Galanin Immunoreactivity Research Articles

The innervation of the gastrointestinal tract of a chelonian reptile, Pseudemys scripta elegans

The myenteric plexus of the stomach, midgut and hindgut of the red-eared turtle, Pseudemys scripta elegans, has been investigated for the occurrence of immunoreactivity to nine neuropeptides. Neuropeptide Y (NPY)-, calcitonin gene-related peptide (CGRP)-, bombesin (BOM)- as well as substance P (SP)-like immunoreactivity (LI) were found in nerve fibres of all investigated gut regions. From all peptides investigated immunoreactivity for NPY was more pronounced. In the stomach NPY-LI was mainly found in the perikarya, while in the midgut region both NPY-immunoreactive (IR) somata and nerve fibres were revealed. The hindgut harboured few NPY-IR nerve cells and nerve fibres. A few SP-IR nerve cell bodies were observed in the stomach and midgut region. In the hindgut BOM-IR neuronal cell bodies were found. Neuromedin U (NMU)-LI was mainly observed in the stomach region, revealing both immunoreactive perikarya and nerve fibres. Immunoreactivity for vasoactive intestinal polypeptide, somatostatin, galanin and enkephalin could not be detected so far. Double labelling experiments revealed the coexistence of CGRP and SP in some nerve fibres in all three gut regions examined. Some SP-IR fibres in the midgut were immunoreactive for NMU.

Immunoreactive nerve fibers in the nasal mucosa

The presence of immunoreactive nervous fibers in the respiratory nasal mucosa of rats and guinea pigs was studied by means of a modified peroxidase antiperoxidase technique for whole mounting. The fibers with neuropeptide Y (NPY) always appeared in the walls of blood vessels, while the fibers immunoreactive to calcitonin gene-related peptide (CGRP) were found in nerve tracts near the vessels and the acini of seromucous glands as thick networks located in the subepithelial layers. Immunoreactivity (IR) for galanin was found in the mucosa studied. The findings after surgical and chemical denervation of the trigeminal and superior cervical ganglia may support the theory that the fibers with NPY are of a sympathetic nature with the superior cervical ganglion their site of origin, while the CGRP-IR fibers may have a sensory nature.

Galanin mRNA in the nucleus basalis of Meynert complex of baboons and humans.

Galanin, a 29-amino acid peptide, has been shown by immunocytochemistry to occur in most large acetylcholinergic neurons of the complex that includes the nucleus basalis of Meynert and the nucleus of the diagonal band of Broca in nonhuman primates. In contrast, several studies have reported that most large neurons of the human nucleus basalis of Meynert complex appear to lack galanin immunoreactivity. We investigated this apparent species-difference by hybridization histochemistry for galanin messenger ribonucleic acid (mRNA) in humans and baboons. The results confirm previous immunocytochemical data; very few large neurons of the nucleus basalis of Meynert complex in humans contained detectable galanin messenger RNA, whereas most such cells in baboons were labeled by the oligodeoxynucleotide probe. The few labeled neurons in humans were primarily medial or ventral to the main body of the nucleus basalis of Meynert and corresponded in location to a minor population of relatively intensely labeled cells in baboons. These findings indicate that the indetectability of immunoreactive galanin in most cells of the nucleus basalis of Meynert complex in humans is due to a paucity or an absence of galanin messenger RNA and not to differences in posttranslational processing or transport of the peptide. Inasmuch as the probe labeled neurons in several other nuclei of both species, it is unlikely that differences in galanin messenger RNA sequences underlie the species-related disparity in hybridization in the nucleus basalis of Meynert complex. The indetectability of galanin messenger RNA in most cells of the human nucleus basalis of Meynert complex indicates that the expression of the galanin gene is regulated by as yet unidentified influences that differ in human and nonhuman primates. The varying phenotypes of galanin in primates suggest potentially important species-differences in the function of galanin in neurons of the nucleus basalis of Meynert complex.

