Adenosine receptor localization in rat testes: biochemical and autoradiographic evidence for association with spermatocytes.

[3H]Cyclohexyladenosine ( [3H]CHA) labels adenosine receptors in rat testes. Testicular adenosine receptors are regulated by guanine nucleotides and divalent cations in a similar fashion to brain adenosine receptors. Endocrine manipulations which selectively decrease sperm cells reduce biochemically determined numbers of [3H]CHA labeled adenosine receptors, whereas adenosine receptor number is not affected by manipulations that primarily influence Leydig cells. Autoradiographic analysis of [3H]CHA binding in the rat testes reveals a localization within seminiferous tubules. Receptor related silver grains occur within tubular epithelium as well as in the lumen of tubules but are absent in interstitial tissue and blood vessels. These data suggest an association of adenosine receptors with spermatocytes within the seminiferous tubule epithelium.