NPY-like peptides occur in the nervous system and midgut of the migratory locust, Locusta migratoria and in the brain of the grey fleshfly, Sarcophaga bullata

The distribution of the NPY-like substances in the nervous system and the midgut of the migratory locust, Locusta migratoria and in the brain of the grey fleshfly, Sarcophaga bullata was determined by immunocytochemistry using an antiserum directed against synthetic porcine NPY. The peroxidase-antiperoxidase procedure revealed that NPY immunoreactive cell bodies and nerve fibers were observed in the brain, optic lobes, corpora cardiaca, suboesophageal ganglion and ventral nerve cord of the locust and in the brain, optic lobes and suboesophageal ganglion of the fleshfly. In the locust midgut, numerous endocrine cells and nerve fibers penetrating the outer musculature contained NPY-like immunoreactivity. The concentrations of NPY immunoreactive material in acetic acid extracts of locust brain, optic lobes, thoracic ganglia, ovaries and midguts was measured using a specific radioimmunoassay technique. The dilution curves of the crude tissue extracts were parallel to the standard curve. The highest amount of NPY-like immunoreactivity was found in the locust ovary and midgut. Reverse-phase high-performance liquid chromatography (RP-HPLC) and radioimmunoassay were used to characterize the NPY-like substances in the locust brain and midgut. HPLC-analysis revealed that NPY-immunoreactivity in the locust brain eluted as three separate peaks. The major peak corresponded to a peptide less hydrophobic than synthetic porcine NPY. RP-HPLC analysis of midgut extracts revealed the presence of an additional NPY-immunoreactive peak which had a retention time similar to the porcine NPY standard. The present data show the existence of a widespread network of NPY immunoreactive neurons in the nervous system of the locust and the fleshfly. Characterization of the immunoreactive substances indicates that peptides similar but not identical to porcine NPY are present in the central nervous system and midgut of insects.     

Localization and identification of Neuropeptide Y (NPY)-like immunoreactivity in the frog brain

The distribution of neuropeptide Y (NPY) in the central nervous system of the frog Rana ridibunda was determined by immunofluorescence using a highly specific antiserum. NPY-like containing perikarya were localized in the infundibulum, mainly in the ventral and dorsal nuclei of the infundibulum, in the preoptic nucleus, in the posterocentral nucleus of the thalamus, in the anteroventral nucleus of the mesencephalic tegmentum, in the part posterior to the torus semicircularis, and in the mesencephalic cerebellar nucleus. Numerous perikarya were also distributed in all cerebral cortex. Important tracts of immunoreactive fibers were found in the infundibulum, in the preoptic area, in the lateral amygdala, in the habenular region, and in the tectum. The cerebral cortex was also densely innervated by NPY-like immunoreactive fibers. A rich network of fibers was observed in the median eminence coursing towards the pituitary stalk. Scattered fibers were found in all other parts of the brain except in the cerebellum, the nucleus isthmi and the torus semicircularis, where no immunoreactivity could be detected. NPY-immunoreactive fibers were observed at all levels of the spinal cord, with particularly distinct plexus around the ependymal canal and in the distal region of the dorsal horn. At the electron microscope level, NPY containing perikarya and fibers were visualized in the ventral nuclei of the infundibulum, using the peroxidase-antiperoxidase and the immunogold techniques. NPY-like material was stored in dense core vesicles of 100 nm in diameter. A sensitive and specific radioimmunoassay was developed. The detection limit of the assay was 20 fmole/tube. The standard curves of synthetic NPY and the dilution curves for acetic acid extracts of cerebral cortex, infundibulum, preoptic region, and mesencephalon plus thalamus were strictly parallel. The NPY concentrations measured in these regions were (pmole/mg proteins) 163±8, 233±16, 151±12 and 60±13, respectively. NPY was not detectable in cerebellar extracts. After Sephadex G-50 gel filtration of acetic acid extracts from whole frog brain, NPY-like immunoreactivity eluted in a single peak. Reverse phase high performance liquid chromatography (HPLC) and radioimmunoassay were used to characterize NPY-like peptides in the frog brain. HPLC analysis revealed that infundibulum, preoptic area and telencephalon extracts contained a major peptide bearing NPY-like immunoreactivity. The retention times of frog NPY and synthetic porcine NPY were markedly different. HPLC analysis revealed also the existence, in brain extracts, of several other minor components cross-reacting with NPY antibodies. These results provide the first evidence for the presence of NPY in the brain of a non-mammalian chordate and indicate that the structure of NPY is preserved among the vertebrate phylum. The abundance of NPY producing neurons in the hypothalamus and telencephalon suggests that this peptide may play both neuroendocrine and neurotransmitter functions in amphibians.     

