A: Slot blots analysis of GnRH peptide in the testis of Parkes strain mice of different age groups. *Values are significantly (P < 0.05) decreased in prepubertal period versus birth. **Values are significantly (P < 0.05) increased during puberty, reproductively active, and senescence versus birth and prepubertal stage of mice. B: Immunoblot analysis of GnRH-R protein expression in the testis of mice of different age groups. *Values are significantly (P < 0.05) decreased in prepubertal period versus birth. **Values are significantly (P < 0.05) increased during pubertal and reproductively active stages versus birth, prepubertal, and senescent mice. #Values are significantly (P < 0.05) decreased in senescence versus birth, pubertal, and reproductively active stages of mice. [Color figure can be seen in the online version of this article, available at http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1932-5231]