The effect of steroid contraceptives on the concentrations of brain monoamines in rats and mice.

The effect of three estrogen-progestin combinations on biogenic amines in discrete brain areas of rats and mice has been investigated. With the exception of a significant decrease of brain 5-hydroxyindolacetic acid in the rats treated for 30 days with the combination norethynodrel + mestranol, no significant changes in the levels of serotonin, noradrenaline or dopamine in the rat brain were found following the administration of the compounds under study. On the other hand, in mice moderate but significant changes in the levels of serotonin, dopamine, noradrenaline and 5-hydroxyindolacetic acid were found in various brain areas depending on the estrogen-progestin combination used. The potential importance of these effects for the contraceptive as well as for some central actions of these compounds is discussed.