Oxytocin and oxytocin receptor expression in reproductive tissues of the male marmoset monkey

Using a combination of reverse transcriptase polymerase chain reaction to detect specific mRNA and immunohistochemistry employing antibodies that recognize two different epitopes for each molecule, the local production of oxytocin (OT) and its cognate receptor was investigated in the male marmoset monkey (Callithrix jacchus). There was synthesis of both OT and the oxytocin receptor (OTR) within the testis, and both were markedly expressed within the Leydig cells, A weak staining for both OT and its associated neurophysin could also be detected in Sertoli cells in some animals. Expression of OT or neurophysin does not appear to be significant in the epididymis, though there appears to be synthesis of the receptor in some peritubular muscle cells of the epididymis and in the vas deferens, Within the prostate, there appears to be no production of OT or neurophysin, though there appears to be weak expression of the OTR in the basal layers of the secretory epithelium. Similarly in the bulbourethral gland, only OTR immunoreactivity could be detected. Receptors appear to be present in the myoid cells encompassing the glandular lobules and are presumably able to respond to systemic OT. An analysis of juvenile marmosets indicates that the testicular OT system appears to become established during puberty. Thus, in this New World monkey the testis is able to support a local OT-based paracrine-type system, though the prostate and bulbourethral gland are probably only able to respond to exogenous OT.