Jacobson W, Kalra S P
Department of Obstetrics and Gynecology, University of Florida College of Medicine, Gainesville 32610.
Endocrinology. 1989 Jan;124(1):199-206. doi: 10.1210/endo-124-1-199.
In view of evidence implicating hypothalamic opioid systems in the control of LH release, we have examined the binding of [3H]naloxone (NAL) to slices of mediobasal hypothalamus (MBH) and preoptic area (POA) during the induction of an afternoon LH surge (1630-1700 h) in estradiol benzoate (EB)-primed ovariectomized (OVX; day 0) rats by treatment with progesterone (P; day 2). Such a surge was invariably accompanied by a decrease from early morning (1000 h) values in the number of NAL-binding sites detectable in the MBH, while the affinity of the binding site was not affected over the course of the day. Time-course studies indicated that P injection at 1000 h on day 2 was followed by a transient midday elevation in the amount of NAL bound to slices of MBH; the binding decreased significantly before the onset of and during the LH surge. A similar diurnal change was not observed in MBH slices of either oil-treated OVX rats (controls) or EB-treated OVX rats, which displayed only a 2-fold increase in LH release in the afternoon. Further studies indicated a similar change in NAL binding to slices of the POA of EBP-treated rats. Since hypothalamic opioid systems inhibit LH release, the decrease in opioid binding to MBH as well as POA slices suggests that P may curtail the existing opioid inhibitory influence in these areas before and during the course of the afternoon LH surge.
鉴于有证据表明下丘脑阿片系统参与促黄体生成素（LH）释放的调控，我们研究了在经苯甲酸雌二醇（EB）预处理的去卵巢（OVX；第0天）大鼠中，于下午（1630 - 1700时）通过注射孕酮（P；第2天）诱导LH峰时，[3H]纳洛酮（NAL）与中基底下丘脑（MBH）和视前区（POA）切片的结合情况。这样的LH峰总是伴随着MBH中可检测到的NAL结合位点数量从清晨（1000时）的值下降，而结合位点的亲和力在一天中不受影响。时间进程研究表明，在第2天1000时注射P后，MBH切片上结合的NAL量在中午有短暂升高；在LH峰开始前和峰期，结合量显著下降。在接受油处理的OVX大鼠（对照）或接受EB处理的OVX大鼠的MBH切片中未观察到类似的昼夜变化，这些大鼠下午的LH释放仅增加了2倍。进一步研究表明，EBP处理的大鼠的POA切片上NAL结合也有类似变化。由于下丘脑阿片系统抑制LH释放，阿片与MBH以及POA切片结合的减少表明，P可能在下午LH峰之前和峰期减少这些区域现有的阿片抑制作用。
