Immunochemical studies on big gastrin using NH2-terminal specific antisera

Methods are described for obtaining antisera specific for the NH₂-terminal regions of human and porcine big gastrin (G34) that can be used in radioimmunoassays. Three antisera have been characterized in detail: one (L66) raised to human 1–15 (Tyr⁷Pro⁸Ser⁹) G34 has an antigenic determinant in the 1–6 region of human G34; a second (L107) raised to 1–19 hG34 has an antigenic determinant in the 1–12 region. Both these antisera react weakly with porcine G34. A third antiserum (L33) raised to porcine G34 has an antigenic determinant in the 1–12 region of this peptide, and reacts weakly with human G34. In human antral extracts fractionated on Sephadex G50. L66 and L107 revealed a minor peak of immunoreactivity corresponding to G34, and a major peak corresponding to the NH₂-terminal tryptic peptide of G34. Concentrations of the latter peptide were closely similar to those of G17 (i.e. the COOH-terminal tryptic peptide of G34), consistent with the idea that G34 is cleaved within G-cells by a trypsin-like enzyme to yield G17. Antiserum L33 revealed small amounts of immunoreactivity in antral extracts of dog and cat, but did not reveal significant immunoreactivity in rat antral extracts. In contrast, L66 reacted with rat antral extracts, but not dog or cat. The sequences of G34 in these species are not known, but the results suggest significant differences compared with human and porcine G34, and indicate a high degree of species-specificity with NH₂-terminal G34 antisera.     

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.     

Arg3]substance P and neurokinin A from chicken small intestine

Using antisera specific for NH2-terminal and COOH-terminal regions of substance P and for the COOH-terminal region of neurokinin A, peptides with tachykinin-like immunoreactivity were isolated from extracts of chicken small intestine. The peptide Arg-Pro-Arg-Pro-Gln-Gln-Phe-Phe-Gly-Leu-Met-NH2 differs from human substance P by substitution of the lysyl residue by an arginyl residue at position 3. Synthetic [Arg3]substance P showed identical chromatographic and immunochemical properties to chicken substance P and was equipotent with substance P in contracting the guinea pig ileum. A second peptide His-Lys-Thr-Asp-Ser-Phe-Val-Gly-Leu-Met-NH2 isolated from the extracts is identical to human neurokinin A. A third peptide was immunoreactive towards the COOH-terminally directed anti-serum to substance P only but was not characterized structurally in this study.     

Identification, characterization and release of GRP gene-associated peptides from the normal porcine and human gastro-intestinal tract

Using a radioimmunoassay directed towards human proGRP (42-53) on acetic acid extracts, immunoreactivity was measured throughout the porcine GI-tract in concentrations that were parallel to those of GRP (gastrin-releasing peptide or 'mammalian bombesin'). Gel filtration and HPLC studies of human and porcine tissue extracts revealed that the immunoreactivity was mainly due to a peptide with a molecular size of 8-9 kDa. The peptide did not contain the GRP sequence, making it a major fragment of the GRP C-flanking part of proGRP. Furthermore, a peptide of similar size with proGRP (42-53) immunoreactivity was released from isolated, perfused preparations of porcine antral and non-antral stomach and pancreas in parallel with GRP in response to electrical stimulation of the vagus nerves. Our results suggest that a processing of preproGRP occurs in normal, adult human and porcine tissues, that is similar to that previously demonstrated in small cell lung carcinomas and human fetal lungs. The finding that the immunoreactive proGRP fragment is released from the tissues upon appropriate stimulation raises the question of a possible physiological role for proGRP products other than GRP.     

