The serotoninergic system of the brain of the viper, Vipera aspis. An immunohistochemical study

Serotoninergic cell bodies and fibers in the brain of the viper, Vipera aspis, were visualized by immuno-histochemistry. Immunoreactive cell bodies were observed in the diencephalic hypothalamic periventricular organ and in the dorsal wall of the infundibular recess, in the nuclei raphe superior and inferior of the midbrain and hindbrain, and to a lesser extent in the nuclei reticularis superior, reticularis inferior and reticularis lateralis. In contrast to other reptilian species, serotoninergic cells were also observed in the central gray matter of the midbrain in the neighbourhood of the nucleus of the trochlear nerve. Immunoreactive fibers are widely distributed throughout the brain of the viper. In the olfactory bulb. fibers were observed in the internal plexiform layer and mitral cell layer. The cerebral cortex contains the highest density of fibers in the dorsal region. The distribution of immunoreactive fibers in the dorsal ventricular ridge is extremely heterogeneous, and five subcomponents of this structure can be distinguished. The majority of diencephalic and mesencephalic structures that contain immunoreactive fibers are also primary visual centres: the nuclei geniculatus lateralis pars dorsalis, the n. posterodorsalis and n. opticus tegmenti, and the optic tectum. Serotoninergic fibers in the nuclei of the oculomotor and motor crainal nerves (III, IV, V, VII, X) are disposed in a tightly woven basket around the non-immunoreactive cell bodies of the motoneurons. These findings, together with the available literature, suggest that the serotoninergic system in snakes is comparable to that in lizards, with a massive ascending projection of fibers from the n. raphe superior to mesencephalic and prosencephalic structures, and a descending projection from the n. raphe inferior to the spinal cord.     

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.     

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.     

Distribution of methionine-enkephalin in the minipig brainstem

We have studied the distribution of immunoreactive cell bodies and axons are containing methionine-enkephalin in the minipig brainstem. Immunoreactive axons were widely distributed, whereas the distribution of perikarya was less widespread. A high or moderate density of axons containing methionine-enkephalin were found from rostral to caudal levels in the substantia nigra, nucleus interpeduncularis, nucleus reticularis tegmenti pontis, nucleus dorsalis raphae, nucleus centralis raphae, nuclei dorsalis and ventralis tegmenti of Gudden, locus ceruleus, nucleus sensorius principalis nervi trigemini, nucleus cuneatus externalis, nucleus tractus solitarius, nuclei vestibularis inferior and medialis, nucleus ambiguus, nucleus olivaris inferior and in the nucleus tractus spinalis nervi trigemini. Immunoreactive perikarya were observed in the nuclei centralis and dorsalis raphae, nucleus motorius nervi trigemini, nucleus centralis superior, nucleus nervi facialis, nuclei parabrachialis medialis and lateralis, nucleus ventralis raphae, nucleus reticularis lateralis and in the formatio reticularis. We have also described the presence of perikarya containing methionine-enkephalin in the nuclei nervi abducens, ruber, nervi oculomotorius and nervi trochlearis. These results suggest that in the minipig the pentapeptide may be involved in many physiological functions (for example, proprioceptive and nociceptive information; motor, respiratory and cardiovascular mechanisms).     

The serotoninergic system of the brain of the lamprey, Lampetra fluviatilis: an evolutionary perspective.

