The Distribution of Growth Hormone and Prolactin in Subcellular Fractions of Porcine Adenohypophysis1

Abstract

Porcine growth hormone (pGH) and porcine prolactin (pPRL) were measured by radioimmunoassay in pituitary homogenates and subcellular fractions derived therefrom. A nonnormal population distribution was found for pPRL content and concentration; larger anterior pituitary glands exhibited a high pPRL content and concentration, and prolactin cell hyperplasia. Nearly 90% of both hormones present in the post-nuclear supernatant sedimented with the large secretory granule fraction, and the bulk of the protein found in this fraction was accounted for by these two hormones. Electrophoresis of secretory granule extracts on polyacrylamide gel, followed by radioimmunoassay of gel segment eluates, revealed a distribution of immunoreactive hormone which paralleled the migration of stainable protein bands, with the exception of very slowly migrating protein species which were not immunoreactive in either assay system. (Endocrinology92: 477, 1973)