[Changes of plasma serotonin precursor metabolite concentrations in postmenopausal women with hot flushes]

To investigate the relationship between changes of serotonin metabolism and hot flushes in climacteric women.

Ninety seven climacteric women, aged 40 - 60 were enrolled and divided into 4 groups, group A: early menopausal transition 20 cases, group B: late menopausal transition, 26 cases with skip of periods 3 - 12 months, group C: early postmenopause (1 - 3 years) 28 cases, group D: late postmenopause (> 3 - 6 years) 24 cases. Twelve normal women of reproductive age were served as young controls. Fifty two postmenopausal women were subdivided into 3 groups according to presence or absence of hot flushes. (1) postmenopausal controls without hot flush, 17 cases, (2) mild hot flushes group fewer < or = 5 times/day. (3) severe hot flushes group more than 5 times/day. Plasma concentrations of tryptophan (TP), 5-hydroxytryptophane (5-HTP), 5-hydroxytryptamine (5-HT or serotonin) and 5-hydroxyindoleacetic acid (5-HIAA) were measured in all participants by high pressure liquid chromatography-fluorescence spectrophotometer. Plasma level luteinizing hormone (LH) was measured in postmenopausal women by radioimmuno assay. The relationship between serotonin metabolic parameters and menopause, hot flushes and LH level were analysed.

(1) Mean 5-HT and 5-HIAA concentrations in plasma were significantly higher in climacteric women than those in young controls, especially in the group B. Mean 5-HTP and 5-HT levels were higher and 5-HIAA lower in group D as compared with those of young controls. (2) Plasma 5-HT levels was positively correlated to luteinizing hormone concentration in postmenopausal women (P < 0.001). (3) In the mild hot flushes group, only plasma 5-HTP levels was significantly higher than that in the postmenopausal control group. In severe hot flushes group, plasma 5-HT and 5-HTP contents were significantly higher and 5-HIAA/5-HT ratio lower than those in the postmenopausal control groups.

Our results suggest that the catabolic disorder of serotonin may involve in the underlying mechanism of hot flushes in postmenopausal women.