Mitsuhiro Matsumura

Immunoreactive somatostatin and vasoactive intestinal polypeptide in adrenal pheochromocytoma. An immunochemical and ultrastructural study.

An adrenal pheochromocytoma producing somatostatin (SRIF) and vasoactive intestinal polypeptide (VIP) in a 17‐year‐old boy is presented. High concentrations of immunoreactive (IR)‐SRIF were found in plasma taken from the antecubital vein (31.0–33.0 pg/ml) and the inferior caval vein near the tumor (54.6 pg/ml), but after removal of the tumor the values became normal (11.0–15.2 pg/ml). In two portions of the resected tumor, considerable but different amounts of IR‐SRIF (151.7 and 12.1 ng/g wet wt) and IR‐VIP (13.0 and 5.5 ng/g wet wt) were demonstrated with size heterogeneities. Immunohistochemically, many IR‐SRIF cells and a few IR‐VIP cells were observed, but no cell reacting with both anti‐SRIF and anti‐VIP sera was found. Electronmicroscopically, many tumor cells had catecholamine‐like granules (250–350 nm in diameter) while some others had VIP‐like granules (100–140 nm in diameter). However, no granules resembling the SRIF granules seen in the pancreatic D cells were found. This seems to be the first report of an adrenal pheochromocytoma that produces SRIF and VIP simultaneously. It provides information on the histogenesis of hormone‐producing neurogenic tumors. Cancer 52:282‐289, 1983.

In vivo and in vitro Effects of Cholecystokinin Octapeptide on the Release of β-Endorphin-Like Immunoreactivity

The effect of cholecystokinin octapeptide (CCK-8) on the release of beta-endorphin-like immunoreactivity (beta-EpLI) in rats was studied in vivo and in vitro. Intravenous injection of 5 micrograms/100 g body weight of CCK-8 resulted in significant increase in the plasma beta-EpLI level after 10 and 20 min. CCK-8 at concentrations of 10(-10) - 10(-6) M also caused dose-dependent stimulation of beta-EpLI release from dispersed cells of rat anterior pituitary. However, CCK-4 and desulfated CCK-8 had no effect. On gel chromatography, the beta-EpLI released by incubation of the cells with 10(-8) M CCK-8 separated into two components, eluted in the same positions as human beta-lipotropin and human beta-endorphin, respectively. CCK-8 did not stimulate beta-EpLI release in Ca++-free medium. A 23187 at concentrations of 10(-6) - 10(-3) M caused dose-dependent stimulation of beta-EpLI release from the cells. Addition of 2 X 10(-3) M CoCl2, 10(-3) M verapamil or 10(-7) M dexamethasone to the incubation medium inhibited CCK-8-induced beta-EpLI release from the cells. Dibutyryl cyclic GMP (3 X 10(-3) M) inhibited CCK-8-induced beta-EpLI release from the cells. Ouabain (10(-5) M) also stimulated beta-EpLI release but its effect was not additive with that of CCK-8. These results indicate that CCK-8 acts directly and specifically on anterior pituitary cells to stimulate beta-EpLI release and that calcium ion is involved in the mechanism of this effect.

Effects of solution of low pH and taurocholate on release of β-endorphin-like immunoreactivity from human duodenal mucosa in vitro

The presence of beta-endorphin-like immunoreactivity (beta-EpLI) in human duodenum and its release were studied. beta-EpLI was detected in the duodenum (mucosa, 26.7 +/- 6.3 pmol/g wet weight, mean +/- SEM; remaining tissue 23.1 +/- 5.3 pmol/g wet weight) and the stomach (7.1 pmol/g wet weight). The two activities gave similar curves for inhibition of beta-Ep radioimmunoassay of synthetic beta-Ep. On gel-filtration chromatography of a duodenal extract, two components of beta-EpLI were separated. When human duodenal mucosa was perfused with a solution of pH2 or 1mM or 5mM taurocholate, the release of beta-EpLI from mucosa into the perfusate increased 2-4 fold. These results indicate that beta-EpLI present in human duodenal is released by the direct action of low pH or taurocholate on the duodenal mucosa and suggest that it may have a physiological role.