Neuropeptide Y in the intermediate lobe of the frog pituitary acts as an alpha-MSH-release inhibiting factor

The presence of neuropeptide tyrosine (NPY) in the intermediate lobe of the frog pituitary was demonstrated using indirect immunofluorescence, the immunogold technique and a specific radioimmunoassay combined with high pressure liquid chromatography (HPLC). A high density of NPY-containing fibers, was found among the parenchymal cells of the intermediate lobe. These fibers originated from the ventral infundibular nucleus, travelled via the median eminence to the pars intermedia. At the electron microscopic level, NPY-like material was found exclusively in nerve fibers where the product of the immunoreaction was associated to dense-core vesicles. High concentrations of NPY-like peptide were found in neurointermediate lobe extracts. After Sephadex G-50 gel filtration the major peak of immunoreactive material appeared to co-elute with synthetic porcine NPY. Conversely, HPLC analysis revealed that the NPY-like peptide of the frog pituitary had a retention time shorter than the porcine NPY. The localization of NPY-like material in the pars intermedia suggested a possible role of NPY in the regulation of melanotropic cell secretion. In fact, graded concentrations of synthetic NPY induced a dose-dependent inhibition of alpha-melanotropin (alpha-MSH) release in vitro. The lack of effect of a dopaminergic antagonist on NPY-induced alpha-MSH release inhibition demonstrated that the local dopaminergic system could not account for the NPY action. These results indicate that NPY located in the hypothalamo-hypophyseal system of the frog may act as a melanotropin-release inhibiting factor.     

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

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

Neuropeptide Y (NPY)-like immunoreactive amacrine cells in retinas of frog and goldfish

Summary The distribution of neuropeptide Y (NPY)-like immunoreactivity in rat, rabbit, chick, frog and goldfish retinas was investigated by immunohistochemistry. Positive results were observed only in the frog and goldfish retinas. NPY immunoreactivity was associated with a small population of amacrine cell bodies in the inner nuclear layer and cell processes in the inner plexiform layer of both retinas. In the frog retina, three distinct layers containing immunoreactivity were observed in the inner plexiform layer. In contrast, the immunoreactivity in the same area of the goldfish retina was more or less separated into two layers. Convincing evidence could not be found for the co-existence of NPY-like material with other putative transmitter-like substances in the two retinas.Radioimmunoassay revealed the presence of small amounts of NPY-like immunoreactivity in the rabbit retina; the goldfish and frog retinas contained significantly more immunoreactive material. High performance liquid chromatography of the immunoreactive material in frog and goldfish retinas showed each retina containing different molecular forms of NPY-like proteins, neither of which resembled porcine NPY or PYY.The endogenous NPY-like material of the frog retina can be released by potassium depolarisation in a calciumdependent way. In view of all these data an NPY-like protein must now be considered a potential retinal transmitter.     

