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J J Holst

Publications and source records attributed to J J Holst.

At least 19 recordsLinked to original sources
PubMed1992

Antidiabetogenic effect of glucagon-like peptide-1 (7-36)amide in normal subjects and patients with diabetes mellitus.

BACKGROUND: Glucagon-like peptide-1 (7-36) amide (glucagon-like insulinotropic peptide, or GLIP) is a gastrointestinal peptide that potentiates the release of insulin in physiologic concentrations. Its effects in patients with diabetes mellitus are not known. METHODS: We compared the effect of an infusion of GLIP that raised plasma concentrations of GLIP twofold with the effect of an infusion of saline, on the meal-related release of insulin, glucagon, and somatostatin in eight normal subjects, nine obese patients with non-insulin-dependent diabetes mellitus (NIDDM), and eight patients with insulin-dependent diabetes mellitus (IDDM). The blood glucose concentrations in the patients with diabetes were controlled by a closed-loop insulin-infusion system (artificial pancreas) during the infusion of each agent, allowing measurement of the meal-related requirement for exogenous insulin. In the patients with IDDM, normoglycemic-clamp studies were performed during the infusions of GLIP and saline to determine the effect of GLIP on insulin sensitivity. RESULTS: In the normal subjects, the infusion of GLIP significantly lowered the meal-related increases in the blood glucose concentration (P less than 0.01) and the plasma concentrations of insulin and glucagon (P less than 0.05 for both comparisons). The insulinogenic index (the ratio of insulin to glucose) increased almost 10-fold, indicating that GLIP had an insulinotropic effect. In the patients with NIDDM, the infusion of GLIP reduced the mean (+/- SE) calculated isoglycemic meal-related requirement for insulin from 17.4 +/- 2.8 to 2.0 +/- 0.5 U (P less than 0.001), so that the integrated area under the curve for plasma free insulin was decreased (P less than 0.05) in spite of the stimulation of insulin release. In the patients with IDDM, the GLIP infusion decreased the calculated isoglycemic meal-related insulin requirement from 9.4 +/- 1.5 to 4.7 +/- 1.4 U. The peptide decreased glucagon and somatostatin release in both groups of patients. In the normoglycemic-clamp studies in the patients with IDDM, the GLIP infusion significantly increased glucose utilization (saline vs. GLIP, 7.2 +/- 0.5 vs. 8.6 +/- 0.4 mg per kilogram of body weight per minute; P less than 0.01). CONCLUSIONS: GLIP has an antidiabetogenic effect, and it may therefore be useful in the treatment of patients with NIDDM:

Adult↗
PubMed1992

Nervous control of the release of substance P and neurokinin A from the isolated perfused porcine ileum.

Using isolated perfused porcine ileum we studied the release of substance P (SP) and neurokinin A (NKA) in response to electrical stimulation of the mixed periarterial nerves and to infusion of different neuroactive agents. Nerve stimulation (8 Hz) had no significant effect on the release of SP and NKA. Nerve stimulation also had no effect on the release of SP and NKA during infusion of atropine (10(-6) M) or phentolamine (10(-5) M), whereas a significant increase (from 8.2 +/- 1.9 to 20.1 +/- 4.6 pmol/l for SP and from 12.3 +/- 2.7 to 34.2 +/- 7.7 pmol/l for NKA, n = 7) was observed during nerve stimulation after pretreatment with both atropine and phentolamine. This increase was abolished by hexamethonium (3 x 10(-5) M). Also acetylcholine infusion causes a significant release of SP and NKA after infusion of both atropine and phentolamine (to 172 +/- 56% and 232 +/- 69% of basal release, n = 7), an effect that was abolished by hexamethonium infusion. Infusion of atropine alone increased the release of SP and NKA significantly (to 337 +/- 92% and 386 +/- 124% of basal output, n = 5). Norepinephrine (10(-6) M) inhibited the release of SP and NKA (to 69 +/- 6% and 80 +/- 6% of basal release, n = 7). Our results suggest that the SP- and NKA-producing neurons receive intrinsic tonic muscarinic inhibitory impulses, extrinsic nicotinic excitatory impulses, and extrinsic adrenergic inhibitory impulses.

Acetylcholine↗
PubMed1992

Extrinsic control of the release of galanin and VIP from intrinsic nerves of isolated, perfused, porcine ileum.

