Erskine M S
Department of Biology, Boston University, MA 02215.
Physiol Behav. 1989 Apr;45(4):753-9. doi: 10.1016/0031-9384(89)90290-4.
Although 5 alpha-dihydrotestosterone (DHT) is a potent inhibitor of lordosis behavior in ovariectomized estrogen-primed female rats, the mechanism(s) by which this steroid has this action is unknown. The present experiments sought to determine whether DHT inhibits lordosis by preventing the known facilitatory actions of luteinizing hormone-releasing hormone (LHRH), naloxone, and Substance P on lordosis. Lordosis behavior was examined in ovariectomized, estrogen-primed rats prior to or 30, 60, 90, and 180 min following intracerebroventricular (ICV) infusion of LHRH (500 ng), naloxone (1 microgram). Substance P (1 microgram), or saline and 0.01 N acetic saline vehicles, and the effects of DHT (2.5 mg/rat) following similar treatment were examined. In Experiment 1, LHRH and naloxone increased lordosis within 30 min after infusion, while Substance P and the saline or acetic saline vehicles had no effect. Treatment with DHT in combination with estrogen prevented the facilitation of lordosis by LHRH and naloxone. In Experiment 2, ovariectomized, estrogen-primed females shown to be responsive to LHRH during a first screening test were tested for lordosis after receiving either DHT or DHT in combination with the androgen receptor antagonist, Flutamide (7.5 mg/injection x 3). Again, DHT prevented the facilitatory action of LHRH; however, Flutamide did not counteract that effect. In Experiment 3, Flutamide did not counteract the inhibitory effect of DHT on estrogen and progesterone-induced lordosis. These results demonstrate that the inhibitory effect of DHT cannot be overridden by neuroactive peptides which themselves stimulate receptivity. It seems unlikely that DHT inhibits lordosis either by interfering with the behavioral action of these peptides or by activation of the androgen receptor.
虽然5α-二氢睾酮（DHT）是去卵巢并用雌激素预处理的雌性大鼠中脊柱前凸行为的强效抑制剂，但这种类固醇产生这种作用的机制尚不清楚。本实验旨在确定DHT是否通过阻止促黄体生成素释放激素（LHRH）、纳洛酮和P物质对脊柱前凸的已知促进作用来抑制脊柱前凸。在脑室内（ICV）注入LHRH（500 ng）、纳洛酮（1微克）、P物质（1微克）或生理盐水和0.01 N醋酸生理盐水载体之前或之后30、60、90和180分钟，检测去卵巢并用雌激素预处理的大鼠的脊柱前凸行为，并检测类似处理后DHT（2.5 mg/只大鼠）的作用。在实验1中，LHRH和纳洛酮在注入后30分钟内增加了脊柱前凸，而P物质以及生理盐水或醋酸生理盐水载体则没有效果。DHT与雌激素联合处理可阻止LHRH和纳洛酮对脊柱前凸的促进作用。在实验2中，在首次筛选试验中对LHRH有反应的去卵巢并用雌激素预处理的雌性大鼠，在接受DHT或DHT与雄激素受体拮抗剂氟他胺（7.5 mg/注射×3）联合处理后，检测其脊柱前凸情况。同样，DHT阻止了LHRH的促进作用；然而，氟他胺并没有抵消这种作用。在实验3中，氟他胺没有抵消DHT对雌激素和孕酮诱导的脊柱前凸的抑制作用。这些结果表明，DHT的抑制作用不能被本身刺激接受性的神经活性肽所克服。DHT似乎不太可能通过干扰这些肽的行为作用或通过激活雄激素受体来抑制脊柱前凸。
