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Biomedical subjects

E Ekblad

Publications and source records attributed to E Ekblad.

At least 55 records · Page 3Linked to original sources

[The impact of psychological factors on the treatment of somatic diseases. The situation today, as exemplified by cardiovascular disorders and cancer].

Prospective intervention studies have shown that cognitive-behavioral interventions can improve morbidity and mortality both in cancer and in circulatory disorders. Research in fields like molecular biology, psychoneuroendocrinology and psychoneuroimmunology has identified some of the links between emotions and biological reactions. The paper reviews the situation today and concludes that psychobiologically based interventions may make important contributions to somatic medicine.

Behavior Therapy↗

Pituitary adenylate cyclase activating polypeptide is expressed in autonomic neurons.

Pituitary adenylate cyclase activating polypeptide (PACAP) is a novel vasoactive intestinal peptide (VIP)-like peptide, which is present in neuronal elements of several peripheral organs, and thus a putative neurotransmitter/modulator. In the present study, the expression of PACAP in two parasympathetic ganglia (otic, sphenopalatine) and one mixed parasympathetic/sensory ganglion (jugular-nodose) in rat was characterized by use of in situ hybridization and immunocytochemistry and compared to that of VIP and calcitonin gene-related peptide (CGRP). PACAP and VIP were expressed in virtually all nerve cell bodies in the otic and sphenopalatine ganglia; PACAP and VIP were also expressed in subpopulations of nerve cell bodies in the jugular-nodose ganglion. CGRP was expressed in numerous nerve cell bodies in the jugular-nodose ganglion and in a few, scattered, nerve cell bodies in the sphenopalatine ganglion. In the otic and sphenopalatine ganglia, PACAP- and VIP-like immunoreactivities were frequently co-localized; in the jugular-nodose ganglion, PACAP-like immunoreactivity was frequently co-localized with CGRP-like immunoreactivity in presumably sensory neurons and to a lesser extent with VIP in parasympathetic neurons. Thus, PACAP is synthesized and stored in autonomic parasympathetic neurons as well as in vagal sensory neurons, which provides an anatomical basis for the diverse effects of PACAP previously described.

Animals↗

Expression and characterization of preproVIP derived peptides in the human male urogenital tract.

Expression of the gene sequence encoding vasoactive intestinal polypeptide (VIP) leads to the synthesis of a 170 amino acid precursor molecule which can be processed to five fragments: preproVIP 22-79, peptide histidine methionine (PHM), or peptide histidine valine (PHV), preproVIP 111-122, VIP and preproVIP 156-170. Using region specific radioimmunoassays and antisera against the functional domains of the VIP precursor in combination with immunocytochemistry and chromatography, the localization, distribution and identity of the preproVIP derived peptides within the human male urogenital tract were investigated. Postmortem as well as fresh tissue specimens were used. All the preproVIP derived peptides were expressed and could be demonstrated in nerve fibres throughout the urogenital tract in close relation to the epithelial lining and in vascular as well as non-vascular smooth muscle. The VIP-related peptide containing fibres were most abundant in the prostate parenchyma and the seminal vesicle. Using double immunostaining, co-localization of the various preproVIP derived peptides could be evidenced. The fact that all preproVIP derived peptides are present in the urogenital tract, should be taken into consideration when the regulatory aspects of neuropeptides in physiological and pathophysiological functions are discussed.

Adult↗

Lack of neuronal nitric oxide synthase in nerve fibers of aganglionic intestine: a clue to Hirschsprung's disease.

The lack of nonadrenergic, noncholinergic (NANC) inhibitory innervation in aganglionic intestine is typical of Hirschsprung's disease. Several neuropeptides participating in the intestinal NANC innervation are greatly reduced in aganglionic intestine. However, these findings do not fully explain the pathophysiology of the disease. Recently, nitric oxide (NO) has been presented as a potent smooth muscle relaxant, and the enzyme responsible for its formation, nitric oxide synthase (NOS) has been demonstrated in neuronal elements in both the central and peripheral nervous system. In our study, nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase staining, a marker for NOS, and NOS immunohistochemistry revealed a dense innervation of the smooth muscle layers and the myenteric ganglia in ganglionic non afflicted intestine from patients with Hirschsprung's disease. By contrast, there was an almost complete lack of NOS-immunoreactive and NADPH-diaphorase-positive nerve fibers in the afflicted aganglionic bowel. NOS and vasoactive intestinal peptide were found to be partially colocalized in nerve fibers and neuronal cell bodies in the ganglionic but not in the aganglionic intestine. The lack of NO-producing nerve fibers in the aganglionic intestine probably contributes to the inability of the smooth muscle to relax, thereby causing lack of peristalsis in Hirschsprung's disease.

