Changes in dopamine sensitivity in isolated neurons of the preoptic region during the estrous cycle.

The dopamine sensitivity of individual neurons of the midbrain preoptic region as a center of the cyclic regulation of hypophyseal gonadotropic function was investigated under conditions of dopamine microiontophoretic delivery during various stages of the estrous cycle in rats. It was shown that most neurons do not respond to dopamine during the diestrus-1 stage. The first half of the day of the diestrus-2 stage was characterized by a high representation of neurons with an activation response. Cells with an inhibitory response to dopamine were observed to increase among the spontaneously active neurons of the preoptic region starting from the second half of the day of this stage of the estrous cycle. The greatest quantity of neurons with an inhibitory response was observed during proestrus.