Changing P2X receptor localization on maturing sperm in the epididymides of mice, hamsters, rats, and humans: a preliminary study

ObjectiveTo study using immunohistochemistry the localization of P2X receptor subtypes on the head of immature sperm in the human, mouse, hamster, and rat caput epididymidis.DesignBasic research.SettingUniversity-based hospital.Patient(s)Three human epididymides were obtained from patients undergoing orchidectomy for metastatic prostate cancer.Main Outcome Measure(s)P2X1, P2X2, P2X3, and P2X4 receptor immunolocalization on sperm.Result(s)In the present study, P2X1,2, and 3 receptor localization was immunohistochemically demonstrated on the head of immature sperm in the human, mouse, hamster, and rat caput epididymidis. P2X4 receptor immunostaining was also observed on the head of sperm in the caput epididymidis of mice, hamsters, and humans, but not rats. There was a subsequent loss of receptor staining on sperm in the cauda epididymidis, except in humans where staining of P2X4 receptors persisted. Comparision with peanut agglutinin (PNA) binding studies suggested the P2X receptors were located on the acrosome membrane. P2X5–7 receptors were examined but found to be absent.Conclusion(s)The change in localization of receptor subtypes is coincidental with the functionally essential morphologic and maturational changes seen in sperm as they travel through the epididymis, and is suggestive of a role for purinergic signaling in sperm maturation and possibly fertility.