A rat seminiferous epithelial factor that inhibits Leydig cell cAMP and testosterone production: mechanism of action, stage-specific secretion, and partial characterization.
To elucidate further the seminiferous tubule-Leydig cell interaction we studied the effect of spent medium from 20 h rat seminiferous tubule cultures (STCM) on cyclic adenosine monophosphate (cAMP) and testosterone (T) production of Percoll-purified Leydig cells. 8% of STCM inhibited the human chorionic gonadotropin (hCG)-stimulated cAMP production by 30% in a 3 h, and 33% of STCm by 60% in a 20 h incubation. Likewise, a 40% decrease was found in the presence of 8% of STCM in the hCG-stimulated T production in a 3 h incubation. A similar inhibitory activity could be demonstrated in steroid-free rat interstitial fluid. STCM did not affect the viability of the Leydig cells (90-95% after a 20 h incubation) as judged by trypan blue exclusion and the adenosine triphosphate (ATP) content of the cells. Heating (80 degrees C for 10 min) abolished the inhibiting activity, and fractionation with Millipore Ultrafree filters showed that the inhibiting factor had an Mr of 30,000-100,000. When media from different stages of the seminiferous epithelial cycle were analyzed, only stages IX-I showed inhibition of T production (P less than 0.05). The cAMP production inhibiting activity was present in all stages, but stages IX-I showed significantly (P less than 0.05) greater inhibition than stages II-VI. STCM (16%) also inhibited cholera toxin- and forskolin-stimulated cAMP formation (approximately 50 and 60%, respectively; P less than 0.01), and the inhibitory activity persisted after a 3 h preincubation of Leydig cells with 100 micrograms/l pertussis toxin.(ABSTRACT TRUNCATED AT 250 WORDS)
Vihko
K K
KK
Department of Physiology, University of Turku, Finland.
Huhtaniemi
I
I
D000818:Animals; D001685:Biological Factors / Q000378:metabolism / Q000502:physiology*; D002470:Cell Survival; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000096:biosynthesis*; D019204:GTP-Binding Proteins / Q000502:physiology; D006358:Hot Temperature; D066298:In Vitro Techniques; D007985:Leydig Cells / Q000166:cytology / Q000378:metabolism*; D008297:Male; D008970:Molecular Weight; D051381:Rats; D011919:Rats, Inbred Strains; D011974:Receptors, LH / Q000032:analysis; D012671:Seminiferous Tubules / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D013737:Testis / Q000032:analysis / Q000502:physiology*; D013739:Testosterone / Q000096:biosynthesis*
D001685:Biological Factors; D006063:Chorionic Gonadotropin; D011974:Receptors, LH; D005576:Colforsin; D013739:Testosterone; D000242:Cyclic AMP; D019204:GTP-Binding Proteins