The organization of serotonin-immunoreactive neuronal systems in the brain of the crested newt,Triturus cristatus carnifex Laur.

Summary The distribution of serotonin (5-HT) immunoreactive structures has been investigated in the brain of the crested newt by means of indirect immunofluorescence, and unlabeled antibody peroxidase-antiperoxidase-complex (PAP) or biotin-avidin-system (BAS) techniques. In the newt, the bulk of the serotoninergic system extends from the raphe region of the medulla oblongata, through the isthmus, toward the mesencephalic tegmentum, and is characterized by pyriform neurons mainly located in a subependymal position, close to the midline. Also in the caudal hypothalamus, in addition to some 5-HT-positive adenohypophysial cells, many immunoreactive CSF-contacting neurons are found lining the paraventricular organ and the nucleus infundibularis dorsalis. A rich serotoninergic innervation was observed in the preoptic area and in the habenular complex. Concerning the telencephalon, immunopositive nerve fibers are encountered in the dorsal pallium, primordium hippocampi, striatum and olfactory bulbs. The general organization of serotoninergic systems in the newt brain exhibit close similarities to that described in higher vertebrates.     

Cerebrospinal fluid-contacting neurons in the paraventricular organ and in the spinal cord of the quail embryo: a fluorescence-histochemical study

Although the cerebrospinal fluid-contacting neurons of the avian paraventricular organ exhibit considerable amounts of catecholamines, they show no tyrosine hydroxylase immunoreactivity. In the quail embryo, the development of these neurons has been studied using the paraformaldeyde-glutaraldeyde method for the fluorescence-histochemical localization of catecholamines. The timing of the appearance of catecholamine fluorescence in cerebrospinal fluid-contacting neurons and that in catecholamine-containing neurons of the brainstem have been compared. The first neurons displaying catecholamine fluorescence are found within the locus coeruleus and the nucleus subcoeruleus ventralis on the 5.5th day of incubation. Catecholaminergic neuronal groups of the medulla and mesencephalon can be identified by embryonic day 7, and fluorescent cerebrospinal fluid-contacting neurons of the hypothalamic paraventricular organ can be first recognized at the 8th day of incubation. If the catecholamine content of cerebrospinal fluid-contacting neurons that lack tyrosine hydroxylase depends upon an uptake mechanism, it may be significant that, in fluorescence-histochemical preparations, these neurons can be identified 1–3 days later than those in which catecholamines are synthesized and from which catecholamines are released at an earlier developmental stage. Moreover, cerebrospinal fluid-contacting neurons that have previously been shown to be tyrosine-hydroxylase immunoreactive, and that lie at the spinal-medullary junction display a different developmental pattern. By fluorescence histochemistry, they can be detected only by embryonic day 10.5. The chemical, developmental and topographical differences suggest that the catecholamine-containing cerebrospinal fluid-contacting elements of the paraventricular organ and those of the spinal cord represent two different subsets of cerebrospinal fluid-contacting neurons whose respective functional roles remain to be investigated.     

The nucleus raphe dorsalis of the rat and its projection upon the caudatoputamen. A combined cytoarchitectonic, immunohistochemical and retrograde transport study

The nucleus raphe dorsalis of the albino rat has been studied in the following three ways: (1) the cell mass was subjected to a detailed cytoarchitectonic analysis, based upon Nissl-stained material; (2) serotonin--as well as the noradrenaline--immunoreactive neurons present in the area of the nucleus raphe dorsalis were plotted; (3) following large injections of the fluorescent dye propidium iodide into the caudatoputamen complex, the cells in the nucleus raphe dorsalis projecting to this complex were labeled and subsequently stained with an antibody against serotonin. Cytoarchitectonic analysis showed that three cell types are present within the confines of the nucleus raphe dorsalis: small, medium and large. Moreover, differences in concentrations of cell bodies made it possible to subdivide the nucleus raphe dorsalis into four regions. Immunohistochemical analysis showed that the borders of the serotoninergic cell groups B6 and B7 of DAHLSTROM and FUXE do not coincide with those of the nucleus raphe dorsalis. Serotonin-immunoreactive perikarya in the nucleus raphe dorsalis were categorized as medium and large neurons; noradrenaline-immunoreactive neurons in the nucleus raphe dorsalis do all belong to the category--large neurons. With the combined use of immunofluorescence and fluorescent retrograde tracing, it was found that the projection from the nucleus raphe dorsalis to the caudatoputamen complex originates from serotoninergic as well as non-serotoninergic cells, both of which can be categorized as being medium-sized neurons. The data presented in this paper provides a guide for further studies of afferent and efferent connections of the nucleus raphe dorsalis and for electrophysiological experiments on its constituent neurons.     

