Spiroperidol, which blocks dopamine (DA) receptors, attenuated self-stimulation of the nucleus accumbens, septal area, hippocampus, anterior hypothalamus and ventral tegmental area. Dopamine is thus involved in self-stimulation of many sites (in addition to the lateral hypothalamus). The attenuation was not a simple motor impairment of the speed of bar-pressing in that the nucleus accumbens and septal self-stimulation rates were lower than those in treated animals self-stimulating at other sites (Experiment 1). Feeding was partly attenuated, and drinking was much less attenuated by the spiroperidol. Since the rats bar-pressed for brain-stimulation reward, chewed pellets to eat, and licked a tube to drink, dopamine-receptor blockade may attenuate complex motor responses most. Alternatively, the blockade could affect brain-stimulation reward more than the controls of eating, and these latter more than the controls of drinking (Experiment 2). In Experiment 3, feeding and drinking were equally and severely attenuated when rats had to bar-press to obtain food or water. The attenuation was to a level similar to that found for self-stimulation. These experiments suggest that dopamine receptor blockade impairs eating, drinking and self-stimulation by interfering with complex motor responses.
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