| Abstract: | An isocratic liquid chromatographic method with electrochemical detection for the determination of -3,4-dihydroxyphenylalanine, dopamine, norepinephrine, epinephrine, serotonin, and their major metabolites, 3,4-dihydroxyphenylacetic acid, 4-hydroxy-3-methoxyphenylacetic acid and 5-hydroxyindole-3-acetic acid in chicken brain tissue is described. Chickens were killed at different ages, the brains were quickly frozen and 300-μm cryostat sections were made. From these sections, two to six tissue micropunches (1 mm in diameter) were punched out from 20 different areas of the hypothalamus and homogenated in 100 μl 0.1 M perchloric acid which included 0.01% cysteine as antioxidant. Fifty-μl supernatants were injected directly onto the LC system, separated on a 3-μm Phase II ODS column (100×3.2 mm I.D.) and detected by an electrochemical detector at a potential of +0.75 V. Standard curves, recoveries, analytical precision and detection limits were investigated for each monoamine neurotransmitter and its metabolites. The method was applied to study the influence of food restriction on the concentration of monoamine neurotransmitters in different brain areas, known to be involved in feeding and reproductive behaviour of female broiler chickens. Over 1000 micropunched tissue samples from ad libitum fed and food-restricted female broiler chickens were analyzed. Our results provide a possible role for catecholamines and indolamines in the altered feeding and reproductive behaviour of the broiler chicken. |