Anglerfish islets contain NPY immunoreactive nerves and produce the NPY analog aPY

It has recently been demonstrated that aPY, a peptide which has significant homology with neuropeptide Y (NPY) is present in extracts of anglerfish islets. The purpose of this study was to determine whether cells or nerves which contain NPY-like immunoreactivity could be identified in anglerfish islet tissue and whether aPY is synthesized by this tissue. Antisera against bovine pancreatic polypeptide (BPP), NPY and the 200 kd neurofilament polypeptide were used for immunohistochemical analysis of islets. Identical cells were stained by both the NPY and BPP antisera. The NPY and 200 kd neurofilament antisera also labeled nerve fibers in the tissue which were not stained with the BPP antiserum. The nature of the NPY-like peptide synthesized in islet cells was determined by subjecting differentially radioactively labeled Mr 2,500-8,000 peptides from islet extracts to reverse phase HPLC. Labeled aPY was unequivocally identified in the extracts and was labeled appropriately (as predicted from its sequence) with 13 different radioactive amino acids. These results demonstrate that one form of NPY-like peptide synthesized in anglerfish islets is aPY. The form of NPY-like peptide which was immunolocalized in nerves remains to be determined.     

Demonstration of a neuropeptide Y-like immunoreactivity in human phaeochromocytoma extracts

Using a porcine neuropeptide Y directed radioimmunoassay it was shown that acid extracts of human phaeochromocytoma tumour tissue contained a neuropeptide Y-like peptide. Further fractionation and purification of this immunoreactivity showed that this human neuropeptide Y-like immunoreactivity was closely similar in molecular size and separation characteristics to porcine neuropeptide Y. The possible contribution of neuropeptide Y to the hypertension characterizing human phaeochromocytoma is discussed.     

The primary structure of peptide Y (PY) of the spiny dogfish, Squalus acanthias: immunocytochemical localisation and isolation from the pancreas.

1. Endocrine cells within islets, exocrine parenchyma and ductal epithelium in the pancreas of the spiny dogfish, Squalus acanthias, were immunostained with an antiserum to the C-terminal region of mammalian neuropeptide Y (NPY). 2. Radioimmunoassay of pancreatic extracts with the same antiserum detected immunoreactivity in the dorsal lobe (338 pmol/g) and ventral lobe (433 pmol/g). Reverse phase HPLC analysis of both extracts resolved a single immunoreactive peptide. 3. The primary structure of the isolated peptide was established as: YPPKPENPGEDAPPEELAKYYSALRHYINLITRQRY.NH2. 4. Peptide Y (PY) from Squalus acanthias is identical in primary structure to an NPY-related peptide isolated from the pancreas of Scyliorhinus canicula and has a 31/36 residue homology with porcine NPY. The 5 substitutions are highly-conservative.     

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.     

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.     

Re-evaluation of the effects of neuropeptide Y on aggregation of human platelets.

Several studies have shown that platelets are a major source of circulating neuropeptide Y (NPY) immunoreactivity in rats, but the effects of this vasoconstrictor peptide on platelets are not well-defined. Recently, it was reported that porcine NPY was an inhibitor of in vitro human platelet aggregation induced by epinephrine, an observation which would have important implications regarding platelet-vascular interactions during states involving platelet activation and thrombosis. Thus, we undertook the present studies, in an attempt to confirm the earlier report, and to extend those observations to human NPY. In contrast to the recent report, we found no inhibitory effect of either human or porcine NPY on epinephrine- or collagen-induced aggregation of human platelets from normal subjects. Likewise, specific NPY Y-1 and Y-2 agonists had no direct or indirect action on platelet aggregation. Finally, the effect of human NPY on intraplatelet cAMP was measured. The peptide had no effect on either basal or iloprost-stimulated cAMP levels. We hypothesize that the role of NPY in the platelet-vascular interaction is in promoting vasoconstriction associated with platelet aggregation, and does not include inhibition of further thrombosis.     