Galanin-like immunoreactivity in the chicken brain

The anatomical distribution of neurons containing galanin has been studied in the central nervous system of the chicken by means of immunocytochemistry using antisera against rat galanin. Major populations of immunostained perikarya were detected in several brain areas. The majority of galanin-immunoreactive cell bodies was present in the hypothalamus and in the caudal brainstem. Extensive groups of labeled perikarya were found in the paraventricular, periventricular, dorsomedial and tuberal hypothalamic nuclei, and in the nucleus of the solitary tract in the medulla oblongata. In the telencephalon, immunoreactive perikarya were observed in the preoptic area, in the lateral septal nucleus and in the hippocampus. The mesencephalon contained only a few galanin-positive perikarya located in the interpeduncular nucleus. Immunoreactive nerve fibers of varying density were detected in all subdivisions of the brain. Dense accumulations of galanin-positive fibers were seen in the preoptic area, periventricular region of the diencephalon, the ventral hypothalamus, the median eminence, the central gray of the brainstem, and the dorsomedial caudal medulla. The distributional pattern of galanin-immunoreactive neurons suggests a possible involvement of a galanin-like peptide in several neuroregulatory mechanisms.     

Colocalization of neuropeptide Y (NPY)-like and FMRFamide-like immunoreactivities in the brain of the Atlantic salmon (Salmo salar)

Summary The colocalization of the peptides neuropeptide Y (NPY) and Phe-Met-Arg-Phe-NH₂ (FMRFamide) in the brain of the Atlantic salmon was investigated with double immunofluorescence labeling and peroxidase-antiperoxidase immunocytochemical techniques. Colocalization of NPY-like and FMRE amide-like immunoreactivities was observed in neuronal cell bodies and fibers in four brain regions: in the lateral and commissural nuclei of the area ventralis telencephali, in the nucleus ventromedialis thalami, in the laminar nucleus of the mesencephalic tegmentum, and in a group of small neurons situated among the large catecholaminergic neurons in the isthmal region of the brainstem. All cell bodies in these nuclei were immunoreactive to both NPY and FMRF. We consistently observed larger numbers of FMRF-immunoreactive than NPY-immunoreactive fibers. In the nucleus ventromedialis thalami NPY- and FMRFamide-like immunoreactivities were colocalized in cerebrospinal fluid (CSF)-contacting neurons. NPY-immunoreactive, but not FMRF-immunoreactive, neurons were found in the stratum periventriculare of the optic tectum, and at the ventral border of the nucleus habenularis (adjacent to the nucleus dorsolateralis thalami). Neurons belonging to the nucleus of the nervus terminalis were FMRF-immunoreactive but not NPY-immunoreactive. The differential labeling indicates, as do our cross-absorption experiments, that the NPY and FMRFamide antisera recognize different epitopes. Thus, it is probable that NPY-like and FMRFamide-like substances occur in the same neurons in some brain regions.     

