Hamada T, Ootomi M, Horikawa K, Niki T, Wakamatu H, Ishida N
Ishida Group of Clock Gene, National Institute of Bioscience and Human Technology, AIST, MITI, 1-1 Higashi, Tsukuba Science City, 305-8566, Japan.
Biochem Biophys Res Commun. 1999 May 19;258(3):772-7. doi: 10.1006/bbrc.1999.0668.
The hormone melatonin, secreted primarily from the pineal gland, plays an important physiological role in synchronizing biological rhythms and neuroendocrine. Presently, we find the expression of the serotonin N-acetyltransferase (arylalkylamine N-acetyltransferase, AA-NAT) mRNA, the rate-limiting enzyme in the conversion of serotonin to melatonin, in the rat suprachiasmatic nucleus (SCN) which contains the biological circadian clock in mammals. AA-NAT mRNA content in rat SCN did not show a significant circadian rhythm. However, AA-NAT enzyme activity was lowest at midday and highest at early night, and the rhythm persisted under constant dark conditions. These results indicate that the rat SCN is capable of synthesizing melatonin and suggest that melatonin synthesis in the SCN may be regulated by the circadian clock at the post transcriptional level.
褪黑素主要由松果体分泌，在同步生物节律和神经内分泌方面发挥着重要的生理作用。目前，我们在大鼠视交叉上核（SCN）中发现了血清素N - 乙酰基转移酶（芳基烷基胺N - 乙酰基转移酶，AA - NAT）mRNA的表达，该酶是血清素转化为褪黑素过程中的限速酶，而视交叉上核包含哺乳动物的生物钟。大鼠视交叉上核中的AA - NAT mRNA含量未显示出明显的昼夜节律。然而，AA - NAT酶活性在中午最低，在深夜最高，并且这种节律在持续黑暗条件下依然存在。这些结果表明大鼠视交叉上核能够合成褪黑素，并提示视交叉上核中褪黑素的合成可能在转录后水平受生物钟调控。
