Effects of near-ultraviolet light on the nocturnal serotonin N-acetyltransferase activity of rat pineal gland.
Effects of near-ultraviolet (UV-A; 325-390 nm, peak at 365 nm) light on the activity of the pineal serotonin N-acetyltransferase (NAT; a penultimate and key regulatory enzyme in melatonin biosynthesis) were examined in rats. Acute exposure of dark-adapted animals to UV-A radiation produced a marked suppression of NAT activity of the pineal gland, the effect being dependent on exposure time. The decrease in the night-time NAT activity evoked by a 1-min pulse of UV-A light (as well as by a 15-s pulse of broad-band visible light) gradually deepened during the first 40 min of treatment of animals with constant darkness, then the enzyme activity began to rise reaching control values by 3 h. Treatment of rats with a protein synthesis inhibitor, cycloheximide, attenuated this night-driven reactivation of the pineal NAT activity. The presented results provide evidence that UV-A light is a powerful signal capable of controlling melatonin biosynthesis in rat pineal gland.
Zawilska
J B
JB
Department of Biogenic Amines, Polish Academy of Sciences, Lódź, Poland.
Rosiak
J
J
Nowak
J Z
JZ
D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000378:metabolism*; D002940:Circadian Rhythm / Q000502:physiology; D003513:Cycloheximide / Q000494:pharmacology; D008297:Male; D010870:Pineal Gland / Q000187:drug effects / Q000201:enzymology* / Q000528:radiation effects*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D014466:Ultraviolet Rays
D011500:Protein Synthesis Inhibitors; D003513:Cycloheximide; D001191:Arylamine N-Acetyltransferase