The use of region-specific antibodies in the characterization and localization of vasoactive intestinal polypeptide-like substances in the rat gastrointestinal tract

Antisera specific for different regions of porcine VIP have been used in radioimmunoassay and immunohistochemical studies of immunoreactive VIP in rat small and large intestine. Cation exchange chromatography of intestinal extracts separated two major and one minor peak of immunoreactivity. One major peak eluted in a similar position to natural porcine VIP and was read equally by NH₂-terminal-specific, and mid- and COOH-terminal-specific antisera. A second major peak, and the minor peak, eluted earlier than porcine VIP, and were read significantly less well with mid- and COOH-terminal antisera compared with NH₂-terminal-specific antisera. All forms of VIP occurred mainly in extracts of muscle layers of the gut, and no antiserum revealed more than trace amounts of immunoreactivity in mucosal extracts. In immunohistochemical studies all antisera demonstrated fluorescent nerve fibres in the enteric plexuses, circular smooth muscle and lamina propria; some antisera demonstrated nerve cell bodies predominantly in the submucous plexus. NH₂-terminal-specific antisera also demonstrated a sparse population of mucosal endocrine-like cells in the ileum and colon that were not seen with other antisera. It is concluded that VIPergic neurons of the rat gut contain a peptide closely resembling porcine VIP and at least two less basic variants with similar NH₂-terminal antigenic determinants. VIP-like peptides may also occur in endocrine cells, but since these peptides appearto fact that the majority of neuronal VIP in rat gut exists in a form that is both chromatographically and immunochemically distinct from porcine VIP, and may well possess different biological properties.     

Immunohistochemical localisation of natriuretic peptides in the heart and brain of the gulf toadfish Opsanus beta

Summary The distribution of natriuretic peptide immunoreactivity was determined in the heart and brain of the gulf toadfish Opsanus beta using the avidin-biotin peroxidase technique. Four antisera were used: the first raised against porcine brain natriuretic peptide which cross-reacts with atrial natriuretic and C-type natriuretic peptides (termed natriuretic peptide-like immunoreactivity); the second raised against porcine brain natriuretic peptide which cross-reacts with C-type natriuretic peptide but not with atrial natriuretic peptide (termed porcine brain natriuretic peptide-like immunoreactivity); the third raised against rat atrial natriuretic peptide; and the fourth raised against eel atrial natriuretic peptide. Natriuretic peptide- and porcine brain natriuretic peptide-like immunoreactivity was observed in all cardiac muscle cells of the atrium. In the ventricle, natriuretic peptide-like immunoreactivity was found in all cardiac muscle cells, however porcine brain natriuretic peptidelike immunoreactivity was confined to muscle cells adjacent to the epicardium. There was no discernible difference in the distribution of natriuretic peptide-like immunoreactivity and porcine brain natriuretic peptide-like immunoreactivity in the brain. Immunoreactive perikarya were observed only in the preoptic region of the diencephalon, and many immunoreactive fibres were found in the telencephalon, preoptic area, and rostral hypothalamus, lateral to the thalamic region. There was no immunoreactivity in any region of the hypophysis. A pair of distinct immunoreactive fibre tracts ran caudally from the preoptic area to the thalamic region, from which fibres extended to the posterior commissure, area praetectalis, dorsolateral regions of the midbrain tegmentum, and tectum. Many immunoreactive fibres were present in the rostral regions of the inferior lobes of the hypothalamus and in the dorsolateral and ventrolateral aspects of the rhombencephalon. No immunoreactivity was observed in the heart and brain using rat atrial natriuretic and eel natriuretic peptide antisera. Although the chemical structure of natriuretic peptides in the heart and brain of toadfish is unknown, these observations show that a component of the natriuretic peptide complement is similar to porcine brain natriuretic and/or porcine C-type natriuretic peptides. The presence of natriuretic peptides in the brain suggests that they could be important neuromodulators and/or neurotransmitters.     

Co-localization of peptides in the Brockmann bodies of the cod (Gadus morhua) and the rainbow trout (Oncorhynchus mykiss)

