Effects of soy isoflavones on the concentration of hyaluronic acid in the vagina of type 1 diabetic rats.

OBJECTIVE

To assess the effects of isoflavones and 17β-estradiol on the vaginal epithelium extracellular matrix and hyaluronic acid (HA) in the diabetic rat model.

METHODS

Sixty adult, virgin, female rats underwent ovariectomy, then randomization into six groups of ten animals each: GI, sham ovariectomized control animals; GII, sham ovariectomized control diabetic animals; GIII, control ovariectomized rats receiving propylene glycol vehicle; GIV, control ovariectomized diabetic animals receiving propylene glycol vehicle; GV, diabetic ovariectomized animals treated with soy isoflavones (150 mg/kg by gavage); GVI, ovariectomized diabetic rats treated with estrogen (17β-estradiol, 10 mg/kg, subcutaneously). Treatment took place over 30 consecutive days. After euthanasia, a portion of the vagina was immersed in liquid nitrogen for RT-qPCR and Western blotting. Another portion was processed for paraffin embedding. Sections were stained with hematoxylin & eosin for histomorphometry and Picro Sirius Red for collagen quantification.

RESULTS

Vaginal epithelium histomorphometry in GIII (15.3 ± 1.1 µm) and GIV (14.5 ± 1.8 µm) was thinner than in GV (41.3 ± 1.5 µm) and GVI (74.3 ± 1.6 µm). There was an increase in collagen content in GV (84.1 ± 1.2 µm) and GVI (88.2 ± 1.7 µm). HA quantification was higher in GV (0.38 ± 1.1 μg/mg) and GVI (0.49 ± 1.4 μg/mg) when compared with GIII (0.12 ± 1.1 μg/mg) and GIV (0.10 ± 1.2 μg/mg), p < 0.05.

CONCLUSIONS

Soy isoflavones increase hyaluronic acid concentration in the vagina of diabetic ovariectomized rats. Such findings might help to attenuate the effects of vulvovaginal atrophy in women.