Modifications of the striatal dopamine metabolism during the estrus cycle in mice.

The metabolism of striatum dopamine (DA) was studied in mice during proestrus, estrus and diestrus. The following results have been obtained: (1) the concentration of DA is higher in diestrus than in proestrus and estrus; (2) the concentration of its metabolite, homovanillic acid (HVA), is maximum in the estrus phase; (3) the DA turnover, evaluated by measuring the DA disappearance after blocking synthesis with methyltyrosine, is faster in estrus than in the other phases. These results have been discussed in view of the possible role of dopaminergic mechanisms in the control of gonadotropin secretion.