Age difference in responses to cigarette smoke-induced injury in a rat model

Abstract

INTRODUCTION: Cigarette smoking is the major cause of chronic obstructive pulmonary disease. Recent theories suggest that older individuals may be more prone to the effects of cigarette smoking. This study aimed at studying the effects of ageing on inflammatory responses using a rat model of passive smoking. METHODS: Male Sprague-Dawley rats of 4 months old (young) or 8 months old (grown-up adult) were exposed to air as control or cigarette smoke (CS; 4%) twice daily for 1 hour each for 7 consecutive days. Lung function was measured using whole-body plethysmograph (DSI) before the commencement of CS exposure and after the last exposure. On the day of sacrifice, bronchoalveolar lavage fluid (BALF) was collected, total cells were counted, and cytospins were prepared. Levels of CINC-1 and MCP-1 in BALF were measured using ELISA. RESULTS: Short-term CS exposure led to an increase in cell number in BALF (total, neutrophils and macrophages), accompanied by an increase in CINC-1 and MCP-1 levels compared to control treatment. There was a trend of a heightened response in the older group compared with the young group. In addition, there was a reduction in tidal volume in the older rats after 7 days of CS exposure, which was not found in the young rats. CONCLUSION: We conclude that the age of the animals could affect the inflammatory responses to short-term cigarette smoking.