大鼠延髓网状背侧亚核内5-羟色胺能、P物质样和脑啡肽样阳性终末的中枢起源

研究用荧光金（ＦＧ）逆行追踪与免疫荧光组化染色相结合的双标技术对大鼠脑干向延髓网状背侧亚核（ＳＲＤ）的５┐羟色胺（５┐ＨＴ）能、Ｐ物质（ＳＰ）能和亮氨酸┐脑啡肽（Ｌ┐ＥＮＫ）能投射进行了观察。将ＦＧ注入ＳＲＤ后,ＦＧ逆标神经元主要见于中脑导水管周围灰质、脑干中缝核簇（中缝背核、中缝正中核、中缝桥核、中缝大核、中缝隐核和中缝苍白核）、巨细胞网状核α部、延髓网状结构的内侧部和外侧部、延髓外侧网状核、三叉神经脊束核尾侧亚核和孤束核。５┐羟色胺（５┐ＨＴ）样、Ｐ物质（ＳＰ）样和亮氨酸脑啡肽（Ｌ┐ＥＮＫ）样阳性神经元主要见于中脑导水管周围灰质、脑干中缝核簇和巨细胞网状核α部;此外,ＳＰ样和Ｌ┐ＥＮＫ样阳性神经元还见于臂旁核、背外侧被盖核和孤束核。ＦＧ逆标并呈５┐ＨＴ样、ＳＰ样或Ｌ┐ＥＮＫ样阳性的双标神经元也主要见于中脑导水管周围灰质、脑干中缝核簇和巨细胞网状核α部,尤其是位于延髓中缝核团内的双标神经元数量较多。本研究的结果说明ＳＲＤ内的５┐ＨＴ样、ＳＰ样和Ｌ┐ＥＮＫ样阳性终末主要来自中脑导水管周围灰质、脑干中缝核簇和巨细胞网状核α部,向ＳＲＤ发出５┐ＨＴ能、ＳＰ能和Ｌ┐ＥＮＫ能投射的上述核团对ＳＲＤ发挥“弥漫性伤害抑     

Brain natriuretic peptide (BNP)-like immunoreactivity in the central nervous system of the crested newt.

The distribution of brain natriuretic peptide (BNP)-like immunoreactivity (ir) was studied in the brain of a urodele amphibian, the crested newt Triturus carnifex Laur. BNP-like immunoreactive neurons were found mainly in the caudal hypothalamus (retro- and supra-chiasmatic areas) and in the preoptic area. A widespread innervation throughout the brainstem as far as the spinal cord was also observed. By double immunostaining (after section incubation with a-BNP and a-tyrosine hydroxylase-TH-antibodies), close topographical relationships between BNP-like and TH-like immunoreactive neurons within the hypothalamus were found.     

Immunocytochemical and electron-microscopic study of the elasmobranch nucleus sacci vasculosi

Summary The elasmobranch nucleus sacci vasculosi was studied by means of electron microscopy (in the dogfish) and immunocytochemistry (in the dogfish and the skate) by using antibodies against tyrosine hydroxylase, alpha-melanocyte-stimulating hormone, somatostatin, serotonin, and substance P. Ultrastructural study of the dogfish nucleus sacci vasculosi shows the presence of medium-sized cells that possess numerous mitochondria but that have no dense-core vesicles in the cytoplasm or in cell processes. Fibres of the conspicuous tractus sacci vasculosi have a beaded appearance and form conventional synapses with dendrites and cell perikarya of the nucleus sacci vasculosi. The perikarya of this hypothalamic nucleus were not immunoreactive to any of the antibodies tested, and fibres immunopositive to tyrosine hydroxylase, alpha-melanocyte-stimulating hormone, somatostatin, serotonin, and substance P were scarce within this nucleus, in both the dogfish and the skate. Dorsal to the nucleus sacci vasculosi, there are numerous positive neuronal processes in addition to many small neurons that show immunoreactivity to alpha-melanocyte-stimulating hormone, somatostatin and tyrosine hydroxylase. Two types of neuron occur in this dorsal region, displaying dense-core vesicles of either 100–160 nm or 60–100 nm diameter in their cytoplasm; they were identified as peptide-containing and monoamine-containing neurons, respectively. The neuropil of this region has a significantly different ultrastructure from that of the nucleus sacci vasculosi, with many processes containing dense-core vesicles. This group of neurons, located dorsal to the nucleus sacci vasculosi and showing (a) immunoreactivity to neuropeptides or to monoamine-synthesizing enzyme, and (b) cytoplasm with dense-core vesicles, was considered not to be a part of the nucleus sacci vasculosi but rather part of the nucleus tuberculi posterioris. These results support the non-peptidergic and non-aminergic character of the nucleus sacci vasculosi.     