By immunohistochemistry galanin-like immunoreactivity and vasoactive intestinal polypeptide (VIP)-like immunoreactivity were found in nerve cell bodies mostly in the submucous plexus and in nerve fibres in the mucosa, submucosa and muscularis including the myenteric plexus of the porcine ileum and were found to co-exist in most of these structures. Using isolated, perfused porcine ileum we studied the release of galanin and VIP in response to electrical stimulation of the mixed periarterial nerves or to intraarterial infusions of different neuroactive agents. Nerve stimulation (4-10 Hz) inhibited the basal release of galanin and VIP from the ileum (to 69 +/- 6 and 62 +/- 6% of basal release). After infusion of the alpha-adrenergic blocker, phentolamine, (10(-6) M) electrical stimulation increased the release of both galanin and VIP (to 140 +/- 12 and 133 +/- 13% of basal output). This increase was abolished by atropine (10(-6) M) and by hexamethonium (3.10(-5) M). Infusion of norepinephrine (10(-6) M) inhibited, whereas acetylcholine (10(-6) M) stimulated the release of both peptides. The effect of the latter was abolished by atropine. The inhibitory effect of nerve stimulation was not influenced by atropine. Our results suggest that the galanin- and VIP-producing intrinsic neurons receive inhibitory signals by noradrenergic nerve fibers and stimulatory signals mediated by cholinergic nerves, possibly via a cholinergic interneuron.

Acetylcholine↗
PubMed1992

Immunohistochemical localization of pancreatic spasmolytic polypeptide (PSP) in the pig.

Pancreatic spasmolytic polypeptide (PSP) is a peptide that is isolated from the porcine pancreas and that affects intestinal motility and growth of intestinal tumour cells in vitro. The peptide was recently demonstrated to be present in large amounts in pancreatic juice. The cellular origin of the peptide, however, is largely unclarified and the localization was therefore studied of PSP in pigs using immunohistochemistry. Positive immunoreactions were seen in the pancreas, the stomach, the duodenum, the jejunum and the ileum. In the pancreas, the PSP immunoreaction was seen in all acinar cells; no immunoreaction was seen in the endocrine islets. In the stomach, it was localized to the mucous cells of the glands in the cardiac gland region, the corpus and the pylorus. In the duodenum a strong immunoreaction was present in Brunner's glands and in the cells of their excretory ducts. In the jejunum and ileum, PSP immunoreactivity was seen in some of the cells in the epithelium of the crypts of Lieberkühn. A peptide chromatographically identical to highly purified PSP was identified in pancreas and stomach extracts. Thus epithelial cells in all parts of the stomach and small intestine contribute to the supply of PSP to the gut lumen.

Animals↗
PubMed1992

Effects of oleic acid and endogenous bile on duodenal secretion of somatostatin in man.

We studied the effects of intraduodenal oleic acid on the release of somatostatin to plasma and the correlation between endogenous bile output and plasma somatostatin. In five normal persons infusion of 0, 5, 10, 20, and 40 mM oleic acid dose-dependently increased the levels of somatostatin during as well as after gallbladder emptying. The difference between somatostatin concentration during and after gallbladder emptying was not significant. The amylase secretion also was significantly correlated to the dose of fat, whereas the output of bile salts was the same for all fat doses used. Our observations indicate that intraduodenal oleic acid--and not bile salts--releases somatostatin from the gut.

Adult↗
PubMed1992

Circulating galanin: origin, metabolism, and pharmacokinetics in anesthetized pigs.

The concentration of galanin-like immunoreactivity (GAL-LI) was 12.9 +/- 0.9 pmol/l in porcine arterial plasma (n = 9) and ranged from 1 to 14 pmol/g in extracts of porcine gastrointestinal tract (n = 5), the colon being the richest gut segment. A significant (P less than 0.05) arteriovenous concentration difference of circulating endogenous GAL-LI occurred across the kidney (15.1 +/- 2.3 vs. 6.2 +/- 0.5 pmol/l) and a hind leg (15.7 +/- 2.5 vs. 10.2 +/- 1.0 pmol/l), whereas a negative gradient was observed across the intestine (12.5 +/- 2.0 vs. 17.7 +/- 3.3 pmol/l) of anesthetized pigs. Passage through the brain, liver, or lungs did not change the concentration of endogenous GAL-LI significantly. During basal circumstances, the major source of circulating GAL-LI is therefore the gut. During infusion of 20 pmol.kg-1.min-1 of synthetic porcine galanin, a significant extraction occurred across the kidney (64.8 +/- 4.3%), hind leg (20.3 +/- 3.8%), and liver (19.7 +/- 4.3%). The overall metabolic clearance rate was 37.8 +/- 3.7 ml.min-1.kg-1. The half-life of galanin in plasma was 4.6 +/- 0.3 min, and the apparent distribution space was 255.6 +/- 31.4 ml/kg. Incubation studies in vitro showed that the concentration of galanin, added to blood and plasma at 37 degrees C, was halved in 1 h, unless stabilized with EDTA and aprotinin.

