Research Of The Effects And Mechanisms Of Small Dose Capsaicin On Rats’ Gastric Motility In Different Periods

Objective: To explore the role of small dose capsaicin(CAP) on rats’ gastric motility through testing migrating myoelectric complexes(MMC) and gastric emptying rate in different periods; to explore the role of CAP on gastric mucosal barrier through observing the histology changes of rats’ gastric mucosa; to explore the mechanisms of CAP through testing the plasma motilin level, evaluating the expression of transient receptor potential type 1(TRPV1), substance P(SP), calcitonin gene-related peptide(CGRP) in rats’ gastric mucosa. Methods :(1) The grouping: Totally 60 Sprague-Dawley(SD) rats were randomly divided into two groups: the control group(group A) and experimental group(group B), each group had 30 rats. The control group were fed with normal diet and the experimental group were fed with CAP diet. In order to explore the effects of CAP on gastric motility in different periods, the experiment was divided into I, II, III periods. According to the corresponding periods, group A and group B were randomly divided into 3 groups, namely the control group was divided into group A1, group A2 and group A3; the experimental group was divided into group B1, group B2 and group B3, with 10 rats in each groups. The installment method: phase I(A1, B1) for 1 days, phase II(A2, B2 group) for 1 weeks, phase III(A3, B3) for 4 weeks.(2)The preparation of CAP feed: According 1mg/Kg/d(one kilogram weight needed one milligram capsaicin) we weighted 1.53mgproper paprika and mixed with 100 mg common fodder to get capsaicin fodder. The content of CAP in the feed was 10mg/Kg. Rats were given 10 g CAP feed per 100 g body weight.(3) Feeding method: The rats were divided into cages(1 rats per cage) after electrodes placed. Rats were fasted but drunk at the first days after operation. Rats of the experimental groups were fed with corresponding CAP feed at the eighth day. CAP feed were mopped up can add ordinary feed. The control group had free normal diet. The rats were used in the following experiments after feeding on time.(4)The specific method: All the rats were implanted a pairs of bipolar electrodes in the gastric antrum, postoperative recoveried for 1 weeks. Rats were fed by stages and groups with common feed and CAP feed respectively for 1 day, 1 week and 4 weeks. Determination the gastric antrum MMC after rats fasted for 8 hours, then each rats were given 2ml phenol red solution by gavage. Blood was collected from the abdominal aorta in rats after 20 minutes. Then killed all the rats,collected stomach cleaning solution and stomach tissues.(4)Detection index: The organism functional experiment system BL-420 E was used to record the MMC of gastric antrum in the interdigestive of SD rats in all. The plasma MTL was detected by ELISA method. Gastric emptying rate was determined by the phenol red method. The stomach tissues were used for pathological examination and scored the gastric mucosa injury index under light microscope. The expression of TRPV1,SP and CGRP in gastric mucosa from these rats were assayed by immunohistochemis try and the stain positive indexs(PIs) wascalculated and compared by Color pmho-image analysis software. Results:(1)General state: All the rats were in mental state actionflexible,, shiny coat, urine normal during the experimental process. Group A1, B1, B2, B3 were respectively had 1 rats died after electrode buried. Group A2, A3 each had 1 rat’ s back wire offed, group B3 has 2 rat with back wire offed.The rest rats were survived with good fixed wires on back. Dead rats were withdrew from the experimental groups. The rats which wires ripped out were exited the MMC measurement.(2)MMC cycle and 3 phase duration(min): The gastric MMC cycle of group A1, B1, A2, B2 respectively was 11.56±0.83, 11.29±1.43, 11.78±0.79, 15.05±2.39. The gastric MMC cycle of group B2 was significantly longer than group A2(P<0.001) and group B1(P<0.001). The duration of phases 3(min) of group A1, B1, A2, B2 respectively was 2.28±0.38, 2.27±0.43, 2.64±0.16, 4.79±1.40. The phases 3 of group B2 was significantly longer than group B1(P<0.001)and group A2(P<0.001).