Endocrine cells exhibiting immunoreactivity to FMRFamide-like, LPLRFamide-like, neuropeptide Y(NPY)-like and peptide YY(PYY)-like peptides were found in the periphery of the Brockmann bodies of the cod, Gadus morhua, and rainbow trout, Oncorhynchus mykiss. No immunoreactivity or very weak labelling was found with antisera to pancreatic polypeptide (PP). Vasoactive intestinal polypeptide (VIP)-like immunoreactivity was found in nerve fibres, whereas labelling with VIP antiserum in endocrine cells disappeared after preincubation with nonimmune serum. There were always more immunoreactive cells in the rainbow trout than in the cod. No immunoreactivity could be seen with antisera to gastrin/cholecystokinin (CCK) or enkephalin. Double-labelling studies were performed to study the colocalization of the peptides in peripheral endocrine cells. Cells immunoreactive to NPY were also labelled with antisera to FMRFamide, LPLRFamide and PYY. The co-localization pattern of NPY varied; in some Brockmann bodies, a population of the immunoreactive cells showed co-localization and others contained NPY-like immunoreactivity only, whereas in other Brockmann bodies, all NPY-labelled cells also contained FMRFamide-like, LPLRFamide-like and PYY-like immunoreactivity. Cells immunoreactive to PYY similarly contained FMRFamide-like, LPLRFamide-like and NPY-like immunoreactivity, comparable to the patterns observed with NPY. Glucagon-like immunoreactivity was found at the periphery of the Brockmann bodies. A subpopulation of the glucagon-containing cells contained NPY-like immunoreactivity. PYY-like immunoreactivity was also found co-localized with glucagon-like immunoreactivity, as were FMRFamide-like and LPLRFamide-like immunoreactivity. Therefore, either NPY-like and PYY-like immunoreactivity together with FMRFamide-like and LPLRFamide-like immunoreactivity occur in the same endocrine cells of the Brockmann body of the cod and rainbow trout, or a hybrid NPY/PYY-like peptide recognized by both NPY and PYY antisera is present in the Brockmann body.     

Circulating neuropeptide Y in dog plasma consists of multiple peptide fragments

Neuropeptide Y-like immunoreactivity (NPY-LI) in dog plasma was characterized and quantified using three extraction methods (Sep-Pak:acetonitrile, HCl:ethanol, and ethanol). Sep-Pak extraction yields the best recovery and preserves the integrity of the peptide. Oxidized NPY is not generated during blood collection. Using two antisera of different specificities, at least three peptide forms in normal dog arterial and venous plasma were detected. A peptide with retention times similar to oxidized NPY or peptide YY is the major component of plasma NPY-LI under basal conditions, but NPY(1–36) predominates during sympathetic stimulation. The mature peptide in dog plasma is similar to human NPY. The antiserum ABII provides a more accurate measure of circulating NPY(1–36) and its oxidized form. The antiserum ABI is useful for detecting NPY-like fragments.     

The nerves of the juxtaglomerular apparatus of man and other mammals contain the potent peptide NPY

The juxtaglomerular apparatus, a neuroendocrine unit located in the vascular pole of the glomerulus and influencing blood pressure by the secretion of renin, is known to have a rich supply of monoaminergic nerve fibres. Neuropeptide Tyrosine (NPY), a newly discovered, potent, vasoconstrictor peptide of 36 amino acids, has been found by immunocytochemistry to be present in a dense plexus of fibres around the juxtaglomerular apparatus of man, monkey, mouse, hamster, rat and guinea pig. NPY-immunoreactivity was markedly depleted after chemical sympathectomy by 6-hydroxydopamine. The concentration of NPY within the whole mouse kidney was 29.6 +/- 6.8 pmol/g and fractionation of the extracts demonstrated that the NPY-like immunoreactivity co-eluted from the column in the same position as the porcine NPY standard. The role of this peptide in renal physiology and pathology now needs urgent investigation.     

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 and biochemical characterization of guanine nucleotide-binding regulatory proteins in mammalian spermatozoa