Differential occurrence and distribution of galanin in adrenal nerve fibres and medullary cells in rodent and avian species

The presence and distribution of galanin (GAL) in adrenal glands of rodent and avian species was investigated by light microscopic immunohistochemistry. GAL immunoreactivity was found in all medullary cells of guinea pig, duck and chicken adrenals. In contrast, only a subpopulation of medullary cells stained for GAL in Phodopus (Djungarian hamster) while the neuropeptide was completely missing in chromaffin cells of rat and pigeon. In rat, guinea pig and pigeon, GAL-immunoreactive nerve fibres were frequent in subcapsular regions and sparse in deeper cortical layers and in the chromaffin tissue. In contrast, only very few GAL fibres were found in Phodopus and no GAL fibres were observed in the adrenal glands of duck. In the chicken adrenal gland, fibres containing GAL were numerous throughout the organ and occurred in close vicinity to both steroidogenic as well as catecholaminogenic cells. The striking differences in the presence of GAL-positive cells and fibres are more pronounced between species within the rodent or avian group, respectively, than between the different vertebrate orders. The hitherto unknown and surprising variability of GAL expression and distribution in adrenal glands of various species suggests species-dependent functional (autocrine, paracrine and/or endocrine) roles of GAL in the neuroadrenal axis.

Galanin immunoreactivity in the mudpuppy cardiac ganglion

The source of galanin-immunoreactive fibers in the cardiac ganglion and on cardiac muscle in mudpuppy ( Necturus maculosus) has been determined utilizing immunohistochemical techniques. The galanin-immunoreactive fibers are not processes of afferent fibers originating in either the rostral four dorsal root ganglia or vagal sensory ganglia. Following colchicine treatment, all of the postganglionic parasympathetic neurons and a subpopulation of the small intrinsic neurons in the cardiac ganglion exhibit galanin immunoreactivity. The majority of the galanin-immunoreactive fibers that form complexes on the parasympathetic postganglionic neurons are derived from galanin-immunoreactive small intrinsic neurons, although some of these connections may represent collateral processes from other parasympathetic postganglionic neurons. All of the galanin-immunoreactive processes that innervate cardiac muscle are derived from postganglionic parasympathetic neurons in the cardiac ganglion.

Galanin immunoreactivity is increased in the nucleus basalis of meynert in Alzheimer's disease

A depletion of large cholinergic neurons in the nucleus basalis of Meynert is a consistent finding in Alzheimer's disease (AD). The nucleus basalis of Meynert also contains interneurons and afferents that may modulate its functioning. In the present study we examined neurochemical markers for neuropeptides, amino acid neurotransmitters, and monoaminergic neurotransmitters in postmortem samples of the nucleus basalis in 16 control subjects and 30 patients with AD. There were no significant changes in glutamate, aspartate, taurine, gamma-aminobutyric acid (GABA), and catecholamines; however, concentrations of serotonin, 5-hydroxyindoleacetic acid, and 5-hydroxytryptophol were significantly reduced. Choline acetyltransferase activity was significantly reduced, consistent with previous reports. Galanin immunoreactivity was significantly increased twofold in the patients with AD, but there were no significant changes in substance P, somatostatin, or neuropeptide Y immunoreactivity. Since galanin inhibits acetylcholine release, and produces cognitive deficits in animals, increased galanin immunoreactivity in the nucleus basalis of Meynert in AD may contribute to the cognitive deficits that characterize the illness.

Distinct distribution of CGRP-, enkephalin-, galanin-, neuromedin U-, neuropeptide Y-, somatostatin-, substance P-, VIP- and serotonin-containing neurons in the two submucosal ganglionic neural networks of the porcine small intestine

In addition to differences between the two submucosal ganglionic neural networks, i.e., the plexus submucosus externus (Schabadasch) and the plexus submucosus internus (Meissner), with respect to the occurrence and distribution of serotonin as neurotransmitter, immunocytochemistry also revealed a distinct distribution for various neuropeptides in these two plexuses. Immunoreactivity for galanin, vasoactive intestinal polypeptide, calcitonin gene-related peptide, substance P, neuromedin U, enkephalin, somatostatin and neuropeptide Y was found in varicose and non-varicose nerve fibres of both submucosal ganglionic plexuses, albeit with a distinct distributional pattern. The difference in neurotransmitter and/or neuromodulator content between both neural networks became even more obvious when attention was focussed on the immunoreactivity of the nerve cell bodies for these substances. Indeed, neuropeptide Y, enkephalin- and somatostatin-immunoreactive neuronal perikarya as well as serotonergic neuronal cell bodies appear solely in the plexus submucosus externus. Neuromedin U-immunoreactive perikarya, mostly coexisting with substance P, are observed in large numbers in the plexus submucosus internus, whilst they are rare in the plexus submucosus externus. Double-labelling immunostaining for substance P with CGRP and galanin revealed a different coexistence pattern for the two submucosal ganglionic plexuses. The differing chemical content of the neuronal populations supports the hypothesis that the existence of the two submucosal ganglionic plexuses, present in most large mammals including man, not only reflects a morphological difference but also points to differentiated functions.

