Marín Bivens C L, Olster D H
Department of Psychology, University of California, Santa Barbara 93106, USA.
Endocrinology. 1997 Jan;138(1):143-8. doi: 10.1210/endo.138.1.4849.
Obese Zucker female rats are infertile. The present study was designed to assess estrous cyclicity in adult, ovary-intact, lean and obese Zucker rats and to compare reproductive behaviors induced by exogenous steroid hormones in ovariectomized (ovx) lean and obese Zucker rats. The majority (90%) of obese rats had incomplete cycles in comparison with the normal, 4-day cycles displayed by lean Zucker rats. After ovariectomy, all rats were treated with estradiol benzoate (EB, 15-100 micrograms/kg) or EB plus progesterone (P, 2-20 mg/kg), and tested for sexual receptivity and proceptivity (PRO). At the highest EB dose, obese Zucker females displayed lordosis less frequently than lean rats (lordosis quotient, LQ, 8 +/- 6% vs. 32 +/- 13%, respectively). At the lowest doses of EB plus P, lean females were extremely receptive and proceptive (LQ = 93 +/- 4%, PRO = 6.2 +/- 2 bouts/min). Zucker obese females, in contrast, were only slightly receptive (LQ = 26 +/- 11%) and showed less PRO than lean rats (PRO = 2.4 +/- 0.6 bouts/min). Increasing the dose of either EB or P, administered in combination with the lowest dose of the other hormone, produced receptivity and PRO in obese Zucker females that were comparable with those observed in lean rats. Serum estradiol and P levels in ovx obese rats were either equivalent to or higher than those in the ovx lean rats when both were given the same doses of hormones. These data suggest that considerably higher doses and serum concentrations of EB and/or P are required to elicit robust lordosis and PRO in ovx obese Zucker than in lean rats. This behavioral hyporesponsiveness to sex steroid hormones may contribute to infertility in the obese Zucker female rat.
肥胖的 Zucker 雌性大鼠不育。本研究旨在评估成年、卵巢完整的瘦型和肥胖型 Zucker 大鼠的发情周期，并比较去卵巢（ovx）的瘦型和肥胖型 Zucker 大鼠中外源类固醇激素诱导的生殖行为。与瘦型 Zucker 大鼠呈现的正常 4 天周期相比，大多数（90%）肥胖大鼠的周期不完整。去卵巢后，所有大鼠接受苯甲酸雌二醇（EB，15 - 100 微克/千克）或 EB 加孕酮（P，2 - 20 毫克/千克）治疗，并测试其性接受能力和求偶行为（PRO）。在最高 EB 剂量下，肥胖 Zucker 雌性大鼠呈现脊柱前凸的频率低于瘦型大鼠（脊柱前凸商数，LQ，分别为 8 ± 6% 对 32 ± 13%）。在最低剂量的 EB 加 P 时，瘦型雌性大鼠具有极高的接受能力和求偶行为（LQ = 93 ± 4%，PRO = 6.2 ± 2 次/分钟）。相比之下，Zucker 肥胖雌性大鼠仅表现出轻微的接受能力（LQ = 26 ± 11%），且求偶行为比瘦型大鼠少（PRO = 2.4 ± 0.6 次/分钟）。将 EB 或 P 的剂量与另一种激素的最低剂量联合增加，可使肥胖 Zucker 雌性大鼠产生与瘦型大鼠相当的接受能力和求偶行为。当给予相同剂量的激素时，ovx 肥胖大鼠的血清雌二醇和 P 水平与 ovx 瘦型大鼠相当或更高。这些数据表明，与瘦型大鼠相比，ovx 肥胖 Zucker 大鼠需要相当高剂量和血清浓度的 EB 和/或 P 才能引发强烈的脊柱前凸和求偶行为。这种对性类固醇激素的行为低反应性可能导致肥胖 Zucker 雌性大鼠不育。