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

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

Distribution of GABA-immunoreactive neurons in the forebrain of the goldfish,Carassius auratus

Summary The distribution of gamma-aminobutyric acid (GABA) immunoreactivity was studied in the forebrain (tel-and diencephalon) of the goldfish by means of immunocytochemistry on Vibratome sections using antibodies against GABA. Positive perikarya were detected in the olfactory bulbs and in all divisions of the telencephalon, the highest density being found along the midline. In the diencephalon, GABA-containing cell bodies were found in the hypothalamus, in particular in the preoptic and tuberal regions. The inferior lobes, the nucleus recessus lateralis, and more laterodorsal regions, such as the nucleus glomerulosus and surrounding structures, also exhibited numerous GABA-positive perikarya. Cell bodies were also noted in the thalamus, in particular in the dorsomedial, dorsolateral and ventromedial nuclei. The relative density of immunoreactive fibers was evaluated for each brain nucleus and classified into five categories. This ubiquitous distribution indicates that, as in higher vertebrates, GABA most probably represents one of the major neurotransmitters in the brain of teleosts.     

Relationship between melanin-concentrating hormone- and neuropeptide Y-containing neurons in the goldfish hypothalamus

Intracerebroventricular (ICV) administration of melanin-concentrating hormone (MCH) inhibits food intake in goldfish, unlike the orexigenic action in rodents, via the melanocortin system with suppression of neuropeptide Y (NPY) mRNA expression. We therefore investigated the neuronal relationship between MCH- and NPY-containing neurons in the goldfish brain, using a double-immunofluorescence method and confocal laser scanning microscopy. MCH- and NPY-like immunoreactivities were distributed throughout the brain. In particular, MCH-containing nerve fibers or endings lay in close apposition to NPY-containing neurons in a specific region of the hypothalamus, the nucleus posterioris periventricularis (NPPv). These observations suggest that MCH-containing neurons provide direct input to NPY-containing neurons in the NPPv of goldfish, and that MCH plays a crucial role in the regulation of feeding behavior as an anorexigenic neuropeptide, inhibiting the orexigenic activity of NPY.     

Localization of corticotropin-releasing factor-immunoreactive nervous tissue and colocalization with neuropeptide Y-like substance in the optic lobe and peduncle complex of the octopus (<Emphasis Type="Italic">Octopus vulgaris</Emphasis>)

The distribution of corticotropin-releasing factor (CRF)-like immunoreactivity and its colocalization with neuropeptide Y (NPY)-like substances were investigated in the optic lobe and peduncle complex of the octopus (Octopus vulgaris) using immunohistochemical techniques. In the optic lobe cortex, CRF-immunoreactive (CRF-IR) and NPY-immunonegative varicose fibers were observed in the plexiform layer. In the medulla, CRF-IR somata were seen in the cell islands, and CRF-IR varicose fibers were observed in the neuropil. About half of the CRF-IR structures in the medulla showed NPY-like immunoreactivity. In the peduncle lobe, no CRF-IR somata but abundant CRF-IR varicose fibers were observed, and about half of them showed NPY-like immunoreactivity. In the olfactory lobe, CRF-IR somata and abundant CRF-IR varicose fibers were observed. Almost all the CRF-IR somata located in the posterior olfactory lobule showed NPY-like immunoreactivity, whereas those seen in the median olfactory lobule were immunonegative for NPY. About half of the CRF-IR fibers in the anterior lobule neuropil were immunopositive for NPY, but those in the median and posterior lobule neuropils were immunonegative for NPY. In the optic gland, almost all the CRF-IR varicose fibers were immunoreactive for NPY. Western blot analysis of the optic lobe and peduncle complex indicated that anti-CRF antiserum labeled approximate 16.4- and 14.6-kDa bands and that anti-NPY antiserum labeled an approximate 16.2-kDa band. CRF-IR and NPY-immunoreactive neurons in the optic lobe may participate in the modulation of visual information and those in the optic gland may be involved in the regulation of endocrine function.     

