Organization of histaminergic fibers in the rat brain

Detailed information on innervation of the histaminergic system in the brain is essential to an understanding of the physiological roles of this system. In a previous immunocytochemical study with antihistidine decarboxylase (HDC) antibody, we detected extensive networks of histaminergic fibers in many areas of the rat brain (Watanabe et al., '84). In the present study, we improved the immunocytochemical procedure and examined the detailed distribution of histaminergic innervation in the rat brain with anti-HDC antibody. As reported previously, the highest concentrations of fibers were found in the hypothalamic nuclei and medial forebrain bundle. With the modified procedure, we detected more dense networks of HDC-immunoreactive (HDCI) fibers. Furthermore, we demonstrated for the first time the existence of HDCI fibers in other regions, namely, the thalamic nuclei, median eminence, fimbria of the hippocampus, habenular nuclei, superior colliculus, nucleus of the optic tract, parabrachial nuclei, mesencephalic trigeminal nucleus, superior, lateral, and spinal vestibular nuclei, posterior lobe of the hypophysis, and vascular organ of the lamina terminalis. We also found dense transverse fibers in the retrochiasmatic area and supraoptic decussation, which suggests bilateral innervation of the histaminergic system. These results indicate that innervation of the rat brain by the histaminergic system is more extensive than observed previously.     

Peptide-immunocytochemistry of neurosecretory cells in the brain and retrocerebral complex of the sphinx moth Manduca sexta.

Antisera against a variety of vertebrate and invertebrate neuropeptides were used to map cerebral neurosecretory cells in the sphinx moth Manduca sexta. Intense immunoreactive staining of distinct populations of neurosecretory cells was obtained with antisera against locust adipokinetic hormone, bovine pancreatic polypeptide, FMRFamide, molluscan small cardioactive peptide (SCPB), leucine-enkephalin, gastrin/cholecystokinin, and crustacean beta-pigment dispersing hormone (beta PDH). Other antisera revealed moderate to weak staining. Each type of neurosecretory cell is immunoreactive with at least one of the antisera tested, and most of these neurons can be identified anatomically. The staining patterns provide additional information on the organization of cerebral neurosecretory cells in M. sexta. Based upon anatomical and immunocytochemical characteristics, 11 types of neurosecretory cells have been recognized in the brain, one type in the suboesophageal ganglion, and one in the corpus cardiacum. Extensive colocalization experiments show that many neurosecretory cells are immunoreactive with several different antisera. This raises the possibility that these cells may release mixtures of neuropeptides into the hemolymph, as has been demonstrated in certain other systems. The immunocytochemical data should be helpful in efforts to identify additional peptide neurohormones released from the brain of this and other insects.     

Substance P-like immunoreactive amacrine cells in the cat retina

Substance P-like immunoreactivity was localized by immunocytochemical techniques to two subpopulations of amacrine cells in the cat retina. One cell was a unistratified amacrine with processes ramifying within stratum 4 of the inner plexiform layer. The other cell type was a bistratified cell with processes in both stratum 1 (s1) and stratum 4 (s4). Both cell types were seen with their somas displaced to the ganglion cell layer as well as in the conventional amacrine location in the inner nuclear layer. Substance P cells were present in the greatest density within the area centralis and decreased in number toward the periphery. The ratio of amacrine to displaced amacrine cells also decreased peripherally. However, the coverage by immunoreactive fibers in s4 remained three times that seen in s1. Computer-assisted analysis confirmed the location of substance P-containing processes at 5-15% (s1) and 50-70% (s4) depth levels in the inner plexiform layer. A comparison of substance P-like immunoreactivity in light- and dark-adapted cat retinas showed no apparent differences in the distribution of immunoreactivity due to lighting conditions.     