Origins and projections of peptide-immunoreactive nerves in the male rat genitofemoral nerve

Following injection of retrograde tracer to one genitofemoral nerve of male rats, motoneurones and dorsal root ganglion cells of segmental levels L 1/L 2 were labelled ipsilaterally. Many labelled motoneurones were calcitonin gene-related peptide- (CGRP) immunoreactive. In the ganglia, a proportion of the labelled cells were CGRP-, tachykinin- or galanin-immunoreactive (10%: 6%: 53% respectively). In comparison with ganglia of the contralateral side, galanin-immunoreactive cells were significantly increased in the ipsilateral ganglia. Unilateral genitofemoral nerve section induced a loss of CGRP- or tachykinin- and an increase of galanin-immunoreactive cells in the ipsilateral L 1/L 2 ganglia. In the ipsilateral L 1/L 2 dorsal horn, CGRP and tachykinin, but not galanin, immunoreactivity was reduced. In the cremaster muscle and scrotal skin of either side galanin-immunoreactive fibres were not visible and CGRP- and tachykinin-immunoreactive fibres were depleted in the ipsilateral side. Capsaicin induced a loss of CGRP- and tachykinin-immunoreactive ganglion cells and of CGRP, tachykinin or galanin immunoreactivity from the dorsal horn. In the scrotal skin, CGRP- and tachykinin-immunoreactive fibres were depleted. By contrast in the muscle, a few CGRP-immunoreactive fibres persisted. The data demonstrate that (i) the genitofemoral nerve originates at segmental levels L 1/L 2; (ii) CGRP- and tachykinin-immunoreactive sensory and CGRP-immunoreactive motor neurones project to the cremaster muscle and scrotal skin; and (iii) nerve pertubation induces an increase of galanin-immunoreactive sensory neurones, the significance of which remains to be elucidated.

Anatomical distribution of galanin-like immunoreactivity in the brain and pituitary of teleost fishes

Immunohistochemical study of brains of five teleost fishes (molly, sea bass, killifish, flounder, tilapia) revealed similar extensive systems of galanin immunoreactive (GAL-ir) neurons. Cell bodies were located in the anterior preoptic recess (where coexistence with corticotrophin-releasing factor-like-ir was found), posterior tuberal hypothalamus and vagal lobe of the medulla oblongata. Fibres in the fingers of neurohypophysial tissue penetrating the pituitary pars distalis suggested an anatomical relationship between GAL-ir terminals and the hormone secreting cells. Electron microscopic studies on sea bass pituitary revealed contacts of GAL-ir fibres with growth hormone cells and gonadotrophs. Thus a GAL-like peptide may be released from nerve terminals in the teleost pituitary, where it may act locally to modulate the secretion of one or more pituitary hormones.

The immunocytochemical distribution of seven peptides in the spinal cord and dorsal root ganglia of horse and pig