神经肽Y和β—内啡肽样免疫阳性物质在文昌鱼神经系统和哈氏窝的分布

用免疫组织化学方法首次发现,神经肽Y（NPY）和β－内啡肽（β－Ep)样免疫阳性物质分布在文昌鱼神经系统和哈氏窝。NPY样免疫阳性神经元出现在端脑前部和中部、中脑前部和中部以及后脑,NPY样免疫阳性神经纤维在文昌鱼脑的各部分与神经元交错呈网状密集分布。神经管的背面与中部均可观察到NPY样免疫阳性神经元及其阳性性纤维。β－Ep样免疫阳性神经元及其神经纤维定位在中脑前部和中部以及神经管,且分布范围明显小于NPY。文昌鱼哈氏窝也有NPY和β－Ep样免疫阳性物质分布。这些结果表明,NPY和β－Ep可能作为脑内的一种神经递质,像鱼类那样,参与调节文昌鱼哈氏窝促性腺激素分泌细胞的分泌活动,这为文昌鱼脑－哈氏窝复合体的密切关系提供新的形态学证据。     

Three GnRH systems in the brain and pituitary of a pleuronectiform fish,the barfin flounder Verasper moseri

To clarify the possible function of gonadotropin-releasing hormone (GnRH) in the brain of a pleuronectiform fish, the barfin flounder Verasper moseri, the distribution of three forms of GnRH in various areas of the brain was examined by radioimmunoassay, and the localization of GnRH-immunoreactive (ir) cell bodies and fibers in the brain and pituitary was determined by immunocytochemistry. The dominant form in the pituitary was seabream GnRH (sbGnRH), levels of which were much higher than those of salmon GnRH (sGnRH) and chicken GnRH-II (cGnRH-II). In contrast, sbGnRH levels were extremely low in all other brain areas examined. Levels of sGnRH and cGnRH-II were high in the anterior and posterior part of the brain, respectively. sbGnRH-ir cell bodies were located in the preoptic area, whereas sbGnRH-ir fibers were localized mainly in the preoptic area-hypothalamus-pituitary and formed a distinctive bundle of axons projecting to the pituitary. sGnRH-ir cell bodies were located in the ventromedial part of the rostral olfactory bulbs and in the terminal nerve ganglion (the transitional area between the olfactory bulb and the telencephalon). cGnRH-II-ir cell bodies were localized to the midbrain tegmentum. sGnRH-ir and cGnRH-II-ir fibers were observed throughout the brain except in the pituitary gland. These results indicate that sbGnRH is responsible for the neural control of the reproductive endocrinology of the barfin flounder (hypothalamo-hypophysial system), and that sGnRH and cGnRH-II function as neurotransmitters or neuromodulators in the brain.     

Distribution of salmon gonadotrophin releasing-hormone in the brain and pituitary of the sea bass (Dicentrarchus labrax)

Summary The distribution of salmon gonadotrophin-releasing hormone (sGnRH) was studied in the brain and pituitary of two-year-old immature sea bass (Dicentrarchus labrax) by means of an enzymoimmunoassay (EIA) for sGnRH and immunocytochemistry. The EIA for sGnRH is a competitive assay using a tracer made of sGnRH coupled to acetylcholinesterase from an electric eel. The separation of free and bound tracer is achieved by coating the plates with mouse anti-rabbit IgG monoclonal antibodies. Displacement curves generated by sGnRH and extracts from pituitary and different brain regions showed a good parallelism allowing the assay to be used for sGnRH measurements in this species. Although all parts of the brain contained measurable levels of sGnRH, the highest concentrations were found in the pituitary, the olfactory bulbs and the telencephalon. These data were confirmed by immunocytochemistry. Cell bodies were found in the olfactory bulbs, ventral telencephalon, preoptic region and mediobasal hypothalamus. Immunoreactive fibers could be observed in all parts of the brain including the optic tectum, the cerebellum (corpus and valvula), the vagal lobe, the medulla oblongata and the rostral spinal cord. In most cases, these fibers do not form well defined bundles; however, there was clearly a continuum of immunoreactive fibers, extending from the olfactory bulbs to the pituitary, and along which all the cell bodies described above were located. In the ventral telencephalon and the preoptic region, clear pictures of varicose positive fibers contacting immunoreactive perikarya could be observed. These data indicate that sGnRH is most likely an endogenous peptide in the brain of the sea bass, although the presence of other forms of GnRH cannot be excluded at this point. This study also demonstrates that the general organization of the GnRH systems in the sea bass is highly similar to what has been described in most freshwater teleost species, and provides basis for further studies on the neuroendocrine control of gonadotrophin release in this commercially important species.     

