Neuroendocrine effects of raloxifene hydrochloride in postmenopausal women

Raloxifene is a selective estrogen modulator able to exert an estrogen-like action on some target tissues and a specific antiestrogenic action on the uterus and breast. In ovariectomized rats ,it has been shown to stimulate the β-endorphin and allopregnanolone concentrations of the anterior and neurointermediate pituitary lobes ,the hypothalamus and the hippocampus. The present study aimed to evaluate, in 12 healthy postmenopausal women ,the effect of 60 mg/day raloxifene hydrochloride administration for 6 months on plasma β-endorphin and allopregnanolone levels ,and on the dynamic changes of both β-endorphin and allopregnanolone secretion after the administration of: (1) clonidine ,an α2-presynaptic adrenergic agonist; (2) naloxone ,an opioid receptor antagonist; and (3) fluoxetine, a serotonin selective reuptake inhibitor. The administration of raloxifene significantly increased both circulating β-endorphin and allopregnanolone concentrations ,at both the third and sixth months of treatment (p < 0.01). ...