Daily variation in melatonin synthesis and AA-NAT activity in the nematode Caenorhabditis elegans

MIGLIORI, ML; ROMANOWSKI, A; SIMONETTA, SH; VALDEZ, D; GUIDO, M; GOLOMBEK DA

JOURNAL OF PINEAL RESEARCH

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2012 vol. 53 p. 38 - 46

0742-3098

Melatonin influences circadian rhythms and seasonal behavioral changes in vertebrates; it is synthesized from serotonin by N-acetylation by arylalkylamine N-acetyltransferase (AA-NAT) and O-methylation by N-acetylserotonin methyltransferase (ASMT). However, its physiology and function in invertebrate models is less understood. In this work, we studied daily variations in melatonin synthesis and AA-NAT activity in the nematode Caenorhabditis elegans. Under light-dark conditions (LD) a rhythmic pattern of melatonin levels was observed, with higher levels towards the middle of the night, peaking at zeitgeber time (ZT) 18 and with a minimum value around ZT0-6. AA-NAT activity showed a diurnal and circadian fluctuation with higher levels of activity during the early night, both under LD and constant darkness (DD) conditions. A peak was found around ZT12 and circadian time (CT) 12. In addition, we investigated whether this nocturnal AA-NAT activity is inhibited by light. Our results show that both white and blue light pulses significantly inhibited AA-NAT activity at ZT18. This work demonstrates the daily fluctuation of melatonin synthesis and AA-NAT activity in the adult nematode C. elegans. In summary, this study takes additional advantage of an extremely useful invertebrate model system which has only recently been exploited for circadian studies.