The distribution of calcitonin gene-related peptide (CGRP), enkephalin, galanin, neuropeptide Y (NPY), somatostatin, tachykinins and vasoactive intestinal polypeptide (VIP) was compared in cervical, thoracic, lumbar and sacral segmental levels of spinal cord and dorsal root ganglia of horse and pig. In both species, immunoreactivity for the peptides under study was observed at all segmental levels of the spinal cord. Peptide-immunoreactive fibres were generally concentrated in laminae I-III, the region around the central canal, and in the autonomic nuclei. A general increase in the number of immunoreactive nerve fibres was noted in the lumbosacral segments of the spinal cord, which was particularly exaggerated in the case of VIP immunoreactivity. In the horse, some CGRP-, somatostatin- or tachykinin-immunoreactive cell bodies were present in the dorsal horn. In the pig, cells immunoreactive for somatostatin, enkephalin or NPY were noted in a similar location. In the ventral horn most motoneurones were CGRP-immunoreactive in both species. However, in pig many other cell types were CGRP-immunoreactive not only in the ventral horn, but also in laminae V-VI of the dorsal horn. With the exception of enkephalin and NPY immunoreactivity, which was not seen in pig dorsal root ganglia, all peptides studied were localised to neuronal cell bodies and/or fibres in the dorsal root ganglia. In both species, immunolabeled cell bodies were observed in ganglia from cervical, thoracic, lumbar and sacral levels, with the exception of VIP-immunoreactive cells that were detected only in the lumbosacral ganglia. Numerous CGRP- and tachykinin-immunoreactive cell bodies were visualised in both species, while the cells immunolabeled with other peptide antisera were much lower in number. In both species, immunostaining of serial sections revealed that a subset of CGRP-immunoreactive cells co-expressed tachykinin, galanin or somatostatin immunoreactivity. In the horse some enkephalin-immunoreactive cells were also CGRP positive and occasionally combinations of three peptides, e.g. CGRP, tachykinin and galanin or CGRP, tachykinin and enkephalin were identified. The results obtained suggest that the overall pattern of distribution of peptide immunoreactivities is in general agreement with that so far described in other mammals, although some species variations have been observed, particularly regarding the presence of immunoreactive cell bodies in the dorsal horn of the spinal cord.

Distribution of galanin-like peptide in various tissues of Necturus maculosus

Galanin is a biologically active peptide which has a wide pattern of distribution in the mammalian central and peripheral nervous systems. However, the distribution of galanin-like immunoreactivity in amphibian species has not been well elucidated. In the present study, biochemical and immunohistochemical techniques were used to determine the relative concentrations, biochemical nature, and cellular localization of galanin-like immunoreactivity in the brain, heart, urinary bladder, and small intestine of Necturus maculosus (common name: mudpuppy). The results of this study indicate that each of these types of tissue contain a galanin-like peptide which is similar to porcine galanin. Brain and heart concentrations of galanin-like immuno-reactivity were particularly high, although substantial amounts were also present in the small intestine and urinary bladder. Galanin immunoreactivity was observed in ascending fiber tracts of the brainstem and in fibers in the hypothalamus. In addition, galanin immunoreactivity was observed in autonomic neurons and processes in the heart, bladder, and small intestine. The pattern of distribution of galanin-like immunoreactivity in many tissues of this amphibian species is similar to the previously described mammalian pattern; however, galanin-immunoreactive innervation of cardiac tissue has not been reported in mammals. We suggest that galanin-like immunoreactivity in the heart may be more extensive in amphibian species than in mammals.

The co-localization of neuropeptides in the submucosa of the small intestine of normal wistar and non-diabetic bb rats

Immunocytochemical double and triple staining techniques were employed on whole mounts of the submucosal plexus from normal Wistar and non-diabetic BB rat jejunum and ileum, to determine the patterns of co-localization of vasoactive intestinal polypeptide-, peptide histidine-isoleucine-, somato statin-, neuropeptide Y-, calcitonin gene-related peptide-, substance P-, and galanin-immunoreactive nerves. Neuropeptide Y immunoreactivity was found in 38% of submucosal plexus neurons, within the same neuronal elements as vasoactive intestinal polypeptide immunoreactivity (39% of submucosal plexus neurons) and peptide histidine-isoleucine immunoreactivity. A small population (1% of submucosal plexus neurons) containing vasoactive intestinal polypeptide- and peptide histide isoleucine-like immunoreactivity without NPY-like immunoreactivity was also observed. A significant population of fibers containing vasoactive intestinal polypeptide and galanin immunoreactivity were observed in the mucosa and submucosa, although no cell bodies were detected which contained both neuropeptides. Galanin-like immunoreactivity was seen in a small (2% of submucosal plexus neurons) population, not co-localized with any of the other neuropeptides examined. All somatostatin-immunoreactive neuronal elements (18% of submucosal plexus neurons) contained calcitonin gene-related peptide immunoreactivity, just over half of which also contained substance P immunoreactivity. An additional 25% of submucosal plexus neurons contained calcitonin gene-related peptide- without somatostatin-like immunoreactivity and 28% of submucosal plexus neurons contained substance P without somatostatin-like immunoreactivity. Some degree of co-localization was seen between calcitonin gene-related peptide- and substance P-like immunoreactivity, however, this could not be directly quantified. These results were consistent in both regions of the small intestine and in both species, and indicate that at least five populations of neurons exist as defined by neuropeptide co-localization in the submucosal plexus of the rat intestine.