Quantitative ultrastructural analysis of enkephalin-, substance P-, and VIP-immunoreactive nerve fibers in the circular muscle of the guinea pig small intestine

The present work was undertaken to determine what proportion of all nerve fibers in the circular muscle of the guinea pig small intestine contain the neuropeptides enkephalin, substance P, and vasoactive intestinal peptide and in which combinations these peptides occur in the fibers. It was envisaged that such an analysis would provide insights into the chemical identity of excitatory and inhibitory nerve fibers that innervate the muscle. Whole-mount preparations from normal and extrinsically denervated gut were labelled with antiserum to the individual peptides or with combinations of antipeptide antisera and processed for electron microscopy. Reactive and nonreactive vesicle-containing nerve fiber profiles were examined and counted in ultrathin sections. Vesicle-containing nerve fiber profiles immunoreactive for enkephalin, substance P, or vasoactive intestinal peptide had similar morphologies in that they all contained variable proportions of small clear and large granular vesicles. In all samples stained for single peptides or combinations of peptides, a small proportion of immunoreactive profiles approached smooth muscle cells to within 15-20 nm with no intervening basal lamina. A total of 14,694 vesiculated nerve fiber profiles from three control and three extrinsically denervated animals were scored for the presence of immunoreactivity to enkephalin, substance P, vasoactive intestinal peptide, or combinations of these peptides. Analysis of variance showed that the number of profiles labelled for substance P was not different from the number of profiles labelled for vasoactive intestinal peptide and that the number labelled with the substance P and vasoactive intestinal peptide antisera simultaneously were not different from the sum of the numbers obtained with each alone. The number of profiles labelled for substance P plus enkephalin was greater than the number labelled for substance P alone and the number labelled with vasoactive intestinal peptide plus enkephalin was greater than that with vasoactive intestinal peptide alone. Simultaneous labelling for substance P and vasoactive intestinal peptide resulted in immunoreactivity in the same number of profiles as did reaction for all three peptides at the same time. In both cases, about 95% of the profiles were labelled. The results from extrinsically denervated muscle were not different from control circular muscle. These results indicate that nearly all the intrinsic nerve fibers supplying the circular muscle of the guinea pig small intestine contain either substance P or vasoactive intestinal peptide but not both.(ABSTRACT TRUNCATED AT 400 WORDS)     

Synaptic organization of enkephalinlike-immunoreactive amacrine cells in the goldfish retina

Immunoelectron microscopy was used to examine the synaptic organization of enkephalinlike-immunoreactive amacrine cells in the goldfish retina. Enkephalin-immunostained processes sometimes contained dense-cored vesicles (115-145 nm) in addition to a generally homogeneous population of small, round, clear synaptic vesicles. A total of 194 synaptic relationships were observed that involved the immunostained processes of enkephalin-amacrine cells. The large majority of these were observed in sublayer 5 of the inner plexiform layer. In greater than 95% of the synaptic relationships, the enkephalin-immunostained profile served as the presynaptic element. In 58.8% of these relationships, enkephalin processes synapsed onto amacrine cell processes, while 30.4% of their synapses were onto processes that lacked synaptic vesicles. They also occasionally formed synaptic contacts (6.7%) onto the somas of cells located either in the inner nuclear or in the ganglion cell layers. Enkephalin profiles received synaptic input only from amacrine cells (4.1%), while no direct synaptic interaction was observed between enkephalin processes and bipolar cells. However, in sublayer 1, enkephalin profiles were found to synapse onto amacrine cell processes that were presynaptic to bipolar cell terminals. In the proximal inner plexiform layer, enkephalin processes were presynaptic to amacrine cell processes that as a group surrounded and sometimes provided synaptic input to extremely large and round bipolar cell endings.     

