雌性大鼠离体垂体前叶内在促黄体生成激素释放节律性现象

PHENOMENON OF INTRINSIC RHYTHM OF LUTEINIZING HORMONE RELEASE FROM ISOLATED ANTERIOR PITUITARY GLAND OF FEMALE RAT

众所周知，下丘脑促性腺激素释放激素（GnRH）以脉冲形式驱使垂体前叶释放促黄体生成激素（LH），但垂体前叶本身释放LH的形式却遭忽略。直到MarcoGambacciani（1987）［1］和谢（1987）［2］才发现人和大鼠离体垂体的LH释放呈节律性。本文目的在于进一步证实是否确实存在LH释放的内在节律。取出SD雌性大鼠垂体后，经Tc-199培液灌流，在整个120min的实验过程中，每5min收集一次0.5ml的灌流液，由放射免疫测定出的LH值经消除趋势后，再用时间序列的潜周期分析法、极大熵MaximumEntropy方法检验和检测出LH中的周期性节律。实验结果为：（1）不同生殖激素条件下LH释放的内在节律不同。动情前期组的释放频率（F，min／cycle）与振幅（A，ng／ml）最高，其次为去卵巢组；最低的是哺乳期组。（2）多肽激素或甾体激素能改变LH释放的内在节律性。（3）Verapamil和EGTA能使动情前期组的内在节律变慢。本工作表明垂体前叶LH释放的内在节律随生殖内分泌条件而异，并受外源性激素的影响，推测这种节律可能有Ca2+的参与。垂体前叶LHn释放的内在节律的真正生理意义还不清楚。

The intrinsic nature of rthymic release of luteinizing hormone (LH) of isolated human and rat anterior pituitare gland reported independently by Macro Gambacciani and Xie in 1987 can be more directly demonstrated by a computer programme of Time Series-HSY Hidden Periodic Analytic Approach for continuous monitoring the LH output of the perfusate from a perfusion system with in vitro anterior pituitary of SD female rat. The results are as follows: (1) Under various reproductive conditions the average frequency (min/cycle) and amplitude (ng/ml) of the intrinsic rhythm of LH release were quite different: In proestrous group the frequency and amplitude were the highest, being intermediate in the ovariectomized group and lowest in the lactation group. (2) The intrinsic rhythm of LH release could be changed by either peptide or steriod hormones. In proestrous group with 30 min of gonadotropin-releasing hormone (GnRH), stimulation would reduce both frequency and amplitude. In case of lactation, the frequency was unchanged, but amplitude lowered, while in the ovariectomized rat pituitap, the 30 min GnRH stimulation decreased the frequency of release only. The intrinsic rhythm of the LH release could also be influenced by steriod hormones (Ru486 and Anordrin). With 120 min before removal of the anterior pituitary gland the rats receiving i. m. injection ofRu486 (2 mg/kg bw) or Anordrin (2 mg/kg), the results showed that Ru486 decreased frequency, while Anordrin decreased only the frenquency to a less extent, both without amplitude affected. (3) Verapamil and EGTA added to the perfusion system did not abolish but only decreased the rhythmic phenomenon by using proestrous pituteq. This suggests that participation of Ca2+ may take place in the intrinsic release of LH.The above results indicated that the intrinsic rhythm of LH release of isolated anterior pituitary gland is different from various reproductive hormonal conditions and capable of being modified by exogenous hormones. The physiological function of the intrinsic rhythm of LH release of anterior pituitare gland remains to be elucidated.