Study on Serotonine Metabolism in Fish

1993 Fiscal Year Final Research Report Summary

• Project/Area Number: 04454096
• Research Category: Grant-in-Aid for General Scientific Research (B)
• Allocation Type: Single-year Grants
• Research Field: Fisheries chemistry
• Research Institution: Tokyo University of Fisheries
• Principal Investigator: NAGAYAMA Fumio Tokyo Univ. Fisheries Prof., 水産学部, 教授 (90017020)
• Co-Investigator(Kenkyū-buntansha): TAKEUCHI Toshio Ass. Prof., 水産学部, 助教授 (70092591) ; KIMURA Shigeru Ass. Prof., 水産学部, 助教授 (10017056)
• Project Period (FY): 1992 – 1993
• Keywords: fish / tryptophan / serotonine / melatonine / enzyme

Research Abstract

Distribution and properties of several enzymes which are involved in serotonine pathway in fish were investigated. The method of matabolte analysis was also examined.
1. Triptophan hydroxylase : Higher activity of this enzyme was observed in fish liver, whileitwas reported that the activity is high in brain tissue in mammals. However, the activity varied depending on fish species. The molecular weight of the skipjack enzyme was 290,000(oligomer), the optimum pH was 8.0, and Km for tryptopha was 7.0 x 10^<-5>M.
2. Aromatic amino acid decarboxylase : The moleclar weight of the skipjack enzyme was 220,000(dimer), the optimum pH was 7.0, and Km for hydroxytroptohan was 6.97 x 10^<-4>M.The substrate specificity was rather wide.
3. Monoamine oxidase : There were 2 types of the enzyme in fish, and the patern of the activation and inhibition by inorganic ions differed each other.
4. Method of metabolite analysis : HPLC system for analysis of metabolites in serotonine pathway was examined. The condition was as follows : (a) reverse phase, JASCO SIL C18 coolumn, (b) mobile phase, a mixture of 10mM sodium acetate soltion and acetonitrile, (c) flow rate, 1ml/min, (d) monitor, fluoressence, Ex 285 nm, Em 345 nm. By changing the ratio of actate solution and acetonitrile, we were able to determine the metabolites quantitatively (2 - 12 ng of each compound).