Course of retinogeniculate projection fibers in the cat optic nerve

The fiber courses of the cat optic nerve were studied by using wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP), which was iontophoretically applied to electrophysiologically defined positions in the lateral geniculate nucleus (LGN). Grossly, there were two distinct bends along the length of the optic nerve. The ventrally flexing anterior bend was located approximately 2 mm from the eyeball, while the dorsally flexing posterior bend was found at some 6 mm distant. The optic nerve fibers showed a tendency to scatter toward the chiasm. At the optic nerve head, the fibers from the different retinal areas maintained the retinal topography in a simplified form according to the trajectory of optic fibers surrounding the optic disc. Between the anterior and posterior bends, the fibers from the pericentral, middle-temporal, and most upper areas of the dorsal retina migrated ventrally and were arranged in the middle of the lateral, middle, and medial parts of the optic nerve, respectively, while fibers from the middle-temporal area of the ventral retina migrated dorsally and scattered into the lateral half. The fibers from the temporal and nasal horizontal meridian areas tended to hold their respective positions in the lateral and medial halves of the optic nerve. As a result, in this level they displayed a complex retinotopy in that the fibers from each part of the retina were mixed. Passing the posterior bend, as the optic nerve proceeded toward the chiasm, the characteristic pattern became less defined. Near the chiasm, the retinotopy became very scattered, showing a partial dorsoventral inversion of the retinal topography with substantial overlapping. It was noted from the present findings that the fibers from ventral retina scattered more quickly than the fibers from the dorsal retina, which tended to hold their grouping until the anterior bend, but the central or pericentral retinal fibers proceeded without significant scatter as far as the posterior bend. The analysis of labelled ganglion cells suggested that even if fibers that arise from one certain "mode" of ganglion cells are selected, it is unlikely that they maintain their initial fiber topography along the entire length of the optic nerve.     

The distribution of cholecystokinin-like immunoreactivity in the hippocampal formation of the guinea pig: Localization in the mossy fibers

Immunocytochemical techniques were used to localize cholecystokinin octapeptide (CCK-8)-like immunoreactivity in the hippocampal formation of the guinea pig. As in the rat, CCK immunoreactive perikarya are most dense in and around the stratum pyramidale, within the superficial cell layer of the subiculum, and within the polymorph zone of the hilus. Immunoreactive axons are observed within and loosely surrounding the stratum pyramidale, within the stratum lacunosum moleculare, and diffusely distributed across the subiculum. In contrast to the rat, the mossy fiber system also exhibited significant CCK immunoreactivity. The latter system has previously been demonstrated to contain enkephalin-like immunoreactivity in the guinea pig. The present results suggest, therefore, that the enkephalin-like and CCK-like substances either coexist within the mossy fiber boutons or are present within separate subpopulations of the mossy fibers.     

Distribution of calcitonin gene-related peptide-like immunoreactivity in the brain of the small-spotted dogfish,scyliorhinus canicula L

The distribution of neuropeptides has been useful in comparing neuronal aggregates of elasmobranchs with those in other vertebrates. The distribution of calcitonin gene-related peptide (CGRP)-like immunoreactivity in the brain of the dogfish was examined with an antiserum to rat α-CGRP. Western blot analysis confirms that our antiserum recognizes a single peptide in the dogfish brain very similar to mammalian CGRP. CGRP-like immunoreactivity was located in discrete neuronal groups. CGRP-like-immunoreactive (CGRP-ir) neurons were found in the motor nuclei III, IV, V, VI, VII, IX, and X of the brainstem motor column and in the octavolateral efferent neurons. In the isthmal region, two groups of CGRP-ir neurons appeared in the parabrachial region and reticular substance. Three other CGRP-ir cell groups were observed in the mesencephalon: in the ventral tegmental area, in the substantia nigra, and one widely scattered but numerous population in superficial layers of the optic tectum. In the diencephalon, CGRP-ir cells were observed in the magnocellular preoptic nucleus and the organon vasculosum hypothalami. A population of CGRP-ir cells was also observed in the entopeduncular nucleus in the impar telencephalon. CGRP-ir fibers of central origin were widely distributed in the brain, but the most conspicuous areas were found in the ventral telencephalon, the hypothalamus, the mesencephalic lateral reticular area, and the dorsolateral isthmal region. The neurointermediate lobe of the hypophysis was also richly innervated by CGRP-ir fibers. CGRP-ir sensory fibers of cranial nerves IX and X and of dorsal spinal roots formed very conspicuous terminal fields in the lobus vagi and Cajal's nucleus commissuralis and in the dorsal region of the substantia gelatinosa, respectively. Comparison of the distribution of fibers and perikarya in dogfish and other vertebrates suggests that this CGRP-ir system has been well conserved during evolution. © 1995 Wiley-Liss, Inc.     

