Could increased expression of aquaporin-1 be an etiological cause in childhood noncommunicating hydroceles that do not regress spontaneously?

Background: Aquaporins are membrane water channel proteins that are expressed in the epithelium and endothelium. Their primary function is to control the flow of water in the membranes of the cells.

Objective: In this study, we investigated whether there is increased expression of aquaporin-1 in the tunica vaginalis of hydrocele patients in childhood that do not regress spontaneously an whether it has an effect on the etiology of hydrocele.

Study Design: Boys who were diagnosed with hydrocele and scheduled for surgery were included and formed the hydrocele group. Boys in the same age range who underwent surgery for inguinal hernia or undescended testicles were included as a control group. Aquaporin-1 expression was evaluated by immunohistochemical examination of capillaries in tissue samples taken from the tunica vaginalis during the operation. Aquaporin-1-positive vessels were counted by selecting 5 unrelated areas with the highest vascular density, and the average number of vessels was calculated for each case.

Results: A total of 48 male patients were included in the study. Of these, 27 constituted the hydrocele group (mean age 3.51 ± 2.59 years), and 21 constituted the control group (inguinal hernia, n = 17; undescended testicle, n = 4) (mean age 3.95 ± 3.80 years). The mean ages of both groups were statistically similar (p = 0.32). The mean numbers of aquaporin-1-positive vessels at the capillaries in the tunica vaginalis of the patients were 20.74 ± 7.10 in hydrocele group and 17.23 ± 4.07 in the control group. The expression of aquaporin-1 in the hydrocele group was significantly higher (p = 0.037).

Discussion: It was shown that aquaporin-1 expression was higher in adult cases with hydrocele. Also an increase in aquaporin-1 expression was detected in tunica vaginalis of children with hydrocele in our study.

Conclusion: It was thought that aquaporin-1 overexpression may play a role in non-communicating hydroceles in children.