Yehuda S, Carasso R L
Peptides. 1983 Nov-Dec;4(6):865-9. doi: 10.1016/0196-9781(83)90082-7.
Thermoregulatory and motor activity circadian cycles are age-dependent. While the level of thermoregulation and motor activity remained almost at the same level during the first 1-15 months during the light portion of the 24-hr cycle, a significant decrease in the level of both rhythms was observed during the dark period. Therefore, older rats exhibited reversed cycles compared with younger rats. Treatments with d-amphetamine resulted in the enhancement of reversal of the cycles. Rats treated with alpha-MSH failed to exhibit a reversal of the cycles. While the effects of d-amphetamine are mediated by the brain DA mesolimbic pathway, it seems that alpha-MSH acts on the dopaminergic system at different sites of action.
体温调节和运动活动的昼夜节律具有年龄依赖性。在24小时周期的光照阶段的前1至15个月期间，体温调节和运动活动水平几乎保持在同一水平，但在黑暗期，两种节律的水平均显著下降。因此，与年轻大鼠相比，老年大鼠表现出相反的周期。用右旋苯丙胺治疗导致周期反转增强。用α-促黑素治疗的大鼠未能表现出周期反转。虽然右旋苯丙胺的作用是由脑多巴胺中脑边缘通路介导的，但α-促黑素似乎在多巴胺能系统的不同作用部位起作用。
