INTERACTION OF SELF-STIMULATION AND ETHANOL-INTAKE BEHAVIORS IN RATS

The effect of ethanol (10% v/v) intake was studied on the rate of self-stimulation (SS) in rats implanted with bipolar electrodes in the posterior hypothalamus. The rats were divided into 3 groups: in Group A, 6 rats were trained to press a bar for SS, and allowed to drink water only; in Group B, 6 rats were trained also for SS, and in Group C, 5 rats were put on to rotarod performance and served as controls for the physical exercise incurred in SS schedule; rats of both Groups B and C were offered ethanol and water in free choice. At the termination of the experiment, the contents of norepinephrine (NE) and serotonin (5-HT) in diencephalon-midbrain (DM) and pons-medulla (PM), and dopamine (DA) contents in DM and caudate nucleus (CN) of these rats were estimated. While in Group A rats the SS rate decreased gradually, in Group B rats the SS rate increased significantly and their ethanol intake increased to approximately 60% of their total fluid intake (TFI). In Group C rats ethanol intake was low (about 30% of TFI), compared to Group B. Neurochemical studies in Group B and C showed increased NE and 5-HT contents in DM and PM and decreased DA contents in CN and DM, compared to controls. The interaction between the two reinforcing behaviors seems to be related to induced changes in the brain amines. © 1979.