Selective cyclooxygenase-2 inhibitor ameliorates cholecystokinin-octapeptide-induced acute pancreatitis in rats

AIM： To investigate the effect of selective Cyclooxygenase-2 （COX-2） inhibitor 4-[5-（4-Chloro-phenyl）-3- （trifluoromethyl）- 1H-pyrazol- 1-yl] benzenesulfonamide （SC-236）, on the cholecystokinin （CCK）-octapeptideinduced acute pancreatitis （AP） in rats. METHODS： Wistar rat weighing 240 g to 260 g were divided into three groups. （1） Normal DMSO treated group, （2） SC-236 at 4 mg/kg treated group; SC-236 systemically administered via the intravenous （i.v.） catheter, followed by 75 μg/kg CCK octapeptide subcutaneously three times, after 1, 3 and 5 h. This whole procedure was repeated for 5 d. （3） Dimethyl sulfoxide （DMSO） treated group： an identical protocol was used in this group as in the SC-236 cohort （see 2. above）. Repeated CCK octapeptide treatment resulted in a typical experimentally induced pancreatitis in the Wistar rats. RESULTS： SC-236 improved the severity of CCK- octapeptide-induced AP as measured by laboratory criteria [the pancreatic weight/body weight （p.w/ b.w） ratio, the level of serum amylase and lipase]. The SC-236 treated group showed minimal histologic evidence of pancreatitis and a significant reduction in myeloperoxidase activity. SC-236 also increased heat shock protein （HSP）-60 and HSP72 compared with the DMSO-treated group in the CCK-octapeptide-induced AP and also reduced the pancreatic levels of COX-2. Furthermore, SC-236 reduced proinflammatory cytokine synthesis and inhibited NF-KB activation compared with the DMSO-treated group in the CCK-octapeptide-induced AP. CONCLUSION： Our results suggested that COX-2 plays pivotal role in the development of AP and COX-2 inhibitors may play a beneficial role in preventing AP.

Insulin is necessary for the hypertrophic effect of cholecystokinin-octapeptide following acute necrotizing experimental pancreatitis

AIM:In previous experiments we have demonstrated that by administering low doses of cholecystokinin-octapeptide (CCK-8),the process of regeneration following L-arginine (Arg)-induced pancreatitis is accelerated.In rats that were also diabetic(induced by streptozotocin,STZ),pancreatic regeneration was not observed.The aim of this study was to deduce whether the administration of exogenous insulin could in fact restore the hypertrophic effect of CCK-8 in diabetic-pancreatitic rats. METHODS:Male Wistar rats were used for the experiments. Diabetes mellitus was induced by administering 60mg/kg body mass of STZ intraperitoneally(i.p.),then,on d 8, pancreatitis was induced by 200mg/100 g body mass Arg i.p.twice at an interval of 1 h.The animals were injected subcutaneously twice daily(at 7 a.m.and 7 p.m.)with 1 μg/kg of CCK-8 and/or 2 IU mixed insulin(300g/L short- action and 700g/L intermediate-action insulin) for 14 d after pancreatitis induction.Following this the animals were killed and the serum amylase,glucose and insulin levels as well as the plasma glucagon levels,the pancreatic mass/body mass ratio(pm/bm),the pancreatic contents of DNA,protein,amylase,lipase and trypsinogen were measured.Pancreatic tissue samples were examined by light microscopy on paraffin-embedded sections. RESULTS:In the diabetic-pancreatitic rats treatment with insulin and CCK-8 significantly elevated pw/bm and the pancreatic contents of protein,amylase and lipase vs the rats receiving only CCK-8 treatment.CCK-8 administered in combination with insulin also elevated the number of acinar cells with mitotic activities,whereas CCK-8 alone had no effect on laboratory parameters or the mitotic activities in diabetic-pancreatitic rats. CONCLUSION:Despite the hypertrophic effect of CCK-8 being absent following acute pancreatitis in diabetic-rats, the simultaneous administration of exogenous insulin restored this effect.Our results clearly demonstrate that insulin is necessary for the hypertrophic effect of low-doses of CCK-8 following acute pancreatitis.

Cholecystokinin octapeptide improves cardiac function by activating Cholecystokinin octapeptide receptor in endotoxic shock rats

AIM: To explore the effect of sulfated cholecystokinin octapeptide (sCCK-8) on cardiac functions and its receptor mechanism in endotoxic shock (ES) rats. METHODS: The changes of the mean arterial pressure (MAP), heart rate (HR), the left ventricular pressure (LVP) and the maximal/minimum rate of LVP (±LVdp/dt max) were measured by using physiological record instrument in eight groups of rats. The expression of cholecystokinin-A receptor (CCK-AR) and cholecystokinin-B receptor (CCK-BR) mRNA of myocardium in ES rats was examined by reverse transcription polymerase chain reaction (RT-PCR). RESULTS: (1) Low doses of sCCK-8 (0.4 μg/kg) caused tachycardia (441±27, normal control 391±22 s/min) and slight increase in MAP, LVP and ±LVdp/dtmax (16.96±1.79, 18.21±1.69 and +768.85±31.28/-565.04±27.71 kPa, respectively, all P<0.01), while medium doses (4.0 μg/kg) and high doses of sCCK-8 (40 μg/kg) elicited bradycardia and marked increase in MAP, LVP and ±LVdp/dtmax (17.29±1.63, 19.46±2.57 and +831.46±22.57/-606.08 ±31.32; 17.46±1.08, 19.83±2.91 and +914.52±35.95/ -639.15±30.23 kPa, respectively, all P<0.01). Proglumide (1.0 mg/kg), a nonselective antagonist of CCK-receptor (CCK-R), significantly inhibited the pressor effects of sCCK-8 (15.96±1.38, 17.36±0.66 and +748.18±19.29/-512.12±14.39 kPa, respectively, all P<0.01), whilst reversing the bradycardiac responses. (2) High doses of LPS (8 mg/kg) elicited marked decrease in MAP, LVP and ±LVdp/dtmax. (7.16±0.59, 7.6±0.68 and +298.01±25.52/ -166.96±19.25 kPa, respectively, all P<0.01). Pretreatment with sCCK-8 (40 μg/kg) could reverse the decline of cardiac functions (10.71±0.45, 11.7±1.26 and +446.04±67.18/ -347.90±36.98 kPa, respectively, all P<0.01), while proglumide could cause further decline of cardiac function in ES rats (4.71±0.67, 5.58±1.25 and +226.48±15.84/ -142.83±20.23 kPa, respectively, all P<0.01). (3) CCK-A/BR mRNAs were expressed in myocardium of control rats. Gene expression of CCK-AR and CCK-BR significantly increased in myocardium of ES rats. The increase of CCK-AR mRNA induced by LPS began at 0.5 h, peaked at 2 h, kept a high level at 6 h and declined at 12 h, respectively. Similar to CCK-AR mRNA, the expression of CCK-BR mRNA peaked at 2 h and kept a high level at 6 h, but it did not change at the first 0.5 h and was stable at a high level at 12 h. CONCLUSION: The above results indicate that endogenous and exogenous sCCK-8 may significantly improve cardiac function and intractable hypotension of ES rats, which was likely related to high expression of CCK-A/BR in myocardium induced by LPS.