Creighton J A, Rudeen P K
Department of Anatomy, School of Medicine, University of Missouri-Columbia 65212.
J Pineal Res. 1989;6(4):317-23. doi: 10.1111/j.1600-079x.1989.tb00427.x.
The effects of exogenous thyroid hormone administration on melatonin-induced gonadal atrophy were studied in young adult male hamsters. Animals were given daily afternoon injections of 25 micrograms melatonin and/or thrice-weekly injections of 7 micrograms thyroxine. A control group received injections of saline vehicle only. No significant effect of either treatment was seen on body weight. Melatonin-treated animals had significantly reduced testicular and seminal vesicle weights, compared with vehicle-treated control animals: serum T4 levels and the FT4I were reduced by melatonin treatment, but serum T3 and the FT3I were increased. No effect of melatonin was seen on in vitro T3 uptake. Thyroxine treatment alone, while leading to elevated serum T4 levels and FT4I, had no effect on T3, the FT3I, or T3 uptake. Thyroxine treatment normalized circulating T4 levels and the FT4I in melatonin-treated animals, without preventing the melatonin-induced testicular regression. The results are taken as evidence that the inhibitory effects of melatonin on gonadal and thyroid function are independently mediated.
研究了外源性甲状腺激素给药对褪黑素诱导的成年雄性仓鼠性腺萎缩的影响。动物每天下午注射25微克褪黑素和/或每周三次注射7微克甲状腺素。对照组仅接受生理盐水注射。两种处理对体重均无显著影响。与接受赋形剂处理的对照动物相比，接受褪黑素处理的动物睾丸和精囊重量显著降低：褪黑素处理降低了血清T4水平和FT4I，但血清T3和FT3I升高。褪黑素对体外T3摄取无影响。单独使用甲状腺素治疗，虽然导致血清T4水平和FT4I升高，但对T3、FT3I或T3摄取无影响。甲状腺素治疗使褪黑素处理动物的循环T4水平和FT4I恢复正常，但并未阻止褪黑素诱导的睾丸退化。这些结果被视为褪黑素对性腺和甲状腺功能的抑制作用是独立介导的证据。
