Özet:

Cannabinoid receptor-1 (CB1R) and cannabinoid receptor-2 (CB2R) have significant roles in the motility of the esophagus, small intestine, and colon in the postprandial period as well as gastric emptying, secretion, and defecation in the gastrointestinal system. Also, our previous study showed that activation of peripheral CB1R inhibited migrating myoelectric complex (MMC), forming the source of fasted small intestinal motility. However, the role of the cannabinoid receptor-2 (CB2R) on the MMC pattern is still unknown. The present study aimed to investigate the roles of peripheral and central CB2Rs in the formation and regulation of small intestine MMC patterns in rats. In this study, 42 adult male Sprague-Dawley rats were used (n:7). Bipolar electrodes were implanted in three different jejunum sites of rats (J1, J2, J3) to record the MMC pattern. A cannula was implanted in the right lateral ventricle to perform drug intracerebroventricular (i.c.v.) while a catheter was placed in the right jugular vein to inject the drug intravenously (i.v). After the amelioration period, experiments were carried out following an 18-hour fasted period and later was taken at least a one-hour baseline recording of the MMC pattern. Then, JWH 133, a CB2R agonist, was injected i.v. (1.25-10 mg/kg) or i.c.v. (2.5-20 µg/rat) and also AM 630, a CB2R antagonist, was administered i.v. (0.25-2 mg/kg) or i.c.v. (2.5-20 µg/rat). The effects of JWH 133 or AM 630 on the MMC pattern were compared to the vehicle group (10% dimethyl sulfoxide). Centrally or peripherally injected JWH 133 and AM 630 did not cause any change in the spike frequency and the number of the MMC cycle. The results of the present study propose that CB2Rs are involved in neither endogenous formation nor exogenous regulation of the fasting myoelectric activity in healthy fasted rats.

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