comparative study between the effects of dietary soya and estrogen replacement therapy on the lung of ovariectomized albino rats: histological and immunohistochemical study

ABSTRACT

Soy bean phytoestrogens have estrogenic properties and have been reported to be safe on female reproductive tissue. The present work aimed at comparing the effects of soya and estrogen in the lung of ovariectomized rats and demonstrating whether dietary soya could substitute estrogen replacement therapy. Thirty-nine adult female albino rats were divided into four groups. Group I [control] included nine rats. Group II included 10 rats ovariectomized for 6 months. Groups III and IV each included 10 rats ovariectomized for 6 months and received estrogen replacement [group III] or soy bean [group IV]. Lung sections were subjected to H and E, Masson's trichrome stains, and immunohistomchemical staining of alpha smooth muscle actin [alpha SMA]. The mean smooth muscle thickness, area of collagen deposition, and area percent of alpha SMA were assessed. In group II, thick interalveolar septa with condensed collagen fibers, thickened bronchiolar smooth muscles, and cellular infiltration were detected. Positive alpha SMA immunoreactivity was noted in the thickened interalveolar septa. The mean smooth muscle thickness, collagen deposition, and area percent of alpha SMA immunoreactivity showed a significant increase in group II versus other groups, and there was significant decrease in groups III and IV versus group II. In groups III and IV, cellular infiltration and extravasated red blood cells were noted. Otherwise, they were comparable to the control group. It could be concluded that both soya and estrogen led to improved changes in the lung of ovariectomized rats almost to the same extent. Thus, soya might be recommended as a safe therapeutic substitute to estrogen, which has been reported to have side effects on female reproductive tissue