Immunohistochemical mapping of galanin-like neurons in the rat central nervous system

Using an antiserum generated in rabbits against synthetic galanin (GA) and the indirect immunofluorescence method, the distribution of GA-like immunoreactive cell bodies and nerve fibers was studied in the rat central nervous system (CNS) and a detailed stereotaxic atlas of GA-like neurons was prepared. GA-like immunoreactivity was widely distributed in the rat CNS. Appreciable numbers of GA-positive cell bodies were observed in the rostral cingulate and medial prefrontal cortex, the nucleus interstitialis striae terminalis, the caudate, medial preoptic, preoptic periventricular, and preoptic suprachiasmatic nuclei, the medial forebrain bundle, the supraoptic, the hypothalamic periventricular, the paraventricular, the arcuate, dorsomedial, perifornical, thalamic periventricular, anterior dorsal and lateral thalamic nuclei, medial and central amygdaloid nuclei, dorsal and ventral premamillary nuclei, at the base of the hypothalamus, in the central gray matter, the hippocampus, the dorsal and caudoventral raphe nuclei, the interpeduncular nucleus, the locus coeruleus, ventral parabrachial, solitarii and commissuralis nuclei, in the A1, C1 and A4 catechaolamine areas, the posterior area postrema and the trigeminal and dorsal root ganglia. Fibers were generally seen where cell bodies were observed. Very dense fiber bundles were noted in the septohypothalamic tract, the preoptic area, in the hypothalamus, the habenula and the thalamic periventricular nucleus, in the ventral hippocampus, parts of the reticular formation, in the locus coeruleus, the dorsal parabrachial area, the nucleus and tract of the spinal trigeminal area and the substantia gelatinosa, the superficial layers of the spinal cord and the posterior lobe of the pituitary. The localization of the GA-like immunoreactivity in the locus coeruleus suggests a partial coexistence with catecholaminergic neurons as well as a possible involvement of the GA-like peptide in a neuroregulatory role.     

Autoradiographic distribution of 125I calcitonin gene-related peptide binding sites in the rat central nervous system

Using autoradiographic method and 125I-Tyro rat CGRP as a ligand, receptor binding sites were demonstrated in the rat central nervous system. Saturation studies and Scatchard analysis of CGRP-binding to slide mounted tissue sections containing primarily cerebellum showed a single class of receptors with a dissociation constant of 0.96 nM and a Bmax of 76.4 fmol/mg protein. 125I-Tyro rat CGRP binding sites were demonstrated throughout the rat central nervous system. Dense binding was observed in the telencephalon (medial prefrontal, insular and outer layers of the temporal cortex, nucleus accumbens, fundus striatum, central and inferior lateral amygdaloid nuclei, most caudal caudate putamen, organum vasculosum laminae terminalis, subfornical organ), the diencephalon (anterior hypothalamic, suprachiasmatic, arcuate, paraventricular, dorsomedial, periventricular, reuniens, rhomboid, lateral thalamic pretectalis and habenula nuclei, zona incerta), in the mesencephalon (superficial layers of the superior colliculus, central nucleus of the geniculate body, inferior colliculus, nucleus of the fifth nerve, locus coeruleus, nucleus of the mesencephalic tract, the dorsal tegmental nucleus, superior olive), in the molecular layer of the cerebellum, in the medulla oblongata (inferior olive, nucleus tractus solitarii, nucleus commissuralis, nuclei of the tenth and twelfth nerves, the prepositus hypoglossal and the gracilis nuclei, dorsomedial part of the spinal trigeminal tract), in the dorsal gray matter of the spinal cord (laminae I-VI) and the confines of the central canal. Moderate receptor densities were found in the septal area, the "head" of the anterior caudate nucleus, medial amygdaloid and bed nucleus of the stria terminalis, the pyramidal layers of the hippocampus and dentate gyri, medial preoptic area, ventromedial nucleus, lateral hypothalamic and ventrolateral thalamic area, central gray, reticular part of the substantia nigra, parvocellular reticular nucleus. Purkinje cell layer of the cerebellum, nucleus of the spinal trigeminal tract and gracile fasciculus of the spinal cord. The discrete distribution of CGRP-like binding sites in a variety of sensory systems of the brain and spinal cord as well as in thalamic and hypothalamic areas suggests a widespread involvement of CGRP in a variety of brain functions.     

