The present study was conducted to evaluate the influence of estrogen (a female sex hormone) on the experimentally - induced asthma in male mice. The animals were divided into 4 groups; 20 mice each: group I received no treatment and represents control mice, group II were injected intraperitoneally with estrogen (0.25 mg/kg B.W., twice on the day 28 of the experiment), group III injected intraperitoneally with two doses of ovalbumin (OVA) (2 µg of OVA mixed with 100 µg of alum) on day 1 and day 14 of the experiment, then challenged intranasaly with a single dose of OVA (50 µg dissolved in 0.05 ml PBS) on day 28 of the experiment and represents asthmatic mice, and finally group IV included asthma model male mice received the estrogen (0.5 mg/kg B.W. in 40 ml PBS), twice on the day 28 of the experiment and represents asthmatic mice treated with estrogen. Many histopathological changes in the structural integrity were demonstrated in the lung tissues of asthma model mice. The lesions included infiltration of inflammatory cells around and inside terminal bronchioles, loss of the normal alveolar structure and collapse of the majority of alveolar sacs, while others were distended due to ruptured interalveolar septa. Severe congestion in pulmonary blood vessels and increased thickness in smooth muscle layers of terminal bronchioles were also seen. The collagen fibres (by using azan stain) increased severely at the basement membrane of airways and in the alveolar and respiratory bronchiole walls. The treatment of asthmatic male mice with estrogen improved the histological architecture of the lung tissues, reduced the inflammatory cells and restored the thickness of collagen fibres. For this reason, the present findings support the benefit role of estrogen in modulating the inflammatory effects caused by asthma in male mice and it may be helpful to recover the histology of asthmatic lung progressions.
Key words: Asthma, Estrogen, Histology, Collagen fibres, Mice
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