Amino Acid Oxidoreductases↗

Islet amyloid polypeptide (amylin) is expressed in sensory neurons.

Islet amyloid polypeptide (IAPP) or amylin is a hormone candidate predominantly expressed in insulin cells. A role for IAPP in the regulation of glucose homeostasis and the development of non-insulin-dependent diabetes mellitus has been proposed. IAPP is structurally related to the sensory neuropeptide calcitonin gene-related peptide. In the present study, using in situ hybridization, immunocytochemistry, and immunochemistry, the expression of IAPP in sensory neurons in the rat was investigated. IAPP was expressed in a population of small- to medium-sized nerve cell bodies in dorsal root ganglia from all levels and in the jugular-nodose and trigeminal ganglion; IAPP-expressing nerve cell bodies constituted a subpopulation of those expressing calcitonin gene-related peptide. In addition, IAPP-like immunoreactivity occurred in nerve cell bodies storing substance P and pituitary adenylate cyclase-activating polypeptide. IAPP-immunoreactive nerve fibers were encountered in the dorsal horns of the spinal cord, and to a lesser extent in peripheral tissues receiving sensory innervation; IAPP-immunoreactive fibers constituted a subpopulation of those containing calcitonin gene-related peptide and/or substance P. The immunochemical determinations demonstrated a low level of IAPP-like immunoreactivity in the dorsal root ganglia and spinal cord, which chromatographically coeluted with authentic rat IAPP. We conclude that IAPP is expressed in sensory neurons, thus being a novel sensory neuropeptide candidate for which a physiological role remains to be identified.

Amyloid↗

Islet amyloid polypeptide is expressed in endocrine cells of the gastric mucosa in the rat and mouse.

BACKGROUND/AIMS: Islet amyloid polypeptide (IAPP) or amylin is a novel islet hormone candidate with a suggested role in the regulation of glucose homeostasis and the pathogenesis of non-insulin dependent diabetes mellitus. Occurrence of IAPP in the gastrointestinal tract of rats and humans has also been shown. The expression of IAPP in the stomach of the rat and mouse and the possible colocalization of IAPP and known gastric hormones were investigated in this study. METHODS: In situ hybridization, immunofluorescence, and combined in situ hybridization and immunocytochemistry were used. RESULTS: IAPP messenger RNA and IAPP-like immunoreactivity were shown in the same endocrine cells in the antrum and fundus of the rat and in the antrum of the mouse. IAPP was expressed in a major population of somatostatin-immunoreactive cells as well as in small populations of gastrin- and peptide YY-immunoreactive cells. CONCLUSIONS: Our results establish the synthesis and storage of IAPP in gastric endocrine cells in the rat and mouse. The extensive colocalization of IAPP with somatostatin and to a lesser extent with gastrin and peptide YY suggests that IAPP may modulate endocrine activity in the gastric mucosa in a paracrine and/or autocrine mode.

Amyloid↗

NOS-containing neurons in the rat gut and coeliac ganglia.

Nitric oxide (NO) is considered an important inhibitory neurotransmitter in the gut. Nitric oxide synthase (NOS)-containing neurons were visualized by immunocytochemistry using antibodies against neuronal NOS in the oesophagus, the gastrointestinal tract and the coeliac ganglion of rat. NOS-containing nerve cell bodies were numerous in the myenteric but fewer in the submucous ganglia all along the gut. Synthesis of NOS in enteric nerve cell bodies was confirmed by in situ hybridization, demonstrating the presence of NOS mRNA. Varicose nerve fibers formed extensive networks in the circular smooth muscle and the myenteric ganglia. The pyloric sphincter contained abundant NOS-containing nerve fibers. NOS-containing nerve terminals were frequently found around the Brunner glands in the duodenum; scattered nerve terminals occurred in the gastric and colonic mucosa and around blood vessels in the submucosa all along the gut. The neuronal cell bodies in the coeliac ganglion were non-immunoreactive but frequently surrounded by baskets of NOS-immunoreactive nerve fibers. Double staining for NOS and neuropeptides in oesophagus, stomach and small and large intestine revealed that a small subpopulation of the NOS-containing nerve cell bodies stored in addition vasoactive intestinal peptide (VIP), and in oesophagus, stomach and small intestine also neuropeptide Y (NPY). However, NOS-containing nerve terminals, particularly those in the circular muscle of the gut, frequently contained VIP throughout the gut; in the oesophagus, stomach and the small intestine they contained also NPY.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Oxidoreductases↗

Distribution, origin and projections of nitric oxide synthase-containing neurons in gut and pancreas.

