Enrichment of Rat Anterior Pituitary Cell Types by Metrizamide Density Gradient Centrifugation*

Anterior pituitary cells derived from hypothyroid rats were enzymatically dispersed and then fractionated by equilibrium sedimentation through a metrizamide density gradient. Populations relatively enriched in thyrotrophs, somatotrophs, mammotrophs, or gonadotrophs were obtained. The thyrotroph-enriched fraction was put into short term culture and tested for hormone responsiveness. TRH stimulated TSH release with an ED50 of 8 X 10(-10) M, and this TRH effect was inhibited by T3 with an ED50 of 1.6 X 10(-11) M free T3. Metrizamide density gradient centrifugation is a useful technique for obtaining relatively enriched populations of viable anterior pituitary cell types.