Autoradiographic distribution of I-galanin binding sites in the rat central nervous system

Galanin (GAL) binding sites in coronal sections of the rat brain were demonstrated using autoradiographic methods. Scatchard analysis of ¹²⁵I-GAL binding to slide-mounted tissue sections revealed saturable binding to a single class of receptors with a Kd of approximately 0.2 nM. ¹²⁵I-GAL binding sites were demonstrated throughout the rat central nervous system. Dense binding was observed in the following areas: prefrontal cortex, the anterior nuclei of the olfactory bulb, several nuclei of the amygdaloid complex, the dorsal septal area, dorsal bed nucleus of the stria terminalis, the ventral pallidum, the internal medullary laminae of the thalamus, medial pretectal nucleus, nucleus of the medial optic tract, borderline area of the caudal spinal trigeminal nucleus adjacent to the spinal trigeminal tract, the substantia gelatinosa and the superficial layers of the dorsal spinal cord. Moderate binding was observed in the piriform, periamygdaloid, entorhinal, insular cortex and the subiculum, the nucleus accumbens, medial forebrain bundle, anterior hypothalamic, ventromedial, dorsal premamillary, lateral and periventricular thalamic nuclei, the subzona incerta, Forel's field H₁ and H₂, periventricular gray matter, medial and superficial gray strata of the superior colliculus, dorsal parts of the central gray, peripeduncular area, the interpeduncular nucleus, substantia nigra zona compacta, ventral tegmental area, the dorsal and ventral parabrachial and parvocellular reticular nuclei. The preponderance of GAL-binding in somatosensory as well as in limbic areas suggests a possible involvement of GAL in a variety of brain functions.     

Afferent connections of the basolateral division of the amygdaloid complex of the cat brain

Injection of horseradish peroxidase into the basal macrocellular and lateral nuclei of the amygdaloid complex (BLAC) in the cat brain has revealed their rich thalamic afferentation. On the BLAC there are massive projections of: a) nuclei of the middle line of the precommissural pole of the dorsal thalamus (anterior parts of the paratenial, interanteromedial and reunial nuclei), as well as the whole anterior paraventricular nucleus, medial part of the ventral posteromedial nucleus; b) postcommissural nuclei of the dorsal thalamus; some "nonacustical" nuclei of the internal geniculate body (ventrolateral nucleus, medial and macrocellular parts and the most caudal end of the internal geniculate body). Rather essential are projections of the "posterior group nuclei", those of the suprageniculate nucleus, of some parts of the ventral thalamus (subparafascicular nucleus, marginal and peripeduncular nuclei) and parabrachial nucleus. Scattered single projections are obtained from all hypothalamic parts (most of all the ventromedial nucleus), reticular nuclei of the septum, substantia innominata, substantia nigra, truncal nuclei of the raphe. Variety of the dorsal thalamic nuclei, sending their fibers to the BLAC reflects variety of sensory information, that gets here, according to its modality, degree of its differentiation and integrity. A number of the dorsal thalamus nuclei, owing to abundance of labelled neurons, can be considered as special relay thalamic nuclei for the BLAC resembling corresponding relay nuclei for the new cortex.     

Distribution of somatostatinlike immunoreactivity in the brain of the little brown bat (Myotis lucifugus)

The distribution of somatostatinlike immunoreactive (SLI) perikarya, axons, and terminals was mapped in subcortical areas of the brain of the little brown bat, Myotis lucifugus, using light microscopic immunocytochemistry. A preponderance of immunoreactivity was localized in reticular, limbic, and hypothalamic areas including: 1) in the forebrain: the bed nucleus of the stria terminalis; lateral preoptic, dorsal, anterior, lateral and posterior hypothalamic areas; amygdaloid, periventricular, arcuate, supraoptic, suprachiasmatic, ventromedial, dorsomedial, paraventricular, lateral and medial mammillary, and lateral septal nuclei; the nucleus of the diagonal band of Broca and nucleus accumbens septi; 2) in the midbrain: the periaqueductal gray, interpeduncular, dorsal and ventral tegmental, pretectal, and Edinger-Westphal nuclei; and 3) in the hindbrain: the superior central and parabrachial nuclei, nucleus incertus, locus coeruleus, and nucleus reticularis gigantocellularis. Other areas containing SLI included the striatum (caudate nucleus and putamen), zona incerta, infundibulum, supramammillary and premammillary nuclei, medial and dorsal lateral geniculate nuclei, entopeduncular nucleus, lateral habenular nucleus, central medial thalamic nucleus, central tegmental field, linear and dorsal raphe nuclei, nucleus of Darkschewitsch, superior and inferior colliculi, nucleus ruber, substantia nigra, mesencephalic nucleus of V, inferior olivary nucleus, inferior central nucleus, nucleus prepositus, and deep cerebellar nuclei. While these results were similar in some respects to those previously reported in rodents, they also provided interesting contrasts.     