Distribution of FMRFamide-like immunoreactivity in the brain and neurohypophysis of the lamprey,Lampetra japonica

Summary Distribution of molluscan cardio-excitatory tetrapeptide Phe—Met—Arg—Phe—NH₂ (FMRFamide) was determined by means of immunohistochemistry in the brain and neurohypophysis of the lamprey, Lampetra japonica. Many FMRFamide-like immunoreactive neurons were found in the periventricular nuclear region and in a region near the mammillary recess. Neurons situated in the former region were larger. The immunoreactive cell groups were shown to be located at sites differing from those of the AF-positive cell groups. The fibers of immunoreactive neurons extended in all directions within the brain and towards the spinal cord, some reaching the third ventricle and capillaries. Thus, FMRFamide-like immunoreactive peptides appear to function as neurotransmitters or neuromodulators and possibly also as neurohormones. FMRFamide-like immunoreactive material was rarely observed in the posterior neurohypophysis (neural lobe), but was noted to be present to a limited extent in the caudal part of the anterior neurohypophysis (median eminence). It would thus follow that FMRFamide-like immunoreactive neurons may not necessarily be related to the hypothalamo-neural lobe system, but may possibly be associated with the hypothalamoadenohypophysial system. The pineal body showed no FMRFamide-like immunoreactivity.     

Immunohistochemical demonstration of serotonin-containing nerve fibers in the hypothalamus of the monkey,Macaca fuscata

Summary The distributional pattern of serotonin-containing nerve fibers in the hypothalamus of the monkey (Macaca fuscata) was analyzed with the use of the peroxidaseantiperoxidase method in conjunction with a highly sensitive and specific anti-serotonin serum. The highest concentrations of serotonin-immunoreactive varicose fibers were found in the nucleus praeopticus medialis, nucleus ventromedialis hypothalami, and the complex of mammillary nuclei (nucleus praemamillaris, supramamillaris, mamillaris medialis et lateralis). However, the nucleus suprachiasmaticus, where numerous serotoninergic fibers have been reported to occur in the rat, appeared to be almost devoid of these fibers. The infundibular stalk, and the intermediate and posterior lobes of the pituitary contained considerable numbers of immunoreactive fibers. The present study provides a morphological basis for possible clarification of the influence of serotoninergic projections on various neuroendocrine mechanisms in primates. Furthermore, an attempt was made to clarify the differences and similarities concerning the distributional patterns of serotoninergic nerve fibers within the monkey hypothalamus in contrast to the rat hypothalamus.Supported by grants (No. 56440022, 57214028) from the Ministry of Education, Science and Culture, Japan     

Immunocytochemical localization of neurotensin-containing neurons in the hypothalamus of the japanese quail,Coturnix coturnix japonica

Summary The hypothalamus of Japanese quail, Coturnix coturnix japonica, has been studied by means of the peroxidase-antiperoxidase immunocytochemical method, with the use of antibodies to synthetic neurotensin (NT). A number of immunoreactive neuronal perikarya occur in the medial preoptic nucleus of the rostral hypothalamus and a few in the accessory part of paraventricular nucleus and dorsal portion of the infundibular nucleus. Some of them correspond to the parvocellular neurons previously identified tentatively as neurosecretory (Mikami et al. 1975, 1976). Large numbers of immunoreactive neuronal fibers are found in the preoptic area, which extend as a remarkable fiber tract from this area to the ventral septal area and to the subfornical organ. A few immunoreactive fibers also extend ventrocaudally to the infundibular nucleus and to the neural lobe.This investigation was supported by Scientific Research Grants No. 556196 and No. 576176 from the Ministry of Education of Japan to Professor Mikami and Mr. Yamada     

Organization of neuropeptide tyrosine-like immunoreactive system in the brain of the Antarctic fish, Trematomus bernacchii

