Subcellular distribution of dynorphin-like immunoreactivity in rat adenohypophysis in comparison with luteinizing hormone and follicle-stimulating hormone.
Dynorphin and other proenkephalin B-derived peptides exist in the rat adenohypophysis in high concentrations and may have important roles in endocrine function. At the cellular level, dynorphin peptides are colocalized with the gonadotropins in at least a subpopulation of gonadotrophs. In this study dynorphin-containing particles were compared with secretory granules containing luteinizing hormone (LH) and follicle-stimulating hormone (FSH) by means of differential centrifugation and sucrose density gradient centrifugation. When anterior pituitary homogenate of male rats was subjected to differential centrifugation, about 70% of both dynorphin- and LH-containing particles sedimented at 30,000 x g. LH granules and dynorphin-containing particles comigrated in continuous sucrose density gradients both under nonequilibrium conditions as well as when equilibrium was attained. FSH storage granules were found to sediment in slightly denser fractions, with substantial overlap. Hence, dynorphin-containing particles and gonadotropin-containing granules exhibit similar characteristics. These hormones may, therefore, be colocalized also at the subcellular level or stored in separate but similar vesicles.
D000818:Animals; D002458:Cell Fractionation / Q000379:methods; D002499:Centrifugation, Density Gradient / Q000379:methods; D004399:Dynorphins / Q000032:analysis*; D005640:Follicle Stimulating Hormone / Q000032:analysis*; D007986:Luteinizing Hormone / Q000032:analysis*; D008297:Male; D010903:Pituitary Gland, Anterior / Q000032:analysis*; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D013347:Subcellular Fractions / Q000032:analysis
D004399:Dynorphins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone