Tresguerres J A, Esquifino A I
Acta Physiol Lat Am. 1983;33(3):257-74.
The effects of grafting one extra pituitary gland beneath the kidney capsule of prepubertal male and female rats on plasma levels and pituitary content of gonadotropins and prolactin (PRL) in the adult age were studied. Further treatments with dopamine agonistic or antagonistic drugs have been performed in grafted and sham operated controls. PRL and gonadotropin values were measured by specific RIA methods using materials provided by NIAMDD. Plasma prolactin levels showed increased values 48 hr after the grafting, and maintained this elevation throughout the whole studied period. These high PRL levels in grafted rats resulted in a significant decrease of plasma LH values over the whole studied period compared with sham operated controls. Surprisingly an elevation of plasma FSH levels was detected in grafted animals, being the increase only significant in the first 3 months after the grafting. No differences could be detected from control values beyond this period. Female rats showed a constant diestrous anovulatory syndrome. Both male and female grafted rats showed diminished plasma LH and FSH responses to the i.p. LHRH administration. After EB administration control female rats showed a pulsatile response of plasma prolactin, FSH and LH with higher levels found in the afternoon. This pulsatility was abolished for PRL, diminished for LH and exaggerated for FSH in grafted animals. Male grafted rats presented a delay in the EB response pattern compared to control rats. Lisuride treatment (DA agonist) eight months after the grafting resulted in a significant reduction to plasma PRL levels. Acutely Lisuride administration restored LH response to LHRH together with a significant increase in the number of estrus in female rats. Chronic administration of the drug resulted in decreased plasma LH values not only in controls but also in grafted animals, together with an impaired response to LHRH and a significant increase in the number of diestrus in control and experimental rats. On the other hand, both acute or chronic Metoclopramide administration (DA antagonist drug) significantly increased plasma prolactin levels in control and grafted rats. This increase was accompanied by an elevation in the number of estrus in grafted female rats together with a restored LH response to LHRH higher to those observed in control female rats. These data suggest that prolactin influence on gonadotropin secretion and fertility could be mediated by a modification on dopamine secretion.
研究了在青春期前雄性和雌性大鼠肾囊下移植一个额外垂体对成年期血浆促性腺激素和催乳素（PRL）水平及垂体含量的影响。对移植组和假手术对照组进一步用多巴胺激动剂或拮抗剂药物进行了处理。使用美国国立医学与健康研究院提供的材料，通过特定的放射免疫分析方法测定PRL和促性腺激素值。移植后48小时血浆催乳素水平升高，并在整个研究期间维持这一升高水平。与假手术对照组相比，移植大鼠的这些高PRL水平导致整个研究期间血浆LH值显著降低。令人惊讶的是，在移植动物中检测到血浆FSH水平升高，仅在移植后的前3个月升高显著。在此之后，与对照值没有差异。雌性大鼠表现出持续的动情间期无排卵综合征。雄性和雌性移植大鼠对腹腔注射促性腺激素释放激素（LHRH）的血浆LH和FSH反应均减弱。给予己烯雌酚（EB）后，对照雌性大鼠的血浆催乳素、FSH和LH呈现脉冲式反应，下午水平较高。在移植动物中，PRL的这种脉冲性消失，LH的脉冲性减弱，FSH的脉冲性增强。与对照大鼠相比，雄性移植大鼠的EB反应模式延迟。移植8个月后用利舒脲治疗（多巴胺激动剂）导致血浆PRL水平显著降低。急性给予利舒脲可恢复LH对LHRH的反应，并使雌性大鼠的发情次数显著增加。长期给予该药物不仅导致对照组而且导致移植动物的血浆LH值降低，同时对LHRH的反应受损，对照组和实验大鼠的动情间期次数显著增加。另一方面，急性或长期给予甲氧氯普胺（多巴胺拮抗剂药物）均显著提高对照组和移植大鼠的血浆催乳素水平。这种升高伴随着移植雌性大鼠发情次数的增加，以及LH对LHRH的反应恢复，且高于对照雌性大鼠。这些数据表明，催乳素对促性腺激素分泌和生育能力的影响可能是通过多巴胺分泌的改变介导的。
