The effect of progestins on behavioral stress responses in postmenopausal women.

Objective: We assessed the effects of progestin when added to estrogen on the adaptive patterns to provoked stress in postmenopausal women.

Methods: Fourteen postmenopausal women were randomized to receive either a transdermal estrogen patch (TE2) (n = 7) for 6 weeks or TE2 with added medroxyprogesterone acetate (10 mg) (TE2/MPA) (n = 7) for the last 10 days of the 6-week regimen. Behavioral stress tests were administered to each group, with measurements of biophysical and neuroendocrine responses. In a crossover fashion, after each group received the first treatment and testing, treatment was continued for another 6 weeks with the alternate regimen, at which time another stress test was administered. Responses to stress in the two treatment groups were compared to each other and to established placebo responses.

Results: Biophysical responses in the TE2 group were significantly blunted compared to both TE2/MPA and placebo responses (P < .05). Without MPA treatment, there were significantly blunted speech (P < .05) and cold pressor (P < .01) blood pressure responses. With added progestin, there was a greater systolic blood pressure response (P < .01) compared with estrogen alone. Both groups (TE2 and TE2/MPA) had blunted and nonsignificant responses of ACTH and cortisol upon testing, whereas the placebo group showed a significant response (P < .01). Plasma norepinephrine responses, however, were significantly blunted after TE2, compared with the increased responses observed with both TE2/MPA and placebo (P < .01).

Conclusion: Although estrogen significantly reduces behaviorally induced stress reactivity in postmenopausal women, certain doses of progestin administration may blunt this effect.