Projections of chemically-specified neurons in the guinea-pig colon.

The arrangement of the enteric nerve plexuses in the colon of the guinea-pig and the distributions and projections of chemically specified neurons in this organ have been studied. Immunoreactivity for neuron specific enolase was used to examine the total population of neurons and individual subpopulations were studied using antibodies raised against calbindin, calcitonin gene-related peptide (CGRP), leu-enkephalin, gastrin releasing peptide (GRP), galanin, gamma aminobutyric acid, neurokinin A, neuropeptide Y (NPY), somatostatin, substance P, tyrosine hydroxylase and vasoactive intestinal peptide (VIP). Neuronal pathways within the colon were lesioned using myotomy and myectomy operations and extrinsic pathways running between the inferior mesenteric ganglia and the colon were also severed. Each of the antibodies revealed nerve cells and nerve fibres or only nerve fibres within the wall of the colon. VIP, galanin and GRP were in anally projecting pathways in the myenteric plexus, as they are in other species. In contrast, there are differences in the projection directions of enkephalin, substance P, NPY and somatostatin nerve fibres between regions and species. Surprisingly, somatostatin and NPY fibres have opposite projections in the small intestine and colon of the guinea-pig. The majority of nerve fibres that innervate the circular muscle, including fibres with immunoreactivity for VIP, enkephalin, substance P, NPY, galanin and GRP come from the myenteric ganglia. The mucosa is innervated by fibres from both the myenteric and submucous ganglia. The present results suggest that the guinea-pig distal colon is a suitable place in which to determine relations between structure, neurochemistry and functions of enteric neural circuits.

Galanin and vasoactive intestinal polypeptide are colocalised with classical pituitary hormones and show plasticity of expression

The identity of galanin- and vasoactive intestinal polypeptide-(VIP) immunoreactive (IR) cells in the rat anterior pituitary was investigated using immunocytochemistry and, since levels of both peptides are stimulated by oestrogen, the effect of oestrogen treatment and gonadectomy on the expression of both peptides was examined. In normal male rats, few galanin-IR and very few VIP-IR cells were found. Colocalisation studies performed on 2-microns serial paraffin sections revealed that in these animals galanin IR was present in somatotrophs and thyrotrophs. In normal females in dioestrus many lactotrophs, in addition to somatotrophs and thyrotrophs, expressed galanin, but very few VIP-IR cells were seen. In cryostat sections of normal rat pituitaries, slightly more VIP-IR cells were present. Oestrogen treatment in females produced an increase in frequency of galanin-IR cells, the vast majority of which were lactotrophs, and more VIP-IR cells, identified as lactotrophs, also appeared. VIP was present in a subset of galanin-IR lactotrophs after oestrogen treatment. After ovariectomy female pituitaries resembled those of normal males, with few galanin positive cells none of which were lactotrophs, and hardly any VIP-IR cells. Thus these two peptides are present in specific endocrine cell types of rat anterior pituitary and display plasticity of expression in different cell types under the influence of oestrogen. Their roles in control of pituitary hormone secretion are supported by these findings, and it is possible that both peptides act in a paracrine fashion within the pituitary.

Novel peptide pancreastatin: its occurrence and codistribution with chromogranin A in the central nervous system of the pig.