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.     

Oxytocin immunoreactivity in the hypothalamus of female hamsters

In Syrian hamsters (Mesocricetus auratus), oxytocin (OXT) activity within the medial preoptic-anterior hypothalamus (MPOA-AH) and the ventromedial hypothalamus (VMH) plays an important role in the expression of sexual receptivity. Immunocytochemical analysis with OXT-specific antibodies was used to identify the distribution of OXT-containing cell bodies and fibers in female hamster brain and to determine the possible sources of OXT important for sexual receptivity. Oxytocin-immunoreactive cell bodies and fibers were found in several regions of the preoptic area, including the medial preoptic area, the medial preoptic nucleus, and the bed nucleus of the stria terminalis. Large numbers of cell bodies and fibers were localized within the paraventricular and supraoptic nuclei, and in anterior hypothalamus. OXT-immunoreactive fibers were observed in the VMH and the ventral tegmental area. The anatomical data from the present study support the hypothesis that OXT activity in the MPOA-AH and the VMH plays an important role in the regulation of sexual receptivity in hamsters.     

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.     

Ascending and descending efferent pathways of the midbrain reticular formation of the cat (radioautographic study)

By means of the anterograde axoplasmic transport technique for a mixture of labelled aminoacids (3H-leucine and 3H-proline), ascending and descending systems of the reticular formation fibers in the cat mesencephalon have been studied. Projections from the mesencephalon reticular formation (MRF) ascend to the subthalamus, lateral, dorsal and periventricular hypothalamus, to the periventricular nuclei of the midline and to the intralaminar nuclei of the thalamus. The descending pathways project to the grey substance surrounding the aqueduct of cerebrum, locus coeruleus, parabrachial region and reticular formation of the pons and medulla oblongata. The projections to the reticular nucleus of the thalamus, ventral nucleus of the external geniculate body and superior colliculi arise from the dorsal half of the MRF, and projections to the striatum, lateral reticular nucleus of the medulla oblongata--from its ventral half. Most of the structures are reciprocally connected with the MRF.     

Distribution of gastrin-releasing peptide immunoreactivity in the brain of the collared dove (Streptopelia decaocto)

The distribution of immunoreactivity after applying an antibody against gastrin-releasing peptide (GRP) was studied in the brain of the collared dove (Streptopelia decaocto). In the forebrain GRP-immunoreactive (GRP-ir) cells were found in the hyperstriatum accessorium, medial and lateral parts of the neostriatum, corticoidea dorsolateralis and temporoparieto-occipitalis areas, hippocampus, pre- and parahippocampal areas and prepiriform cortex. In the brainstem, GRP-ir cells were restricted mainly to the substantia nigra and ventral tegmental nucleus. Areas with densely packed GRP-ir clusters of varicosities were the medial intermediate hyperstriatum ventrale and lateral septal nucleus; dense GRP-ir neuropil was found in the parolfactory lobe, and in the dorsal half of the intermediate and caudal archistriatum. The ventral lamina medullaris contained many GRP-ir fibers. Forebrain areas devoid of immunoreactivity were the basal nucleus, ectostriatum, rostral archistriatum, most of the paleostriatum augmentatum and the lateral bed nucleus of the stria terminalis. Moderate densities of GRP-ir elements were found in the other telencephalic areas and further in, among others, the preoptic and hypothalamic region, ventral area of Tsai, cerulean nuclei, parabrachial complex, dorsal glossopharyngeal and vagus motor nuclei and medial nuclei of the solitary complex. The observations are compared with data from the literature and the implications for the definition of specific centers within the avian brain are discussed, with emphasis on systems with a role in visceral and motivational functions and in learning.     

