Aquaporin-2 in the human endolymphatic sac.
OBJECTIVE
To detect and localize aquaporin-2 (AQP-2), a water channel regulated by the antidiuretic hormone, in human endolymphatic sac.


METHODS
Human endolymphatic sacs were sampled during removal of vestibular schwannomas via a translabyrinthine approach. Samples were immediately fixed in 10% formalin (24 h) and embedded in paraffin; in situ hybridization and immunohistochemistry were performed with an AQP-2-specific probe and a polyclonal antibody.


RESULTS
Both AQP-2 mRNA and protein were detected in the epithelium of the endolymphatic sac. AQP-2 immunostaining was mainly cytoplasmic, suggesting that most AQP-2 was located in intracellular pools.


CONCLUSIONS
In the endolymphatic sac, AQP-2 probably participates in the homeostasis of endolymph; the possibility of reducing the volume of endolymph by inhibiting its expression and membranous insertion using an antidiuretic hormone inhibitor represents a new therapeutic approach for the treatment of Ménière's disease.
Couloigner
Vincent
V
INSERM EMI-U 0112, Faculté Xavier Bichat, Paris, France. vincent.couloigner@rdb.ap-hop-paris.fr
Berrebi
Dominique
D
Teixeira
Marie
M
Paris
Régine
R
Florentin
Agnès
A
Bozorg Grayeli
Alexis
A
Cluzeaud
Françoise
F
Sterkers
Olivier
O
Peuchmaur
Michel
M
Ferrary
Evelyne
E
D051399:Aquaporin 2; D020346:Aquaporins / Q000032:analysis*; D003593:Cytoplasm / Q000737:chemistry; D004712:Endolymphatic Sac / Q000737:chemistry*; D004848:Epithelium / Q000737:chemistry; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D014722:Vestibule, Labyrinth / Q000737:chemistry
C496023:AQP2 protein, human; D051399:Aquaporin 2; D020346:Aquaporins