Conducted 4 experiments with a total of 70 30-45 and 22 70-90 day old male albino Sprague-Dawley rats. Adult Ss on a food-deprivation schedule showed increased running in activity wheels and a paradoxical depression of food intake. This "self-starvation" effect was markedly potentiated in younger Ss, which, relative to controls, ran more and sustained greater weight loss than did older Ss. Chlorpromazine (a) reversed the self-starvation syndrome by depressing the activity and alleviating weight loss of the older Ss, and (b) exacerbated self-starvation with younger Ss. It is concluded that 30-45 day old Ss reacted to 23-hr deprivation with a severe stress response, perhaps related to the failure of incompletely developed neural and endocrine mechanisms to modulate the reaction to the self-starvation situation. (19 ref.) (PsycINFO Database Record (c) 2006 APA, all rights reserved)