Immunohistochemical localization of neuropeptide Y-like substance in the brain and hypophysis of the brown hagfish,Paramyxine atami

The distribution of neuropeptide Y-like immunoreactivity in the brain and hypophysis of the brown hagfish, Paramyxine atami, was examined by use of the peroxidase-antiperoxidase method. Immunoreactive cells were found in two areas of the brain, the nucleus hypothalamicus of the diencephalon and the ventrolateral area of the caudal tegmentum, at the level of the nucleus motorius V–VII. The labeled cells of the nucleus hypothalamicus were loosely grouped and recognized as bipolar neurons. Immunolabeled fibers were widely distributed in the brain, showing the highest density in the diencephalon. They were sparse, or absent, in the olfactory bulb, habenula, primordium hippocampi, neurohypophysis, corpus interpedunculare, and dorsolateral area of the medulla oblongata. The fibers appeared to project exclusively from the ventral hypothalamus to various other portions of the brain: the anterolateral areas of the telencephalon via the basal hypothalamus, the pars dorsalis thalami, the dorsocaudal region of the mesencephalon, and the ventromedial portions of the tegmentum and anterior medulla oblongata. These findings suggest that, in the brown hagfish, NPY-like substance is involved in neuroregulation of various cerebral areas, but it may be of little significance in the control of pituitary function.     

Neuromedin U--a study of its distribution in the rat

The distribution of neuromedin U, a novel peptide originally isolated from porcine spinal cord, was investigated in the rat using a recently developed radioimmunoassay. High concentrations of neuromedin U-like immunoreactivity were found in the pituitary gland and gastrointestinal tract. Significant concentrations of immunoreactivity were also found in several regions of the rat brain, spinal cord and both male and female genitourinary tracts. In the small intestine, neuromedin U-like immunoreactivity was restricted to the submucosal muscular layers, suggesting localization in neurones rather than in epithelial cells. Chromatographic analysis of pituitary, spinal cord and gut revealed a single peak of immunoreactivity which did not co-elute with either synthetic porcine neuromedin U-25 nor neuromedin U-8, indicating inter-species molecular heterogeneity.     

Immunocytochemical localization of neuropeptide Y (NPY) in the human hypothalamus

Summary In order to study the distribution of neuropeptide Y-like immunoreactivity in the human hypothalamus, an immunocytochemical localization of this peptide was performed. Using antibodies developed against synthetic porcine neuropeptide Y (NPY), we have been able to localize immunoreactivity in neuronal cell bodies located exclusively in the infundibular nucleus. Immunostained fibers were found in several regions in the hypothalamus with a high concentration in the periventricular areas. Fibers were also found in the neurovascular zone of the median eminence, the pituitary stalk and the posterior pituitary. These results suggest that immunoreactive material related to porcine NPY is present in the human hypothalamus, with a distribution similar to that observed in the rat.     

Immunocytochemical localization of a galanin-like peptidergic system in the brain and pituitary of some teleost fish.