In vivo and in vitro Effects of Substance P on the Release of β-Endorphin-Like Immunoreactivity

The effect of substance P (SP) on the release of beta-endorphin-like immunoreactivity (beta-EpLI) in rats was studied in vivo and in vitro. Intravenous injection of 5 micrograms/100 g BW of SP resulted in significant increase in the plasma beta-EpLI level after 15 and 30 min. SP at concentrations of 10(-9) to 10(-6) M also caused dose-dependent stimulation of beta-EpLI release from dispersed cells of rat anterior pituitary. On gel-chromatography, the beta-EpLI released by incubation of the cells with 10(-7) M SP separated into two components, eluted in the same positions as human beta-lipotropin and human beta-Ep, respectively. Release of beta-EpLI from the cells was increased by the addition of K+ at high concentration (53 mM) in a Ca++-dependent manner. Addition of 10(-3) M verapamil to the incubation medium inhibited SP-induced beta-EpLI release from the cells. Ouabain (10(-5) M) had a stimulatory effect on beta-EpLI release which was not additive with that of SP. These results indicate that SP acts directly on the anterior pituitary cells to stimulate beta-EpLI release and that calcium ion is involved in the mechanism of this effect.

Effect of a test meal, duodenal acidification, and tetragastrin on the plasma concentration of β-endorphin-like immunoreactivity in man

The effects of various test materials on plasma beta-endorphin-like immunoreactivity (beta-EpLI) were investigated in man using a specific radioimmunoassay developed by the authors. Plasma beta-EpLI was determined after extraction by the acid/acetone method (recovery 73 +/- 5%). The intraassay and interassay coefficients of variation were 5.0% and 7.6%, respectively. The plasma concentrations of human beta-EpLI in normal subjects were 11.6 +/- 4.0 pmol/l for men (n = 23) and 10.7 +/- 4.8 pmol/l for women (n = 27). Ingestion of a test meal (150 g of Campbells condensed meat soup) resulted in a biphasic rise in plasma beta-EpLI from the basal level of 4.4 +/- 1.0 pmol/l to 29.2 +/- 1.9 pmol/l after 5 min and 24.8 +/- 6.7 pmol/l after 90 min. Intraduodenal infusion of 115 ml of 0.1 M HCl over 10 min increased the plasma beta-EpLI level from 8.7 +/- 0.5 pmol/l to 15.5 +/- 0.4 pmol/l at 10 min after the start of infusion, but the level rapidly returned to the initial value after the end of the infusion. Intramuscular injection of 4 micrograms/kg body weight of tetragastrin markedly stimulated gastric acid output and beta-EpLI release, but pretreatment with 10 mg of histamine H2 receptor antagonist inhibited the gastric acid output and plasma beta-EpLI release induced by tetragastrin. These results indicate that beta-EpLI release is stimulated by ingestion of meat soup, duodenal acidification and tetragastrin administration. It is suggested that gastric acid participates, at least in part, in postprandial release of beta-EpLI, probably from the gastrointestinal tract.

In vivo and in vitro effects of bradykinin on the release of β-endorphin-like immunoreactivity

The effect of bradykinin (BK) on the release of beta-endorphin-like immunoreactivity (beta-EpLI) in rats was studied in vivo and in vitro. Intraperitoneal injection of BK at 5 micrograms/100 g body weight resulted in significant increase in the plasma beta-EpLI level after 15 min. BK at concentrations of 10(-12)-10(-7) M also caused dose-dependent stimulation of beta-EpLI release from dispersed cells of rat anterior pituitary. On gel chromatography, the beta-EpLI released by incubation of the cells with 10(-7) M BK separated into two components, eluted in the same positions as human beta-lipotropin and human beta-endorphin, respectively. BK did not stimulate beta-EpLI release in Ca++-free medium. Addition of 10(-3) M verapamil or 10(-6) M dexamethasone to the incubation medium inhibited BK-induced beta-EpLI release from the cells. Quabain (10(-5) M) also stimulated beta-EpLI release, but its effect was not additive with that of BK. These results indicate that BK stimulates beta-EpLI release and that calcium ion is involved in the mechanism of this effect.

