencephalon.     

Distributions and colocalization of neuropeptide Y and somatostatin in the goldfish brain.

The distributions of single- and double-labelled neuropeptide Y- (NPY-) and somatostatin-immunoreactive (SOM-IR) perikarya and processes were determined in the goldfish brain using immunoperoxidase and immunofluorescence techniques, respectively. In double-labelled material, it was evident that although these two peptides showed markedly similar distributions, they were colocalized in very few instances. A high degree of colocalization of NPY and SOM was noted in the neurons of the ventrolateral telencephalon (VI), the entopenduncular nucleus (NE) and, to a lesser extent, in the dorsocentral nucleus of the telencephalon (Dc). In Vl and NE, neurons showing NPY-IR displayed SOM-IR and vice versa. The only other instance of colocalization was that noted in the brainstem, where SOM and NPY were colocalized in the large cell bodies of the medial column of the vagal motor complex. Single-labelled SOM- and NPY-IR neurons shared a very similar distribution in various nuclei in the diencephalon and in the optic tectum. Colocalization was also noted within fibers throughout many nuclei of the telencephalon and within fibers innervating the swim bladder, one of the peripheral organs to which neurons of the medial column of the vagal motor complex project. Processes in the torus semicircularis and vagal lobe showed single-labelled immunoreactivity for both SOM and NPY in distinct laminar patterns. Large single-labelled SOM-IR terminals appeared to form pericellular baskets in the eminentia granularis of the cerebellum. Single-labelled NPY- or SOM-IR fibers were also found in the secondary gustatory nucleus and tract, the facial lobe, descending trigeminal tract, reticular formation and spinal cord. As in mammalian species, select groups of neurons in teleosts colocalize the neuropeptides SOM and NPY.     

Distribution of atrial natriuretic factor-like immunoreactive neurons in the rat brain

Using antisera generated in rabbits against rat atriopeptin III [alpha-rANP(5-28)] and human alpha-atrial natriuretic polypeptide we mapped the distribution of atrial natriuretic factor-like immunoreactivity throughout the rat central nervous system. Cell bodies were observed in the telencephalon (nucleus interstitialis striae terminalis and between the amygdala centralis and medialis), throughout the diencephalon in all nuclei of the "anteroventral third ventricle", the base of the hypothalamus, the subzona incerta area, the medial forebrain bundle and the medial habenula, in the mesencephalon (mamillary body, substantia nigra lateralis, dorsal and ventral parabrachial nuclei) and very sparse in the medulla oblongata along the fourth ventricle towards the vestibular nuclei, the nucleus tractus solitarii and nervi trigemini. Fibers were present wherever cell bodies were located. The highest relative densities were observed in the anteroventral third ventricle area and the medial habenula. Sparse fibers were also seen in the spinal cord (dorsal and ventral horn and around the central canal) and in the posterior pituitary. The predominance of the atrial natriuretic factor-like perikarya and fibers in the anteroventral third ventricle area suggests an involvement of this peptide in central blood pressure control.     

Somatostatin and leu-enkephalin in the rat auditory brainstem during fetal and postnatal development

