Systemic oxytocin treatment modulates glucocorticoid and mineralocorticoid receptor mRNA in the rat hippocampus.

The present study investigated the effects of oxytocin treatment on hippocampal glucocorticoid receptors. Oxytocin (1 mg/kg s.c.) was administered once a day for 5 days to male Sprague-Dawley rats. The animals were sacrificed 1 day after treatment and expression of glucocorticoid and mineralocorticoid receptor (GR and MR) mRNA in the dorsal hippocampus was measured with in situ hybridization. The oxytocin treatment decreased GR mRNA expression in CA1+2 and the dentate gyrus (P<0.05), tended to decrease GR mRNA expression in CA3 (P=0.07), and increased MR mRNA expression in the dentate gyrus (P<0.05). These findings demonstrate that systemic oxytocin treatment induces changes in the hippocampal glucocorticoid receptors. Thus, oxytocin may modulate the activity of the hypothalamic-pituitary-adrenal-axis also at the hippocampal level in rats.