Melatonin entrainment of the circadian N-acetyltransferase rhythm in the newborn rat pineal gland.
In 15-day-old control and vehicle-treated rats, the evening rise of the pineal N-acetyltransferase occurred at the same time as in their mothers, whereas in 5-day-old pups, the rise occurred by 2-3 hr earlier. Four-day administration of melatonin in the late day phase advanced the N-acetyltransferase rise in 15-day-old rats as compared with the rise in the vehicle-treated animals; a slight melatonin induced phase advance in 5- and 27-day-old rats was not significant. The data indicate that the newborn rat's circadian pacemaker controlling the rhythmic N-acetyltransferase rise may be entrained by exogenous melatonin. It appears, however, that the maternal melatonin transferred via milk cannot entrain the pup's pacemaker by phase advancing it, since the N-acetyltransferase rise in the pups begins earlier or at the same time as maternal melatonin production driven by the N-acetyltransferase rhythm.
Trávnícková
Z
Z
Institute of Physiology, Academy of Sciences of the Czech Republic, Prague.
Illnerová
H
H
D000818:Animals; D000831:Animals, Newborn; D000975:Antioxidants / Q000008:administration & dosage / Q000494:pharmacology*; D001191:Arylamine N-Acetyltransferase / Q000378:metabolism*; D002940:Circadian Rhythm / Q000187:drug effects*; D005260:Female; D007279:Injections, Subcutaneous; D008550:Melatonin / Q000008:administration & dosage / Q000494:pharmacology*; D010870:Pineal Gland / Q000201:enzymology*; D011247:Pregnancy; D051381:Rats; D017208:Rats, Wistar
D000975:Antioxidants; D001191:Arylamine N-Acetyltransferase; D008550:Melatonin