Antarctic notothenioids have developed unique freezing-resistance adaptations, including brain diversification, to survive in the subzero waters of the Southern Ocean surrounding Antarctica. In this study we have investigated the anatomical distribution of neuropeptide tyrosine (NPY)-like immunoreactive elements in the brain of the Antarctic fish Trematomus bernacchii, by using an antiserum raised against porcine NPY. Perikarya exhibiting NPY-like immunoreactivity were observed in distinct regions of the brain. The most rostral group of immunoreactive perikarya was found in the telencephalon, within the entopeduncular nucleus. In the diencephalon, three groups of NPY-like immunoreactive perikarya were found in the hypothalamus. Two groups of positive cell bodies were found in distinct populations of the preoptic nucleus, whereas the other group was found in the nucleus of the lateral recess. More caudally, NPY immunoreactivity was detected in large neurons located in the subependymal layers of the dorsal tegmentum of the mesencephalon, medially to the torus semicircularis. NPY-like immunoreactive nerve fibres were more widely distributed throughout the telencephalon to the rhombencephalon. High densities of nerve fibres and terminals were observed in several regions of the telencephalon, olfactory bulbs, hypothalamus, tectum of the mesencephalon and in the ventral tegmentum of the rhombencephalon. The distribution of NPY-like immunoreactive structures suggests that, in Trematomus, this peptide may be involved in the control of several brain functions, including olfactory activity, feeding behaviour, and somatosensory and visual information. In comparison with other neuropeptides previously described in the brain of Antarctic fish, NPY is more widely distributed. Our data also indicate the existence of differences in the brain distribution of NPY between Trematomus and other teleosts. In contrast with previous results reported in other fish, Trematomus contains positive fibres in the olfactory bulbs and immunoreactive perikarya in the nucleus of the lateral recess, whereas NPY-immunopositive cell bodies are absent in the thalamus and rhombencephalon, and no NPY immunoreactivity is present in the pituitary. These differences could be related to the Antarctic ecological diversity of notothenioids living at subzero temperatures.     

Serotonin-immunoreactive neurons in the median protocerebrum and suboesophageal ganglion of the sphinx moth Manduca sexta

Summary Serotonin-immunoreactive neurons in the median protocerebrum and suboesophageal ganglion of the sphinx moth Manduca sexta were individually reconstructed. Serotonin immunoreactivity was detected in 19–20 bilaterally symmetrical pairs of interneurons in the midbrain and 10 pairs in the suboesophageal ganglion. These neurons were also immunoreactive with antisera against DOPA decarboxylase. All major neuropil regions except the protocerebral bridge are innervated by these neurons. In addition, efferent cells are serotonin-immunoreactive in the frontal ganglion (5 neurons) and the suboesophageal ganglion (2 pairs of neurons). The latter cells probably give rise to an extensive network of immunoreactive terminals on the surface of the suboesophageal ganglion and suboesophageal nerves. Most of the serotonin-immunoreactive neurons show a gradient in the intensity of immunoreactive staining, suggesting low levels of serotonin in cell bodies and dendritic arbors and highest concentrations in axonal terminals. Serotonin-immunoreactive cells often occur in pairs with similar morphological features. With one exception, all serotonin-immunoreactive neurons have bilateral projections with at least some arborizations in identical neuropil areas in both hemispheres. The morphology of several neurons suggests that they are part of neuronal feedback circuits. The similarity in the arborization patterns of serotonin-immunoreactive neurons raises the possibility that their outgrowing neurites experienced similar forces during embryonic development. The morphological similarities further suggest that serotonin-immunoreactive interneurons in the midbrain and suboesophageal ganglion share physiological characteristics.Abbreviations CNS central nervous system - DDC DOPA decarboxylase - LAL lateral accessory lobe - SLI serotonin-like immunoreactivity - SOG suboesophageal ganglion - VLP ventro-lateral protocerebrum     

Distribution of aromatase-immunoreactive cells in the forebrain of zebra finches (Taeniopygia guttata): Implications for the neural action of steroids and nuclear definition in the avian hypothalamus

