Different effects of trypsin inhibitors on intestinal gene expression of secretin and on pancreatic bicarbonate secretion in CCK-A-receptor-deficient rats

Structural aspects of flavonoids as trypsin inhibitors

In the search for new proteinase inhibitors we have focused on the screening and Computer Assisted Drug Design (CADD) studies of polyphenolic compounds. In this paper we report CADD of flavonoles and flavones as trypsin inhibitors concomitant by the screening results. 5,7-Dihydroxy flavonoid have been found to be a perspective trypsin/trypsin-like-enzyme inhibitor. Flavanones and isoflavones are less effective trypsin inhibitors due to a lost of the optimal geometry leading to hydrogen bond interactions. Four different interaction modes were observed, flavonoids are stabilised in S(1) region of beta-trypsin by formation of two (apigenin) or at least one hydrogen bond and other significant electrostatic interactions. Quercetin, myricetin and morin have shown to be the best trypsin inhibitors tested. In general, flavonoids with suitably located hydroxy groups and planar conformation are the building blocks able to replace guanidinobenzoyl part of successful inhibitors. Physiological nature of flavonoids reveals biotechnological source of new trypsin inhibitors as antipancreatitis, anticancer and anti-inflammation drugs.

Role of 5-ht1b receptors in entrainment disorder of otsuka long evans tokushima fatty (oletf) rats

The role of 5-HT1A and 5-HT1B receptors in entrainment function was studied in Otsuka Long Evans Tokushima fatty (OLETF) rats and control Long Evans Tokushima Otsuka (LETO) rats. Light-induced (100 lux, 30 min) Fos expression in the suprachiasmatic nucleus was studied. Light-induced Fos expression was significantly decreased in OLETF rats compared to that in LETO rats. The decrease of light-induced Fos expression in OLETF rats was significantly reversed by pretreatment with the 5-HT1B receptor antagonist, isamoltan (3 mg/kg, i.p.). Simultaneous administration of CGS12066B (5 mg/kg, i.p.), a 5-HT1B agonist, blocked the reversal effect of isamoltan on Fos expression. Fos expression was not changed in LETO rats by pretreatment with isamoltan (3 mg/kg, i.p.). The Fos expression in LETO and OLETF rats was significantly decreased by pretreatment with the 5-HT1A antagonist, WAY-100,635. Phase shifts in locomotor activity paralleled the Fos expression. Light-induced phase shifts of locomotor activity in OLETF rats were significantly smaller than those in LETO rats. The phase shifts were significantly increased by isamoltan (3 mg/kg, i.p.) in OLETF rats. These results suggest that 5-HT1B receptors are involved in the reduced entrainment function of OLETF rats.

Effects of protease inhibitor ONO-3403 on pancreatic exocrine response to CCK in rats

AIM

To examine the pancreatic exocrine response to CCK-8 and to clarify the mechanism of the pancreatic exocrine hypersecretion after oral administration of synthetic protease inhibitor ONO-3403 in rats.

METHODS

A single oral dose of synthetic protease inhibitor ONO-3403 was given to rats by orogastric tube 6h and 12 h before experiments. The pancreatic juice was collected before test and after stimulation of stepwise increasing doses of CCK-8. The output of protein, amylase, lipase and bicarbonate in pancreatic juice or pancreatic tissue were determinated by Lowry method, Chromogenic method with blue-dyed starch polymer, Whitaker method and by the DST 800 multititration system, respectively.

RESULTS

Oral administration of ONO-3403 had no influence on pancreatic juice flow and output of protein in basal and CCK-8 stimulation at 6h after ONO-3403 pretreated, but it caused a significant increase in pancreatic juice flow (peak level 215±9 ulper 30 min vs 93±6 ulper 30 min, P<0.01) and protein output (peak level 16475±1 801 ug per 30 min vs 5 920±593 ug per 30 min, P<0.01) of the basal and CCK-8 stimulation at 12 h after ONO-3 403 pretreated. The basal pancreatic juice flow and output of amylase (470±32 su per 30 min at 6 h P<0.01, 394±47 su per 30 min at 12 h, P<0.05 vs 251±32 su per 30 min), bicarbonate (2.224±0.333 umolper 30 min at 6 h, P<0.05; 3.148±0.374 umolper 30 min at 12 h, P<0.01 vs 1.428±0.282 umolper 30 min) were significant high after ONO-3403 pretreated than those of control group. There was no change in lipase output compared with control group. The pancreatic weight, pancreatic contents of protein and amylase in ONO-3 403 pretreated rats were similar to those in control rats.

CONCLUSION

ONO-3 403 can increase pancreatic exocrine secretion and sensitivity to CCK-8 stimulation.The mechanism of ONO3 403 induced pancreatic exocrine hypersecretion may be a feedback regulation of the pancreas by increasing CCK secretion.

Different effects of oral administration of synthetic trypsin inhibitor on the pancreas between cholecystokinin-A receptor gene knockout mice and wild type mice

The synthetic trypsin inhibitor camostat has been used for the treatment of acute and chronic pancreatitis in Japan based on the evidences obtained from a rat experimental model. However, rats differ from other rodents and from humans in terms of lacking a gallbladder and no response of pancreatic bicarbonate secretion to cholecystokinin (CCK). In the present study, we determined whether oral administration of camostat showed a trophic effect in mice as observed in rats and whether the trophic effect, if substantial, was mediated via the CCK-A receptor, using CCK-A receptor gene targeting mice. The chow containing 0.1% camostat was fed to 8-month-old mice. Three- and seven-day treatments with camostat did not affect pancreatic wet weight in CCK-A receptor (+/-) mice. After 14-day treatment, the ratio of pancreatic wet weight/body weight was significantly lower in CCK-A receptor (-/-) than (+/+) mice. The protein and chymotrypsin contents were lower and amylase content was higher in CCK-A receptor (-/-) mice, compared to (+/+) mice. No pathological findings were observed by histological examination. Camostat has a trophic effect on the pancreas in mice and this effect is mediated via the CCK-A receptor, but is less potent than in rats.

Effect of camostat mesilate on the expression of pancreatitis-associated protein (PAP), p8, and cytokines in rat spontaneous chronic pancreatitis

An oral protease inhibitor, camostat mesilate (CM) has been used clinically for chronic pancreatitis (CP) in Japan, but it lacks enough scientific evidence of its effectiveness. The aim of this study was to analyze the effect of CM on the gene expressions of pancreatitis-associated protein (PAP), p8, and cytokines such as interleukin-6 and transforming growth factor-beta1 in spontaneous CP model (WBN/Kob rats). CM (10 mg/100 g body weight), mixed in MB-3 diet, was administered orally and gene expressions were analyzed by reverse transcription-polymerase chain reaction. In untreated WBN/Kob rats, the gene expressions of all the four factors peaked at 12 weeks, whereas they were significantly suppressed in the CM-treated rats. CM significantly increased the body weight and pancreatic wet weight, and it significantly inhibited inflammatory changes and fibrosis of the pancreas. These results suggest that CM inhibits pancreatic inflammation and fibrosis through the suppression of gene expressions of PAP, p8, and cytokines in CP.