Anesthesia↗
PubMed1992

Somatostatin restraint of gastrin secretion in pigs revealed by monoclonal antibody immunoneutralization.

We studied the functional coupling between antral somatostatin and gastrin cells in isolated perfused porcine antrum using immunoneutralization with monoclonal antibodies against somatostatin. Their binding affinity was 10(11) l/mol, and the final binding capacity was 11.7 nmol/ml. Antibody infusion within 1 min increased gastrin secretion, reaching a rate of 349 +/- 64% (means +/- SE, n = 7) of basal secretion (59 +/- 5 pmol/l) after 5 min. The effect of somatostatin at 10(-9) mol/l, which inhibited gastrin secretion from 58 +/- 11 to 14 +/- 3 pmol/min (n = 4), was abolished by antibody infusion. Electrical stimulation of the vagus nerves (n = 7) performed during antibody infusion increased gastrin secretion from 224 +/- 61 to 328 +/- 55 pmol/min, not significantly different from the increase in control experiments from 43 +/- 9 to 118 +/- 20 pmol/min, indicating that the vagal stimulation of gastrin secretion does not depend on mechanisms involving somatostatin. We conclude that paracrine antral somatostatin secretion is one of the most important factors regulating basal gastrin secretion in pigs.

Animals↗
PubMed1992

Somatostatin and prosomatostatin immunoreactive nerve fibers in the bovine pineal gland.

An immunohistochemical study of the bovine pineal gland was performed by using polyclonal rabbit antisera raised against synthetic peptide fragments corresponding to the amino acid sequences of somatostatin-14, somatostatin-28, somatostatin-28 (1-12), and prosomatostatin (20-36). Immunoreactive nerve fibers were demonstrated in the pineal gland with all four antisera. The nerve fibers were located throughout the gland, both perivascularly and intraparenchymally, with the highest density of fibers in the proximal part, close to the pineal stalk. A number of immunoreactive nerve fibers were also found in the habenular area and stria medullaris projections. Some of the fibers in the stria medullaris projections could be followed into the pineal gland via the rostral part of the pineal stalk. A few immunoreactive nerve fibers were present in posterior commissure, in the subcommissural organ and pretectal area. Thus, the present study shows that the bovine pineal gland is innervated by nerve fibers containing all four sequences of prosomatostatin. The anatomical location of the somatostatin-immunoreactive nerve fibers in the bovine pineal gland indicates that the perikarya of some of these nerve fibers are located in the brain.

Animals↗
PubMed1992

Somatostatin is an essential paracrine link in acid inhibition of gastrin secretion.

We studied the functional coupling between antral somatostatin and gastrin cells in pigs using isolated perfused preparations of the antrum with intact supply of the vagus nerves. Luminal acidification significantly inhibited gastrin secretion to 61 +/- 3% of basal secretion and increased somatostatin output 9-fold. Intra-arterial infusion of somatostatin to concentrations of 10(-10) and 10(-9) mol/l inhibited gastrin secretion to 18 +/- 9 and 33 +/- 11% of basal secretion. Electrical stimulation of the vagus nerves and intra-arterial infusion of gastrin-releasing polypeptide (GRP; 10(-9) mol/l) significantly increased both gastrin and somatostatin secretion. Addition to the perfusate of Fab fragments of somatostatin antibodies abolished the effect of somatostatin at 10(-10) mol/l and the acid inhibition of gastrin secretion, but had no effect on the response to vagus stimulation of GRP infusion. We conclude that a local release of somatostatin is essential for the acid-induced inhibition of gastrin secretion, whereas changes in the local somatostatin concentration are unlikely to play a major role in vagally or GRP-induced gastrin secretion.

Animals↗
PubMed1992

All products of proglucagon are elevated in plasma from uremic patients.

