Gene expression of aphrodisin in female hamster genital tract segments.

Aphrodisin is a glycoprotein originally isolated from hamster vaginal discharge which was demonstrated to be involved in pheromonal effects on male hamsters. In the present study, we investigated the localization of aphrodisin-synthesizing and -storing cells in the entire genital tract of the female golden hamster using immunohistochemical and molecular biological methods. By use of immunohistochemical methods, significant aphrodisin immunoreactivity was detected within the cervical glandular tissue. Western blot analysis revealed high concentration of aphrodisin in vaginal discharge and in tissue extracts from the vagina and the cervix uteri. According to intracellular localization of aphrodisin, this protein is confined to cytoplasm of the immunoreactive cells. Immunoreactivity was also detected extracellularly on the surface of the anterior vaginal pluristratified epithelium. Semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR) analysis showed an extremely high level of aphrodisin gene expression in the vagina and in the lower part of the uterus comprising the cervix. However, aphrodisin gene expression was also demonstrated in the middle part of the uterus and at a low level even in the ovaries. No aphrodisin gene expression was detectable in the upper part of the uterus and the uterine horns. In situ hybridization confirmed that the maximum expression of the aphrodisin gene is encountered in glandular cells of the cervix uteri. These results indicate that within the female hamster genital tract aphrodisin is predominantly synthesized throughout the vagina and cervical uterus. The protein is then secreted into the vaginal lumen. It is under discussion whether the accumulation of aphrodisin in the vaginal discharge facilitates the transfer of pheromone of low molecular weight to the male hamster's vomeronasal organ during investigatory behavior.