[Seasonal characteristics of the action of morphine and naloxone on the dopamine response of Helix neurons].

Morphine (1 X 10(-5) M) depresses the dopamine responses of Helix neurons in the summer-autumn period. The depolarizing responses are depressed more powerfully than the hyperpolarizing ones. Naloxone (1 X 10(-5) M) has no effect on the dopamine responses but antagonizes the effect of morphine. In the winter-spring period, the morphine effects are less potent (P less than 0.02), while naloxone depresses the dopamine responses. The results show the plasticity of the opiate-neurotransmitter system and relationship of the latter with the functional status of the body (hibernation, activity).