<prompt> Impoant stimuli for prolactin secretion:InsulinGrowth hormoneDopamineEstrogen  <response>: The regulatory factors for prolactin secretion by the pituitary overlap, in pa, with those causing secretion of growth hormone, but there are impoant differences, and some stimuli increase prolactin secretion while decreasing that of growth hormone Factor Prolactin Growth hormone Sleep Nursing - Breast stimulation in nonlactating women - Stress Hypoglycemia Strenuous exercise Sexual intercourse in women - Pregnancy - Estrogens Hypothyroidism - TRH - Phenothiazines, butyrophenones - Opioids Glucose - Somatostatin - L-Dopa Apomorphine Bromocriptine and related ergot derivatives Estrogens produce a slowly developing increase in prolactin secretion as a result of a direct action on the lactotropes. Dopamine is PIH and decreases prolactin secretion 