A transient expression of the neuropeptide somatostatin has been described in several brain areas during early ontogeny and several opioid peptides, such as leu-enkephalin, have also been found in the brain at this stage in development. It is therefore believed that somatostatin and leu-enkephalin may play a role in neural maturation. The aim of the present study was to describe the spatiotemporal pattern of somatostain and leu-enkephalin immunoreactivity in the auditory brainstem nuclei of the developing rat and to correlate it with other developmental events. In order to achieve this goal, we applied peroxidase-antiperoxidase immunocytochemistry to rat brains between embryonic day (E) 17 and adulthood. Somatostatin immunoreactivity (SIR) was found in all nuclei of the auditory brainstem, yet it was temporally restricted in most nuclei. SIR appeared prenatally and reached maximum levels around postnatal day (P) 7, when great numbers of immunoreactive neurons were present in the ventral cochlear nucleus (VCN) and in the lateral lemniscus. At that time relatively low numbers of cells were labeled in the dorsal cochlear nucleus, the lateral superior olive (LSO), and the inferior colliculus (IC). During the same period, when somata in the VCN were somatostatin-immunoreactive (SIR), a dense network of labeled fibers was also present in the LSO, the medial superior olive (MSO), and the medial nucleus of the trapezoid body (MNTB). As these nuclei receive direct input from VCN neurons, and as the distribution and morphology of the somatostatinergic fibers in the superior olivary complex (SOC) was like that of axons from VCN neurons, these findings suggest a transient somatostatinergic connection within the auditory system. Aside from the LSO, MSO, and MNTB, labeled fibers were found to a smaller extent in all other auditory brainstem nuclei. After P7, the SIR decreased and only a few immunoreactive elements were found in the adult auditory brainstem nuclei, indicating that somatostatin is transiently expressed in the rat auditory brainstem. Leu-enkephalin immunoreactivity showed a lower number and weaker intensity of labeled structures as compared to SIR, with E18 being the earliest day at which labeled fibers appeared in the SOC. At birth, immunoreactive fibers were also present in the cochlear nuclear complex and in the IC. Leu-enkephalin immunoreactive somata were found only after P12 in the CN and after P16 in the IC. Leu-enkephalin immunoreactivity was not transient, but increased progressively with age until about P21, when the adult levels were reached. Our results demonstrate somatostatinergic and leu-enkephalinergic inputs onto auditory brainstem neurons during perinatal life, i.e., during a period when the processes of synapse maturation occur. It is thus likely that both neuropeptides may influence the development of synaptic connections in the auditory brainstem.     

Comparative distribution of NADPH-diaphorase activity and tyrosine hydroxylase immunoreactivity in the diencephalon and mesencephalon of the domestic chicken (Gallus domesticus)

We described the distribution of NADPH-diaphorase-containing neurons in relation to tyrosine hydroxylase immunoreactivity in the diencephalon and mesencephalon of the chicken. In the diencephalon, both markers were found in the lateral hypothalamus, dorsal hypothalamic area, hypothalamic periventricular nucleus, paraventricular nucleus and mamillary area. A close examination showed that the fine distribution of these markers differed slightly, so that they were never observed in the same neurons. In the mesencephalon, NADPH-diaphorase and tyrosine hydroxylase immunoreactivity were found in the ventral pedunculopontine area (nucleus tegmenti pedunculopontinus pars compacta, adjacent areas surrounding the quintofrontal tract and the nucleus mesencephalicus profundus ventralis), the coeruleus complex (locus coeruleus, ventral and dorsal subcoeruleus nuclei), the ventral tegmental area and the central gray. The majority of these neurons contained either diaphorase or tyrosine hydroxylase. Nevertheless, in a few cases both markers appeared to colocalize in the same neuron, typically in large perikarya of the ventral pedunculopontine area.     

Immunohistochemical mapping of neurophysins and calcitonin gene-related peptide in the human brainstem and cervical spinal cord

Our study investigates the distribution of neurophysins (Nph), proteins that are part of the precursors for vasopressin and oxytocin, and calcitonin gene-related peptide (CGRP) in the human brainstem by immunohistochemistry. Both peptides were found in discrete regions of the human hindbrain. Nph could be demonstrated exclusively in fibers and punctate perineural varicosities that were travelling within the mesencephalic central gray, substantia nigra, as well as locus coeruleus, medial longitudinal fascicle, raphe, nucleus of the solitary tract, lateral reticular nucleus and area postrema. A few varicosities were seen in the substantia gelatinosa of the spinal trigeminal tract and its continuation into the dorsal horn of the cervical spinal cord. In contrast to these observations. CGRP-immunoreactive fibers were found to be densest in the spinal tract of the trigeminal nerve and the dorsal horn of the spinal cord. In addition, fibers and varicosities could be demonstrated in numerous distinct brain regions, such as locus coeruleus and subcoeruleus, solitary tract, cuneate nucleus, raphe and periaqueductal gray. CGRP-immunoreactivity was also present in perikarya in the ventral horn of the spinal cord, as well as motor nuclei of cranial nerves, i.e., hypoglossal nucleus, ambiguous nucleus. Our results suggest that Nph-immunoreactivity in the human brainstem may be present predominantly within long fiber projections from hypothalamic neurosecretory nuclei, in analogy to data obtained from rodents, whereas CGRP may play a role in the branchiomotor system as well as in intrinsic or extrinsic projections involved in autonomic regulation and integration of sensory information.     

