Evaluation of adaptive relaxation of the rat stomach using an orally inserted balloon instead of surgical intervention by demonstrating the effects of capsaicin and <i>N</i>^ω-nitro-L-arginine methylester

Abstract

Gastric functions such as adaptive relaxation have usually been monitored in rats using a surgically inserted barostat's balloon. However, surgery causes physiological damage to the rat stomach. This study is an investigation of adaptive relaxation of the rat stomach using a slightly modified balloon, which is introduced into the stomach through the mouth of anesthetized rats without the need for balloon surgery, attached to a brostat. In this case, the balloon was placed between the fore-stomach and the fundus, but towards the fore-stomach. The balloon volume increased gradually just after an increment in the balloon pressure, and reached a plateau within 1 min. This increased volume just after the increment of the balloon pressure was defined as adaptive relaxation. Adaptive relaxation increased with pressure increases in a pressure dependent manner. Pre-treatment with N ω -nitro-L-arginine methylester (30 mg/kg, i.v.) caused this adaptive relaxation to be significantly inhibited as compared with the control. On the contrary, adaptive relaxation was significantly enhanced by pre-treatment with capsaicin (0.5 mg/kg, p.o.). These findings show that this method is both useful for investigating the physiology of adaptive relaxation of the stomach without surgery and to show that nitric oxide plays an important role in the adaptive relaxation of the stomach as reported previously.

Correlation Between Gastric Emptying and Gastric Adaptive Relaxation Influenced by Amino Acids

“…24,25 However, it is easy to speculate that such a surgical procedure affects the gastric physiological function in an animal study, and that an animal study does not always reflect in vivo and human physiology. We improved the method for investigating gastric adaptive relaxation with the use of a barostat without the need for a surgical procedure, 15 and used this method in the present study. Adaptive relaxation has been known to be mediated by the capsaicin-sensitive afferent nerve.…”

“…26 We also reported that nitric oxide (NO) plays an important role in the gastric adaptive relaxation as demonstrated with the use of a barostat. 15 Indeed, NO formed from L-arginine was detected in the murine stomach in vivo. 27 In the present study, L-cysteine, L-aspartic acid and Larginine significantly enhanced the gastric adaptive relaxation.…”

“…15 In brief, rats were anesthetized by urethane (1.2 g/kg, ip). For fitting the balloon to the fundus, a slightly improved balloon was obtained by removing the tube within the balloon.…”

Effects of l-tryptophan on gastric emptying evaluated by breath test in relation to gastric accommodation evaluated by Barostat in rats

“…In clinical study, Barostat study was considered to be gold standard for evaluating gastric accommodation. We recently improved the method to evaluate gastric accommodation in rats without surgical operation (7). Then in the present study we used our method for evaluating the effect of Ltryptophan on the gastric accommodation, and found that L-tryptophan significantly enhanced the gastric accommodation.…”

“…Gastric accommodation was evaluated by the method previously reported by us (7). Rats were anesthetized by urethane (1.2 g/kg, i.p.).…”