Immunocytochemical study of the relations of acetylcholinesterase, enkephalin-, substance P-, choline acetyltransferase- and calcitonin gene-related peptide-immunoreactive structures in the ventral horn of rat spinal cord.

Calcitonin gene-related peptide (CGRP)-like immunoreactivity was localized immunocytochemically in the large motoneurons in the ventral horn of rat spinal cord. Using fluorescence double-labelling substance P (SP)-immunoreactive nerve fibres were found to surround both the CGRP-positive and negative motoneurons, whereas enkephalin (ENK)-immunoreactive fibres surrounded mainly CGRP-negative cells. All CGRP-like immunoreactive motoneurons were also choline acetyltransferase (ChAT)- and acetylcholinesterase (AChE)-positive. On the other hand a large population of ChAT- and AChE-positive motoneurons were devoid of CGRP-immunoreactivity. It is probable that CGRP/ChAT/AChE-positive cells surrounded by SP-positive fibres have different functions in motoric nervous system than the CGRP-negative ChAT/AChE-positive cells, which are surrounded by ENK-immunoreactive fibres.     

Immunocytochemical study of the relations of acetylcholinesterase,enkephalin-, substance P-, choline acetyltransferase- and calcitonin gene-related peptide-immunoreactive structures in the ventral horn of rat spinal cord

Summary Calcitonin gene-related peptide (CGRP)-like immunoreactivity was localized immunocytochemically in the large motoneurons in the ventral horn of rat spinal cord. Using fluorescence double-labelling substance P (SP)-immunoreactive nerve fibres were found to surround both the CGRP-positive and negative motoneurons, whereas enkephalin (ENK)-immunoreactive fibres surrounded mainly CGRP-negative cells. All CGRP-like immunoreactive motoneurons were also choline acetyltransferase (ChAT)- and acetylcholinesterase (AChE)-positive. On the other hand a large population of ChAT- and AChE-positive motoneurons were devoid of CGRP-immunoreactivity. It is probable that CGRP/ChAT/AChE-positive cells surrounded by SP-positive fibres have different functions in motoric nervous system than the CGRP-negative ChAT/AChE-positive cells, which are surrounded by ENK-immunoreactive fibres.     

Distribution of gastrin and CCK-like peptides in rat brain

Summary The distribution of gastrin and CCK-like peptides in the rat brain was studied by immunocytochemistry using an antiserum reacting equally well with both groups of peptides. Immunoreactive nerve cell bodies were detected in all cortical areas, in the hippocampus where they were particularly numerous, in the mesencephalic central gray and in the medulla oblongata. After colchicine treatment immunoreactive material appeared also in cell bodies of the magnocellular hypothalamic system. Immunoreactive nerve fibers were widely distributed in the brain. Particularly dense accumulations were seen in the hippocampus near the ventral surface of the brain, in the caudate nucleus, in the interpeduncular nucleus, the parabrachial nucleus, the dorsal part of the medulla oblongata and in the dorsal horn of the spinal cord. In the hypothalamus immunoreactive nerve fibers were observed in all nuclei, being most frequent in the ventromedial, dorsal and lateral hypothalamic nuclei. A rich supply of nerve fibers was seen in the outer zone of the median eminence and in the neurohypophysis. From previous immunochemical analysis it appears that the peptide demonstrated in most parts of the brain is identical with CCK-8. In the neurosecretory cell bodies of the hypothalamus, the median eminence and the neurohypophysis, however, the immunoreactive material is probably identical with gastrin.     