Amacrine and ganglion cells with corticotropin-releasing-factor-like immunoreactivity in the turtle retina

This study, which uses immunocytochemical methods at the light microscopical, level, examines the cell types in the turtle retina that contain corticotropin-releasing factor (CRF)-like immunoreactivity. Two anatomically distinct amacrine cell types are labeled when antiserum directed against ovine CRF is used to label the turtle retina. These cell types each have a different dendritic arborization pattern and regional distribution. Type A cells are found only in the visual streak and have elongated dendritic arborizations that run parallel to the visual streak. These cells arborize primarily in stratum 1 and near the border of strata 2 and 3, with some processes extending into stratum 5. Type B amacrine cells are found only ventral to the visual streak and arborize primarily in a wide band in strata 4 and 5 with sparse dendritic arborizations in stratum 1. No labeled amacrine cells of any type were found dorsal to the visual streak. The asymmetric dendritic arborizations of the type A amacrine cells and the different regional distributions of the A and B cell types suggest that these two amacrine cell types perform distinct physiological functions. In addition to these labeled amacrine cells, there are also some immunoreactive cell bodies in the ganglion cell layer. Rhodamine crystals were applied to the optic tectum to retrogradely label the ganglion cell bodies. Double label studies indicate that some of the rhodamine-labeled ganglion cells also contain CRF-like immunoreactivity. The localization of CRF-like immunoreactivity in two distinct amacrine cell types and in ganglion cells suggests that it may play multiple roles in visual processing in the turtle retina.     

Ultrastructure and synaptic contacts of enkephalinergic amacrine cells in the retina of turtle (Pseudemys scripta)

Bistratified amacrine cells of the turtle retina containing enkephalin-like immunoreactivity were examined with the electron microscope with the aid of peroxidase immunocytochemical techniques. Our goal was to determine the nature and the location of the synaptic contacts of these cells and the intracellular localization of the immunoreactivity. There was a diffuse reaction product throughout the cytoplasm which coated the surfaces of all the organelles and a dense reaction product which filled the core of some large cytoplasmic vesicles (130 nm in dia.). These labeled amacrine cells received conventional synaptic contacts from other unlabeled amacrine cells and ribbon synaptic contacts from unlabeled bipolar cells, in both the proximal and distal inner plexiform layer. These enkephalin-positive amacrine cells made conventional synaptic contacts containing unlabeled synaptic vesicles (60 nm in dia.), with ganglion cells in the proximal inner plexiform layer and with bipolar cells in the distal inner plexiform layer. These results suggest that enkephalin-like material coexists with another neurotransmitter within these neurons and that these amacrine cells are able to integrate information from both amacrine cells and bipolar cells and provide synaptic input to bipolar cells, ganglion cells, and possibly other amacrine cells.     

Distribution of cholecystokinin-like immunoreactivity in the rat main olfactory bulb

The anatomical localization of cholecystokinin-like immunoreactivity (CCK-I) within the rat main olfactory bulb was analyzed by using the peroxidase-antiperoxidase immunocytochemical technique. Neurons or neuronal processes containing CCK-I were localized within all laminae of the olfactory bulb except the olfactory nerve fiber layer. A large population of CCK-I neurons, with morphology, size, and distribution corresponding to that of the middle and external tufted cells, was observed within a zone extending from the deep periglomerular region through the superficial one-half to one-third of the external plexiform layer. A smaller number of immunoreactive perikarya were found in the deep external plexiform layer, the glomerular layer, and rarely within the inner plexiform layer. These CCK-I neurons appeared to correspond to internal tufted cells, periglomerular cells, and deep short-axon cells, respectively. Dense CCK-I staining of fibers and terminals was present within the internal plexiform layer and, less densely, within the neuropil of the granule cell layer. In addition, terminal-like CCK-I was localized within layer 1A of the anterior olfactory nucleus, the olfactory tubercle, and the most rostral piriform cortex. This observation provides corroboration for the identification of the principal CCK-I neuron in the rat olfactory bulb as the centrally projecting middle tufted cell. The present results, demonstrating the localization of CCK-I to both local circuit and projection neurons of the olfactory bulb and to terminal-like puncta in the internal plexiform and granule cell layers, suggest that CCK may be significantly involved in olfactory processing at several levels.     