The distribution of pancreastatin immunoreactivity was investigated in porcine brain, spinal cord, dorsal root ganglia, and pituitary. In the brain, immunoreactive cell bodies were present in many areas including the cortex, basal ganglia, hippocampus, thalamus, hypothalamus, mesencephalic reticular formation, cerebellum, and medulla oblongata. Immunoreactive fibres were most abundant in the globus pallidus, stria terminalis, entopeduncular nucleus, hippocampus, and in the substantia nigra. In the spinal cord, immunoreactive cells were found in laminae IV-IX. Immunoreactive fibres were concentrated in the dorsal horn. Pancreastatin immunoreactivity was localised to fibres and small cells (5-10% of the total) in the dorsal root ganglia. In the posterior pituitary, many immunoreactive fibres were present and in the anterior lobe subsets of gonadotrophs and thyrotrophs were pancreastatin-immunoreactive. The localisation of pancreastatin showed a parallel distribution with chromogranin A. Coexistence of pancreastatin with calcitonin gene-related peptide (CGRP) immunoreactivity in cell bodies in the spinal cord, including motoneurones, and with CGRP or galanin immunoreactivities in dorsal root ganglion cells was also noted. The differential pattern of pancreastatin immunostaining was reflected in the extractable levels of peptide with highest concentrations in the cortex (55.8 +/- 6.0 pmol/g wet weight, mean +/- S.E.M.), thalamus (60.0 +/- 5.0 pmol/g), hypothalamus (54.4 +/- 6.5 pmol/g), and anterior pituitary (2,714 +/- 380 pmol/g). Characterisation of pancreastatin immunoreactivity in the hypothalamus and pituitary by gel permeation and high-pressure liquid chromatography revealed multiple molecular forms, one of which was indistinguishable from natural porcine pancreastatin. The widespread distribution of pancreastatin immunoreactivity suggests this peptide may play a part in several neuroendocrine, autonomic, somatic, and sensory functions, and its colocalisation with chromogranin A is consistent with a precursor-product relationship.

Light and electron microscopic study of galanin‐immunoreactive nerve fibers in the rat posterior thalamus

Light and electron microscopic immunocytochemistry was used to study certain cell groups in the posteromedial thalamus which contain galanin-immunoreactive (GAL-IR) fibers. The nuclei subparafascicularis pars parvicellularis (SPFpc) and parafascicularis (PF) contain a dense network of GAL-IR fibers which form basketlike structures around unstained cells. The periventricular area also contains numerous GAL-IR fibers and these also occasionally form basketlike structures. The GAL-IR terminal fields continue caudally in the mesodiencephalic junction and merge with other GAL-IR fibers in the dorsal aspects of the substantia nigra and around the dorsolateral tip of the medial lemniscus. Ultrastructural analysis of the GAL-IR basketlike structures revealed that GAL-IR terminals make numerous synapses with the cell bodies and proximal dendrites of SPFpc neurones. These results suggest that the activity of cells in the SPFpc and PF nuclei may be strongly influenced by galanin-containing nerve fibers probably originating in the spinal cord.

Distribution and function of enteric GAL-IR nerves in dogs: comparison with VIP

The distribution of nerves containing galanin-immunoreactive (GAL-IR) material was compared to the distribution of neurons containing vasoactive intestinal polypeptide (VIP) immunoreactivity in the canine gastrointestinal tract. The actions of intra-arterially administered galanin and VIP on motility in the gastric antrum and corpus and the intestines were also studied. All sphincter muscles contained galanin- and VIP-immunoreactive nerve profiles. VIP-immunoreactive nerve profiles were present in all layers of the stomach, small intestine, and colon. GAL-IR nerve somata were common in the submucous plexus of ileum and colon and in the myenteric plexus of the terminal antrum, as were nerve processes in various layers. In the small intestine, galanin inhibited contractile responses to field stimulation of intrinsic nerves and also reduced the contractions after nerve blockade with tetrodotoxin (TTX). VIP often enhanced field-stimulated contractions at low doses but inhibited these and the contractions after TTX at higher doses. In the stomach and colon, both peptides inhibited responses to field stimulation; whether these effects were due to actions on smooth muscle was not tested. The distribution and actions of galanin in gut are consistent with the hypothesis that it acts at smooth muscle sites and possibly at prejunctional sites.

Morphology of peptide‐immunoreactive neurons in the rat central nucleus of the amygdala

