Attenuating effect of drugs on an impairment of anticipatory activity in various animal models.

点击翻译按钮获取中文摘要

The suprachiasmatic nucleus (SCN) has been identified as a pacemaker for mammalian circadian rhythms. There are two different entraining pathways : one is retinohypothalamic tract and the othere is geniclohypothalamic tract. As glutamate has been suggested as a transmitter of the retinohypothalamic tract, we examined the effect of NMDA,a glutamate NMDA receptor agonist on the SCN neuronal activity thythem. NMDA produced phase changes similar to light-induced phase shifts through the nitric oxide production in the SCN.In addition, AMPA,an ionotropic glutamate receptor agonist caussed similar phase shifts via the activation of protein synthesis.Restricted feeding at a fixed time of the day produced an entrainment in hamsters and rats. At present, the neuronal mechanism of this anticipatory food-entrainable rhythms are uncertain. The food-and methamphetamine-associated anticipation were impaired by aging and a treatment with NMDA receptor antagonist, MK-801. The impairment of this anticipation in aging animals was attenuated by cholinergic drugs such as arecoline and physostigmine. In addition, daily lever pressing at a fixed time of day to drink water was also established in operant experiment paradgim. These results suggest that cholinergic drugs may be important in the performance of the anticipatory activity rhythms.