Immunohistochemical localization of substance P and enkephalin in the nucleus tractus solitarii of the rhesus monkey, Macaca mulatta

The nucleus tractus solitarii in the monkey Macaca mulatta was found to have several subdivisions based upon cytoarchitectonics and immunohistochemistry. Subdivisions that could be identified included commissural, medial, parvicellular, dorsolateral, ventrolateral, intermediate, and interstitial. Substance P and enkephalin immunoreactivity was localized within discrete regions of the nucleus tractus solitarii, by means of the peroxidase-antiperoxidase technique. Substance P immunoreactivity occurred most frequently in the interstitial subdivision of the nucleus tractus solitarii. Moderate accumulations of substance P immunoreactivity were present in the commissural, medial, parvicellular, dorsolateral, and intermediate subdivisions, but very little was present in the ventrolateral subdivision. Enkephalin immunoreactivity followed the staining patterns of substance P; however, the amounts of enkephalin immunoreactivity were less than amounts for substance P. Following colchicine treatment, large numbers of enkephalin-immunoreactive neurons were distributed throughout all subdivisions, many being located in the parvicellular and medial subdivisions. The few substance P-immunoreactive neurons found were restricted to the parvicellular subdivision. The distribution of substance P and enkephalin immunoreactivity in M. mulatta is very similar to that described in the cat and rat. In addition, the extensive overlap of the distribution of these two putative neurotransmitters provides morphological evidence for their possible participation in the autonomic regulation within the nucleus tractus solitarii.     

Distribution of galanin-like immunoreactivity in the brain of Rana esculenta and Xenopus laevis.

The immunocytochemical distribution of galanin-containing perikarya and nerve terminals in the brain of Rana esculenta and Xenopus laevis was determined with antisera directed toward either porcine or rat galanin. The pattern of galanin-like immunoreactivity appeared to be identical with antisera directed toward either target antigen. The distribution of galanin-like immunoreactivity was similar in Rana esculenta and Xenopus laevis except for the absence of a distinct laminar distribution of immunoreactivity in the optic tectum of Xenopus laevis. Galanin-containing perikarya were located in all major subdivisions of the brain except the metencephalon. In the telencephalon, immunoreactive perikarya were detected in the pars medialis of the amygdala and the preoptic area. In the diencephalon, immunoreactive perikarya were detected in the caudal half of the suprachiasmatic nucleus, the nucleus of the periventricular organ, the ventral hypothalamus, and the median eminence. In the mesencephalon, immunoreactive perikarya were detected near the midline of the rostroventral tegmentum, in the torus semicircularis and, occasionally, in lamina A and layer 6 of the optic tectum. In the myelencephalon, labelled perikarya were detected only in the caudal half of the nucleus of the solitary tract. Immunoreactive nerve fibers of varying density were observed in all subdivisions of the brain with the densest accumulations of fibers occurring in the pars lateralis of the amygdala and the preoptic area. Dense accumulations of nerve fibers were also found in the lateral septum, the medial forebrain bundle, the periventricular region of the diencephalon, the ventral hypothalamus, the median eminence, the mesencephalic central gray, the laminar nucleus of the torus semicircularis, several laminae of the optic tectum, the interpeduncular nucleus, the isthmic nucleus, the central gray of the rhombencephalon, and the dorsolateral caudal medulla. The extensive system of galanin-containing perikarya and nerve fibers in the brain of representatives of two families of anurans showed many similarities to the distribution of galanin-containing perikarya and nerve fibers previously described for the mammalian brain.     

Comparative analysis of the vasotocinergic and mesotocinergic cells and fibers in the brain of two amphibians, the anuran Rana ridibunda and the urodele Pleurodeles waltlii.

