Brabant G, Wickings E J, Nieschlag E
Acta Endocrinol (Copenh). 1981 Oct;98(2):189-94. doi: 10.1530/acta.0.0980189.
Histidyl-proline-diketopiperazine (DKP) -- a stable degradation product of TRH -- has been shown to selectively inhibit prolactin secretion in vitro in rat pituitary tissue. In this study the effects of DKP on serum prolactin in intact and anaesthetized male rhesus monkeys and on TRH-stimulated prolactin levels have been investigated. In conscious monkeys 400 micrograms DKP significantly suppressed prolactin levels by 27%, and under ketamine anaesthesia, serum prolactin was suppressed in a dose-dependent manner by 150 and 400 micrograms DKP. The maximum prolactin response and the cumulative response to TRH (20 micrograms) was significantly and specifically inhibited by 400 micrograms DKP, while the lower dose was without effect. TSH levels were not affected by DKP in any instance. Hence DKP can specifically inhibit prolactin release in the rhesus monkey, and may be discussed as a possible regulatory factor in prolactin secretion.
组氨酰 - 脯氨酰 - 二酮哌嗪（DKP）——促甲状腺激素释放激素（TRH）的一种稳定降解产物——已被证明在体外能选择性抑制大鼠垂体组织中的催乳素分泌。在本研究中，已对DKP对完整和麻醉的雄性恒河猴血清催乳素的影响以及对TRH刺激的催乳素水平的影响进行了研究。在清醒的猴子中，400微克DKP可使催乳素水平显著降低27%，在氯胺酮麻醉下，150微克和400微克DKP可使血清催乳素呈剂量依赖性降低。400微克DKP可显著且特异性地抑制对TRH（20微克）的最大催乳素反应和累积反应，而较低剂量则无此作用。在任何情况下，TSH水平均不受DKP影响。因此，DKP可特异性抑制恒河猴的催乳素释放，可作为催乳素分泌的一种可能调节因子进行讨论。
