Effect of acute desipramine on rectal temperature. A single i.p. injection of either water or desipramine (DMI) was given to adult (10 mg/kg) and post-natal day 13 (3 mg/kg) rats immediately after measuring their rectal temperatures (0 time). The rectal temperatures were measured again at 30 min and 60 min. Immediately thereafter brimonidine was injected (1 and 0.6 mg/kg i.p. for adult and post-natal day 13 rats, respectively) and rectal temperature determined at the times noted. The mean change in rectal temperature ± S.E.M. from the zero time for each rat is given. Number of rats in the control and desipramine treated groups was 4 for adult rats and 4 and 3 for juvenile rats, respectively. *Significantly different (P < 0.001) than control rats at that time point and age group based on 2-way ANOVA followed by a Bonferroni post-test of the body temperatures prior to administration of brimonidine.