To obtain more insight into the vasotocinergic and mesotocinergic systems of amphibians and the evolution of these neuropeptidergic systems in vertebrates in general, the distribution of vasotocin (AVT) and mesotocin (MST) was studied immunohistochemically in the brains of the anuran Rana ridibunda and the urodele Pleurodeles waltlii. In Rana, AVT-immunoreactive cell bodies are located in the nucleus accumbens, the dorsal striatum, the lateral and medial part of the amygdala, an area adjacent to the anterior commissure, the magnocellular preoptic nucleus, the hypothalamus, the mesencephalic tegmentum, and in an area adjacent to the solitary tract. In Pleurodeles, AVT-immunoreactive somata are confined to the medial amygdala, the preoptic area, and an area lateral to the presumed locus coeruleus. In both species, the distribution of MST-immunoreactive cell bodies is more restricted: in the frog, MST-immunoreactive somata are present in the medial amygdala and the preoptic area, whereas, in the urodele, cell bodies are found only in the preoptic area. Both in Rana and Pleurodeles, AVT- and MST-immunoreactive fibers are distributed throughout the brain and spinal cord. A major difference is that in Rana the number of MST-immunoreactive fibers is evidently higher than that of AVT-immunoreactive fibers, whereas the opposite is found in Pleurodeles. This holds, in particular, for the forebrain and the brainstem. The presence of several extrahypothalamic AVT-immunoreactive cell groups and the existence of well-developed extrahypothalamic networks of AVT- and MST-immunoreactive fibers are features that amphibians share with amniotes. However, this study has revealed that major differences exist not only between species of different classes of vertebrates, but also within a single class. In order to determine whether features of these neuropeptidergic systems are primitive or derived, a broad selection of species of each class of vertebrates is needed.     

Light and Electron Microscopic Localization of the Neutral Metalloendopeptidase EC 3.4.24.16 in the Mesencephalon of the Rat

The topographic and cellular distribution of the neurotensin-hydrolysing neutral metalloendopeptidase 24.16 (EC 3.4.24.16) was examined by light and electron microscopic immunohistochemistry in adult rat mesencephalon. Light microscopic immunoradioautography revealed a ubiquitous distribution of the enzyme throughout the midbrain with a relative enrichment of grey matter areas including the substantia nigra, ventral tegmental area, interfascicular nucleus, interpeduncular nucleus, rostral and caudal linear raphe nuclei, central grey and superficial grey of the superior colliculus. Peroxidase - antiperoxidase immunocytochemistry revealed two distinct cellular patterns of immunostaining: (1) weakly labelled neuronal perikarya more or less uniformly distributed throughout the grey matter, and (2) intensely immunoreactive glial cells heterogeneously distributed across the mesencephalon. Areas exhibiting dense concentrations of endopeptidase 24.16-containing glial cells corresponded to those displaying enhanced immunoreactivity in immunoradioautographs, suggesting that a major proportion of brain endopeptidase 24.16 is associated with glia. Electron microscopic examination of the substantia nigra and ventral tegmental area confirmed the association of the enzyme with a subpopulation of neurons and allowed identification of labelled glial cells as protoplasmic astrocytes. In neurons, endopeptidase 24.16 immunoreactivity was distributed heterogeneously within the cytoplasm of perikarya, dendrites and axons. Reaction product was also characteristically associated with restricted zones of the plasma membrane and underlying neuroplasm. In astrocytes, endopeptidase 24.16 immunostaining was densely and uniformly distributed throughout the cytoplasm of cell bodies and processes. Many of these processes were in direct contact with endopeptidase 24.16-immunopositive neuronal elements. The present results demonstrate that within the midbrain, endopeptidase 24.16 is both intracytoplasmic and membrane-associated in neurons and predominantly intracytoplasmic in glia. The presence of a large number of immunostained elements within areas of the midbrain known to display high levels of neurotensin and/or neurotensin receptors, together with the demonstrated catabolic activity of the enzyme on neurotensin in vitro, is consistent with a role of endopeptidase 24.16 in the functional inactivation of endogenous neurotensin in this region of the brain.     

