title: Follicle-stimulating hormone activation of glycogen phosphorylase in the Sertoli cell-enriched rat testis.
abstract: The potential role of glycogen phosphorylase in providing energy for the Sertoli cell-enriched testis has been investigated. This enzyme is detectable in testes from rats 6-54 days of age. Glycogen phosphorylase in isolated Sertoli cell-enriched testes is specifically stimulated by FSH. Maximal activation (2-fold) is obtained within 10 min after adding 0.5 micrograms FSH/ml to isolated immature testes (16 days old). There is only a 1.1-fold activation by FSH in testes from mature (34 days old) animals. The sensitivity to the gonadotropin can be restored by adding 1-methyl-3-isobutylxanthine, a phosphodiesterase inhibitor, with the FSH. Phosphorylase can be activated by effectors that mimic the actions of the two proposed mediators of FSH action, cAMP and Ca+2. Phosphorylase from testis of either age is maximally activated by an analog of cAMP, 8-bromo-cAMP. While phosphorylase is rapidly activated 1.4-fold by incubating isolated testis for 2 min with A23187, a Ca+2 ionophore, the age, time, and dose dependence of FSH activation are consistent with conversion mediated by cAMP. Phosphorylase was localized in cultured Sertoli cells by indirect immunofluorescence microscopy. Affinity-purified antiphosphorylase decorated cytoskeletal structures that resemble stress fibers, suggesting that phosphorylase may function in Sertoli cells to provide energy for cytoskeletal motility.
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000375:Aging; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D005640:Follicle Stimulating Hormone / Q000494:pharmacology*; D006003:Glycogen / Q000378:metabolism; D006006:Glycogen Synthase / Q000378:metabolism; D007700:Kinetics; D008297:Male; D006005:Phosphorylases / Q000378:metabolism*; D051381:Rats; D012708:Sertoli Cells / Q000201:enzymology*
chemical_list: D015124:8-Bromo Cyclic Adenosine Monophosphate; D000001:Calcimycin; D005640:Follicle Stimulating Hormone; D006003:Glycogen; D006005:Phosphorylases; D006006:Glycogen Synthase; D015056:1-Methyl-3-isobutylxanthine