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Adenosine receptor–adenylate cyclase system in the trout testis: Involvement in the regulation of germ cell proliferation
Author(s) -
Loir Maurice
Publication year - 2001
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/1098-2795(200103)58:3<307::aid-mrd9>3.0.co;2-f
Subject(s) - adenosine , biology , endocrinology , medicine , adenosine receptor , cyclase , adenosine a1 receptor , adenosine a3 receptor , adenosine a2b receptor , adenylate kinase , purinergic signalling , agonist , receptor , growth hormone releasing hormone receptor , cgs 21680 , biochemistry , stimulation , hormone receptor , cancer , breast cancer
To ascertain the presence of adenosine receptors in the trout testis, cells isolated from testes at different spermatogenetic stages were cultured in the presence or absence of adenosine, adenosine receptor agonists, or antagonists and of cAMP analogs, for up to 20 min, or 20 hr, or 4.5 days. Cyclic AMP production was then assayed or 3 H‐thymidine incorporation was measured. Cellular content of cAMP was enhanced by adenosine, by the adenosine receptor agonist 5′‐ N ‐ethylcarboxamidoadenosine (NECA), and by 2‐ p (2‐carboxyethyl)phenethylamino‐5′‐ N ‐ethylcarboxamidoadenosine (CGS‐21680), an adenosine A 2A receptor‐selective agonist. The increase in cAMP induced by the adenylate cyclase activator L‐858051 was inhibited by the adenosine A 1 receptor‐selective agonists R‐ N 6 ‐(2‐phenylisopropyl)adenosine (R‐PIA) and N 6 ‐cyclopentyladenosine (CPA). These effects were antagonized by the two adenosine A 2 receptor antagonists 3,7‐dimethyl‐1‐propargylxanthine (DMPX) and 8‐(3‐chlorostyryl)caffeine (CSC), and by the adenosine A 1 receptor‐selective antagonist 8‐cyclopentyl‐1,3dipropylxanthine (CPX), respectively. Increase in the cAMP content induced by adenosine was inhibited by the cell permeable adenylate cyclase inhibitor 2′,5′‐dideoxyadenosine. These data suggest that A 1 and A 2 adenosine receptors which respectively inhibit and stimulate adenylate cyclase activity are present on trout testicular cells (unidentified), while the presence of A 3 adenosine receptor subtype was not apparent. 3 H‐thymidine incorporation decreased in the presence of the adenylate cyclase activator L‐858051 and of the cAMP analogs 8‐CPT cAMP and Sp‐5,6‐DCI‐cBiMPS, regardless of the presence or absence of the phosphodiesterase inhibitor RO 20‐1724. This suggests that an increase in testicular cAMP may act as a negative growth regulator for the mitotic germ cells. In agreement with these data, the activation of A 2 stimulatory receptors inhibited short‐term (20 hr) DNA synthesis. However, the activation of A 1 inhibitory receptors had the same effect. This suggests that events, cAMP‐dependent or independent, induced by the activation of testicular adenosine receptors, may participate in the regulation of trout male germ cell proliferation. Mol. Reprod. Dev. 58:307–317, 2001. © 2001 Wiley‐Liss, Inc.