The distribution of serotonin(5HT)-immunoreactive cell bodies, nerve fibers and terminals was investigated by light microscopy in the lamprey Lampetra fluviatilis. Twenty-three distinct groups of 5HT neuronal somata were identified from diencephalic to rhombencephalic levels in the brain. The diencephalon contained a subependymal population of immunoreactive cells in contact with the cerebrospinal fluid (CSF), which could be subdivided into five separate groups situated in the hypothalamus and ventral thalamus; five additional groups of immunoreactive diencephalic neurons, situated in the dorsal thalamus and thalamo-pretectum, which were not in contact with the CSF, were also identified. In the midbrain, in addition to a few labelled neurons in the optic tectum, two structures containing immunoreactive cells were identified in the tegmentum mesencephali. None of these 5HT cells corresponded to the retinopetal neurons which are situated in the same region. A very large number of 5HT neurons were observed in the hindbrain which could be divided into seven groups in the isthmus rhombencephali and a further three in the rhombencephalon proper. Immunoreactive fibers and terminals were widely distributed throughout the neuraxis. In the telencephalon two 5HT fibers assemblies, lateral and medial, could be identified which terminated in both pallial and subpallial structures. The richest serotoninergic innervation in the telencephalon was found in the lateral portion of the primordium hippocampi and the medial part of the corpus striatum. In the diencephalon, the distribution of immunoreactive fibers and terminals was heterogeneous, being most pronounced in the lateral hypothalamic area and in the infundibulum. The densest arborization of fibers in the mesencephalon was found in the stratum fibrosum et cellulare externum of the optic tectum, a major site of retinal projection, and in the nucleus interpeduncularis mesencephali as well as in the oculomotor nuclei. The rhombencephalon is richly endowed with serotoninergic fibers and terminals, many labelled arborizations being found in the nuclei isthmi rhombencephali and around the nucleus motorius nervi trigemini. Comparative analysis of the serotoninergic systems of petromyzontiforms and gnathostomes indicates that the evolution of this system involves a progressive elimination of the rostral immunoreactive cells and an increasing complexity of the caudal population of serotoninergic neurons.     

An immunocytochemical mapping of methionine-enkephalin-Arg(6)-Gly(7)-Leu(8) in the human brainstem

Using an indirect immunoperoxidase technique, we studied the distribution of immunoreactive fibers and cell bodies containing methionine-enkephalin-Arg(6)-Gly(7)-Leu(8) in the adult human brainstem. Immunoreactive cell bodies were found in the reticular formation of the medulla oblongata (in which we observed the highest density of immunoreactive cell bodies) and the pons, the solitary nucleus, the hypoglossal nucleus, the medial and spinal vestibular nuclei, the lateral cuneate nucleus, the nucleus prepositus, the central gray of the pons and mesencephalon, the central and pericentral nuclei of the inferior colliculus, the superior colliculus, ventral to the superior olive and in the midline region of the pons and mesencephalon. The highest density of immunoreactive fibers containing methionine-enkephalin-Arg(6)-Gly(7)-Leu(8) was found in the spinal trigeminal nucleus, the central gray and the reticular formation of the medulla oblongata, pons and mesencephalon, the solitary nucleus, the spinal vestibular nucleus, the dorsal accessory olivary nucleus, the raphe obscurus, the substantia nigra and in the interpeduncular nucleus. The widespread distribution of immunoreactive structures containing methionine-enkephalin-Arg(6)-Gly(7)-Leu(8) in the human brainstem indicates that this neuropeptide might be involved in several physiological mechanisms, acting as a neurotransmitter and/or neuromodulator.     

Distribution of nerve growth factor receptor-like immunoreactivity in the adult rat central nervous system. Effect of colchicine and correlation with the cholinergic system--II. Brainstem, cerebellum and spinal cord

Multiple nuclei and fiber tracts in the adult rat brainstem and spinal cord were found to contain nerve growth factor receptor-related protein, as recognized by the monoclonal antibody 192-IgG. Both cholinergic and non-cholinergic sensory and motor regions demonstrated immunoreactive cell bodies and fibers. Nerve growth factor receptor-immunoreactive cells were seen in the mesencephalic nucleus of trigeminal nerve, superior colliculus, parabrachial, prepositus hypoglossal, raphe, dorsal and ventral cochlear, interstitial nucleus of the vestibular nerve, ambiguus and reticular nuclei, cerebellum and ventral spinal cord. Immunoreactive cells resembling neuroglia were distributed subpially along the superior colliculus. Intracerebroventricular injection of colchicine resulted in significantly increased nerve growth factor receptor immunoreactivity in all previously positive neurons and especially in certain neurons of the cochlear and ambiguus nuclei. It also resulted in the visualization of receptor immunoreactivity in certain neurons which were normally non-immunoreactive including cerebellar Purkinje cells, neurons of the central gray, locus coeruleus, facial, dorsal motor vagal and hypoglossal nuclei. In normal animals, nerve growth factor receptor-immunoreactive fibers and varicosities occurred in the trigeminal nerve nuclei, pontine, vestibular, parabrachial, facial, hypoglossal, dorsal motor vagal, solitary, gracile and cuneate nuclei and spinal cord. Although most fiber-like immunoreactive structures were probably axons and nerve terminals, neuroglial or extracellular localizations could not be excluded in some areas. For example, the medial nucleus of the inferior olive and most cerebellar nuclei contained diffuse non-fibrillar receptor immunoreactivity. The presence of nerve growth factor receptor-like immunoreactivity in cell bodies and fibers of several sensory and motor areas of the adult rat brainstem, cerebellum and spinal cord suggests multifocal actions of nerve growth factor or a nerve growth factor-like substance. Although the degree of overlap between nerve growth factor receptor- and choline acetyltransferase-containing regions in the brainstem is not as great as in the forebrain, our findings suggest a potential influence of nerve growth factor or nerve growth factor-like substances on cholinergic systems outside the forebrain. Furthermore, the disparities which occur imply that non-cholinergic nerve growth factor receptor-containing neurons of the brainstem, cerebellum and spinal cord may be affected by such trophic substances.     

