The effect of Low-Dose Dopamine Infusion on Anterior Pituitary Hormone Secretion in Normal Female Subjects

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Abstract
The effect of low-dose dopamine infusion on anterior pituitary hormone secretion was studied in a group of 7 healthy female subjects. Subjects were infused with NaCl solution (154 mmol/l) (control) or dopamine (0.01 and 0.1 .mu.g min-1 kg-1 for 120 min at each rate) on separate days in the early follicular phase of consecutive menstrual cycles. Serum prolactin decreased during infusion of dopamine at 0.01 .mu.g min-1 kg-1 but a similar fall was found in the control group. When the rate of dopamine infusion was increased to 0.1 .mu.g min-1 kg-1 a further substantial decrease in prolactin concentration occurred, whereas prolactin in the control group showed no change. At the end of the period of dopamine infusion at 0.1 .mu.g min-1 kg-1 serum prolactin remained significantly (P < 0.025) lower than in the control group (85 .+-. 12 vs. 180 .+-. 21 m-units/l). No change in TSH, growth hormone (GH) or luteinizing hormone (LH) was seen during either rate of dopamine infusion compared with control. While dopamine infusion at 0.1 .mu. min-1 kg-1 caused significant inhibition of prolactin secretion in normal female subjects, other pituitary hormone secretion was not affected: dopamine in hypophysial portal blood evidently is not of primary importance in the control of basal TSH, GH and LH release.