Pigment-dispersing hormone-immunoreactive neurons in the nervous system of wild-type Drosophila melanogaster and of several mutants with altered circadian rhythmicity

Antisera against the crustacean pigment-dispersing hormone (β-PDH) were used in immunocytochemical preparations to investigate the anatomy of PDH-immunoreactive neurons in the nervous system of wild-type Drosophila melanogaster and in that of several brain mutants of this species, some of which express altered circadian rhythmicity. In the wild-type and in all rhythmic mutants (small optic lobes, sine oculis, small optic lobes;sine oculis), eight cell bodies at the anterior base of the medulla (PDFMe neurons) exhibit intense PDH-like immunoreactivity. Four of the eight somata are large and four are smaller. The four large PDFMe neurons have wide tangential arborizations in the medulla and send axons via the posterior optic tract to the contralateral medulla. Fibers from the four small PDFMe neurons ramify in the median protocerebrum dorsal to the calyces of the mushroom bodies. Their terminals are adjacent to other PDH-immunoreactive somata (PDFCa neurons) which send axons via the median bundle into the tritocerebrum. The results suggest a possible involvement of the PDFMe neurons in the circadian pacemaking system of Drosophila. The location and size of the PDFMe neurons are identical with those of neurons containing the period protein which is essential for circadian rhythmicity. Changes in the arborizations of the PDFMe neurons in small optic lobes; sine oculis mutants are suited to explain the splitting in the locomotor rhythm of these flies. In the arrhythmic mutant, disconnected, the PDFMe neurons are absent. The arrhythmic mutant per°, however, shows normal PDH immunoreactivity and therefore, does not prevent the expression of PDH-like peptides in these neurons.© 1993 Wiley-Liss, Inc.     

Somatostatin- and neuropeptide Y-like immunoreactivity in the dentate area, hippocampus, and subiculum of the domestic pig.

With the principal aim of providing baseline observations for future experimental studies, the distribution of somatostatin-like and neuropeptide Y-like immunoreactivities is described in the dentate area, hippocampus, and subiculum of the domestic pig (Sus scrofa domesticus) and compared with the distribution described in other mammals. Intensely stained somatostatin-like immunoreactive nerve cell bodies were present throughout the region, with highest densities in the dentate hilus, stratum radiatum and stratum oriens of the hippocampal regio inferior, stratum oriens of the hippocampal regio superior, and in the subicular cell layer. Somatostatin-like immunoreactive terminals were represented by both stained fibers and stained puncta. Scattered somatostatin-like immunoreactive nerve fibers were seen in most areas, but regular fiber plexuses were present in the dentate molecular layer and dentate hilus, stratum moleculare of the hippocampus, and in the subicular plexiform layer. Somatostatin-like immunoreactive puncta were seen in the dentate molecular layer, stratum moleculare of the hippocampus, and in the subicular plexiform layer. Neuropeptide Y-like immunoreactive nerve cell bodies were less numerous than somatostatin-like immunoreactive ones. They were mainly seen in the dentate granule cell layer and dentate hilus, stratum radiatum and stratum oriens of the hippocampus, and in the subicular cell layer. Intensely stained neuropeptide Y-like immunoreactive fibers were numerous, and present in all areas examined. They formed fiber plexuses in the dentate molecular layer and dentate hilus, stratum moleculare of the hippocampal regio superior, and in the subicular plexiform layer. Neuropeptide Y-like immunoreactive puncta were present in the dentate molecular layer, stratum moleculare of the hippocampus, and in the subicular plexiform layer. Consistent and very characteristic variation in the distribution of somatostatin-like and neuropeptide Y-like immunoreactivity was found along the septotemporal axis of the hippocampus. The distribution of somatostatin-like and neuropeptide Y-like neurons and terminals in the domestic pig displayed striking similarities with the basic pattern of organization of these neuropeptides in other species, although more subtle species-specific characteristics were also observed in the pig.     

Cholecystokinin-, enkephalin-, and substance P-like immunoreactivity in the dentate area,hippocampus, and subiculum of the domestic pig

