Daily rhythms of norepinephrine, beta1-adrenoceptor mRNA, serotonin, arylalkylamine N-acetyltransferase mRNA, arylalkylamine N-acetyltransferase and hydroxyindol-O-methyltransferase activities, and melatonin in the pineal gland of viscacha

C. CALDERON; L. FUENTES; E. MUÑOZ; M. MOLLER; L. PELZER.

BIOLOGICAL RHYTHM RESEARCH

Año: 2007

0929-1016

We described the daily rhythms of parameters involved in the melatonin production in the pineal of viscacha. The norepinephrine showed the highest levels at night. A peak in b1-adrenoceptor mRNA was observed at the end of the light phase. Serotonin exhibited higher values during the light period. AA-NAT mRNA showed the highest expression at Zeitgeber time 0 (ZT0), reaching the minimum at night. AA-NAT activity and melatonin content exhibited a nocturnal peak at ZT16, a lower diurnal increase during the light period and minimal level at ZT8. HIOMT activity showed a peak at ZT16. The daily pattern in norepinephrine content was similar to those of AA-NAT activity and melatonin levels. Our data suggest that the melatonin synthesis in viscacha might be activated via adrenergic induction; the differences observed in the daily rhythms of AA-NAT activity and its mRNA suggest that post-transcriptional mechanisms may be involved; and other Zeitgeber and other mechanisms might also control melatonin production.