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 accilmbens 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 coeruJeus, and nucleus reticularis gigantocellularis. Other areas containing SLI included the striatum (caudate nucleus and putamen), zona incerta, infundibulum, supramammiilary 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.     

Retrograde labeling of neurons in the brain stem following injections of [3H]choline into the forebrain of the rat

Summary In an attempt to identify cholinergic neurons of the brain stem which project to the forebrain, retrograde labeling of neurons in the brain stem was examined by autoradiography following injections of 20 Ci [³H]choline into the thalamus, hypothalamus, basal forebrain and frontal cortex. After injections into the thalamus, retrogradely labeled neurons were evident within the lateral caudal mesencephalic and dorsolateral oral pontine tegmentum (particularly in the laterodorsal and pedunculopontine tegmental nuclei) and in smaller number within the latero-medial caudal pontine (Reticularis pontis caudalis, Rpc) and medullary (Reticularis gigantocellularis, Rgc) reticular formation. Following [³H]choline injections into the lateral hypothalamus and into the basal forebrain, retrogradely labeled neurons were localized in the dorsolateral caudal midbrain and oral pontine tegmentum and in smaller number in the medial medullary reticular formation (Rgc), as well as in the midbrain, pontine and medullary raphe nuclei. After injections into the anterior medial frontal cortex, a small number of retrogradely labeled cells were found in the brain stem within the laterodorsal tegmental nucleus and the dorsal raphe nucleus. In a parallel immunohistochemical study, choline acetyltransferase (ChAT)-positive neurons were found to be located in most of the regions of the reticular formation where cells were retrogradely labeled from the forebrain following [³H]choline injections. These results suggest that multiple cholinergic neurons within the lateral caudal midbrain and dorsolateral oral pontine tegmentum and a few within the caudal pontine and medullary reticular formation project to the thalamus, hypothalamus and basal forebrain and that a limited number of pontine cholinergic neurons project to the frontal cortex.Abbreviations of Neuroanatomical Terms 3 oculomotor nuc - 4 trochlear nuc - 4V fourth ventricle - 6 abducens nuc - 7 facial nuc - 7n facial nerve - 8n vestibulocochlear nerve - 10 dorsal motor nuc vagus - 12 hypoglossal nuc - 12n hypoglossal nerve - Amb ambiguus nuc - Aq cerebral aqueduct - bic brachium inf colliculus - CB cerebellum - CG central gray - CLi caudal linear nuc raphe - Cnf cuneiform nuc - cp cerebral peduncle - Cu cuneate nuc - D nuc Darkschewitsch - DCo dorsal cochlear nuc - DLL dorsal nuc lateral lemniscus - DPB dorsal parabrachial nuc - DR dorsal raphe nuc - dsc dorsal spinocerebellar tract - DTg dorsal tegmental nuc - dtgx dorsal tegmental decussation - ECu external cuneate nuc - Fl flocculus - IC inferior colliculus - icp inferior cerebellar peduncle - IF interfascicular nuc - InC interstitial nuc Cajal - IO inferior olive - IP interpeduncular nuc - KF Kolliker-Fuse nuc - LC locus coeruleus - Ldt laterodorsal tegmental nuc - Ifp longitudinal fasciculus pons - ll lateral lemniscus - LRt lateral reticular nuc - LRtS5 lateral reticular nucsubtrigeminal - LSO lateral superior olive - LTz lateral nuctrapezoid body - LVe lateral vestibular nuc - mcp middle cerebellar peduncle - Me5 mesencephalic trigeminal nuc - MGD medial geniculate nuc, dorsal - ml medial lemniscus - mlf medial longitudinal fasciculus - MnR median raphe nuc - Mo5 motor trigeminal nuc - MSO medial superior olive - MTz medial nuc trapezoid bbody - MVe medial vestibular nuc - PBg parabigeminal nuc - Pgl nuc paragigantocellularis lateralis - Pn pontine nuc - PPTg pedunculopontine tegmental nuc - Pr5 principal sensory trigeminal - PrH prepositive hypoglossal nuc - py pyramidal tract - Rgc reticularis gigantocellularis - Rgca reticularis gigantocellularis pars alpha - Rmes reticularis mesencephali - RMg raphe magnus nuc - RN red nuc - Ro nuc Roller - ROb raphe obscurus nuc - Rp reticularis parvicellularis - RPa raphe pallidus nuc - Rpc reticularis ponds caudalis - RPn raphe pontis nuc - Rpo reticularis pontis oralis - RR retrorubral nuc - rs rubrospinal tract - RtTg reticulotegmental nuc pons - s5 sensory root trigeminal nerve - SC superior colliculus - SCD superior colliculus,deep layer - SCI superior colliculus, intermediate layer - scp superior cerebellar peduncle - SCS superior colliculus, superficial layer - SGe suprageniculate nuc pons - SNC substantia nigra compact - SNL substantia nigra,lateral - SNR substantia nigra, reticular - SolL solitary tract nuc,lateral - SolM solitary tract nuc, medial - sp5 spinal tract trigeminal nerve - sp5I spinal trigeminal nuc, interpositus - Sp5O spinal trigeminal nuc, oral - spth spinothalamic tract - SpVe spinal vestibular nuc - SuVe superior vestibular nuc - tp tectopontine - ts tectospinal tract - tz trapezoid body - VCo ventral cochlear nuc - VLL ventral nuc lateral lemniscus - VPB ventral parabrachial nuc - vsc ventral spinocerebellar tract - VTA ventral tegmental area - VTg ventral tegmental nuc - vtgx ventral tegmental decussation - xscp decussation superior cerebellar peduncle This investigation was supported by grants from the Medical Research Council (MRC) of Canada (MT-6464: BEJ and MT 7376: AB). B.E. Jones holds a Chercheur Boursier Senior Award from the Fonds de la Recherche en Santé du Quebec (FRSQ), and A. Beaudet a Scientist Award from MRC     

