Influence of food restriction on dopamine receptor densities, catecholamine concentrations and dopamine turnover in chicken brain

To investigate further a putative role of dopamine in control of food restr iction-induced behavioural stereotypies, chickens were fed during rearing o n either a daily restricted ration recommended by a breeding company, twice the recommended restricted ration, or ad libitum food. They were killed at 60 days of age and their excised brains were dissected into six regions an d homogenized. Densities of dopamine D-1 and D-2 receptors were assessed, a fter first estimating binding parameters for [H-3]SCH 23390 (D-1) and [H-3] spiperone (D-2) in chicken brain homogenates. Specific binding of both liga nds was highest in basal telencephalon. Concentrations of dopamine and its metabolites 3,4-dihydroxyphenylacetic acid and homovanillic acid were also highest in basal telencephalon, whereas noradrenaline and adrenaline levels were highest in diencephalon. Dopamine concentration in basal telencephalo n and noradrenaline concentration in diencephalon were increased significan tly in response to food restriction, but no effect of feeding treatment was found in dopamine turnover, adrenaline levels, or D-1 and D-2 receptor den sities in any brain region studied. The observed changes in brain catecholamine levels are consistent with role s for dopaminergic and adrenergic mechanisms in the control of food restric tion-induced behavioural stereotypies in chickens. (C) 1999 IBRO. Published by Elsevier Science Ltd.