Nitric oxide has been put forward as an important inhibitory neurotransmitter in the gut. Nitric oxide synthase-containing neurons were visualized by immunocytochemistry using antibodies against neuronal nitric oxide synthase or by beta-nicotinamide adenine dinucleotide phosphate diaphorase staining in whole mounts and cryostat sections from the gastrointestinal tract and pancreas of several mammals (mouse, rat, hamster, guinea-pig, cat and man). Nitric oxide synthase-containing neuronal cell bodies were numerous in the myenteric but fewer in the submucous ganglia all along the gut of all species. Varicose nerve terminals formed extensive networks in the circular smooth muscle and the myenteric ganglia. Nitric oxide synthase-containing nerve terminals were frequently found around the Brunner glands in the duodenum; scattered nerve terminals were also found in the gastric and colonic mucosa and around blood vessels in the submucosa all along the gut. In the rat small and large intestine nitric oxide synthase-containing submucous neurons terminated within the mucosa/submucosa and nitric oxide synthase-containing myenteric neurons issued short descending projections, approximately 3 mm, to the smooth muscle and other myenteric ganglia. In the pancreas of all species nitric oxide synthase-containing nerve cell bodies were regularly seen in intrapancreatic ganglia. Positive nerve fibers were mainly found within nerve trunks in interlobular spaces and as delicate fibers within the islets. Double staining for nitric oxide synthase and neuropeptides in intestine and pancreas of rat, guinea-pig and man revealed that only occasionally the nitric oxide synthase-containing nerve cell bodies stored in addition vasoactive intestinal peptide and neuropeptide Y, or enkephalin. However, nitric oxide synthase-containing nerve terminals, particularly those in the circular muscle of the gut, frequently contained vasoactive intestinal peptide/neuropeptide Y (rat and man) or vasoactive intestinal peptide/enkephalin (guinea-pig). In intrapancreatic ganglia few nitric oxide synthase-containing nerve cell bodies were also vasoactive intestinal peptide-immunoreactive. Coexistence of nitric oxide synthase and vasoactive intestinal peptide in nerve terminals could here be detected around blood vessels and interlobular ducts. The distribution of nitric oxide synthase indicates a major role of nitric oxide in the regulation of gut motility; a role in the regulation of blood flow and secretion in both gut and pancreas is also likely.

Amino Acid Oxidoreductases↗

Pituitary adenylate cyclase activating polypeptide expression in sensory neurons.

Pituitary adenylate cyclase activating polypeptide (PACAP) is a novel vasoactive intestinal peptide (VIP)-like peptide isolated from ovine hypothalami. The presence of PACAP-like immunoreactivity was recently demonstrated in nerve cell bodies of sensory ganglia in the rat. Since PACAP belongs to a large family of chemically related neuropeptides, we have, in the present study, tried to establish the synthesis of PACAP in neurons of sensory ganglia, using in situ hybridization with a 35S-labelled oligonucleotide probe complementary to PACAP mRNA. The expression of PACAP was compared to that of calcitonin gene-related peptide (CGRP) using a radiolabelled CGRP oligonucleotide probe. The PACAP probe labelled small to medium-sized neurons in the trigeminal ganglion and dorsal root ganglia at different levels, indicating the presence of PACAP mRNA. The CGRP probe labelled nerve cell bodies of varying size, outnumbering those labelled by the PACAP probe. In dorsal root ganglia, cells expressing PACAP constituted c. 10% and those expressing CGRP 46% of the total number of nerve cell bodies. Expression of PACAP was seen in a small subpopulation of cells expressing CGRP. We conclude that PACAP is synthesized in a subpopulation of neurons of sensory ganglia in the rat. Therefore, the recently described effects of PACAP--cutaneous vasodilation, potentiation of oedema formation and depression of nociceptive spinal reflexes--may be physiological and related to neurogenic inflammation and modulation of pain transmission.

Animals↗

The association between enteric bacterial overgrowth and gastrointestinal motility after subtotal liver resection or portal vein obstruction in rats.

