Conn P M, Cooper R, McNamara C, Rogers D C, Shoenhardt L
Endocrinology. 1980 May;106(5):1549-53. doi: 10.1210/endo-106-5-1549.
In the present work we have compared a pituitary LH extract and circulating LH from adult male rats (5 months old) with those from rats 10, 13, or 24 months old. The pituitary and circulating forms of LH prepared from old animals had a higher apparent molecular weight, judged by gel filtration, than LH preparations from younger animals. This difference may be due to increased sialic acid content of the larger form, since simultaneous neuraminidase treatment of this gonadotropin preparation and our internal reference standard ([125I]LH prepared from a normal adult rat) abolished the apparent size difference. In addition, the larger form prepared from old rats was cleared more slowly from the circulation of immature females than the form prepared from young rats. The apparent increase in sialation during normal aging could be mimicked in young animals which were castrated. Injections of testosterone propionate reversed the effect in both castrates and old animals. The data suggest that the diminished levels of metabolically active testosterone or other steroid metabolites in old male rats may result in qualitative alterations in the stored and released forms of LH.
在本研究中，我们比较了成年雄性大鼠（5月龄）与10、13或24月龄大鼠的垂体促黄体生成素（LH）提取物及循环中的LH。通过凝胶过滤判断，老年动物制备的垂体和循环形式的LH比年轻动物的LH制剂具有更高的表观分子量。这种差异可能是由于较大形式的唾液酸含量增加，因为对这种促性腺激素制剂和我们的内部参考标准品（由正常成年大鼠制备的[125I]LH）同时进行神经氨酸酶处理消除了表观大小差异。此外，老年大鼠制备的较大形式的LH从未成熟雌性动物的循环中清除的速度比年轻大鼠制备的形式更慢。正常衰老过程中唾液酸化的明显增加在阉割的年轻动物中也可出现。注射丙酸睾酮可逆转阉割动物和老年动物的这种效应。数据表明，老年雄性大鼠中代谢活性睾酮或其他类固醇代谢物水平的降低可能导致LH储存和释放形式的质量改变。
