Altered pituitary responsiveness to gonadotropin- releasing hormone in middle-aged rats with 4-day estrous cycles.
Altered pituitary responsiveness to gonadotropin- releasing hormone in middle-aged rats with 4-day estrous cycles.
复制标题
改变具有 4 天动情周期的中年大鼠垂体对促性腺激素释放激素的反应。
作者：
W. Smith;R. Cooper;P. Conn
我们采用灌流系统比较了年轻（3-6个月大）和中年（10-14个月大）雌性大鼠垂体的GnRH反应性，以确定该位点的变化是否可能导致LH分泌的改变，从而导致规律的发情周期的丧失。在4天周期的每一天，切除垂体并减半;保留一个半脑垂体用于测量（通过RIA）LH含量。后半部分用199 + BSA灌注2.5 h，再用10（-7）M GnRH的199 + BSA溶液刺激6 h。结果如下。1)在青年和中年组，GnRH刺激的LH释放的幅度随发情周期的阶段而变化（发情前期，发情间期第2天大于发情期，发情间期第1天）。LH释放的一般模式之间的年龄组相似，但是，垂体从中年女性释放显着减少LH的发情前期和发情间期的第1天比那些从年轻女性。2)达到对GnRH最大反应所需的时间也随发情阶段而变化;在两个年龄组中，发情前期和发情期的反应时间最短。除发情间期第2天外，在发情周期的所有日期，中年组与年轻组相比，达到最大反应的时间显著更长。3)在年龄组内，垂体LH含量随动情周期变化的模式类似的GnRH反应。两组之间，在周期的所有日期，中年女性的LH含量等于或大于年轻女性。这些结果表明，垂体对GnRH的反应性降低，可能有助于延迟衰减发情前期LH峰，在雌性大鼠生殖衰老之前。
We employed a perifusion system to compare the GnRH responsiveness of pituitaries removed from young (3-6 months old) and middle-age (10-14 months old) female rats with 4-day estrous cycles in order to determine whether changes at this locus may contribute to alterations in LH secretion which precede a loss of regular estrous cycles. Pituitaries were removed and halved on each day of the 4-day cycle; one hemipituitary was retained for measurement (by RIA) of LH content. The second half was perifused for 2.5 h with medium 199 plus BSA, then stimulated for 6 h with 10(-7) M GnRH in medium 199 plus BSA. Results were as follows. 1) Within young and middle-aged groups, the magnitude of GnRH-stimulated LH release varied with stage of the estrous cycle (proestrus, diestrous day 2 greater than estrus, diestrous day 1). General patterns of LH release were similar between age groups; however, pituitaries removed from middle-aged females released significantly less LH on proestrus and diestrous day 1 than did those removed from young females. 2) The time required to reach maximal response to GnRH also varied with the estrous stage; response times were shortest on proestrus and estrus in both age groups. The time to maximal response was significantly longer in the middle-aged vs. the young group on all days of the estrous cycle except diestrous day 2. 3) Within age groups, pituitary LH content varied with the estrous cycle in a pattern similar to that of GnRH responsiveness. Between groups, LH content in middle-age females was equivalent to or greater than that in young females on all days of the cycle. These results indicate that reduced pituitary responsiveness to GnRH may contribute to the delayed attenuated proestrous LH surge that precedes reproductive senescence in the female rat.
大鼠垂体灌注：最佳 GnRH 刺激 LH 释放的要求。
DOI：
10.1152/ajpendo.1981.240.5.e504
发表时间：
1981
期刊：
The American journal of physiology
影响因子：
--
作者：
Stern,JE;Conn,PM
通讯作者：
Conn,PM