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Effect of melatonin administration on qPer2 , qPer3 , and qClock gene expression in the suprachiasmatic nucleus of Japanese quail
Author(s) -
Yasuo Shinobu,
Yoshimura Takashi,
Bartell Paul A.,
Iigo Masayuki,
Makino Eri,
Okabayashi Naritoshi,
Ebihara Shizufumi
Publication year - 2002
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1046/j.1460-9568.2002.02222.x
Subject(s) - melatonin , suprachiasmatic nucleus , circadian rhythm , medicine , quail , endocrinology , biology , clock , gene expression , melatonin receptor , endogeny , light effects on circadian rhythm , messenger rna , circadian clock , gene , genetics
Temporal changes of mRNA expression of three clock genes, qPer2 , qPer3 and qClock, were studied in the suprachiasmatic nucleus (SCN) of Japanese quail under different light conditions, as well as under the condition of continuous melatonin. In addition, the expression of melatonin receptor genes, Mel 1a and Mel 1c , in the SCN were also examined. The expression of qPer2 mRNA showed robust oscillation during both light and dark (LD) 12:12 cycles and under constant dark conditions (DD), but did not exhibit circadian rhythmicity in constant light conditions (LL), instead being expressed at a consistently high level. Expression of qPer3 also showed robust oscillation under both LD and DD conditions. Unlike qPer2 however, qPer3 mRNA expression remained rhythmic under LL conditions. Contrary to the findings on the other clock genes, no remarkable rhythmicity was detectable in either light condition. Both Mel 1a and Mel 1c mRNAs were detected in the SCN, however, Mel 1a mRNA levels were higher than Mel 1c and showed daily rhythmicity. Although implantation of melatonin tubes caused constant high levels of plasma melatonin and consequently masked the endogenous daily melatonin rhythm, no significant differences in the expression pattern of any of the three clock genes were observed between birds with and without constant melatonin. In addition, a single injection of melatonin did not affect mRNA expression of these clock genes. These results suggest that melatonin does not affect transcription of clock genes, but may act on the mechanism of synchronization among SCN oscillatory cells.