Dauphin-Villemant C, Tonon M C, Vaudry H
Ecole Normale Supérieure, CNRS-URA 686, Paris, France.
Gen Comp Endocrinol. 1992 Aug;87(2):183-8. doi: 10.1016/0016-6480(92)90021-b.
Thyrotropin-releasing hormone (TRH) is a potent stimulator of melanotropin (alpha-MSH) release from pituitary melanotrophs in pig, frog, and fish. Concurrently, it has recently been shown that injection of TRH induces skin darkening in the lizard Anolis carolinensis (Licht and Denver, 1988). In the present study, we have thus investigated in vitro the possible effect of TRH on alpha-MSH release from the lizard (Lacerta vivipara) neurointermediate lobe, by means of the perifusion technique. Using our radioimmunoassay procedure, we found that serial dilutions of L. vivipara NIL extracts and synthetic alpha-MSH gave parallel binding curves. Administration of graded doses of TRH (10(-8)-10(-6) M) did not cause any modification of alpha-MSH release. In contrast, infusion of a depolarizing concentration of K+ induced a robust stimulation of alpha-MSH secretion. These results indicate that, in the lizard L. vivipara, the neuropeptide TRH does not stimulate pituitary melanotrophs.
促甲状腺激素释放激素（TRH）是猪、蛙和鱼垂体黑素细胞刺激素（α-MSH）从垂体黑素细胞释放的有效刺激物。同时，最近有研究表明，注射TRH会导致卡罗来纳安乐蜥皮肤变黑（利希特和丹佛，1988年）。因此，在本研究中，我们通过灌流技术体外研究了TRH对蜥蜴（胎生蜥蜴）神经中间叶α-MSH释放的可能影响。使用我们的放射免疫分析程序，我们发现胎生蜥蜴神经中间叶提取物和合成α-MSH的系列稀释液给出了平行的结合曲线。给予分级剂量的TRH（10^(-8)-10^(-6)M）不会引起α-MSH释放的任何改变。相反，注入去极化浓度的K+会强烈刺激α-MSH分泌。这些结果表明，在胎生蜥蜴中，神经肽TRH不会刺激垂体黑素细胞。
