Bromocriptine suppression of dispersed pituitary lactotrophs from estrogen-pretreated rats: a quantitative electron microscopic study.

Dispersed rat lactotrophs were treated with bromocriptine (10(-10) M) for either 30 min or 3 h to investigate its effect on cell morphology using light and electron microscopy and ultrastructural morphometry. After 30 min, lactotrophs treated with bromocriptine exhibited an increase in storage granule size (p less than 0.05). Crinophagy was also evident and a significant increase in lysosome volume density was observed (p less than 0.001). However, no significant change in prolactin content in the media was detected until 3 h of incubation in bromocriptine (p less than 0.05). At this time a nonsignificant decrease in Golgi region volume density was also observed.