Effect of the chronic ingestion of chlorimipramine and desipramine on the hole board response to acute stresses in male rats

The effect of the chronic ingestion of chlorimipramine (CI) or desipramine (DS) on the alterations of hole board behavior caused by a model stress (2 IP injections of physiological saline) and by a short restraint stress (5 min) is analyzed in this study. The experimental groups ingested about 3 mg/kg/24 hr CI or DS for 15 days. Then some experimental and control rats were assigned to control of drug effects on baseline activity. The remaining rats were submitted to saline stress (Experiment I) or restraint stress (Experiment II). The baseline scores of hole board locomotion, head dipping, grooming and defecation were not affected by DS treatment but locomotion slightly increased in the CI treated group. Saline stress impaired significantly head dipping and caused excessive grooming in control rats. The CI treatment induced almost full protection against these behavioral effects of saline stresses better than Restraint stress was found to cause a pronounced inhibition of head dipping as well as great increase of the scores of grooming in the control group. The CI treatment clearly attenuated these effects of restraint but DS treatment was not effective. The results suggest that (1) male rats treated chronically with CI tolerated both acute stresses better than untreated rats, and that (2) a similar treatment with DS did not provide protection against the effect of such stresses on hole board responding. Inasmuch as CI and DS have different relative potency at noradrenergic and serotonergic systems, it is speculated that this might be in part responsible for their differences as stress protectors.