Acute effects of L-tryptophan on tryptophan hydroxylation rate in brain regions (hypothalamus and medulla) of rainbow trout (Oncorhynchus mykiss).

Abstract

Levels of 5-hydroxytryptophan (5-HTP) in brain regions (hypopthalamus and medulla) of rainbow trout were analysed by HPLC-EC 0, 10, 30, and 40 min after intraperitoneal administration of different doses of L-tryptophan (Trp) (0, 12.5, and 25 mg. kg(-1) body weight) in fish treated with 3-hydroxybenzylhydrazine (NSD1015; 75 mg. kg(-1)). The results show that, in control fish, 5-HTP levels in hypothalamus (58.03 +/- 6.36 pg. mg(-1) brain tissue) were significantly higher than those observed in medulla (28.04 +/- 4.32 pg. mg(-1) brain tissue). Basal tryptophan hydroxylation rates (after 0 mg. kg(-1) Trp administration) were 0.42 +/- 0.07 pg 5-HTP. mg(-1). min(-1), and 0.63 +/- 0.24 pg 5HTP. mg(-1). min(-1), for hypothalamus and medulla respectively. On the other hand, the results demonstrate that L-tryptophan administration induced significant increases in the rate of tryptophan hydroxylation, both in hypothalamus and medulla. These findings indicate that, in a way similar to that observed in mammals, brain tryptophan hydroxylase is unsaturated by its substrate (tryptophan) under normal physiological conditions. J. Exp. Zool. 286:131-135, 2000.

• Authors: M Aldegunde, J L Soengas, G rozas
• Journal: The Journal of experimental zoology (J Exp Zool) Vol. 286 Issue 2 Pg. 131-5 (Feb 01 2000) ISSN: 0022-104X [Print] United States
• PMID: 10617854 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright 2000 Wiley-Liss, Inc.

Chemical References

• Serotonin
• Tryptophan
• 5-Hydroxytryptophan
• Tryptophan Hydroxylase

Topics

• 5-Hydroxytryptophan (metabolism)
• Animals
• Hypothalamus (enzymology)
• Medulla Oblongata (enzymology)
• Oncorhynchus mykiss (metabolism)
• Serotonin (biosynthesis)
• Tryptophan (pharmacology)
• Tryptophan Hydroxylase (metabolism)