Dorsal thalamic connections of the ventral lateral geniculate nucleus of rats

In order to understand better the organisation of the ventral lateral geniculate nucleus of the ventral thalamus, this paper has examined the patterns of connections that this nucleus has with various nuclei of the dorsal thalamus in rats. Injections of biotinylated dextran or cholera toxin subunit B were made into the parafascicular, central lateral, posterior thalamic, medial dorsal, lateral dorsal, lateral posterior, dorsal lateral geniculate, anterior, ventral lateral, ventrobasal and medial geniculate nuclei of Sprague-Dawley rats and their brains were processed using standard tracer detection methods. Three general patterns of ventral lateral geniculate connectivity were seen. First, the parafascicular, central lateral, medial dorsal, posterior thalamic and lateral dorsal nuclei had heavy connections with the parvocellular (internal) lamina of the ventral lateral geniculate nucleus. This geniculate lamina has been shown previously to receive heavy inputs from many functionally diverse brainstem nuclei. Second, the visually related dorsal lateral geniculate and lateral posterior nuclei had heavy connections with the magnocellular (external) lamina of the ventral lateral geniculate nucleus. This geniculate lamina has been shown by previous studies to receive heavy inputs from the visual cortex and the retina. Finally, the anterior, ventral lateral, ventrobasal and medial geniculate nuclei had very sparse, if any, connections with the ventral lateral geniculate nucleus. Overall, our results strengthen the notion that one can package the ventral lateral geniculate nucleus into distinct visual (magnocellular) and non-visual (parvocellular) components.     

A reinvestigation of the Gn-RH (gonadotrophin-releasing hormone) systems in the goldfish brain using antibodies to salmon Gn-RH

Summary The organization of Gn-RH systems in the brain of teleosts has been investigated previously by immunohistochemistry using antibodies against the mammalian decapeptide which differs from the teleostean factor. Here, we report the distribution of immunoreactive Gn-RH in the brain of goldfish using antibodies against synthetic teleost peptide.Immunoreactive structures are found along a column extending from the rostral olfactory bulbs to the pituitary stalk. Cell bodies are observed within the olfactory nerves and bulbs, along the ventromedial telencephalon, the ventrolateral preoptic area and the latero-basal hypothalamus. Large perikarya are detected in the dorsal midbrain tegmentum, immediately caudal to the posterior commissure. A prominent pathway was traced from the cells located in the olfactory nerves through the medial olfactory tract and along all the perikarya described above to the pituitary stalk. In the pituitary, projections are restricted to the proximal pars distalis. A second immunoreactive pathway ascends more dorsally in the telencephalon and arches to the periventricular regions of the diencephalon. Part of this pathway forms a periventricular network in the dorsal and posterior hypothalamus, whereas other projections continue caudally to the medulla oblongata and the spinal cord. Lesions of the ventral preoptic area demonstrate that most of the fibers detected in the pituitary originate from the preoptic region.     

Somatostatin-immunoreactive fiber projections into the brain stem and the spinal cord of the rat

Summary By use of the PAP-immunohistochemical staining technique with serial sections, somatostatin-immunoreactive fiber projections into the brain stem and the spinal cord are described. These projections originate in the periventricular somatostatin-immunoreactive perikarya of the hypothalamus and form three main pathways: (1) along the stria medullaris thalami and the fasciculus retroflexus into the interpeduncular nucleus; (2) along the medial forebrain bundle into the mammillary body; and (3) via the periventricular gray and the bundle of Schütz into the midbrain tegmentum. Densely arranged immunoreactive fibers and/or basket-like fiber terminals are observed within the following afferent systems: somatic afferent systems (nucleus spinalis nervi trigemini, substantia gelatinosa dorsalis of the entire spinal cord), and visceral afferent systems (nucleus solitarius, regio intermediolateralis and substantia gelatinosa of the sacral spinal cord). These projections form terminals around the perikarya of the second afferent neuron. Perikarya of the third afferent neuron are influenced by somatostatin-immunoreactive projections into the auditory system (nucleus dorsalis lemnisci lateralis, nucleus corporis trapezoidei). Furthermore, a somatostatin-immunoreactive fiber projection is found in the ventral part of the medial accessory olivary nucleus, in nuclei of the limbic system (nucleus habenularis medialis, nuclei supramamillaris and mamillaris lateralis) and in the formatio reticularis (nucleus Darkschewitsch, nuclei tegmenti lateralis and centralis, nucleus parabrachialis lateralis, as well as individual perikarya of the reticular formation). Targets of these projections are interneurons within interlocking neuronal chains.Supported by the Deutsche Forschungsgemeinschaft (Grant Nr. Kr 569/3) and Stiftung Volkswagenwerk     

