Armada-Dias L, Carvalho J J, Breitenbach M M, Franci C R, Moura E G
Departamento de Fisiologia, Instituto de Biologia Roberto Alcântara Gomes, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, RJ, Brasil.
Braz J Med Biol Res. 2001 Sep;34(9):1209-15. doi: 10.1590/s0100-879x2001000900015.
The objective of the present study was to examine whether hypothyroidism affects the reproductive system of adult female rats by evaluating ovarian morphology, uterus weight and the changes in serum and pituitary concentrations of prolactin and gonadotropins. Three-month-old female rats were divided into three groups: control (N = 10), hypothyroid (N = 10), treated with 0.05% 6-propyl-2-thiouracil (PTU) in drinking water for 60 days, and T4-treated group (N = 10), receiving daily sc injections of L-thyroxine (0.8 microg/100 g body weight) during the last 10 days of the experiment. At the end of 50 days of hypothyroidism no hypothyroid animal showed a regular cycle, while 71% of controls as well as the T4-treated rats showed regular cycles. Corpora lutea, growing follicles and mature Graafian follicles were found in all ovaries studied. The corpora lutea were smaller in both the hypothyroid and T4-replaced rats. Graafian follicles were found in 72% of controls and only in 34% of hypothyroid and 43% of T4-treated animals. Serum LH, FSH, progesterone and estradiol concentrations did not differ among the three groups. Serum prolactin concentration and the pituitary content of the three hormones studied were higher in the hypothyroid animals compared to control. T4 treatment restored serum prolactin concentration to the level found in controls, but only partially normalized the pituitary content of gonadotropins and prolactin. In conclusion, the morphological changes caused by hypothyroidism can be a consequence of higher prolactin production that can block the secretion and action of gonadotropins, being the main cause of the changes observed.
本研究的目的是通过评估卵巢形态、子宫重量以及血清和垂体中催乳素与促性腺激素浓度的变化，来检验甲状腺功能减退是否会影响成年雌性大鼠的生殖系统。将3月龄雌性大鼠分为三组：对照组（N = 10）、甲状腺功能减退组（N = 10），用含0.05% 6-丙基-2-硫氧嘧啶（PTU）的饮用水处理60天，以及T4治疗组（N = 10），在实验的最后10天每天皮下注射L-甲状腺素（0.8微克/100克体重）。甲状腺功能减退50天后，没有甲状腺功能减退的动物表现出规律的周期，而71%的对照组以及T4治疗的大鼠表现出规律的周期。在所研究的所有卵巢中均发现了黄体、生长卵泡和成熟的格拉夫卵泡。甲状腺功能减退和T4替代的大鼠的黄体均较小。格拉夫卵泡在72%的对照组中发现，而在甲状腺功能减退组中仅为34%，在T4治疗组中为43%。三组之间血清促黄体生成素（LH）、促卵泡生成素（FSH）、孕酮和雌二醇浓度没有差异。与对照组相比，甲状腺功能减退动物的血清催乳素浓度以及所研究的三种激素的垂体含量更高。T4治疗使血清催乳素浓度恢复到对照组的水平，但仅部分使促性腺激素和催乳素的垂体含量正常化。总之，甲状腺功能减退引起的形态学变化可能是催乳素产生增加的结果，催乳素产生增加会阻断促性腺激素的分泌和作用，这是观察到这些变化 的主要原因。
