Loperamide effects on anxiety level and feeding behavior in rats. Role of vagal afferentation

摘要

We investigated the role of vagal afferentation in the interaction of the peripheral and central parts of the endogenous opioid system, in the mechanisms of sensorial satiation and anxiety in rats. It has been established that vagotomized rats spent less time in open arm of the plus-maze in comparison with sham-operated animals. Peripheral administration of μ-opioid receptor agonist loperamide was shown to reduce anxiety level in sham-operated rats and had no effect on this parameter in vagotomized animals. Testing in a PhenoMaster module system showed that loperamide administration suppressed feeding behavior in sham-operated animals and partially suppressed it in vagotomized animals. Vagotomy virtually completely blocked the anxiolytic effect of loperamide and partially blocked the anorexigenic effect of the μ-opioid receptor agonist.