Characterization and localization of oxytocin receptors in the rat testis

Abstract

In this study oxytocin (OT) receptors have been characterized and localized in the testis of the rat using the radioiodinated OT receptor antagonist 125I-labelled d(CH2)5[Tyr(Me)2,Thr4,Tyr9-NH2]-vasotocin (OTA). Receptor density and localization have been compared with the rat testis arginine vasopressin (AVP) receptor using the radioiodinated AVP V(1a) receptor antagonist 125I-labelled d(CH2)5Sar7-AVP and the radioiodinated linear AVP V(1a) antagonist 125I-labelled [(C6H5-CH2CO)- O-methyl-D-Tyr-Phe-Gln-Asn-Arg-Pro-Arg-Tyr-NH2]. 125I-labelled OTA bound with high affinity to membrane fractions of the rat testis (K(a) = 13.8 ± 1.25 litres/nmol), mammary tissue (K(a) = 20.3 ± 4.36 litres/nmol) ..