Different effects of vitamin D hormone treatment on depression-like behavior in the adult ovariectomized female rats.

Vitamine D (VD) has important functions in the human brain and may play a role in affective-related disorders. VD receptors are expressed in multiple brain regions associated with depressive disorders. The aim of the preclinical study was to examine the effects of chronic cholecalciferol administration (1.0, 2.5 or 5.0mg/kg/day,s.c., once daily, for 14days) on the depression-like behavior and corticosterone levels in the blood samples following ovariectomy in female rats. Cholecalciferol was administered to the ovariectomized (OVX) rats and OVX rats treated with 17β-estradiol (17β-E2, 0.5μg/rat,s.c., once daily, for 14days). Depression-like behavior and spontaneous locomotor activity were assessed in the forced swimming test (FST) and the open field test (OFT), respectively. The corticosterone levels in the blood serum before and after FST were measured in all experimental groups. Treatment with cholecalciferol in high dose (5.0mg/kg/day,s.c.) significantly decreased the immobility time of OVX rats in the FST. Co-administration of cholecalciferol in high dose with 17β-E2 exerted a markedly synergistic antidepressant-like effect in the OVX rats on the same model of depression-like behavior testing. Cholecalciferol in high dose (5.0mg/kg/day,s.c.) administered alone or together with 17β-E2 significantly enhanced frequency of grooming for the OVX rats in the OFT. Moreover, cholecalciferol in high dose administered alone or together with 17β-E2 significantly decreased the elevated corticosterone levels in the blood serum of OVX rats following the FST. These results indicate that Cholecalciferol in high dose has a marked antidepressant-like effect in the adult female rats with low levels of estrogen.