OBJECTIVE: To test the hypothesis that intestinal motility is delayed after hepatectomy, which alters the ecology of the enteric microflora and contributes to the development of bacterial translocation from the gut. DESIGN: Open experimental study. SETTING: University department of surgery. MATERIAL: Adult male Sprague-Dawley rats (n = 6 in each group at each time point). INTERVENTIONS: Sham operation, 90% hepatectomy, and portal venous obstruction. MAIN OUTCOME MEASURES: Intestinal morphology, immunocytochemistry of the enteric nervous system, enteric bacterial growth in the small intestine and colon, and intestinal transit time. RESULTS: Intestinal transit was already delayed one hour after 90% hepatectomy, and histopathological alterations and overgrowth by Escherichia Coli had developed after two hours. There were significant differences in intestinal transit time between sham operated rats and those subjected to portal venous obstruction on the one hand, and those that underwent 90% hepatectomy on the other. There was no difference in intestinal transit time between rats with portal venous obstruction and the sham operated animals. CONCLUSION: Delayed intestinal transit after 90% hepatectomy may contribute to enteric bacterial overgrowth and thereby contribute to the development of bacterial translocation from the gut.

Animals↗

Peptide YY: a neuropeptide in the gut. Immunocytochemical and immunochemical evidence.

Peptide YY immunoreactivity was detected in neuronal elements in the upper digestive tract of the rat, cat, ferret and pig by immunocytochemistry and radioimmunoassay combined with high-performance liquid chromatography. The two peptide YY antisera used do not recognize the related peptides neuropeptide Y and pancreatic polypeptide. In the rat peptide YY-immunoreactive nerve fibres were virtually restricted to the stomach smooth muscle of the minor curvature where they were numerous. Peptide YY-immunoreactive nerve cell bodies occurred in small ganglia on the serosal surface of the minor curvature. In the cat and ferret peptide YY-immunoreactive nerve fibres occurred in the circular smooth muscle layer of both the minor and major curvatures of the stomach and also in the upper small intestine; such fibres were numerous also in myenteric ganglia in these regions. In the pig, they were few but had roughly the same distribution as in the cat and ferret, except that they were quite numerous in thick muscle bundles close to the oesophagogastric junction. The presence of peptide YY-immunoreactive nerve cell bodies within the myenteric ganglia along the upper digestive tract of cat, ferret and pig, and in serosal ganglia of the rat stomach, indicates that at least some of the peptide YY-immunoreactive fibres demonstrated originate in or close to the gut wall. Double-staining experiments revealed that virtually all peptide YY-containing neurons and nerve fibres were distinct from those storing neuropeptide Y. Peptide YY-immunoreactive endocrine cells were encountered not only in the lower intestines but also in the stomach of the four species studied. In the antrum such cells were numerous and constituted a subpopulation of the gastrin-containing cells. In the oxyntic mucosa they were few and contained somatostatin. Radioimmunoassay revealed peptide YY-like peptides in gastric mucosa and smooth muscle from the upper digestive tract of all four species examined. The results of high-performance liquid chromatography suggest that the peptide YY-like material in the upper digestive tract is distinct from neuropeptide Y and pancreatic polypeptide and identical with authentic peptide YY except in the antral mucosa where only a small proportion of the peptide YY-immunoreactive material eluted like authentic peptide YY.

Animals↗

Peptide-containing neurons remain unaffected after intestinal autotransplantation: an experimental study in the piglet.

The gut is richly supplied with peptide-containing nervous elements. In the present immunocytochemical study the origin, occurrence and topographical distribution of nerves containing vasoactive intestinal polypeptide (VIP), enkephalin, substance P (SP), somatostatin, neuropeptide Y (NPY), calcitonin gene-related peptide (CGRP), gastrin-releasing peptide (GRP) and galanin were investigated in the porcine small intestine. In order to study the origin (extrinsic or intrinsic) of the nerve fibers, specimens from autotransplanted and extrinsically denervated jejunum were examined. Furthermore, possible changes in the distribution of intrinsic neurons after extrinsic denervation were studied. In the control jejunum each nerve fiber population had its own characteristic topographic distribution. There was no overt difference in distribution pattern of peptide-containing nerve fibers and cell bodies between the transplanted and the control segment except that NPY-, SP- and CGRP-containing nerve fibers disappeared around blood vessels. Thus VIP-, somatostatin-, GRP-, enkephalin- and galanin-containing nerve fibers were visibly unchanged in the transplanted segment. The results support the view that the peptide-containing nerve fibers are mainly intrinsic in origin except the NPY-, SP- or CGRP-containing perivascular nerve fibers which are extrinsic to the gut wall. In addition, the results of the present study suggest that transplantation and extrinsic denervation have no major effect on the distribution pattern of the intrinsic neuronal systems.