Cells immunoreactive for the enzyme aromatase were localized in the forebrain of male zebra finches with the use of an immunocytochemistry procedure. Two polyclonal antibodies, one directed against human placental aromatase and the other directed against quail recombinant aromatase, revealed a heterogeneous distribution of the enzyme in the telencephalon, diencephalon, and mesencephalon. Staining was enhanced in some birds by the administration of the nonsteroidal aromatase inhibitor, R76713 (racemic Vorozole) prior to the perfusion of the birds as previously described in Japanese quail. Large numbers of cells immunoreactive for aromatase were found in nuclei in the preoptic region and in the tuberal hypothalamus. A nucleus was identified in the preoptic region based on the high density of aromatase immunoreactive cells within its boundaries that appears to be homologous to the preoptic medial nucleus (POM) described previously in Japanese quail. In several birds alternate sections were stained for immunoreactive vasotocin, a marker of the paraventricular nucleus (PVN). This information facilitated the clear separation of the POM in zebra finches from nuclei that are adjacent to the POM in the preoptic area-hypothalamus, such as the PVN and the ventromedial nucleus of the hypothalamus. Positively staining cells were also detected widely throughout the telencephalon. Cells were discerned in the medial parts of the ventral hyperstriatum and neostriatum near the lateral ventricle and in dorsal and medial parts of the hippocampus. They were most abundant in the caudal neostriatum where they clustered in the dorsomedial neostriatum, and as a band of cells coursing along the dorsal edge of the lamina archistriatalis dorsalis. They were also present in high numbers in the ventrolateral aspect of the neostriatum and in the nucleus taeniae. None of the telencephalic vocal control nuclei had appreciable numbers of cells immunoreactive for aromatase within their boundaries, with the possible exception of a group of cells that may correspond to the medial part of the magnocellular nucleus of the neostriatum. The distribution of immunoreactive aromatase cells in the zebra finch brain is in excellent agreement with the distribution of cells expressing the mRNA for aromatase recently described in the finch telencephalon. This widespread telencephalic distribution of cells immunoreactive for aromatase has not been described in non-songbird species such as the Japanese quail, the ring dove, and the domestic fowl. © 1996 John Wiley & Sons, Inc.     

Sexually dimorphic distribution of galanin in the preoptic area of red salmon, Oncorhynchus nerka

A sexually dimorphic distribution of galanin in the preoptic region of the molly and goldfish has previously been demonstrated. Females of these species lack galanin-immunoreactive perikarya in the preoptic nucleus. In contrast, we have found, in female red salmon, galanin-immunoreactive neurons in the magnocellular preoptic nucleus, located far lateral to the preoptic recess, whereas many immunoreactive fibers are present in the preoptic area in both genders. In addition, many immunoreactive neurons have been seen in the nucleus preopticus periventricularis and nucleus lateralis tuberis, also in both sexes. These findings support the notion that galanin may play a gender-specific role in red salmon.     

Ultrastructural characterization of the sexually dimorphic medial preoptic nucleus of male Japanese quail

The medial preoptic nucleus is a sexually dimorphic structure whose cytoarchitecture, afferent and efferent connections, and functions have been previously described. No detailed ultrastructural study has, however, been perfomed to date. Here we describe the ultrastructural organization of this important preoptic structure of the male quail. Neuronal cell bodies of the medial preoptic nucleus generally show extensive development of protein-synthesis-related organelles (rough endoplasmic reticulum, polysomes), and of secretory structures (Golgi complexes, secretory vesicles, dense bodies). Previous morphometrical studies at the light-microscopical level have demonstrated the presence of a medial and a lateral neuronal population distinguished by the size of their cell bodies (the medial neurons are smaller than the lateral neurons). The present ultrastructural investigation confirms the difference in size, but no difference has been observed in the ultrastructural organization of the neurons. In both the medial and the lateral part, the nucleus is characterized by a large variety of cell bodies, including some that, on the basis of their ultrastructure, can be considered as putative peptidergic neurons. Close contacts are frequently observed between adjacent cell bodies that are normally arranged in clusters. Various types of synaptic endings are also present, suggesting a rich supply of nerve fibers. A few glial cells are scattered within the nucleus. In view of the crucial role of this region in regulating quail sexual behavior, the large heterogeneity of neurons and of afferent nervous fibers suggest that this region might have an important role in the integration of information arriving from different brain regions.     

