These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Protein kinase C and Gi-protein mediated modulation of cAMP production in different stages of the rat seminiferous epithelium.
    Author: Nikula H, Vihko K, Huhtaniemi I.
    Journal: Mol Cell Endocrinol; 1990 May 07; 70(3):247-53. PubMed ID: 2163336.
    Abstract:
    The modulatory role of protein kinase C (PK-C)- and Gi-protein-mediated signal transduction systems was studied in the cyclic variation of follicle-stimulating hormone (FSH)-stimulated cAMP production of rat seminiferous tubules. FSH (Metrodin, Serono, 30 mg/l) stimulated cAMP production 10-fold (p less than 0.01) in a 3 h incubation of 5 mm segments of seminiferous tubules of stages II-VI of the epithelial cycle, but only 2-fold (p less than 0.01) in stages VII-VIII. The PK-C activator 12-O-tetradecanoylphorbol 13-acetate (TPA, 100 nmol/l) suppressed the FSH effect on cAMP output by 50-70% (p less than 0.01) in stages II-VI, but had no effect in stages VII-VIII. If the tubular segments were preincubated for 3 h in the presence of pertussis toxin (PT, 100 micrograms/l), the FSH-stimulated cAMP production of stages VII-VIII increased by 100-200% (p less than 0.01), and now they also became responsive to the TPA suppression. Conversely, no effect of PT was observed in stages II-VI. Cholera toxin (CT, 100 micrograms/l) and forskolin (Fk, 100 mumol/l) nearly similarly stimulated the cAMP production in both stages studied (about 10-fold, p less than 0.01), and TPA and PT potentiated the effects in a non-additive fashion. In conclusion, both Gi-protein and PK-C-mediated mechanisms modulate cAMP production of rat seminiferous tubules. A clear cyclic variation can only be demonstrated in FSH-stimulated cAMP production, but not if the Gs-protein or adenylate cyclase are directly stimulated.(ABSTRACT TRUNCATED AT 250 WORDS)
    [Abstract] [Full Text] [Related] [New Search]