The immunohistochemical localization of neuronal nitric oxide synthase in the basal forebrain of the dog

The present work describes for the first time the anatomical distribution of neuronal nitric oxide synthase (nNOS) immunoreactivity and NADPH-d activity in the basal forebrain of the dog. As in other species, small, intensely nNOS-immunoreactive cells were seen within the olfactory tubercle, caudate nucleus, putamen, nucleus accumbens and amygdala. In addition, a population of mixed large and small nNOS positive cells was found in the medial septum, diagonal band and nucleus basalis overlapping the distribution of the magnocellular cholinergic system of the basal forebrain. Our results show that the distribution of NOS containing neurons in these nuclei in the dog is more extensive and uniform than that reported in rodents and primates. When double labeling of nNOS and NADPH-d was performed in the same tissue section most neurons were double labeled. However, a considerable number of large perikarya in the diagonal band and nucleus basalis appeared to be single labeled for nNOS. Thought a certain degree of interference between the two procedures could not be completely excluded, these findings suggest that NADPH-d histochemistry, which is frequently used to show the presence of NOS, underestimates the potential of basal forebrains neurons to produce nitric oxide. In addition, a few neurons mainly localized among the fibers of the internal capsule, appeared to be labeled only for NADPH-d. These neurons could be expressing a different isoform of NOS, not recognized by our anti-nNOS antibody, as has been reported in healthy humans and AD patients.     

胆碱能神经成分在猫下脑干感觉系统中的分布

本文用avidin—biotin免疫细胞化学方法和AEC呈色法对ChAT样神经元胞体和纤维在猫下脑干各感觉系统的分布进行了观察。在薄束核、楔束核、外侧楔核和三叉神经感觉核群发现丰富的ChAT样阳性纤维;在三叉神经脊束核尾侧亚核深层偶见ChAT样阳性胞体。孤束核内有少量散在的ChAT样胞体和纤维;而臂旁核则存在丰富的ChAT样阳性胞体。在上橄榄核、斜方体核、外侧丘系核、前庭内侧核和前庭上核观察到多少不等的ChAT样阳性胞体和纤维;在耳蜗核、下丘见到较多的ChAT样纤维。二叠体旁核有大量的ChAT样胞体;上丘含有ChAT样纤维。上述胆碱能神经元,根据ChAT免疫反应可分为两种,一种胞体中等大小,免疫反应染色较深,突起显示较长;另一种胞体小,免疫反应染色浅,胞起显示短。以上观察说明各感觉传导系中的胆碱能纤维,一部分可能来自各自的胆碱能中间神经元,一部分可能来自其他部位。本研究尚未发现ACh直接参与各感觉传导的证据,因此ACh对各感觉传导路可能只起调节作用。     

Nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase activity in the brain of a cichlid fish, with remarkable findings in the entopeduncular nucleus: a histochemical study

In the entire brain of the African cichlid fish, Haplochromis burtoni, nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) activity was visualized histochemically in fewer nuclei compared to other teleost fish. Intensively labeled perikarya were found in the ventral hypothalamic area, the nucleus of the medial longitudinal fascicle, the nucleus of the midbrain tegmentum, the nucleus of the lateral longitudinal fascicle, the trigeminal motor nucleus and the octavolateral area. Compared to other NADPH-d labeled nuclei in the brain, we saw an unusual localization of NADPH-d activity in the rostral, dorsal, ventral and caudal part of the entopeduncular nucleus. Additionally, some isolated perikarya of different morphological appearance were found at the levels of the preglomerular nucleus, the diffuse nucleus of the lateral torus and the lateral longitudinal fascicle. A widespread distribution of labeled fibers was identified throughout the brain. The remarkable NADPH-d activity, particularly in the entopeduncular nucleus, differs significantly from the existing data on other teleosts. Taking into account the sensory functions of the entopeduncular nucleus described in other vertebrates, the massive NADPH-d activity in this nucleus may indicate an important role of NADPH-d in the modulation of sensory functions.     