Demonstration of a different localization of perikarya immunoreactive to oxytocin and vasopressin in the cat hypothalamus

Using immunohistochemical techniques, we demonstrated oxytocin (OT) and vasopressin (AVP) neurons in the cat hypothalamus. The OT immunoreactive neurons were found mainly in the paraventricular nucleus, supraoptic nucleus and dorsal accessory group located lateral to the fornix. In addition to these hypothalamic structures, the AVP immunoreactive neurons were observed in the suprachiasmatic nucleus, ventral accessory group located in the retrochiasmatic area and lateral accessory group, dorsal to the supraoptic nucleus caudally, and ventral to the medial part of the internal capsule rostrally. We further demonstrated a different localization of the OT and AVP immunoreactive neurons in the paraventricular and supraoptic nuclei.     

Estradiol Mediates Effects of Testosterone on Vasotocin Immunoreactivity in the Adult Quail Brain

In adult male quail, the activation of sexual behavior by testosterone (T) is mediated at the cellular level by the interaction of T metabolites with intracellular steroid receptors. In particular, the aromatization of T into an estrogen plays a key limiting role. Nonaromatizable androgens such 5alpha-dihydrotestosterone (DHT) synergize with estradiol (E2) to activate the behavior. Given that the density of vasotocin (VT) immunoreactive structures is increased by T in adult male quail and that VT injections affect male behavior, we wondered whether the expression of VT is also affected by T metabolites such as E2 and DHT. We analyzed here, in castrated male quail, the effects of a treatment with T, E2, DHT, or E2 + DHT on sexual behavior and brain VT immunoreactivity. The restoration by T of the VT immunoreactivity in the medial preoptic nucleus, bed nucleus striae terminalis, and lateral septum of castrated male quail could be fully mimicked by a treatment with E2. The androgen DHT had absolutely no effect on the VT immunoreactivity in these conditions and, at the doses used here, DHT did not synergize with E2 to enhance the density of VT immunoreactive structures. These effects of T metabolites in the brain were not fully correlated with their effects on the activation of male copulatory behavior, suggesting that the increase in VT expression in the brain does not represent a necessary step for the activation of behavior. Although VT expression in the medial preoptic nucleus and bed nucleus striae terminalis is often tightly correlated with the expression of male copulatory behavior, VT presumably does not represent simply one step in the biochemical cascade of events that is induced by T in the brain and leads to the expression of male sexual behavior.     

Immunocytochemical demonstration of somatostatin-containing neurons in the hypothalamus of the domestic mallard

Summary In the hypothalamus of the adult domestic mallard, small to medium-sized perikarya are stained specifically with rabbit antiserum against cyclic somatostatin (PAP technique of Sternberger). The somatostatin-immunoreactive material is located in neurons different from those containing immunoreactive LHRH, vasotocin or mesotocin. Somatostatin-containing perikarya are observed 1) in a chain-like arrangement extending from the area of the median division of the supraoptic nucleus to the caudal end of the paraventricular nucleus; 2) as single cells in the preoptic region; and 3) as a conspicuous formation in the optic tract division of the supraoptic nucleus. In the rostral portion of the median eminence, somatostatin-immunoreactive axons penetrate into the external zone. Fine accessory fiber bundles project to the neural lobe.     

Mapping of alpha-melanocyte-stimulating hormone-like immunoreactivity in the cat brainstem

The distribution of alpha-melanocyte-stimulating hormone-like immunoreactive structures was studied in the brainstem of the cat using an indirect immunoperoxidase technique. Immunoreactivity was observed in several brainstem nuclei of the cat in which no immunoreactivity had been previously reported. Immunoreactive fibres were observed in the following; the inferior central nucleus; the pontine gray nuclei; the K?lliker-Fuse nucleus; the motor trigeminal nucleus, the anteroventral cochlear nucleus; the abducens nucleus; the retrofacial nucleus; the superior, lateral, inferior, and medial vestibular nuclei; the lateral nucleus of the superior olive; the external cuneate nucleus; the nucleus of the trapezoid body; the postpyramidal nucleus of the raphe; the medial accessory inferior olive; the dorsal accessory nucleus of the inferior olive; the nucleus ambiguus; the principal nucleus of the inferior olive; the preolivary nucleus; the nucleus ruber; the substantia nigra; and in the area postrema. Our results point to a more widespread distribution of alpha-melanocyte-stimulating hormone-like immunoreactive structures in the cat brainstem than that reported in previous studies carried out in the same region of the cat, rat and humans.