Lu K H, Chen H T, Huang H H, Grandison L, Marshall S, Meites J
J Endocrinol. 1976 Feb;68(02):241-50. doi: 10.1677/joe.0.0680241.
In post-partum lactating rats, sucking by the young was associated with high prolactin release and maintenance of lactation but severe inhibition of LH and FSH release and suspension of oestrous cycles. Shortly after the pups were removed on day 22 post partum LH and FSH release returned to normal and oestrous cycles resumed. Twice-daily injections of ergocornine methanesulphonate (ERG) into mothers beginning at 5 or 7 days post partum, resulted in sustained inhibition of prolactin release and diminished mild secretion. By frequent exchange of pups between control and ERG-treated mothers, it was possible to maintain vigorous sucking and almost normal pup growth despite low serum prolactin levels and diminished lactation. In these rats, serum levels of LH remained low during 11 or more days of treatment with ERG, but serum FSH was consistently higher than in untreated control mothers. After 11 or more days of ERG treatment, most rats showed a return to normal LH and FSH release and resumption of oestrous cycles. These results suggest (a) that the sucking stimulus rather than high prolactin levels in the circulation is mainly responsible for inhibition of LH and FSH release during the first 11 days post partum, (b) that the sucking stimulus acts to increase prolactin and inhibit LH release by separate hypothalamic mechanisms, and (c) that administration of ERG results in diminished prolactin release and lactation, and in increased release of FSH and subsequently of LH with earlier resumption of oestrous cycles.
在产后泌乳的大鼠中，幼崽吸吮与催乳素的大量释放及泌乳维持有关，但会严重抑制促黄体生成素（LH）和促卵泡生成素（FSH）的释放，并使发情周期暂停。产后第22天幼崽被移走后不久，LH和FSH的释放恢复正常，发情周期也得以恢复。从产后第5天或第7天开始，每天给母鼠注射两次甲磺酸麦角新碱（ERG），会导致催乳素释放持续受到抑制，乳汁分泌减少。通过在对照母鼠和接受ERG处理的母鼠之间频繁交换幼崽，尽管血清催乳素水平较低且泌乳减少，但仍可维持强烈的吸吮行为和几乎正常的幼崽生长。在这些大鼠中，用ERG处理11天或更长时间期间，LH的血清水平一直较低，但血清FSH始终高于未处理的对照母鼠。ERG处理11天或更长时间后，大多数大鼠的LH和FSH释放恢复正常，发情周期也得以恢复。这些结果表明：（a）在产后的前11天，吸吮刺激而非循环中高催乳素水平是抑制LH和FSH释放的主要原因；（b）吸吮刺激通过下丘脑的不同机制分别作用于增加催乳素释放和抑制LH释放；（c）给予ERG会导致催乳素释放和泌乳减少，以及FSH随后LH的释放增加，并使发情周期更早恢复。