We measured and characterized the proglucagon (PG) products in plasma obtained from nine uremic patients and six control subjects in the fasting state. The concentrations of PG products measured by direct RIAs were significantly higher in the uremic patients than in the normal subjects; the concentration of total glucagon immunoreactivity in plasma was 209 +/- 20 vs. 70 +/- 11 pmol/L, the glucagon-like peptide-1 immunoreactivity was 154 +/- 33 vs. 41 +/- 13 pmol/L, and the concentration of pancreatic-type glucagon immunoreactivity was 53 +/- 6 vs. 30 +/- 7 pmol/L. By chromatography, the predominating PG products in both uremic and normal plasma were shown to be glicentin [corresponding to PG-(1-69)] and the major PG fragment [presumably corresponding to PG-(72-158)]. In addition, glucagon-like peptide-1 [presumably corresponding to PG-(72-107) amide] was a major product in uremic plasma. Our results suggest that the kidneys play an important role in the removal from plasma of these products of PG.

Acute Kidney Injury↗
PubMed1992

Glucagon immunoneutralization in diabetic rats normalizes urea synthesis and decreases nitrogen wasting.

To study the effect of glucagon neutralization on urea synthesis in diabetic rats, animals with newly induced (75 mg/kg streptozocin) experimental diabetes mellitus were divided into two groups. One group was given one weekly injection of nonimmune rabbit serum (n = 6), and the other group was given one weekly injection of a specific high-titer antibody against pancreatic glucagon (n = 6). Four weeks later, serum-treated diabetic rats had fasting glucagon concentrations 2-3 times higher than nondiabetic controls given one weekly injection of saline (control). Plasma glucagon binding capacity of diabetic rats given glucagon antibodies was 10-15 times higher than the glucagon concentration. A second group of nondiabetic controls were given nonimmune serum. Blood glucose concentration and urinary glucose output were identical in both groups of diabetic animals. Food intake doubled in both groups of diabetic rats. In control rats, the accumulated nitrogen balance, determined weekly for 4 wk, was positive at 81 +/- 3.1 mmol/96 h; in serum-treated diabetic rats, the accumulated nitrogen balance was negative, -8.3 +/- 2.4 mmol/96 h throughout the 4 wk, whereas it was higher at 4.7 +/- 2.3 mmol/96 h in the glucagon antibody-treated diabetic rats (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Alanine↗
PubMed1992

Vagal control of the release of somatostatin, vasoactive intestinal polypeptide, gastrin-releasing peptide, and HCl from porcine non-antral stomach.

We studied the secretion of somatostatin and HCl and the release of vasoactive intestinal polypeptide (VIP) and gastrin-releasing peptide (GRP) from isolated, vascularly perfused, porcine non-antral stomach. Electric vagus stimulation increased acid secretion and the release of VIP and GRP and inhibited somatostatin secretion as determined in the venous effluent. Atropine abolished the HCl response and reversed the somatostatin inhibition to a three-fold increase, whereas GRP and VIP responses were unchanged. Both intra-arterial carbachol (10(-6) M) and GRP (10(-8) M) increased acid secretion and inhibited somatostatin secretion. VIP (10(-8) M) increased somatostatin secretion and had no effect on acid secretion. By immunohistochemistry, somatostatin was localized to both open-type and closed-type cells equally spread in the various parts of the gastric glands without particular relation to the parietal cells. Numerous GRP- and VIP-immunoreactive nerve fibers were seen between the glands. It is concluded that the fundic and antral secretion of somatostatin, investigated in a previous study, are differently regulated. The relation of fundic somatostatin release to acid secretion seems to be complex.

Animals↗
PubMed1992

Calcitonin gene-related peptide: effect on contractile activity and luminal cross-sectional area in the isolated, perfused porcine ileum.

Because calcitonin gene-related peptide (CGRP) is an abundant peptide in the enteric nervous system we studied the effect of intra-arterial infusions of synthetic human CGRP I in concentrations from 10(-10) to 10(-8) mol/l on contractile activity and luminal cross-sectional area in the isolated perfused porcine ileum, using manometry and impedance planimetry. The frequency of the basal contractile activity was 0.37 +/- 0.1 contractions per minute. CGRP induced phasic contractions, which at the highest dose were superimposed on tonic contractions, as determined by measurement of luminal cross-sectional area. The frequency of contractions dose-dependently increased to approximately 10/min at 10(-8) mol/l CGRP. The amplitude of contractions increased from a maximum of 35 cm H2O to 51 +/- 3 at 5 x 10(-9) mol/l CGRP and 52 +/- 6 cm H2O at 10(-8) mol/l CGRP. After the termination of CGRP infusion at the highest dose a short phase of up to 5 min with strong tonic contraction was observed. No phasic activity was detected by manometry during this phase. In conclusion, CGRP dose-dependently increased contractile activity in the pig ileum. CGRP may therefore participate in the regulation of small-intestinal motility in the pig.