Central serotonergic projections to the nucleus tractus solitarii: evidence from a double labeling study in the rat

Projections from several brainstem serotonergic nuclei to the nucleus tractus solitarii were investigated in the rat. Experiments were performed using a double labeling method combining retrograde radioautographic tracing and serotonin immunohistochemistry. After injection of the radioactive tracer ([3H] wheat germ agglutinin) into the lateral nucleus tractus solitarii, nerve cell bodies exhibiting both radioautographic labeling and immunostaining were detected in all the serotonergic nuclei investigated, namely the nucleus raphe magnus, the ventromedial paragigantocellular nucleus, the nuclei raphe pontis, medianus and dorsalis, the medial lemniscus and the reticulotegmental nucleus of the pons. Most of the double labeled perikarya observed were in the nucleus raphe magnus, the adjacent part of the paragigantocellular nucleus and the nucleus raphe dorsalis. Nerve cell bodies retrogradely labeled but devoid of immunostaining were also observed, together with the double labeled perikarya, within serotonergic nuclei. These results provide direct evidence that brainstem serotonergic neurons contribute to the innervation of the nucleus tractus solitarii. They indicate that the nucleus raphe magnus and the nucleus raphe dorsalis constitute two major sources of central serotonergic projections to the nucleus tractus solitarii.     

Distribution of dopamine-immunoreactive fibers in the rat brainstem

We describe the distribution of axons immunoreactive for dopamine in pons and medulla oblongata of rat under normal conditions or after inhibition of monoamine oxidase or dopamine beta-hydroxylase. In the pons of non-treated animal, fairly dense plexuses of dopamine-immunoreactive varicose fibers were found in the locus coeruleus, dorsal parabrachial and dorsal raphe nuclei, central gray and reticular formation dorsal to the superior olive. In the medulla oblongata, the immunoreactive fibers were abundant in the dorsal vagal complex, lateral paragigantocellular nucleus, midline raphe nuclei and spinal trigeminal nucleus. Monoamine oxidase inhibition made it possible to increase the intensity of immunoreactivity and consequently the number of labeled fibers in these areas, indicating that dopamine is perpetually oxidized by monoamine oxidase, and consequently in low concentration under normal conditions. Sparse dopamine-immunoreactive fibers were observed in the pontine gray, motor trigeminal nucleus, inferior olive and major axon bundles such as the dorsal and ventral tegmental bundles, where numerous noradrenergic fibers have been reported. In axons of these areas, intense dopamine-immunoreactivity was seen only after inhibition of dopamine-beta-hydroxylase. It appears that dopamine is released and oxidized in response to autonomic changes such as hypoxia, hemorrhage, and cardiovascular variation in the caudal brainstem, as we have described elsewhere.     

Neurotensin receptors in the human amygdaloid complex. Topographical and quantitative autoradiographic study

The distribution of high affinity ¹²⁵I-neurotensin (NT) binding sites were investigated in the amygdaloid complex of adult humans by means of dry film and emulsion autoradiography. Autoradiograms were analysed quantitatively using [¹²⁵I] standards and an image analyser system, and data obtained were converted to nCi of ligand bound per mg tissue. High densities of ¹²⁵I-NT binding sites were found in the following amygdaloid structures: the dorsal part of the accessory basal nucleus, the medial part of the cortical nucleus, the lateral subdivision of the central nucleus, the paralaminar nucleus, the amygdalohippocampal transition area and the rostral portions of the anterior amygdaloid area. The ventral part of the accessory basal nucleus, the intercalated cell groups and the remaining parts of the anterior amygdaloid area showed moderate density of NT binding sites, while the medial, basal and lateral amygdaloid nuclei, the lateral part of the cortical nucleus, the medial subdivision of the central nucleus, as well basal and lateral amygdaloid nuclei, the lateral part of the cortical nucleus, the medial subdivision of the central nucleus, as well as the corticoamygdaloid transition area exhibited low densities of ¹²⁵I-NT binding sites. At microscopic level, silver grains appeared more or less evenly distributed over both neuronal perikarya and the surrounding neuropil. In comparison to NT-immunoreactivity, NT receptors showed mismatching distribution throughout most parts of the amygdala, with the exception of the lateral subdivision of the central nucleus, where NT-immunoreactive perikarya and nerve fibers as well as ¹²⁵I-NT binding sites were found in high density.     

