Tetrodotoxin administration in the suprachiasmatic nucleus prevents NMDA-induced reductions in pineal melatonin without influencing Per1 and Per2 mRNA levels.
Tetrodotoxin administration in the suprachiasmatic nucleus prevents NMDA-induced reductions in pineal melatonin without influencing Per1 and Per2 mRNA levels.
复制标题
在视交叉上核中施用河豚毒素可防止 NMDA 诱导的松果体褪黑激素减少，而不影响 Per1 和 Per2 mRNA 水平。
DOI：
10.1111/j.0953-816x.2004.03387.x
复制
发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Albers,HElliott
中科院分区：
文献类型：
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作者：
Paul,KetemaN;Gamble,KarenL;Fukuhara,Chiaki;Novak,ColleenM;Tosini,Gianluca;Albers,HElliott
The suprachiasmatic nucleus (SCN) of the anterior hypothalamus contains a light‐entrainable circadian pacemaker. Neurons in the SCN are part of a circuit that conveys light information from retinal efferents to the pineal gland. Light presented during the night acutely increases mRNA levels of the circadian clock genesPer1andPer2in the SCN, and acutely suppresses melatonin levels in the pineal gland. The present study investigated whether the ability of light to increasePer1andPer2mRNA levels and suppress pineal melatonin levels requires sodium‐dependent action potentials in the SCN.Per1andPer2mRNA levels in the SCN and pineal melatonin levels were measured in Syrian hamsters injected with tetrodotoxin (TTX) prior to light exposure or injection ofN‐methyl‐d‐aspartate (NMDA). TTX inhibited the ability of light to increasePer1andPer2mRNA levels and suppress pineal melatonin levels. TTX did not, however, influence the ability of NMDA to increasePer1andPer2mRNA levels, though it did inhibit the ability of NMDA to suppress pineal melatonin levels. These results demonstrate that action potentials in the SCN are not necessary for NMDA receptor activation to increasePer1andPer2mRNA levels, but are necessary for NMDA receptor activation to decrease pineal melatonin levels. Taken together, these data support the hypothesis that the mechanism through which light information is conveyed to the pacemaker in the SCN is separate from and independent of the mechanism through which light information is conveyed to the SCN cells whose efferents suppress pineal melatonin levels.