The morphological characteristics of peptide-immunoreactive neurons in the rat central nucleus of the amygdala were examined. Observations were compared with details of neuron morphology available from Golgi-stained tissue to determine whether peptide immunoreactivity was associated with specific cell types in the central nucleus. The lateral subdivision (CL) of the central nucleus contained mainly medium-sized, densely spiny neurons. Larger, pyramiform spiny neurons; medium-sized, sparsely spinous neurons; and small, aspinous cells were also present in CL. Somatostatin-, neurotensin-, corticotropin-releasing factor (CRF)-, and enkephalin-immunoreactive neurons in CL were characterized as the medium spiny and larger, pyramiform types. No obvious morphological differences were evident among medium spiny neurons containing different peptides. In the medial subdivision, substance P, neurotensin, somatostatin, and CRF were present within pyramiform, sparsely spinous neurons with long dendrites. Galanin immunoreactivity in the medial subdivision was associated with moderately spiny, pyramiform neurons and a larger, aspinous, polygonal neuron. The ventral subdivision of the central nucleus contained neurons similar to those found in the adjacent medial and lateral subdivisions. In addition, this subdivision contained a characteristic ovoid neuron with long, sparsely spinous dendrites. Vasoactive intestinal polypeptide (VIP) and neurotensin appeared to be present within this cell type. In the lateral capsular subdivision, neurotensin and enkephalin were present in cells resembling the medium spiny neurons characteristic of this part of the central nucleus. Numbers of spindle-shaped, biopolar somatostatin, and VIP neurons were identified in the medial, lateral, and ventral subdivisions. The present results provide evidence for a heterogeneous morphology of peptide-immunoreactive neurons in the rat central nucleus that are distributed across cytoarchitectonic boundaries. Except for substance P, neuropeptides in the central nucleus appear to be expressed by a variety of neurons rather than morphologically characteristic types of cell.

Galanin-like immunoreactivity is present in human substantia innominata and in senile plaques in Alzheimer's disease

Galanin immunoreactivity has been shown to be present in cholinergic magnocellular basal forebrain neurons in both rat and monkey brain. In the present study galanin immunoreactivity in human substantia innominata was found in both the magnocellular neurons of the nucleus basalis of Meynert and in a dorsomedial group of intensely immunoreactive parvocellular neurons. Scattered galanin-immunoreactive fibers, but no immunoreactive neurons, were found in normal human cerebral cortex. Galanin-immunoreactive neurites were found in a small number of senile plaques in the hippocampus and temporal isocortex of Alzheimer's disease patients. The existence of galanin immunoreactivity in human magnocellular basal forebrain neurons which are depleted in Alzheimer's disease suggests that galanin may be similarly affected.

The presence and possible role of a galanin-like peptide in the mudpuppy heart

A correlated histochemical and pharmacological study was undertaken to establish the presence, origin, and possible function of nerve fibers containing a galanin-like peptide in the mudpuppy ( Necturus maculosus) heart. Whole mount preparations of septum-sinus venosus or atria and sections of ventricular muscle were prepared for immunocytochemistry. Galanin-immunoreactive fibers were found coursing diffusely across the septum-sinus venosus to form complex networks over cardiac muscle strands. Individual atrial muscle strands were densely innervated by galanin-immunoreactive fibers and galaninimmunoreactive fibers were also observed in the epicardial and myocardial layers of the ventricle. Most of the parasympathetic postganglionic neurons in the cardiac ganglion and many of the small intensely fluorescent-like cells exhibited galanin immunoreactivity. Galanin-immunoreactive fibers were present in the nerve trunks connecting clusters of parasympathetic postganglionic neurons. Close associations between galanin-positive fibers and individual parasympathetic postganglionic neurons were also observed. The presence of the galanin-immunoreactive fibers was similar in preparations taken from animals pretreated with 6-hydroxydopamine to that seen in preparations taken from control animals, indicating that the galanin-positive fibers were not sympathetic postganglionic axons. Moreover, the galaninimmunoreactive nerve fibers were separate from fibers containing substance P and/or calcitonin gene-related peptide that have previously been shown to be processes of afferent fibers. In twitch-tension experiments, galanin in the range 1 × 10 −7 to 1 × 10 −6M caused cardioinhibition of spontaneously beating isolated septal-sinus venosus preparations. Galanin also produced a concentrationdependent 1 × 10 −7 to 1 × 10 −6M decrease in the twitch-tension development of electrically stimulated atrial or ventricular preparations. Local application of galanin produced hyperpolarization of cardiac muscle fibers in both isolated septal-sinus venosus preparations and atrial preparations. The response of individual parasympathetic ganglion cells to local application of galanin varied between neurons; some neurons were depolarized whereas others were hyperpolarized. We conclude that a galanin-like peptide is contained in both the parasympathetic postganglionic neurons and small intensely fluorescent-like cells and their processes. Further, we hypothesize that in the case of the parasympathetic postganglionic neurons, the galanin-like peptide may work in conjunction with acetylcholine to regulate cardiac activity.