Distribution of serotonin in the brain of the Senegalese sole, Solea senegalensis: an immunohistochemical study

We report the distribution of serotonin immunoreactive (5-HT-ir) structures in the brain of the adult Senegalese sole, Solea senegalensis, using the streptavidin-biotin-peroxidase complex immunohistochemical method. We have found a wide distribution of immunoreactive fibers throughout the entire brain. 5-HT-ir cell bodies appeared restricted to some periventricular nuclei associated with the diencephalic recesses, and in the rhombencephalic reticular formation and inferior olivary region. Specifically, cerebrospinal fluid-contacting serotoninergic cells were found within the pars dorsalis and pars ventralis of the nucleus recessus lateralis, in the paraventricular organ and in the nucleus recessus posterioris. In the brainstem, 5-HT-ir perikarya appear within the superior and inferior raphe, the nucleus reticularis superioris, the nucleus interpeduncularis and the inferior olive. Although positive fibers were not found in the neurohypophysis, a few 5-HT-ir cells were identified in the adenohypophysis. This distribution is compared with those found in other fishes and discussed in the context of putative roles of 5-HT as a neuroendocrine factor and neurotransmitter in the Senegalese sole.     

Somatostatin 28 and neuropeptide Y innervation in the septal area and related cortical and subcortical structures of the human brain. Distribution, relationships and evidence for differential coexistence

Somatostatin 28- and neuropeptide Y-containing innervations were mapped in the human medial forebrain (eight control brains) with immunohistochemistry, using the sensitive avidin-biotin-peroxidase method. Peptidergic perikarya and fibers had an extensive distribution: they were densest in the ventral striatum (nucleus accumbens, olfactory tubercle and bed nucleus of the stria terminalis) and infralimbic cortex, of intermediate density in the medial septal area and of lowest density in the dorsal and caudal lateral septal nucleus. Somatostatin-like immunoreactive perikarya and fibers were generally more numerous than the neuropeptide Y-like immunoreactive ones, but more faintly labeled. Their pattern of distribution was strikingly similar in some of the limbic structures studied but clearly distinct in others. Excellent overlap of neuropeptide Y and somatostatin-like immunoreactivity was detected in: (1) the medial septal area, where innervation occasionally formed perivascular clusters; (2) the nucleus accumbens and olfactory tubercle, characterized by dense patchy innervation; and (3) the laterodorsal septal nucleus, scarcely innervated. In the latter structures, most peptidergic neurons were double-labeled. On the other hand, both peptidergic innervations clearly differed in the lateroventral septal nucleus and the bed nucleus of the stria terminalis which contained distinct clusters of somatostatin-like immunoreactive neurons devoid of neuropeptide Y-like immunoreactivity. Also, the perineuronal and peridendritic axonal plexuses ('woolly fibers') present in these structures were only labeled with somatostatin. In the infralimbic cortex, the relation between the peptides varied according to the cortical laminae. Coexistence of somatostatin and neuropeptide Y frequently occurred in layer VI and in the subcortical white matter, whereas layer V and particularly layers II and III contained a contingent of neurons labeled only with somatostatin. Dense horizontal terminal networks in layers I and VI however were similar for both peptides. These findings support the existence of two different types of somatostatin-like immunoreactive perikarya as regards colocalization with neuropeptide Y. Their particular topographical segregation within the cortical and subcortical structures analysed suggest that they could have different connections and functional properties.(ABSTRACT TRUNCATED AT 400 WORDS)