(3) Gastric empting rate(%): The gastric empting rate of group A1, B1, A2, B2, A3, B3 respectively was 62.57±18.75, 63.41±15.95, 69.12±16.39, 83.83±13.80, 68.62±13.39, 90.24±12.22. The gastric empting rate of group B3 was significantly higher than group A3(P<0.001)and group B1(P=0.004). The gastric empting rate of group B2 was significantly higher than that in group B1(P=0.041) and A2(P=0.004). There was no significant difference among other groups(P>0.05).(4) MTL(pg/ml): The plasma motilin of group A1, B1, A2, B2, A3, B3 respectively was 47.593±22.248, 54.498±13.317, 56.243±11.313,136.699±12.887, 55.497±24.215, 94.547±13.812. The plasma motilin of group B3 was significantly higher than that in group A3(P<0.001)and group B1(P<0.001). The plasma motilin of group B2 was significantly higher than that in group B3(P<0.001), group A3(P<0.001)and group B1(P<0.001). There was no significant difference among other groups(P>0.05).(5)HE staining results : The changes of rats’ gastric mucosa pathological: the epithelial cells of gastric mucosa of all the rats were normal,arranged in neat rows,and no mucosal lossed,congested,edemaed,infiltrated with inflammatory cell or glandular disordered or necrossed. The score of gastric mucosal injury((Masud standard)in group A1, B1, A2, B2, A3, B3 respectively was 0.54±0.51, 0.56±0.52, 0.65±0.50, 0.59±0.61, 0.60±0.55, 0.66±0.52. Compared the pathological injury score between each two groups showed no statistically significant difference(P>0.05).(6) The positive expression results of TRPV1, SP, CGRP in rats’ gastric mucosa: ①all of these groups( group A1, B1, A2, B2, A3, B3) had TRPV1, SP and CGRP positive nerve secretion production expressed in gastric mucosa. The products were mainly concentrated in the gastric mucosal epithelium and in the lamina propria. The positive products of group A1, B1, A2 and A3 were dispersed, had less volume and light color, especially in the lamina propria. While The TRPV1, SP, CGRP positive products in group B2 and B3 were significantly increased, stained with granular, evenly distributed, also had more product accumulation in the lamina propria. ②The PIs of TRPV1 in group A1, B1, A2, B2, A3, B3 respectively was1.60±0.37, 1.67±0.51, 1.66±0.63, 2.13±0.43, 1.69±0.23, 2.32±0.63. The PIs of TRPV1 in group B3 was significantly higher than that in group A3(P=0.003) and group B1(P=0.006). The PIs of TRPV1 in group B2 was significantly higher than that in group A2(P=0.024) and group B1(P=0.046).There was no significantly difference between other groups(P>0.05). ③The PIs of SP in group A1, B1, A2, B2, A3, B3 respectively was 1.40±0.48, 1.43±0.28, 1.49±0.36, 2.16±0.64, 1.46±0.75, 2.26±0.81. The PIs of SP in group B3 was significantly higher than that in group A3(P=0.003) and group B1(P=0.006). The PIs of SP in group B2 was significantly higher than that in group A2(P=0.008) and group B1(P=0.017). There was no significant difference among other groups(P>0.05).④ The PIs of CGRP in group A1, B1, A2, B2, A3, B3 respectively was 1.13±0.37, 1.13±0.21, 1.13±0.29, 1.46±0.41, 1.14±0.21, 1.44±0.23. The PIs of CGRP in group B3 was significantly higher than that in group A3(P=0.042) and group B1(P=0.046). The PIs of SP in group B2 was significantly higher than that in group A2(P=0.033) and group B1(P=0.037). There was no significant difference among other groups(P>0.05).Conclusion:(1)Rats fed with small doses of CAP(1mg/Kg/d) for 1 day had no effect on gastric motility.(2)Rats fed with small doses of CAP for a long term(1week and 4 weeks)had obvious promoting effect on gastric motility.(3) The rats fed with small doses of CAP for a long term increased the expression of TRPV1, promoted the releasing of MTL, SP, CGRP.(4) Rats fed with small doses of CAP for a long term caused little damage to the gastric mucosa.