Anastomosis, Surgical↗

Immunohistochemical localization of peripheral nitric oxide synthase-containing nerves using antibodies raised against synthesized C- and N-terminal fragments of a cloned enzyme from rat brain.

Antibodies were raised in rabbits against C- or N-terminal fragments of a cloned nitric oxide synthase (NOS) enzyme from rat cerebellum, and used for demonstration of NOS-immunoreactive (NOS-IR) nerves in different tissues from the rat (colon, duodenum, adrenal gland, aorta, caval vein, penis and urethra). Both antisera demonstrated the same neuronal elements, although with differences in intensity in the immunoreaction in some tissues. Sections incubated with antisera preabsorbed with excess of the antigens showed no NOS immunoreactivity. In duodenum and colon, NOS-immunoreactivity was found in the cytoplasm of numerous cell bodies in myenteric ganglia and in some nerve cell bodies in the submucosa. NOS-IR nerve fibres were numerous in the circular muscle layer, while few were found in the longitudinal layer or the mucosa and submucosa. In the penis, strong NOS immunoreactivity was found in nerves surrounding the deep penile and dorsal arteries, and in nerves in the stroma of the cavernous tissue. In the urethra, NOS immunoreactivity was found in nerves in the mucosa. No NOS immunoreactivity was found in the urothelium. The adrenal medulla, and occasionally the cortex, contained nerve cell bodies with strong cytoplasmic NOS immunoreactivity as well as scattered nerve fibres. No NOS immunoreactivity was found in the abdominal aorta or inferior caval vein. Combined NOS immunostaining and NADPH diaphorase staining showed that virtually all NOS-IR nerve structures were also NADPH diaphorase-positive. However, thin nerve fibres and cell linings were sometimes better visualized by NOS-immunohistochemistry. Furthermore, the adrenal cortex, which only occasionally showed NOS immunoreactivity, was strongly NADPH diaphorase-positive.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Oxidoreductases↗

Vasoactive intestinal polypeptide and acetylcholine coexist with neuropeptide Y, dopamine-beta-hydroxylase, tyrosine hydroxylase, substance P or calcitonin gene-related peptide in neuronal subpopulations in cranial parasympathetic ganglia of rat.

Immunohistochemistry has been used to demonstrate that neuropeptide Y, dopamine-beta-hydroxylase, calcitonin gene-related peptide or substance P are colocalized with vasoactive intestinal polypeptide and choline acetyltransferase in subpopulations of neurons in cranial parasympathetic ganglia of rat. These comprise the ciliary, sphenopalatine, otic, glossopharyngeal-vagal and internal carotid ganglia. In the ciliary and glossopharyngeal-vagal ganglia tyrosine hydroxylase is also found in such neurons. The findings emphasize that the combined localization of dopamine-beta-hydroxylase and neuropeptide Y or the presence of tyrosine hydroxylase is not exclusively a marker for peripheral adrenergic neurons. Further, the co-localization of calcitonin gene-related peptide and substance P is not a decisive indication that a neuron is sensory in nature. It is discussed whether the presence of the enzymes and peptides other than vasoactive intestinal polypeptide is a remnant of a different expression during ontogenesis or indicates target-specific functions in the adult.

Acetylcholine↗

Helospectin-like peptides in the gastrointestinal tract: immunocytochemical localization and immunochemical characterization.

Helospectins I and II are two non-amidated, vasoactive intestinal peptide (VIP)-like peptides, isolated from the salivary gland venom of the lizard Heloderma horridum. Helospectin I has 38 amino acid residues and differs from helospectin II in that it has an additional serine residue at the C-terminus. The study was based on an antiserum that recognizes both helospectins I and II (but recognizes VIP only poorly). Immunocytochemistry of the digestive tract revealed helospectin-immunoreactive nerve fibers in the muscle layers, submucosa and mucosa of mouse, rat, hamster, guinea-pig and man. Myenteric and submucous ganglia in all species contained helospectin-immunoreactive nerve fibers and cell bodies. The distribution of helospectin-like immunoreactivity in the gut resembled that of VIP. Double immunostaining for helospectin and VIP revealed their co-existence in the same population of nerve fibers and cell bodies throughout the gut of all species tested. In addition, helospectin (but not VIP) immunoreactivity was observed in a population of endocrine cells in the intestines. The existence of helospectin-like material in the gut was confirmed by immunochemistry. The helospectin-like immunoreactivity in the extracts diluted in parallel to the helospectin standard curve. Analysis by high performance liquid chromatography of extracts of rat intestine revealed one predominant helospectin-immunoreactive peak that eluted close to authentic helospectins I and II. The helospectin-immunoreactive material in the gut may constitute a novel neuropeptide that co-exists with VIP. The distribution of the VIP-helospectin-immunoreactive neurons and fibers indicates their possible involvement in the regulation of gut motor and secretory activities.

