Separation of Pituitary Mammotrophs from the Female Rat by Velocity Sedimentation at Unit Gravity

Abstract

Pituitary mammotrophs were separated by velocity sedimentation at unit gravity. Results from morphological studies showed a) that peak fractions contained prolactin-producing cells to a purity of 70% and b) that the cells retained their ultrastructural integrity during dissociation and separation. The distribution of immunoassayable prolactin in the gradients paralleled that of the mammotrophs, indicating that the cells retained hormone during dissociation and separation. Addition of dopamine (0.10–50.0 μg/ml) to the trypsinization medium and gradient solutions increased cellular prolactin levels by 25–75% and decreased hormone secretion from the cells by ∼ 40%.The sedimentation behavior of the mammotrophs reflected the previous physiologic history of the cell. Cells from estrogen-primed animals sedimented further into the gradient than those prepared from ovariectomized animals. Mammotrophs from lactating rats whose pups were removed 10 hr prior to kill sedimented further than those prepared from rats with suckling young. The cell separation technique offers a new approach to the study of the physiology of the pituitary mammotroph Endocrinology95: 107, 1974