Bartha L, Nagy G M, Kiem D T, Fekete M I, Makara G B
Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest.
Endocrinology. 1991 Aug;129(2):635-40. doi: 10.1210/endo-129-2-635.
The effect of dexamethasone (DEX) treatment (400 and 200 micrograms/kg BW 21 and 2 h before suckling stimulus, respectively) on suckling- and domperidone (DOMP)-induced PRL release was investigated in freely moving, primiparous lactating rats. DEX completely blocked suckling-induced plasma PRL release without affecting DOMP-induced release of the hormone suggesting a central action of DEX. The effect was transient because it could not be detected on the second day of testing. The effect of DEX implanted in three different brain areas on suckling- and DOMP-induced PRL release was also tested. Implants surrounding the hypothalamic paraventricular nuclei and dorsal hippocampus failed to affect PRL release induced by suckling stimulus. Surprisingly, DEX suppressed PRL release induced by suckling stimulus when it was implanted into the medial basal hypothalamus. These findings demonstrate that DEX is a potent inhibitor of the suckling-induced PRL release. They also indicate that the site of action of DEX is not at the anterior pituitary gland or the paraventricular nuclei and hippocampus because DEX treatment and DEX implants had no effect on plasma PRL levels induced by DOMP and suckling stimulus, respectively. Our data suggest that the effect of DEX is mediated through a region of the medial basal hypothalamus. The observed transient block in suckling-induced PRL release may be physiologically relevant during stress in lactating mothers for conserving pituitary stores of the hormone needed for milk production or being able to adapt to a rapid change in osmoregulation.
在地塞米松（DEX）治疗（分别在哺乳刺激前21小时和2小时给予400和200微克/千克体重）对自由活动的初产泌乳大鼠中由哺乳和多潘立酮（DOMP）诱导的催乳素（PRL）释放的影响进行了研究。DEX完全阻断了哺乳诱导的血浆PRL释放，而不影响DOMP诱导的该激素释放，提示DEX具有中枢作用。该作用是短暂的，因为在测试的第二天无法检测到。还测试了植入三个不同脑区的DEX对哺乳和DOMP诱导的PRL释放的影响。围绕下丘脑室旁核和背侧海马的植入物未能影响哺乳刺激诱导的PRL释放。令人惊讶的是，当DEX植入内侧基底下丘脑时，它抑制了哺乳刺激诱导的PRL释放。这些发现表明DEX是哺乳诱导的PRL释放的有效抑制剂。它们还表明DEX的作用部位不在垂体前叶或室旁核和海马，因为DEX治疗和DEX植入物分别对DOMP和哺乳刺激诱导的血浆PRL水平没有影响。我们的数据表明DEX的作用是通过内侧基底下丘脑的一个区域介导的。观察到的哺乳诱导的PRL释放的短暂阻断在哺乳期母亲应激期间可能在生理上相关，以保存垂体中用于产奶所需的激素储备或能够适应渗透压调节的快速变化。
