Food deprivation and motor activity in rats: differences between morphine and clonidine.

The effects of various doses of morphine (0, 1.25, 2.5, 5 mg/kg) and clonidine (0, 1.67, 15, 45 micrograms/kg) on motility were determined in food satiated and in food deprived rats. Food deprivation failed to change the general activity of rats after saline injections. Nevertheless, food-deprived animals tested under morphine were more active than food satiated ones. Clonidine exhibited slight psychomotor stimulant properties that were not increased by food deprivation. The results are discussed in terms of possible mechanisms of deprivation-related hypermotility.