Carpenter A M, Carr J A
Department of Biological Sciences, Texas Tech University, Lubbock 79409-3131, USA.
Horm Behav. 1996 Sep;30(3):236-43. doi: 10.1006/hbeh.1996.0028.
We investigated the ability of various melanocortin peptides and corticosterone to influence habituation of prey-catching behavior in the toad, Bufo cognatus. Male toads were injected with various melanocortin peptide fragments or corticosterone 30 min prior to acquisition. Adrenocorticotropin (ACTH[1-39]), ACTH[4-10], and N-acetyl ACTH[1-13] amide (alpha-MSH) significantly decreased the number of turning reactions during acquisition in relation to controls. The effects of the noncorticotropic ACTH fragments were rapid and transient, occurring within the first 20 min of acquisition. Corticosterone caused a slight but significant decrease in the number of turning reactions. Neither des-acetyl alpha-MSH nor (Nle4, D-Phe7) alpha-MSH had any effect on acquisition. ACTH[1-39] was the only peptide that delayed extinction. The ability of alpha-MSH to facilitate acquisition was not observed in the presence of the alpha-MSH antagonist U-76188E. These data suggest that the effects of ACTH on habituation are, in part, independent of effects on glucocorticoid secretion. Apparently, similar structural requirements are necessary for the behavioral effects of melanocortins in amphibians and mammals.
我们研究了多种促黑素肽和皮质酮对科氏蟾蜍（Bufo cognatus）捕食行为习惯化的影响能力。在训练前30分钟给雄性蟾蜍注射各种促黑素肽片段或皮质酮。促肾上腺皮质激素（ACTH[1-39]）、ACTH[4-10]和N-乙酰基ACTH[1-13]酰胺（α-MSH）与对照组相比，在训练过程中显著减少了转向反应的次数。非促肾上腺皮质激素ACTH片段的作用迅速且短暂，出现在训练的前20分钟内。皮质酮使转向反应的次数略有但显著减少。去乙酰基α-MSH和（Nle4，D-Phe7）α-MSH对训练均无任何影响。ACTH[1-39]是唯一能延迟消退的肽。在存在α-MSH拮抗剂U-76188E的情况下，未观察到α-MSH促进训练的能力。这些数据表明，ACTH对习惯化的影响部分独立于对糖皮质激素分泌的影响。显然，促黑素在两栖动物和哺乳动物中的行为效应需要相似的结构要求。