An autoradiographic analysis of ascending projections from the medullary reticular formation in the rat

Ascending projections from the several nuclei of the medullary reticular formation were examined using the autoradiographic method. The majority of fibers labeled after injections of [3H]leucine into nucleus gigantocellularis ascended within Forel's tractus fasciculorum tegmenti which is located ventrolateral to the medial longitudinal fasciculus. Nucleus gigantocellularis injections produced heavy labeling in the pontomesencephalic reticular formation, the intermediate layers of the superior colliculus, the pontine and midbrain central gray, the anterior pretectal nucleus, the ventral midbrain tegmentum including the retrorubral area, the centromedian-parafascicular complex, the fields of Forel/zona incerta, the rostral intralaminar nuclei and the lateral hypothalamic area. Nucleus gigantocellularis projections to the rostral forebrain were sparse. Labeled fibers from nucleus reticularis ventralis, like those from nucleus gigantocellularis, ascended largely in the tracts of Forel and distributed to the pontomedullary reticular core, the facial and trigeminal motor nuclei, the pontine nuclei and the dorsolateral pontine tegmentum including the locus coeruleus and the parabrachial complex. Although projections from nucleus reticularis ventralis diminished significantly rostral to the pons, labeling was still demonstrable in several mesodiencephalic nuclei including the cuneiform-pedunculopontine area, the mesencephalic gray, the superior colliculus, the anterior pretectal nucleus, the zona incerta and the paraventricular and intralaminar thalamic nuclei. The main bundle of fibers labeled by nucleus gigantocellularis-pars alpha injections ascended ventromedially through the brainstem, just dorsal to the pyramidal tracts, and joined Forel's tegmental tract in the midbrain. With the brainstem, labeled fibers distributed to the pontomedullary reticular formation, the locus coeruleus, the raphe pontis, the pontine nuclei, and the dorsolateral tegmental nucleus and adjacent regions of the pontine gray. At mesodiencephalic levels, labeling was present in the rostral raphe nuclei (dorsal, median and linearis), the mesencephalic gray, the deep and intermediate layers of the superior colliculus, the medial and anterior pretectal nuclei, the ventral tegmental area, zona incerta as well as the mediodorsal and reticular nuclei of the thalamus. Injections of the parvocellular reticular nucleus labeled axons which coursed through the lateral medullary tegmentum to heavily innervate lateral regions of the medullary and caudal pontine reticular formation, cranial motor nuclei (hypoglossal, facial and trigeminal) and the parabrachial complex.(ABSTRACT TRUNCATED AT 400 WORDS)     

