Endocrine Abstracts

To examine the hormonal characteristics related to age of reproductive axis, serum hormone profiles and inhibins A and B were investigated in fertile and menopausal women.

Subjects: Forty-three cycling women (23–40-year-old) and 75 menopausal women (55–70-year-old) were studied. Serum 17-OHP, DHEA, DHEAS, androstendion, estradiol, estrone, progesterone, testosterone, free testosterone, DHT, SHBG, inhibin A and inhibin B, LH, FSH, Prl, TSH, GH, IGF1, insulin, cortisol and thyroid hormones were measured.

Results: Fertile women: The pattern of change in the plasma concentration of inhibin A was: ♦ low in follicular phase negatively correlated to 17-OHP (P=0.003), DHEAS (P=0.008), progesterone, (P=0.001), estrone (P<0.001), free (P=0.04) and total testosterone (P<0.001), dihidrotestosterone (P<0.001), total (P<0.001) and free triodothyronine (P<0.001), and positively with inhibin B (P=0.023), TSH (P=0.003) and T₄ (P<0.001); ♦ significantly increased in mid-cycle, negatively correlated with testosterone (P=0.032) and inhibin B (P=0.021) and positively with estradiol (P=0.001) and hGH (P=0.025).

Inhibin B showed a decreasing trend throughout menstrual cycle. In folicular phase, the higher levels of inhibin B were negatively correlated with DHEA (P=0.002), androstendion (P=0.01), progesterone (P<0.001), testosterone (P<0.001), free T₃ (P=0.013) and hGH (P<0.001). In mid-cycle inhibin B negatively correlated with 17OHP (P=0.04), estradiol (P=0.04), progesterone (P=0.009) and positively with testosterone (P=0.004).

Menopausal women: Both inhibins significantly decreased. There were no significant correlations between secretion of inhibins and both gonadal and gonadotropin hormones.

Conclusion: The current study suggests that inhibins A and B contribute to follicular maturation by primary mechanism that mediates gonadal steroids action in the reproductive tract.