Effects of 6-methoxy-2-benzoxazolinone on the pineal melatonin generating system.
6-Methoxy-2-benzoxazolinone (6-MBOA) at concentrations greater than 20 microM stimulates serotonin N-acetyltransferase (NAT) activity of rat pineal glands in 48-hr organ culture as well as of glands freshly cultured, indicating that 6-MBOA acts postsynaptically. The effects of 6-MBOA on NAT activity can be blocked by propranolol but not by prazosin, suggesting that 6-MBOA acts on the beta receptor. At the doses used 6-MBOA stimulation does not block or enhance NAT stimulation by norepinephrine, but is additive with vasoactive intestinal polypeptide which stimulates NAT activity at a site different than the beta receptor. This study demonstrates that 6-MBOA stimulates rather than inhibits melatonin biosynthesis and does not prevent stimulation of melatonin synthesis by norepinephrine. The progonadal association with eating plants containing 6-MBOA in the Montane vole may be due to over stimulation of melatonin receptor sites. Other possible explanations include an extrapineal action such as a blockade of melatonin receptors in the central nervous system, a blockade of receptors on the gonads or to a direct action of this agent on the gonads.
D000123:Acetyltransferases / Q000378:metabolism*; D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000378:metabolism*; D001583:Benzoxazoles / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D008550:Melatonin / Q000096:biosynthesis* / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D009924:Organ Culture Techniques; D010870:Pineal Gland / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D014364:Tryptophan / Q000378:metabolism
D001583:Benzoxazoles; C031896:6-methoxybenzoxazolinone; D014364:Tryptophan; D000123:Acetyltransferases; D001191:Arylamine N-Acetyltransferase; D008550:Melatonin; D009638:Norepinephrine