Olster D H
Psychology Department, University of California, Santa Barbara 93106, USA.
Horm Behav. 1995 Dec;29(4):519-30. doi: 10.1006/hbeh.1995.1271.
Juvenile female guinea pigs rarely display lordosis in response to estradiol and progesterone treatments that elicit sexual receptivity in adults. To test the hypothesis that the medial preoptic area (MPOA) tonically inhibits the display of steroid-induced lordosis in juveniles, 11-day-old guinea pigs were ovariectomized (OVX) and received bilateral, sham, or electrolytic lesions aimed at the MPOA 3-4 days later. At 20-22 days of age, these females were tested for the expression of sexual receptivity following injections of estradiol benzoate (EB, 10 micrograms s.c.) and progesterone (0.5 mg s.c., 40 h after EB). The lesions damaged portions of the MPOA, the nucleus of the diagonal band of Broca, the lateral aspect of the medial preoptic nucleus, the medial part of the preventricular portion of the periventricular nucleus, and the anterior commissure. The lesions did not alter the display of estradiol-induced lordosis. However, after treatment with EB plus progesterone, 20% of the sham-lesioned females displayed lordosis, as compared to 80% of the MPOA-lesioned animals. These data are consistent with the hypothesis that neurons originating in and/or traversing the MPOA tonically suppress the display of progesterone-facilitated lordosis in juvenile guinea pigs. Removal of this inhibitory input allows prepubertal females to respond behaviorally to estradiol and progesterone in an adult-typical fashion.
幼年雌性豚鼠在接受能使成年豚鼠产生性接受能力的雌二醇和孕酮处理时，很少表现出脊柱前凸。为了验证内侧视前区（MPOA）对幼年豚鼠类固醇诱导的脊柱前凸表现具有紧张性抑制作用这一假说，对11日龄的豚鼠进行卵巢切除（OVX），并在3 - 4天后对其MPOA进行双侧假损伤、假手术或电解损伤。在20 - 22日龄时，给这些雌性豚鼠注射苯甲酸雌二醇（EB，10微克，皮下注射）和孕酮（0.5毫克，皮下注射，在注射EB后40小时），然后检测它们的性接受能力表现。这些损伤破坏了MPOA的部分区域、布罗卡斜角带核、内侧视前核的外侧部分、室周核室前部分的内侧部分以及前连合。这些损伤并未改变雌二醇诱导的脊柱前凸表现。然而，在用EB加孕酮处理后，20%的假损伤雌性豚鼠表现出脊柱前凸，而MPOA损伤的动物中这一比例为80%。这些数据与以下假说一致，即起源于MPOA和/或穿过MPOA的神经元对幼年豚鼠孕酮促进的脊柱前凸表现具有紧张性抑制作用。去除这种抑制性输入使青春期前雌性豚鼠能够以成年豚鼠典型的方式对雌二醇和孕酮产生行为反应。
