OBJECTIVETo study the expression of aquaporin 1 (AQP1) in cochlea and endolymphatic sac of guinea pig of two types of animal model of endolymphatic hydrops.

METHODSThirty guinea pigs were divided into three groups at random: surgery group; aldosterone group and control group. Each group included 10 animals. Surgical endolymphatic sac obstruction or aldosterone intraperitoneal injection was used to build the animal models of endolymphatic hydrops. Immunohistochemistry and western blot were used to examine the expression of AQP1 in cochlea and endolymphatic sac of animal models. Image processing soft (Image Tool) was used to do the semiquantitative analysis.

RESULTSMiddle to high grade endolymphatic hydrops were found in surgery group. It was most significant in the apical coil, and lessened from the apical coil to the basal coil. Low to middle expression grade in endolymphatic hydrops was found in aldosterone group. Most of them were found in the basal coil. The positions of AQP1 expression in two animal models of endolymphatic hydrops were identical with the control group. In cochlea, no difference of AQP1 expression was found in the surgery and control group (t = 0.718 , P > 0.05) , but the expression of AQP1 was down regulated in the cochlea of aldosterone group (t = 6.609, P < 0.01) while the expressions of AQP1 in endolymphatic sac of aldosterone and control group were no difference between them (t = 0.998, P > 0.05). The quantization of AQP1 protein in the lateral wall of cochlea of aldosterone group was lower than that of control group (t = 13.626 , P < 0.01).

CONCLUSIONSThe expression of AQP1 is no change in surgery and control group, but decreased in aldosterone group. The expression of AQP1 may be regulated by the ionic concentration in inner ear of guinea pig.