Brain and hypothalamic catecholamine turnover in relation with puberty in the female rat

Turnover of brain and hypothalamic catecholamines was determined in prepuberal, puberal and adult female rats. Turnover was evaluated by measuring the rate of disappearance of endogenous noradrenaline and dopamine after inhibition of synthesis with alpha-methyltyrosine. Rates of falling were significantly high in brains of 30 and 35 day-old-rats and low in brains of 25 and 40 day-old-rats. Hypothalamic noradrenaline decrease exhibited similar changes in relation with age. The increase of NA and DA turnover taking place before puberty was coincident with a high response in plasma luteinizing hormone induced by treatment with ovarian steroids. At the time of puberty and not directly related with the vaginal opening, both brain catecholamine turnover and LH induced response were found to decrease. The results suggest that brain adrenergic mechanisms play some role in the onset of puberty.