Effect of solution of low ph on releases ofβ-endorphin-like immunoreactivity and ACTH-like immunoreactivity from human gastric antral mucosa in vitro

SummaryThe presence ofβ-endorphin-like and ACTH-like immunoreactivities (β-EpLI, and ACTH-LI, respectively) in human gastric antral mucosa and their release were studied.β-EpLI (14.1 ± 4.8ng/g wet weight) and ACTH-LI (11.1 ± 1.2ng/g wet weight) were detected in human gastric antral mucosa. The two activities gave similar curves for inhibition of humanβ-Ep and ACTH on radioimmunoassay, respectively. On gelfiltration chromatography of a gastric antral extract, three components ofβ-EpLI and two components of ACTH-LI were separated. When human gastric antral mucosa was incubated with a solution of pH 4.0 or pH 2.0, the release ofβ-EpLI and ACTH-LI from the mucosa into the incubation medium increased 2.3–9.8-fold. However, incubation with 20 mM glucose or 20 mM amino acids did not have any effect on the release ofβ-EpLI and ACTH-LI.These results indicate thatβ-EpLI and ACTH-LI present in human gastric antral mucosa are released by direct action of a solution of low pH on the gastric antral mucosa.

Effects of gut hormones on bile acid uptake and release in cultured rat hepatocytes

SummaryIn cultured rat hepatocytes, the effects of gut hormones on bile acid uptake and release were studied. It was found that cultured hepatocytes continued to secrete bile acids into the culture medium and incorporated them effectively as a function of incubation time. Gut hormones such as secretin, glucagor., vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine (PHI), gastric inhibitory polypeptide (GIP), tetragastrin, cholecystokinin-octapeptide (CCK-8), pancreatic polypeptide (PP), neurotensin. substance P, β-endorphin (β-End), methioninc-enkephalin (Met-enk), motilin. bombesin and somatostatin (SS) had no effect on bile acid uptake by cultured hepatocytes. In bile acid release studies, only secretin caused a dose-dependent stimulation of bile acid release, while other gut hormones had no effect on bile acid release into medium. These results indicate that secretin acts directly on cultured rat hepatocytes and/or bile canaliculi, besides its effect on the bile duct, and influences bile acid metabolism.

β-Endorphin in the human gallbladder

The presence of beta-endorphin-like immunoreactivity (beta-END-LI) in human gallbladder and its release were examined by means of radioimmunochemical measurements and immunohistochemical stainings. beta-END-LI was detected in the gallbladder (27.2 +/- 3.2 ng/g wet weight, mean +/- S.E.). The immunoreactivity in beta-END-LI extracted from the gallbladder was similar to that of synthetic beta-END, judging from the result of its inhibition curve parallel to that of the synthetic substance in the radioimmunoassay (RIA) system. On gel-filtration chromatography of a gallbladder extract, two components of beta-END-LI were found; one eluted on a position of beta-lipotropin (beta-LPH) and another on a position of synthetic beta-END. Specific beta-END-LI positive cells were detectable in metaplastic mucous glands. When human gallbladder mucosa was perfused with a solution of 10(-8) M or 10(-6) M cholecystokinin octapeptide (CCK-8), the release of beta-END-LI from mucosa into the perfusate increased 2-3 fold. These results indicate that beta-END-LI present in human gallbladder is released by the direct action of CCK-8 on the gallbladder mucosa and suggest that it may have a physiological or pathophysiological role.

Effects of somatostatin on gastrointestinal hormone-induced glycogenolysis and gluconeogenesis in cultured liver cells

SummaryWhen isolated rat liver cells were incubated for 15 min in the presence of vasoactive intestinal peptide, gastric inhibitory polypeptide, secretin or glucagon at a concentration of 2.0μg/ml, glycogenolysis was stimulated by 30%–67% above the control. Slight but significant increase on gluconeogenesis was also observed by the addition vasoactive intestinal peptide, gastric inhibitory polypeptide or secretin. Somatostatin inhibited both glycogenolysis and gluconeogenesis induced by these hormones, but the degrees of inhibition are clearly much higher in the hormone-induced gluconeogenesis than glycogenolysis, and no significant inhibition of glycogenolysis was observed in case of glucagon and VIP.These results suggest the possibility that the so-called enterohepatic axis may play a part of roles in the regulation of serum glucose levels through gastrointestinal hormones belonging to the secretin family, and that it may be further regulated by somatostatin through gluconeogenesis.