title: Aquaporin-9 immunohistochemistry in varicocele testes as a consequence of hypoxia in the sperm production site.
abstract: Aquaporin-9 (AQP-9) regulates tissue hydration by promoting transmembrane exchanges of both water and solutes, such as lactate. The latter is a key metabolite of primary spermatocytes and of maturing haploid germ cells (h-GCs). The present investigation was aimed at immunolocalising human AQP-9 in both normal and varicocele testes. Histology and immmunocytochemistry were investigated in archival biopsies from 20 varicocele testes and in eight unaffected ones. AQP-9 immunostaining was performed using a rabbit antibody, and either focal or diffuse cell membrane labelling was recorded. Varicocele testes showed disarranged tubular compartments, with sloughing h-GCs, tissue hyperhydration, spermiogenesis failure and fibrosis. AQP-9 immunohistology of the control testes showed a diffuse cell membrane staining of the primary spermatocytes and h-GCs, without any positive reaction of spermatogonia and Sertoli cells. AQP-9 cell expression in the varicocele testes was focal or lacking in both adluminal and sloughing GCs. AQP-9 expression occurs in normal human testis, at cell membrane of primary spermatocytes and h-GCs, suggesting a possible role of AQP-9 in the water and lactate transport from Sertoli cells to GCs. AQP-9 is focal or lacking in adolescent varicocele testes, and this suggests AQP-9 to be downregulated in such testicular disorder, leading to lactate deprivation with subsequent hypospermatogenesis.
authors.affiliation: Department of Pediatric Surgery, University of Catania, Italy. arenasal@inwind.it
authors.forename: S
authors.initials: S
authors.lastname: Arena
authors.forename: F
authors.initials: F
authors.lastname: Arena
authors.forename: D
authors.initials: D
authors.lastname: Maisano
authors.forename: V
authors.initials: V
authors.lastname: Di Benedetto
authors.forename: C
authors.initials: C
authors.lastname: Romeo
authors.forename: P A
authors.initials: PA
authors.lastname: Nicòtina
mesh_terms: D000293:Adolescent; D020346:Aquaporins / Q000378:metabolism*; D001706:Biopsy; D016022:Case-Control Studies; D015687:Cell Hypoxia / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism; D006801:Humans; D008297:Male; D012708:Sertoli Cells / Q000378:metabolism / Q000473:pathology; D013087:Spermatids / Q000378:metabolism / Q000473:pathology; D013090:Spermatocytes / Q000378:metabolism* / Q000473:pathology; D013091:Spermatogenesis / Q000502:physiology*; D013094:Spermatozoa / Q000378:metabolism / Q000473:pathology; D013737:Testis / Q000378:metabolism* / Q000473:pathology; D014646:Varicocele / Q000378:metabolism* / Q000473:pathology
chemical_list: C109669:AQP9 protein, human; D020346:Aquaporins