CIRCADIAN EXPRESSION OF PINEAL 5-LIPOXYGENASE MESSENGER-RNA

IN lymphocytes, the pineal hormone, melatonin, suppresses 5-lipoxygena se (5-LO) gene expression. Because circadian fluctuations in melatonin content are prominent in the pineal, we hypothesized that 5-LO mRNA l evel in this gland is greater when melatonin is low (day) than at nigh t. Using the reverse transcription/polymerase chain reaction we assaye d the levels of mRNAs coding for 5-LO, serotonin N-acetyltransferase ( NAT), and for a constitutive gene, cyclophilin, in rat pineals obtaine d at 10:30-11:00 h (day) or 24:30-01:00 (night). Cyclophilin mRNA was not affected by circadian rhythm, whereas 5-LO and NAT were affected i n an opposite manner: 5-LO mRNA was high during the day, NAT mRNA at n ight. We propose that circadian pineal 5-LO expression might play a ro le in circadian regulation of pineal functioning. (C) 1998 Rapid Scien ce Ltd.