Mechanism of inhibition of small intestinal motility by restraint stress differs from that with norepinephrine treatment in rats.

We have previously reported that restraint stress inhibits small intestinal motility in rats, and that the adrenergic beta3-antagonist SR59230A administration recovered the inhibition. In the present study, we compared the effects of restraint stress and norepinephrine on small intestinal motility using alpha- and beta-adrenergic antagonists. SR59230A did not recover the norepinephrine-induced inhibition of small intestinal motility. The norepinephrine-induced inhibition of small intestinal motility was recovered after administration of the alpha2-antagonist yohimbine, but not by alpha1-, beta1-, and beta2-antagonists. Considering these results, it is reasonable to assume that the mechanisms of inhibition of small intestinal motility due to restraint stress and norepinephrine treatment are different.