Analysis of trace amino acid neurotransmitters in hypothalamus of rats after exhausting exercise using microdialysis

A simple but effective coupling of microdialysis and capillary electrophore sis with laser induced fluorescence detection technique was applied to anal ysis of amino acid neurotransmitters in the hypothalamus of rats after acut e exhausting exercise. The separation of amino acids was achieved using an uncoated fused-silica capillary (57 cm x 75 mum I.D.) with a buffer of 10 m M disodium tetraborate at pH 10 and an applied voltage of 12.5 kV. The dete ction limit was 10(-10) M for each amino acid. It is sufficiently sensitive and rapid for the determination of amino acids in a 5-mul Microdialysate. In comparison to pre-exercise, a significant increase in the levels of six hypothalamic amino acids (arginine, glycine, lysine, glutamic acid, alanine , gamma -amino-n-butyric acid) was found after exercise. These results demo nstrate that the increase of metabolic amino acids in the hypothalamus of r ats can be induced by exhausting exercise and suggests that amino acid neur otransmitters may play functional roles in the central effects of exercise. (C) 2001 Elsevier Science B.V. All rights reserved.