Central projections of the nervus terminalis in the bichir,Polypterus palmas

Summary Central pathways of the nervus terminalis (n.t.) in the bichir, Polypterus palmas, were studied with the use of tracing techniques. After application of horseradish peroxidase to the unilateral olfactory mucosa labeled n.t. fibers were traced in seven distinct bundles through the subpallium. Projection areas are found in the precommissural ventral nucleus of the area ventralis telencephali ipsilaterally, the anterior commissure and commissural parts of the periventricular preoptic nucleus bilaterally; few n.t.-fibers cross via the anterior commissure to the contralateral side; no fibers were observed to turn rostrally to the contralateral olfactory bulb. Major targets of the n.t. include a restricted ventral part of the periventricular preoptic nucleus at the level of the optic chiasma bilaterally, and the periventricular nuclei located between the thalamic nuclei and the hypothalamus bilaterally. N.t. fibers continue their course through the ipsilateral hypothalamus and are traced as far as the mesencephalic tegmentum ipsilaterally. N.t. terminations are found consistently within the boundaries of periventricular cell nuclei, suggesting axosomatic synaptic contacts. We propose a differentiation of the n.t. ganglion cells into a distal (mucosal) and proximal (bulbar) type regarding the peripheral cell processes. Our findings are compared with those of other reports on the n.t. system.     

μ Opiate receptor immunoreactivity in rat central nervous system

Immunoreactivity corresponding to the C-terminus of the rat μ opiate receptor can be detected by light microscopy in fiber- and terminal-like patterns in a number of rat brain and spinal cord regions, and in immunoreactive perikarya in several of these regions. Especially abundant fiber- and terminal-like patterns were localized to superficial layers of the spinal cord dorsal horn and nucleus caudalis of the spinal tract of the trigeminal, the nucleus of the solitary tract, nucleus ambiguous, locus coeruleus, interpeduncular nucleus, medial aspect of the lateral habenular nucleus, presumed “striasomes” of the caudate-putamen and nucleus accumbens. Moderate fiber and terminal densities were found in the ventral tegmental area, more medial aspects of the thalamus and hypothalamus, and several amygdaloid nuclei. Immunostained perikarya were prominent in the nucleus accumbens and also observed in the middle layers of the cerebral cortex, septum and diagonal band, preoptic area, medial thalamic and habenular nuclei, locus coeruleus, nucleus ambiguous, nucleus of the solitary tract, trigeminal nucleus caudalis and spinal cord substantia gelatinosa zones. Many of these localizations correspond well with the previously-determined autoradiographic distributions of μ opiate receptor ligand binding, and with reports of μ opiate receptor immunoreactivity determined using other antisera. Electron microscopic immunohistochemical studies reveal details of the membrane distribution of the μ receptor in nucleus accumbens, caudate/putamen, locus coeruleus, and spinal cord. These results suggest largely neuronal and largely extrasynaptic distributions of μ receptors that show differential patterns of perikaryal, dendritic, and/or axonal immunostaining in different central nervous system zones. Identification of these distributions adds substantially to data identifying the cellular localization of the principal opiate receptor involved in both analgesic and addictive processes. Special issue dedicated to Dr. Eric J. Simon.     

Distribution of oxytocin and vasopressin neurons in the diencephalon of the Japanese horseshoe bat, Rhinolophus ferrumequinum. An immunohistochemical study.

The distribution of oxytocin (OXT) and vasopressin (VP) neurons in the diencephalon of the hibernating Japanese horseshoe bat, Rhinolophus ferrumequinum, was immunohistochemically investigated by the avidin-biotin complex method. Magnocellular OXT and VP neurons were localized mainly in the paraventricular nucleus and the supraoptic nucleus. In addition to these main nuclei, both kinds of magnocellular neurons were also found in the periventricular nucleus, perifornical area and lateral hypothalamic area. Extensively distributed parvocellular neurons containing only VP were observed in the rostral and middle portions of the suprachiasmatic nucleus. The size of OXT and VP magnocellular neurons was almost equal in the paraventricular and ventromedial supraoptic nuclei, whereas VP neurons were significantly larger than OXT neurons in the dorsolateral supraoptic nucleus. The OXT and VP cells in the ventral supraoptic nucleus showed a distinctive elliptical shape. Both OXT and VP fibers were distributed in the lateral habenular nucleus, stria medullaris thalami, lateral preoptic area, stria terminalis, and medial and supracapsular part of the bed nucleus of the stria terminalis. Moreover, OXT fibers were found in the substantia nigra, and VP fibers were noted in the nucleus reunions and the paraventricular nucleus of the thalamus.