Polyclonal antisera directed against conserved and subtype-specific peptide sequences of the alpha-subunits of guanine nucleotide-binding regulatory proteins (G proteins) were used to characterize the nature of mammalian sperm G proteins and to determine whether their localization was consistent with their proposed roles in mediating ZP3-induced acrosomal exocytosis. Mouse and guinea pig sperm exhibit positive immunofluorescence in the acrosomal region using an antiserum directed against a peptide region common to all alpha-subunits of G proteins (G alpha). The immunofluorescence disappears after sperm have undergone the acrosome reaction, suggesting that the immunoreactive material is associated with the plasma membrane/outer acrosomal membrane region overlying the acrosome. The presence of G proteins in this region is confirmed by the presence of a Mr 41,000 substrate for pertussis toxin (PT)-catalyzed [32P]ADP-ribosylation in purified plasma membrane/outer acrosomal membrane hybrid vesicles obtained from acrosome-reacted guinea pig sperm. Immunoprecipitation and polyacrylamide gel electrophoresis of PT-catalyzed [32P]ADP-ribosylated protein(s) using anti-peptide antisera generated against sequences unique to Gi alpha 1, Gi alpha 2, and Gi alpha 3 confirm the existence of all three Gi subtypes in mouse sperm extracts. Indirect immunofluorescence using an antiserum directed against a peptide region present in Gz alpha, a PT-insensitive G protein, demonstrates positive immunoreactivity in the postacrosomal/lateral face region of the mouse sperm head. This immunoreactivity is retained during acrosomal exocytosis in response to solubilized ZP and then disappears subsequent to this exocytotic event. These data demonstrate that Gi protein alpha-subunits are present in the acrosomal region of mammalian sperm, consistent with their postulated role in regulating ZP3-mediated acrosomal exocytosis, and that PT-insensitive Gz alpha is found in a region of the sperm head distinct from that of the Gi alpha subunits.     

Distribution and characterisation of neuropeptide Y immunoreactivity in the brain and gastrointestinal tract of the rainbow trout,Oncorhynchus mykiss

1. Neuropeptide Y (NPY) immunoreactivity has been localised cytochemically in neuronal somata and fibres in rainbow trout brain, nerve fibres and mucosal epithelial endocrine cells within the gastrointestinal tract and in endocrine cells within pancreatic islets.2. Using a C-terminal specific NPY radioimmunoassay, immunoreactivity was detected in extracts of brain (519 pmol/g), cardiac stomach (37.9 pmol/g), pyloric stomach plus pancreas (37.9 ol/g) and intestine (29.2 pmol/g).3. Gel permeation and reverse-phase HPLC analysis of brain and intestinal extracts resolved a single NPY immunoreactive peptide.     

The primary structure and tissue distribution of an amphibian neuropeptide Y.

Neuropeptide Y (NPY) has been isolated and sequenced from brain extracts of the European common frog, Rana temporaria. Plasma desorption mass spectroscopy of the purified peptide indicated a molecular mass of 4243.3 Da which was in agreement with that deduced from the sequence (4243.7 Da), incorporating a C-terminal amide. The primary structure of frog NPY was established as: YPSKPDNPGEDAPAEDMAKYYSALRHYINLITRQRY-NH2. Frog NPY contains a single, highly-conservative amino acid substitution (Lys for Arg at residue 19) with respect to human NPY. NPY immunoreactivity was localised exclusively in nerves within the brain, pancreas and gastrointestinal tract and reverse-phase HPLC of extracts of these tissues resolved a single immunoreactive peptide of identical retention time in each case. The primary structure of NPY has therefore been highly-conserved over a considerable evolutionary time-span.     

The nerves of the juxtaglomerular apparatus of man and other mammals contain the potent peptide NPY

Summary The juxtaglomerular apparatus, a neuroendocrine unit located in the vascular pole of the glomerulus and influencing blood pressure by the secretion of renin, is known to have a rich supply of monoaminergic nerve fibres.Neuropeptide Tyrosine (NPY), a newly discovered, potent, vasoconstrictor peptide of 36 amino acids, has been found by immunocytochemistry to be present in a dense plexus of fibres around the juxtaglomerular apparatus of man, monkey, mouse, hamster, rat and guinea pig. NPY-immunoreactivity was markedly depleted after chemical sympathectomy by 6-hydroxydopamine. The concentration of NPY within the whole mouse kidney was 29.6±6.8 pmol/g and fractionation of the extracts demonstrated that the NPY-like immunoreactivity co-eluted from the column in the same position as the porcine NPY standard. The role of this peptide in renal physiology and pathology now needs urgent investigation.