L-aspartate-evoked inhibition of melatonin production in rat pineal glands.
Our previous studies in rat indicated that pinealocytes secrete L-glutamate through microvesicle-mediated exocytosis to regulate negatively melatonin production. Recently, we further found that pinealocytes secrete L-aspartate through microvesicle-mediated exocytosis. In the present study, we investigated the role of L-aspartate in the melatonin production in isolated rat pineal glands. It was found that L-aspartate inhibits norepinephrine-stimulated melatonin production as well as serotonin N-acetyltransferase activity reversibly and dose-dependently, the concentrations required for 50% inhibition being 150 and 175 microM, respectively. L-Asparagine and oxaloacetate, metabolites of L-aspartate, had no effect on the melatonin production. These results suggest that pinealocytes use L-aspartate, as well as L-glutamate, as a negative regulator for melatonin production.
Yamada
H
H
Department of Cell Membrane Biology, Institute of Scientific and Industrial Research (ISIR), Osaka University, Ibaraki, Japan.
Yamaguchi
A
A
Moriyama
Y
Y
D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000378:metabolism; D001224:Aspartic Acid / Q000494:pharmacology*; D008297:Male; D008550:Melatonin / Q000096:biosynthesis* / Q000378:metabolism; D009433:Neural Inhibition / Q000187:drug effects*; D009638:Norepinephrine / Q000494:pharmacology; D010071:Oxaloacetates / Q000494:pharmacology; D010870:Pineal Gland / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D051381:Rats; D017208:Rats, Wistar; D013566:Sympathomimetics / Q000494:pharmacology; D013572:Synaptic Vesicles / Q000378:metabolism
D010071:Oxaloacetates; D013566:Sympathomimetics; D001224:Aspartic Acid; D001191:Arylamine N-Acetyltransferase; D008550:Melatonin; D009638:Norepinephrine