The distribution of cholecystokinin-like, enkephalin-like, and substance P-like immunoreactivities is described in the dentate area, hippocampus, and subiculum of the domestic pig (Sus scrofa domesticus) as a baseline for future experimental studies. The distributions in the pig are compared with previous observations in other species. Cholecystokinin-like immunoreactive nerve cell bodies were intensely stained and present in large numbers in all subfields studied. Cholecystokinin-like immunoreactive terminals appeared as stained puncta, whereas fibers were only rarely encounterd. The puncta were mainly seen in the dentate molecular layer and dentate granule cell layer, the pyramidal cell layer of the hippocampal regio inferior, stratum moleculare of the hippocampal regio superior, and in the subiculum. Enkephalin-like immunoreactive nerve cell bodies were faintly stained and generally present in very small numbers, except for some pyramidal cells in the subicular cell layer. Enkephalin-like immunoreactive fibers were few in number, whereas stained puncta appeared with variable densities. Puncta of particularly high densities were found in the dentate molecular layer, whereas they appeared of moderate density in the dentate hilus, stratum moleculare of the hippocampal regio superior, and in the subiculum. Substance P-like immunoreactive nerve cell bodies were few and very faintly stined. They primarily occurred in the dentate hilus, stratum oriens of the hippocampus, and in the subicular cell layer. Stained fibers were few in number, whereas stained puncta were present in abundant numbers corresponding to the mossy fiber projection in the dentate hilus and the layer of mossy fibers of the hippocampal regio inferior, and in moderate numbers in stratum moleculare of the hippocampal regio superior and in the subiculum. For all three neuropeptides there were consistent and very characteristic variations in the distribution of immunoreactivity along the septotemporal axis of the hippocampus. When viewed in a comparative perspective the distribution of enkephalin-like and substance P-like terminals in the domestic pig displayed striking differences from the basic pattern observed in other species. This contrasted with the distribution of cholecystokinin-like neurons and terminals, which resembled more closely these species. © 1993 Wiley-Liss, Inc.     

Vasoactive intestinal peptide binding sites and fibers in the brain of the pigeon Columba livia: an autoradiographic and immunohistochemical study.

The distribution of vasoactive intestinal peptide (VIP) binding sites in the pigeon brain was examined by in vitro autoradiography on slide-mounted sections. A fully characterized monoiodinated form of VIP, which maintains the biological activity of the native peptide, was used throughout this study. The highest densities of binding sites were observed in the hyperstriatum dorsale, archistriatum, auditory field L of neostriatum, area corticoidea dorsolateralis and temporo-parieto-occipitalis, area parahippocampalis, tectum opticum, nucleus dorsomedialis anterior thalami, and in the periventricular area of the hypothalamus. Lower densities of specific binding occurred in the neostriatum, hyperstriatum ventrale and nucleus septi lateralis, dorsolateral area of the thalamus, and lateral and posteromedial hypothalamus. Very low to background levels of VIP binding were detected in the ectostriatum, paleostriatum primitivum, paleostriatum augmentatum, lobus parolfactorius, nucleus accumbens, most of the brainstem, and the cerebellum. The distribution of VIP-containing fibers and terminals was examined by indirect immunofluorescence using a polyclonal antibody against porcine VIP. Fibers and terminals were observed in the area corticoidea dorsolateralis, area parahippocampalis, hippocampus, hyperstriatum accessorium, hyperstriatum dorsale, archistriatum, tuberculum olfactorium, nuclei dorsolateralis and dorsomedialis of the thalamus, and throughout the hypothalamus and the median eminence. Long projecting fibers were visualized in the tractus septohippocampalis. In the brainstem VIP immunoreactive fibers and terminals were observed mainly in the substantia grisea centralis, fasciculus longitudinalis medialis, lemniscus lateralis, and in the area surrounding the nuclei of the 7th, 9th, and 10th cranial nerves. The correlation between the distribution of VIP binding sites and immunoreactive fibers and terminals was assessed in a restricted number of regions. A qualitatively good matching was found in the area corticoidea dorsolateralis, hyperstriatum dorsale, hyperstriatum accessorium, nucleus septi lateralis, nuclei dorsomedialis and dorsolateralis thalami, and in some hypothalamic areas. A striking mismatch occurred in the hyperstriatum ventrale, neostriatum, tectum opticum (high to moderate density of binding sites but only few immunoreactive profiles), and in the tuberculum olfactorium, median eminence, and spinal cord (lower density of binding sites but abundant immunoreactive profiles). The paleostriatum, lobus parolfactorius, and ectostriatum were virtually devoid of both binding sites and immunoreactive profiles. The results are discussed in relation to the known actions of VIP in the rodent and avian brain and are compared with previous observations on the distribution of VIP binding sites in the central nervous system of other vertebrates.