Ontogeny of QRFP and its receptor expression in mouse testis during post-natal development.

Pyroglutamylated RFamide peptide (QRFP), a neuropeptide, binds to its receptor GPR103 and influences various biological functions. In the present study, expression and localization of QRFP and GPR103 in mouse testis during post-natal development were investigated. The results showed that QRFP and GPR103 and also the isoforms of the receptor, viz. GPR103A and GPR103B were expressed in mouse testis during post-natal development. Expression of QRFP and its receptor was high during the early periods of post-natal development. Immunohistochemical study demonstrated the localization of QRFP and GPR103 in both interstitial and tubular compartments of the testis throughout post-natal development. A shift in the germ cell types expressing QRFP and its receptor along the course of testicular development and also a prominent immunoreactivity of QRFP in germ cells and of GPR103 in Sertoli cells was observed. Further, the immunoreactivity of QRFP and GPR103 appeared to be stage-specific in spermatogenetically active testis. Besides in intercellular spaces, localization of QRFP was also noticed in nuclei of germ cells. In conclusion, the present results suggest potential involvement of QRFP system in the development, proliferation and differentiation of testicular cells, possibly by regulating the energy requirement for these processes.