Mapping of neurokinin b in the cat brainstem

We studied the distribution of neurokinin B-immunoreactive cell bodies and fibers in the cat brainstem using an indirect immunoperoxidase technique. The highest density of immunoreactive fibers was found in the motor trigeminal nucleus, the laminar and alaminar spinal trigeminal nuclei, the facial nucleus, the marginal nucleus of the brachium conjunctivum, the locus coeruleus, the cuneiform nucleus, the dorsal motor nucleus of the vagus, the postpyramidal nucleus of the raphe, the lateral tegmental field, the K?lliker-Fuse nucleus, the inferior central nucleus, the periaqueductal gray, the nucleus of the solitary tract, and in the inferior vestibular nucleus. Immunoreactive cell bodies containing neurokinin B were observed, for example, in the locus coeruleus, the dorsal motor nucleus of the vagus, the median division of the dorsal nucleus of the raphe, the lateral tegmental field, the pericentral nucleus of the inferior colliculus, the internal division of the lateral reticular nucleus, the inferior central nucleus, the periaqueductal gray, the postpyramidal nucleus of the raphe, and in the medial nucleus of the solitary tract. This widespread distribution of neurokinin B in the cat brainstem suggests that the neuropeptide could be involved in many different physiological functions. In comparison with previous studies carried out in the rat brainstem on the distribution of neurokinin B, our results point to a more widespread distribution of this neuropeptide in the cat brainstem.     

Distribution of serotonin-immunoreactivity in the brain of the pigeon (Columba livia)

The distribution of serotonin (5-HT)-containing perikarya, fibers and terminals in the brain of the pigeon (Columba livia) was investigated, using immunohistochemical and immunofluorescence methods combined with retrograde axonal transport. Twenty-one different groups of 5-HT immunoreactive (IR) cells were identified, 2 of which were localized at the hypothalamic level (periventricular organ, infundibular recess) and 19 at the tegmental-mesencephalic and rhombencephalic levels. Ten of the cell groups were situated within the region of the midline from the isthmic to the posterior rhombencephalic level and constituted the raphe system (nucleus annularis, decussatio brachium conjunctivum, area ventralis, external border of the nucleus interpeduncularis, zona peri-nervus oculomotorius, zona perifasciculus longitudinalis medialis, zona inter-flm, nucleus linearis caudalis, nucleus raphe superior pars ventralis, nucleus raphe inferior). The 9 other cell populations belonged to the lateral group and extended from the posterior mesencephalic tegmentum to the caudal rhombencephalon [formatio reticularis mesencephali, nucleus ventrolateralis tegmenti, ectopic area (Ec) of the nucleus isthmo-opticus (NIO), nucleus subceruleus, nucleus ceruleus, nucleus reticularis pontis caudalis, nucleus vestibularis medialis, nucleus reticularis parvocellularis and nucleus reticularis magnocellularis]. Combining the retrograde axonal transport of rhodamine β-isothiocyanate (RITC) after intraocular injection and immunohistofluorescence (fluoresceine isothiocyanate: FITC/5-HT) showed the centrifugal neurons (NIO, ec) to be immunonegative. Serotonin-IR fibers and terminals were found to be very broadly distributed within the brain and were particularly prominent in several structures of the telencephalon (archistriatum pars dorsalis, nucleus taeniae, area parahippocampalis, septum), diencephalon (nuclei preopticus medianus, magnocellularis, nucleus geniculatus lateralis pars ventralis, nucleus triangularis, nucleus pretectalis), mesencephalon-rhombencephalon (superficial layers of the optic tectum, nucleus ectomamillaris, nucleus isthmo-opticus and in most of the cranial nerve nuclei). Comparing the present results with those of previous studies in birds suggests some major serotonin containing pathways in the avian brain and clarifies the possible origin of the serotonin innervation of some parts of the brain. Moreover, comparing our results in birds with those obtained in other vertebrate species shows that the organization of the serotoninergic system in many regions of the avian brain is much like that found in reptiles and mammals.     