Animals↗
PubMed1992

Distribution and characterization of different molecular products of pro-somatostatin in the hypothalamus and posterior pituitary lobe of the Mongolian gerbil (Meriones unguiculatus).

Antisera raised against various synthetic peptide fragments of the pro-somatostatin molecule were used to visualize immunohistochemically the distributions of different pro-somatostatin fragments in the hypothalamus and posterior pituitary of the Mongolian gerbil. To define the nature of the immunoreactive somatostatin-related molecular forms, gel chromatography combined with radioimmunoassays of hypothalamic and posterior pituitary extracts was performed. Within the hypothalamus, only trace amounts of somatostatin-28 and somatostatin-28(1-12) were present, whereas pro-somatostatin(1-76), pro-somatostatin(1-64), and somatostatin-14 peptides were present in equimolar amounts. In contrast, the posterior pituitary lobe contained equal amounts of somatostatin-14, somatostatin-28, and somatostatin-28(1-12) but no pro-somatostatin(1-76), indicating that pro-somatostatin is further processed during the axonal flow to posterior pituitary nerve terminals. The gel chromatographic data were further substantiated by immunohistochemical data. Thus, perikarya containing all of these five immunoreactivities were strictly confined to the periventricular area and parvocellular subset of the paraventricular nucleus. However, the number of somatostatin-28- and somatostatin-28(1-12)-immunoreactive perikarya was approximately 20% of the number of somatostatin-14- and pro-somatostatin(1-64)-immunoreactive cells. In other hypothalamic areas only somatostatin-14 and pro-somatostatin(1-64) immunoreactivities were detectable in cell bodies. These cell bodies were encountered in the organum vasculosum laminae terminalis; the suprachiasmatic, ventromedial, arcuate, perifornical, and posterior hypothalamic nuclei; and the median preoptic and retrochiasmatic areas. In situ hybridization histochemistry revealed that the cellular distribution of pro-somatostatin mRNA corresponds to that of somatostatin-14 and pro-somatostatin immunoreactivity, suggesting that the immunoreactive material observed within the cell bodies is synthetized there and that the differences in density of immunoreactivities may be explained by intracellular processing of pro-somatostatin. Somatostatinergic nerve fibers and terminals in hypothalamic areas and the posterior pituitary lobe were immunoreactive to all of the employed antisera. From the present results, obvious differences between intrahypothalamic and hypothalamo-pituitary somatostatinergic neurons emerge. Within hypothalamic neurons not projecting to the median eminence and the posterior pituitary lobe, pro-somatostatin is posttranslationally processed in the cell body predominantly into pro-somatostatin(1-64) and somatostatin-14. Otherwise, within periventricular neurons projecting to the median eminence and the posterior pituitary lobe, pro-somatostatin is posttranslationally processed during the axonal flow into pro-somatostatin(1-64), somatostatin-14, somatostatin-28, and somatostatin-28(1-12).

Animals↗
PubMed1991

Human galanin: primary structure and identification of two molecular forms.

From acid/ethanol extracts of surgical specimens of human large intestine we isolated two peptides, in approximately equal amounts, that reacted with an antiserum against porcine galanin. By amino acid analysis, sequence analysis and mass spectrometry, the larger of the two peptides was found to consist of 30 amino acid residues, the sequence of which was identical to that of porcine galanin except for the following substitutions: Val16, Asn17, Asn26, Thr29 and Ser30. Unlike porcine galanin, the carboxy-terminus was not amidated. The smaller peptide corresponded to the first 19 amino acid residues counted from the N-terminus of the 30 residue peptide (again without amidation). The structural analysis was repeated on another batch of tissue with identical results. By HPLC analysis of extracts of specimens from a further 4 patients, the same peptides were identified. Thus, human galanin includes two peptides of 19 and 30 amino acids that share the sequence of the N-terminal 15 residues with other mammalian galanins, but exhibit characteristic differences in the remaining part of the molecules.

Amino Acid Sequence↗
PubMed1991

Oxidation/reduction explains heterogeneity of pancreatic somatostatin.

Somatostatin 14 (SS 14) has been isolated from pancreatic extracts, but open gel filtration immunoreactive SS often elutes in two peaks. We isolated both peaks, but upon sequence analysis only authentic SS 14 could be identified. By further gel filtration experiments it turned out that both synthetic and extractable SS appeared homogeneous at neutral pH 7.5, but showed an additional, earlier peak in acetic acid. After addition of mercaptoethanol, all of the SS eluted at this earlier position regardless of the pH. We conclude that partial reduction/oxidation of SS explains the heterogeneity.

Amino Acid Sequence↗