Animals↗

Pituitary adenylate cyclase activating peptide: a novel vasoactive intestinal peptide-like neuropeptide in the gut.

Pituitary adenylate cyclase activating peptide (PACAP) is a vasoactive intestinal peptide (VIP)-like hypothalamic peptide occurring in two forms, PACAP-27 and the C-terminally extended PACAP-38. The predicted rat and human PACAP sequence is identical to the isolated ovine one. In the present study, the occurrence and distribution of PACAP-like peptides were examined in the gut of several species by immunocytochemistry and immunochemistry using an antibody raised against PACAP-27. PACAP-like immunoreactivity was observed in nerve fibers in the gut wall of all species examined (chicken, mouse, rat, hamster, guinea-pig, ferret, cat, pig, sheep and man). In the chicken and human gut, immunoreactive fibers were numerous in all layers. In the other species examined the fibers were predominantly found in the myenteric ganglia and smooth muscle. Delicate PACAP-immunoreactive fibers were seen in the gastric mucosa of mouse, rat, hamster and man but not in the other species examined. The chicken proventriculus harbored numerous PACAP-immunoreactive endocrine cells which were identical with the serotonin-containing cells storing gastrin-releasing peptide. PACAP-immunoreactive nerve cell bodies were numerous in the submucous ganglia and moderate in number in the myenteric ganglia of the human gut. They were few in the intramural ganglia of the other species examined. Extrinsic denervation (performed on segments of rat and guinea-pig small intestine) did not visibly affect the PACAP innervation, indicating an intramural origin of most PACAP-immunoreactive fibers. Double immunostaining for VIP and PACAP revealed co-existence of the two peptides in nerve cell bodies and nerve fibers of the human and chicken gut and in fibers in the gastric mucosa of mouse and rat. In all other species examined and in all other locations in the gut PACAP-immunoreactive nerve cell bodies and nerve fibers were distinct from those storing VIP; many of them contained gastrin-releasing peptide instead. Immunochemistry revealed PACAP-like peptides in gut extracts of all species studied; upon high performance liquid chromatography the immunoreactive material co-eluted with synthetic PACAP-27. The distribution of PACAP-immunoreactive nerve cell bodies and nerve fibers in the gut wall suggests their involvement in the regulation of both motor and secretory activities.

Amino Acid Sequence↗

Expression of preproVIP-derived peptides in the human gastrointestinal tract: a biochemical and immunocytochemical study.

In order to study biosynthetic processing of the precursor for vasoactive intestinal peptide (preproVIP) in the human gut we have developed antisera against the five functional domains of the precursor molecule: preproVIP 22-79, peptide histidine methionine (PHM), preproVIP 111-122, VIP and preproVIP 156-170. The antisera were used to quantify and characterize VIP-precursor peptides by radioimmunoassay (RIA) together with high-pressure liquid Uchromatography (HPLC) and to examine their cellular localization and colocalization by immunocytochemistry. All five peptides were expressed but not in equimolar amounts as expected from the amino acid sequence of the precursor. However, the ratios between them were fairly constant throughout the gastrointestinal tract. The only exceptions were the lower concentrations of PHM and preproVIP 111-122 in the gastric antrum which could be explained by the presence of PHV (the C-terminally extended form of PHM which includes preproVIP 111-122) in large concentrations in this region. It was also found that the C-terminal lysine residue of preproVIP is not removed during processing. Immunocytochemically all preproVIP-derived peptides were shown in neuronal elements. They had a similar distribution throughout the gut suggesting coexistence, a finding which was supported by doublestaining. The findings indicate that differences in the posttranslational processing of preproVIP exist in subpopulations of neurons in the human gut.

Chromatography, High Pressure Liquid↗