5-HT样阳性结构在新生儿脑干内的分布

用免疫组织化学方法(PAP法,ABC法)对5-HT样结构在生后2天的新生儿脑干内的分布进行了观察。发现脑干内的5-HT样阳性胞体可分为延髓中缝群、延髓外侧群、桥脑中脑中缝群和桥脑中脑外侧群。延髓中缝群分别位于中缝苍白核、中缝隐核和中缝大核。延髓外侧群位于网状结构,又可分为腹侧亚群和背侧亚群,前者位于下橄榄核与锥体之间,自内侧向外侧伸展;后者在下橄揽核的背侧,自背内侧向腹外侧斜行排列。桥脑中脑中缝群包括中缝桥核、中央上核、中缝背核、吻侧线状核以及第四脑室底灰质和中脑中央灰质。桥脑中脑外侧群位于桥脑以及中脑尾段的网状结构内,也可分为腹侧亚群和背侧亚群,腹侧亚群沿内侧丘系分布;背侧亚群位于被盖背侧,自背内侧向腹外侧斜行分布。本文观察到粗有膨体、粗无膨体、细无膨体、细有膨体以及颗粒线状等几种纤维。5-HT样终末有的与非5-HT样胞体或树突接触,有的与5-HT样胞体或树突接触,有的伸至第四脑室室管膜,有的与脑内小血管接触。此外也见到5-HT样胞体或树突与脑内小血管接触。5-HT样纤维或终末在三叉神经脊束核、孤束核、面神经核、三叉神经运动核以及网状结构外侧部比较密集,而黑南内则很稀少。     

大鼠臂旁核内5-羟色胺阳性纤维和终末的来源

本研究采用荧光金(FG)逆行追踪与5-羟色胺(5-HT)免疫荧光组化染色相结合的双重技术观察了臂旁核(PBN)内5-HT阳性神经纤维和终末的来源。将FG注入PBN后,FG逆标神经元主要分布在三叉神经核簇、脑干网状结构外侧小细胞部、中缝核簇和中脑导水管周围灰质(PAG);免疫荧光组化染色的结果显示5-HT阳性神经元主要位于中缝核簇和PAG;在中缝核簇和PAG内可见FG逆标并呈5-HT阳性的双重标记神经元。上述结果表明,中缝核簇和PAG内的5-HT能神经元向PBN发出投射,它们在躯体和内脏感觉信息的传递和调控方面发挥重要作用。     

P物质和亮-脑啡肽样免疫反应神经元在鼠中脑中缝核的分布

本实验采用PAP免疫细胞化学技术,观察P物质和亮-脑啡肽样免疫反应神经元在鼠中脑中缝核的分布并作了计数。1.含P物质样免疫反应神经元胞体仅见于中缝背核最尾侧部,含P物质阳性胞体数平均167个/只;而亮-脑啡肽样免疫反应胞体几乎遍于中缝背核全长,其阳性胞体数平均132个/只。2.亮-脑啡肽样免疫反应胞体主要定位于中缝背核中线区;而P物质样免疫反应胞体除分布于中缝背核中线区以外,也定位在其两侧的延伸。3.亮-脑啡肽样免疫反应胞体恒定地出现在中缝正中核内,平均199个/只;而P物质样免疫反应胞体仅见于2例动物。4.中缝背核内有些含P物质样免疫反应阳性胞体或突起,紧邻血管壁排列,未观察到亮-脑啡肽样免疫反应神经元有类似现象。本实验观察到鼠中缝正中核内存在含P物质样免疫反应神经元胞体。     

Immunocytochemical localization of corticotropin-releasing factor in the brain of the turtle, Mauremys caspica

