Histopathological changes in lungs of Wistar rats treated with aqueous leaf extract of Bryophyllum pinnatum

In the management of respiratory tract diseases (RTDs), a number of therapeutic pharmaceutical agents which have been employed and proven to be potent are expensive hence the need for herbal alternatives. In this study, the effects of Bryophyllumpinnatumin the lungs of adult Wistar rats was investigated. Thirty adult rats comprising equal numbers of both sexes were used and randomly assigned into three groups (A, B and C) with each containing ten rats (n=10/group). Each group was subdivided into (A1, B1 and C1) representing experimental period of 4 weeks and (A2, B2 and C2) representing experimental period of 8 weeks. All the experimental rats were given rat chow and water ad libitum. Group B and C in addition to the feed and water were treated with daily doses of 500 and 1500mg/kg body weight of the extract respectively. Group A served as control, Group B as low dose treatment group (500mg/kg body weight) and Group C as high dose treatment group (1500mg/kg body weight). All animals were weighed at the commencement and end of the study period, and the weights were recorded as initial and final body weights. The rats were anesthetized with chloroform and sacrificed.A median sternotomy was made and developed to enter the thoracic cavity. Lung tissues from the control and treatment groups were dissected out and fixed in 10% neutral buffered formalin. The tissues were processed for histological examination and paraffin sections were stained with hematoxylin and eosin (H & E). Qualitative microscopic examination was made with a light microscope. Data were expressed as Mean ± SEM.Significant difference between means were determined by t-test. Significant difference was expressed as P<0.05.Results on body weight showed that no significant changes were observed in the weights of rats in all the treatment groups when compared to the control group, although, fluctuations in values were recorded. Histopathological findings revealed that control rats showed features of normal lung histology suchas bronchioles, alveoli and bronchial vessels. Rats treated with low dose of extract for4 weeks (Group B1) showed bronchiolar dilatation with marked infiltration of inflammatory cells, distention of the alveoli; while those treated with high dose for the same duration (Group C1) showed bronchiolar dilation with inflammatory infiltrates andthe alveoli showing mild atelectasis. Low dose treatment for a duration of 8 weeks (Group B2), showed bronchiolar dilatation with mild infiltration of inflammatory cells and coalescence of distended alveoli (Emphysema), while high dose treatment for the same duration (Group C2) showed bronchiolar dilation with heavy infiltration of inflammatory cells and severe atelectasis. From this study, it can be concluded that the effects of aqueous leaf extract of Bryophyllumpinnatumon the lungs was both duration and dose dependent, causing progressive bronchiolar dilatation, alveolar distention and inflammatory cells infiltration which eventually resulted in emphysema and atelectasis. The bronchodilatory effects at short duration are desirable in the treatment of conditions such as COPD as exemplified by bronchial asthma while prolonged use at high doses are deleterious.Keywords: Bryophyllum pinnatum, Lungs, Bronchodilation, Emphysema, Atelectasi