Immunostaining of brain and pituitary sections of teleost fishes (eels, salmonidae, cyprinidae, gourami, sculpin, mullet) with anti porcine galanin (GAL) revealed the presence of immunoreactive (ir) perikarya and a rich network of fibers. Ir-perikarya were located rostrodorsally to the recessus preopticus, and in the posterior tuberal hypothalamus. Ir-fibers were abundant in basal telencephalon and around diencephalic ventricular recesses but never contacted their lumen. Furthermore, they were observed in basal hypothalamus, brainstem and ventral medulla. Ir-fibers passed along corticotropic (ACTH), gonadotropic cells and somatotropes (GH cells) in eel and trout pars distalis, but rarely ended in caudal neurohypophysis. In goldfish pituitary ir-fibers occurred in neural digitations and among different cell types which however did not contain a GAL-like peptide. The relation GAL fibers/GH cells appeared more evident in species with a high growth rate. The other species showed a similar distribution of brain GAL. In eels and trout, ir-perikarya were not observed in areas containing somatostatin, GH- and ACTH-releasing factor, and ACTH-like perikarya, suggesting that GAL did not coexist with these peptides. The widespread distribution of a GAL-like peptide in teleost brain suggests that it could play a role of neurotransmitter and/or neuromodulator and regulate the secretion of adenohypophysial hormone(s).     

gamma 2-[corrected]-MSH-like immunoreactivity in porcine pituitary and adrenal medulla. An immunochemical and immunocytochemical study

A sensitive and specific radioimmunoassay for gamma 2-melanotropin (gamma 2-MSH) has been developed that does not recognize alpha-, beta-, gamma 1- or gamma 3-MSH. gamma 2-MSH-like immunoreactivity could be demonstrated in the porcine pituitary and adrenal gland. The highest concentrations were detected in the neurointermediate lobe regardless of extraction procedure. The anterior lobe harboured lower concentrations and in adrenal gland extracts only small amounts were measured. Gel chromatography and high performance liquid chromatography of extracts of both pituitary and adrenal gland revealed several peaks of immunoreactive material, one of which eluted close to the position of synthetic gamma 2-MSH. By immunocytochemistry gamma 2-MSH immunoreactivity was localized to the adrenocorticotropin/alpha-MSH cells in the pituitary and to a subpopulation of the noradrenaline-storing cells in the adrenal medulla. Together, the immunocytochemical and immunochemical findings indicate the existence of gamma 2-MSH-like material in the porcine pituitary and adrenal medulla.     

Splanchnic Nerve Transection Abolishes the Age-Dependent Increase of Neuropeptide Y-Like Immunoreactivity in Rat Adrenal Gland

Using an antiserum directed against porcine neuropeptide Y (NPY), a high concentration of NPY immunoreactivity (NPY-IR) was detected in rat adrenal gland. The level of NPY-IR in the adrenal gland was found to increase considerably with age. Biochemical characterization by reverse-phase HPLC indicated that this increase was due to accumulations of NPY and another molecular form of NPY-like immunoreactive peptide. Chronic denervation of the splanchnic nerve abolished this age-dependent increase of NPY-IR rat adrenal gland.     

Distribution and partial characterisation of immunoreactivity to the putative C-terminus of rat pancreastatin

The presumptive C-terminal nonapeptide of rat pancreastatin was synthesised based upon the sequence of rat chromogranin A (CGA) analogous to that of porcine pancreastatin as contained within porcine CGA. Antisera were produced which were used to determine the qualitative and quantitative distribution of pancreastatin-like immunoreactivity in rat tissues by immunocytochemistry and radioimmunoassay respectively. Pancreastatin-like immunoreactivity was most abundant in pituitary, adrenal, gastric corpus and thyroid with considerably lower levels detected in the remainder of the gastroentero-pancreatic system and brain. Immunoreactivity was localised exclusively in endocrine cells and the relative abundance of immunoreactive cells paralleled the levels obtained radioimmunometrically. Chromatographic characterisation of pancreastatin-like immunoreactivity revealed molecular heterogeneity. Immunoreactive peptides of similar size to synthetic rat pancreastatin were present in gastrointestinal tissues and thyroid. These data indicate a tissue specific processing of CGA in the rat.