[Estrogens as modulators of dopamine activity in the regulation of the gonadotropic function of the pituitary gland].

The effect of dopamine (DA), injected into arcuate nucleus-medial eminence (ARC-ME) region, on luteinizing hormone (LH) secretion, was studied in intact female rats, depending on the estrual cycle stage and in ovariectomized )OE) rats previously treated with estradiol benzoate (OE + E) or untreated animals. The increased blood LH concentration was recorded 30 minutes after dopamine injection during the second half of the 2-diestrus day and in the morning of the proestrus stage. DA injection into ARC-ME to OE rats lowered the blood and hypophyseal LH levels, whereas the increased blood Lh concentration was seen in OE + E rats. From the data obtained it was concluded that the hypothalamic dopaminergic system participates in the ovulatory LH-release regulation, while DA effect on gonadotropic function is determined by the peripheral blood estrogen level.