Brain sections of the turtle, Mauremys caspica were studied by means of an antiserum against rat corticotropin-releasing factor. Immunoreactive neurons were identified in telencephalic, diencephalic and mesencephalic areas such as the cortex, nucleus caudatus, nucleus accumbens, amygdala, subfornical organ, paraventricular nucleus, hypothalamic dorsolateral aggregation, nucleus of the paraventricular organ, infundibular nucleus, pretectal nucleus, periventricular grey, reticular formation and nucleus of the raphe. Many immunoreactive cells located near the ependyma were bipolar, having an apical dendrite that contacted the cerebrospinal fluid. Immunoreactive fibers were seen in these locations and in the lamina terminalis, lateral forebrain bundle, supraoptic nucleus, median eminence, neurohypophysis, tectum opticum, torus semicircularis and deep mesencephalic nucleus. Parvocellular bipolar immunoreactive neurons from the paraventricular and infundibular nuclei projected axons that joined the hypothalamo-hypophysial tract and reached the outer zone of median eminence, and the neural lobe of the hypophysis where immunoreactive fibers terminated close to intermediate lobe cells. From these results it can be concluded that, as in other vertebrates, corticotropin-releasing factor in the turtle may act as a releasing factor and, centrally, as a neurotransmitter or neuromodulator.     

Immunocytochemical localization of corticotropin-releasing factor in the brain of the turtle,Mauremys caspica

Brain sections of the turtle, Mauremys caspica were studied by means of an antiserum against rat corticotropin-releasing factor. Immunoreactive neurons were identified in telencephalic, diencephalic and mesencephalic areas such as the cortex, nucleus caudatus, nucleus accumbens, amygdala, subfornical organ, paraventricular nucleus, hypothalamic dorsolateral aggregation, nucleus of the paraventricular organ, infundibular nucleus, pretectal nucleus, periventricular grey, reticular formation and nucleus of the raphe. Many immunoreactive cells located near the ependyma were bipolar, having an apical dendrite that contacted the cerebrospinal fluid. Immunoreactive fibers were seen in these locations and in the lamina terminalis, lateral forebrain bundle, supraoptic nucleus, median eminence, neurohypophysis, tectum opticum, torus semicircularis and deep mesencephalic nucleus. Parvocellular bipolar immunoreactive neurons from the paraventricular and infundibular nuclei projected axons that joined the hypothalamo-hypophysial tract and reached the outer zone of median eminence, and the neural lobe of the hypophysis where immunoreactive fibers terminated close to intermediate lobe cells. From these results it can be concluded that, as in other vertebrates, corticotropin-releasing factor in the turtle may act as a releasing factor and, centrally, as a neurotransmitter or neuromodulator.     

Topographical organization of the brainstem afferents to the lateral posterior-pulvinar thalamic complex in the cat

Following stereotaxic injections of horseradish peroxidase in the dorsal thalamus of the cat which were restricted to the lateralis posterior-pulvinar complex, labelled neurons were found in the superficial layers of the superior colliculus and in the brainstem. The retrogradely-filled cells of the brainstem were situated principally in the nucleus tegmenti pedunculopontinus, the locus coeruleus complex, the parabrachial nuclei and the dorsal tegmental nucleus of Gudden; in each case, labelled cells were more numerous on the ipsilateral side. In addition, some scattered neurons were observed in the central grey matter, the mesencephalic reticular formation, the central superior and dorsal raphe nuclei, the cuneiform nucleus, the nucleus reticularis gigantocellularis, the nucleus praepositus hypoglossi and the oculomotor nuclei. A differential organization of these projections was observed.It is concluded that the rostrointermediate subdivision of the lateralis posterior-pulvinar complex receives most of its connections from the nucleus tegmenti pedunculopontinus, from the deep layers of the superior colliculus and from the other brainstem nuclei, while the caudal subdivision (extrageniculate visual subdivision) receives its main projection from the superficial layers of the superior colliculus. The findings may have functional implications for the role of the complex in oculomotor control.     

