The expression of Per1 and Aa-nat genes in the pineal gland of postnatal rats

Abstract

Background: The circadian rhythm of melatonin synthesis is controlled by the master clock, suprachiasmatic nucleus (SCN).The level of melatonin changes throughout the aging process. The SCN's rhythm is driven by autoregulatory feedback loopcomposed of a set of clock genes families and their corresponding proteins. The Period (Per1), one of clock gene developsgradually during postnatal ontogenesis in the rat SCN and is also expressed in the pineal gland.Objective: It is of interest to study the relationship between the postnatal development of Per1 and Aa-nat, genes that producethe rate-limiting enzyme in melatonin synthesis, in the pineal.Material and Method: Daily profiles of mRNA expression of Per1 and Aa-nat were analyzed in the pineal gland of pups atpostnatal ages 4 (P4), P8, P16 and P32, at puberty age of 6 weeks; and in 8 week-old adult rats by real-time PCR.Results: As early as P4, Per1 and Aa-nat mRNAs were expressed and existed at relatively high levels during the nighttime.They gradually increased until puberty and decreased at 8 weeks of age. Additionally, the nocturnal changes of Per1 and Aa-nat mRNA levels in the rat pineal gland from P4 to adults were strongly correlated at r = 0.97 (p < 0.01).Conclusion: The present data indicate that there is a close relationship between the expression pattern of Per1 and that ofmelatonin synthesis during the development of postnatal rats.