Oxytocin gene expression and action in goat testis

Abstract

Gene expression, immunohistochemical localization, binding and effects of oxytocin (OT) on androgen production in the testis of adult goats were studied. Using polymerase chain reaction (PCR) analysis we were able to detect OT gene transcripts in the goat testis. Immunohistochemistry revealed that both OT and neurophysin epitopes were expressed together in the intratubular regions, especially in the Sertoli cells, suggesting the production of OT in these cells. However, enzyme immunoassay found no difference in OT concentration between testicular arterial and venous plasma. Saturable, specific [ 3H]-OT binding sites were present in membrane fractions of the goat testis. Scatchard analysis indicated an apparent affinity of 42 ± 7 L/nmol and binding capacity of 24 ± 4 fmol OT bound/mg DNA. In vitro treatment of goat testes for 6 h with 100 nM OT led to a 3.5-fold increase (P<0.001) in 5α-dihydrotestosterone (DHT) production in spite of the induced decrease in testosterone, suggesting that OT not only affects testosterone production but also modulates its conversion to DHT. These results indicate that the goat testis produces OT, which may be involved in the local control of androgen biosynthesis.