Rapid nocturnal increase in ovine pineal N-acetyltransferase activity and melatonin synthesis: effects of cycloheximide.
Thirty minutes after the onset of darkness, ovine pineal arylalkylamine N-acetyltransferase, N-acetylserotonin, and melatonin increase 5- to 10-fold. No significant changes in hydroxyindole-O-methyltransferase, 5-hydroxytryptamine, 5-hydroxyindoleacetic acid, 5-hydroxytryptophol, 5-methoxyindoleacetic acid, and 5-methoxytryptophol are detected at this time. Administration of cycloheximide inhibits the rise in N-acetyltransferase and N-acetylserotonin, but not melatonin. Unexpectedly, 5-methoxytryptophol increases after cycloheximide treatment. Taken together, these results, although consistent in part with a role for serotonin N-acetylation in the regulation of melatonin synthesis in sheep, indicate that an N-acetyltransferase-independent mechanism may also be involved.
M A
MA
Namboodiri
D
D
Sugden
D C
DC
Klein
R
R
Grady
I N
IN
Mefford
D000121:Acetylserotonin O-Methyltransferase / Q000378:metabolism; D000123:Acetyltransferases / Q000378:metabolism*; D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000378:metabolism*; D006224:Cricetinae; D003513:Cycloheximide / Q000494:pharmacology*; D003624:Darkness; D000882:Haplorhini; D006897:Hydroxyindoleacetic Acid / Q000032:analysis; D008297:Male; D008550:Melatonin / Q000032:analysis / Q000096:biosynthesis* / Q000097:blood; D010870:Pineal Gland / Q000032:analysis / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D012701:Serotonin / Q000032:analysis; D012756:Sheep
D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D003513:Cycloheximide; D000121:Acetylserotonin O-Methyltransferase; D000123:Acetyltransferases; D001191:Arylamine N-Acetyltransferase; D008550:Melatonin