[Serotonin excess in the brain modifies the effect of beta-endorphin and dalargin on the processes of learning and...

In experiments on outbred female rats the influence was studied and compared of two representatives of endogenous opioids beta-endorphine and the analogue of leu-enkephalin dalargin on the processes of learning and memory in normal conditions and at the change of functional state of serotoninergic system of the brain. Parallel, the influence was studied of neuropeptides on the content of serotonin (5-OT) and its metabolite--5-oxyindolacetic acid in various areas of the brain in control and at the 5-OT redundancy. Conditioned reflexes (CRs) were used of two-way avoidance and defensive CRs. It has been established that administration of neuropeptides to intact animals influences in different directions the elaboration of the CR of two-way avoidance and maze defensive CR, but also worsens their preservation. Redundancy of 5-OT in the brain modifies behavioural effects of beta-endorphine and dalargin manifested in appearance of new effect and elimination and change of direction of the effects observed in the intact animals. Redundancy of 5-OT in the brain changes metabolic effects of beta-endorphine and particularly of dalargin. The obtained data testify to a dependence of the effects of beta-endorphine and dalargin on the functional state of 5-OT-ergic system.