The effect of estrogen replacement therapy on plasma serotonin and catecholamines of postmenopausal women

We examined the effect of estrogen replacement therapy (ERT) on plasma serotonin (5HT) and norepinephrine (NE) and their correlation with serum estradiol, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in 12 postmenopausal women. Plasma 5HT and NE, estrogen, progesterone, LH and FSH were examined every 4 days for 2 consecutive months (before and during ERT). Serotonin values were low (32.29±38.36 nmol/l) and showed an intrinsic spontaneous cyclicity with a nadir every 10-11 days. Plasma NE was similar to that observed during the follicular phase of the ovulatory cycle (1,216.8±503.4 pmol/l) and showed no cyclicity. ERT significantly increased mean (±SD) serum estrogen values (from 95.40±73.31 to 390.72±347.17 pmol/l, P = 0.0001), significantly decreased serum FSH (from 84.04±14.97 to 52.97±20.74 mIU/ml, P = 0.0001) and LH (from 35.35±13.82 mIU/ml to 29.69±16.46 mIU/ml, P = 0.03). Plasma 5HT levels showed a tendency to rise under the influence of ERT, but this increase was not statistically significant. Plasma NE decreased significantly from 1,216.8±503.4 to 994.1±353.89 pmol/l, P < 0.05. In conclusion, plasma serotonin in postmenopausal women has a 10-11 day cycle and is significantly lower than in the follicular phase of ovulating women. Plasma NE shows no cyclicity and is significantly decreased by ERT.