Distribution of tyrosine hydroxylase- and serotonin-immunoreactive cells in the central nervous system of the thornback guitarfish, Platyrhinoidis triseriata

Brainstem reticular nuclei of amniotes (mammals, birds and reptiles) may share a common phylogenetic origin as demonstrated by their many shared features (hodology, cytoarchitectonics, presence of neurochemicals). By studying characteristics of these nuclei in outgroups of amniotes, we hope to obtain clues about the phylogeny of the reticular formation. In this paper we report the distribution of immunoreactivity to tyrosine hydroxylase (TH) and serotonin (5-HT) in the brain of an elasmobranch, the thornback guitarfish, Platyrhinoidis triseriata. Our working hypothesis is that if morphologically and immunohistochemically similar cell groups are present, they are homologous to cell groups in amniotes. Thus we have used mammalian terminology. The dorsal and lateral pallium of the telencephalon and many diencephalic nuclei contained TH+ cells. In the mesencephalon, TH+ cell groups were located in raphe linearis, the ventral tegmentum and substantia nigra. The rhombencephalon contained TH+ cells in a putative locus coeruleus (A6), and a subcoeruleus group. Probable A5, A2/C2 and A1/C1 groups were also located. A few 5-HT+ cells were located in the telencephalon and many were found in the diencephalon. In the mesencephalon, 5-HT+ cells were located in the nucleus reticularis pedunculopontinus pars dissipatus (B9). Metencephalic cells were found in reticularis pontis oralis lateralis and medialis, the reticulotegmental nucleus, nucleus centralis superior (B8), reticularis magnocellularis and reticularis pontis caudalis. In the myelencephalon, 5-HT+ cells were contained in raphe pallidus, reticularis paragigantocellularis lateralis and reticularis ventralis pars alpha. The cell shapes, locations, and neurochemical content of Platyrhinoidis reticular groups were very similar to those of amniotes. This elasmobranch has most of the 5-HT+ and TH+ cell groups found in mammals with the major exception that no 5-HT+ cells were in a nucleus which might correspond to raphe dorsalis.     

The somatostatin systems of the guinea-pig brainstem

The tetradecapeptide somatostatin has been shown to have a widespread distribution in the rat brain. Except for its role in the inhibition of growth hormone secretion, the function of this molecule in the remainder of the central nervous system is unknown. To address this problem, the distribution of somatostatin-like immunoreactivity in the guinea-pig brainstem was examined systematically. Of 116 nuclei and/or areas, 34 nuclei had somatostatin neurons, 32 did not have any immunoreactivity and the remainder had immunoreactive fibers and/or terminals. Cranial nerve motor nuclei--somatic, branchiomeric and visceral--did not contain somatostatin neurons; somatostatin fibers were present in all nuclei with the exception of the somatic motor nuclei which innervate the ocular muscles. Of the cranial nerve sensory nuclei--both somatic and visceral--somatostatin neurons were present only in the somatic nuclei nervi spinal trigeminal caudalis, interpolaris and oralis; all of these nuclei, however, contained substantial numbers of immunoreactive fibers. Somatostatin neurons and fibers were also present in the spinal somatic sensory nuclei cuneatus medialis and gracilis. Of the cranial nerve special somatic sensory nuclei, somatostatin neurons were present in two vestibular nuclei--spinalis and medialis--and in the ventral cochlear nucleus. Not all of these nuclei contained somatostatin fibers. Of the nuclei related to the auditory system, somatostatin neurons were present only in the dorsal and ventral trapezoid nuclei and in the cortex of the inferior colliculus. In nuclei of the visual system in the brainstem, somatostatin neurons were present only in the superior colliculus. Of the raphe nuclei, four had somatostatin neurons--magnus, obscurus, pallidus and superior centralis; somatostatin fibers were present in all raphe nuclei. Of 24 nuclei in the reticular formation, 12 had somatostatin neurons--most notably nuclei gigantocellularis and paragigantocellularis--and only two nuclei, paranigralis and sagulum, did not contain any immunoreactive fibers. In the cerebellum, somatostatin fibers and terminals were restricted to the deep cerebellar nuclei. Of the 11 nuclei projecting to the cerebellum, five contained somatostatin neurons and the majority received somatostatin fibers. Of the limbic system nuclei, somatostatin neurons were confined to the central grey at both pontine and mesencephalic levels. Somatostatin neurons were present in the substantia nigra--compactus and lateralis, but not in reticularis--and absent from the nucleus ruber.(ABSTRACT TRUNCATED AT 400 WORDS)