Differential effects of ziprasidone and haloperidol on immobilization-stress-induced CRF mRNA expression in the hypothalamic paraventricular nucleus of rats.

OBJECTIVES Corticotropin-releasing factor (CRF) plays a prominent role in mediating the effect of stressors on the hypothalamic-pituitary-adrenal axis. In this study, we examined the effects of chronic administration of second-generation antipsychotic drug ziprasidone on CRF mRNA expression in the hypothalamic paraventricular nucleus (PVN) of rats with or without immobilization stress. METHODS The rats were subjected to immobilization stress 2 h/day for 3 weeks. The effect of ziprasidone (2.5 mg/kg, 21 days) on CRF mRNA expression was determined using in situ hybridization of tissue sections from the rat hypothalamic PVN. Haloperidol (1.0 mg/kg, 21 days) was used for comparison. RESULTS Haloperidol increased the expression of CRF mRNA in the PVN under basal conditions, whereas ziprasidone had no effect. Chronic immobilization stress increased CRF expression. The chronic administration of ziprasidone prevented the increase in CRF mRNA expression caused by immobilization stress. CONCLUSIONS These results suggest that ziprasidone may have a regulatory effect on the stress-induced CRF mRNA expression and a role in the treatment of depressive mood symptom.