Effects of Decapeptide of Mammalian Bombesin and Neuromedin B on Pancreatic Exocrine Secretion in the Rat

Abstract

The effects on pancreatic exocrine secretion of intravenous bolus injections of decapeptide of mammalian bombesin (also called neuromedin C) and neuromedin B, recently isolated mammalian bombesin-like peptides, have been studied and compared with those of amphibian bombesin in anaesthetized rats. Decapeptide of mammalian bombesin and neuromedin B stimulated the volume output from the pancreas with the same potency as that with which they stimulated protein output, as did amphibian bombesin. The maximal peak rates of volume and protein secretion observed in the 5- to 10-min period after the injection of 3 × 10^-10 mol/kg decapeptide of mammalian bombesin were 24.5 ± 1.2 μl/5 min and 8.5 ± 0.5 mg bovine serum albumin equivalents per 5 min (mean ± SEM, n = 5). These rates were equivalent to those produced by the same dose of amphibian bombesin, but the duration of responses to decapeptide of mammalian bombesin were shorter than those of equimolar doses of amphibian bombesin. The relative potencies of decapeptide of mammalian bombesin and neuromedin B, calculated from the doses producing 50% of maximum effect on total responses, were, respectively, 100 and 0.5% of that of amphibian bombesin. The results suggest that decapeptide of mammalian bombesin, and possibly neuromedin B, could play a regulatory role in the control of exocrine pancreatic secretion.

Effect of a new potent CCK antagonist, lorglumide, on caerulein‐ and bombesin‐induced pancreatic secretion and growth in the rat

“…The results of the present investigation confirm the powerful stimulatory effect of both caerulein and bombesin on exocrine pancreatic secretion, already pointed out in different in vitro (Bertaccini, 1976;Gardner & Jensen, 1981;Jensen et al, 1984;Otsuki et al, 1987) and in vivo (Bertaccini, 1976;Namba et al, 1986;Varga et al, 1988a,b) experimental conditions. In our in vitro system, which was used for the first time to assess the pancreatic secretory action of these peptides, caerulein proved to be of equal efficacy compared to bombesin.…”

“…The rats of the remaining three groups were given bombesin (10 Mg kg-) intraperitoneally. This dose of the peptide was chosen because several studies (Gardner & Jensen, 1981;Namba et al, 1986;Otsuki et al, 1987) have shown bombesin to be equally effective, but 10 times less potent than caerulein. Animals of group 4 were pretreated with saline whereas those of groups 5 and 6 were given lorglumide (doses as above).…”

“…Bombesin was found to increase the release of pancreatic hormones (insulin, glucagon and pancreatic polypeptide) in several animal species, including man (McDonald et al, 1988;Scarpignato, 1988). Exocrine pancreatic function was also affected by bombesin and a stimulatory effect of bombesin on pancreatic enzyme secretion was observed in rats (Namba et al, 1986;Lamers et al, 1987), dogs (Erspamer & Melchiorri, 1980;Konturek et al, 1976), pigs (Lilja et al, 1984) and man (Basso et al, 1976). In vitro studies have provided conflicting results.…”

Inhibitory Effects of the New Bombesin Receptor Antagonist RC-3095 on the Luteinizing Hormone Release in Rats

“…The mammalian counterpart of bombesin, gastrin-releasing peptide (GRP), has the same carboxylterminal sequence as bombesin and displays biological effects similar to bombesin. Bombesin/GRP and related Received: January 28, 1992 Accepted after revision : March 31, 1992 peptides were found to stimulate the secretion of gastroenteropancreatic hormones [2,3] and pancreaticjuice [4] and the contraction of various smooth muscles [5], Intracerebroventricular injection of GRP into rats was shown to decrease plasma growth hormone (GH) levels [6]. Bombesin-like immunoreactivity is distributed…”

Effects of Neuromedin B on Insulin and Glucagon Release from the Isolated Perfused Rat Pancreas.

“…Both peptides stimulate gestrin release (Guo et al, 1987), secretion of pancreatic juice (Namba et al, 1986) and smooth muscle contraction (Broccardo et el., 1975;Mayer et al, 1986) in experimental animals as does GRP. Concerning pancreatic hormone release, our recent in vivo and in vitro studies have demonstrated that NMB and GRP-10 clearly stimulate insulin release in dogs and that glucagon release was slightly stimulated by higher doses of GRP-10 and not by NMB (Kawai et al, 1988).…”