Effects of diet-induced obesity on tracheal responsiveness to methacholine, tracheal visfatin level, and lung histological changes in ovalbumin-sensitized female wistar rats

Introduction: Many studies have shown a close relationship between obesity and asthma severity. In the present study, the effects of diet-induced obesity were examinedon airway responsiveness to methacholine in addition to visfatin level in female Wistar rats’ tracheae after sensitization with ovalbumin. Materials and Methods: The rats were divided into four groups: control with normal diet (ND), ovalbumin (OVA)-sensitized with normal diet (S+ND), high-fat diet (HFD), and OVAsensitizedwith a high-fat diet (S + HFD). The animals were fed for 8 weeks with standard pelts or high-fat diet and then sensitized and challenged with OVA or saline for another 4 weeks. At the end of the study, the tracheae were isolated and assessed for airway responsiveness and visfatin protein levels. Results: Diet-induced obesity groups developed increased weight and obesity indices (p < 0.001). After sensitization with OVA and diet-induced obesity, there were marked leftward shifts in methacholine concentration-response curves in S + HFD group compared to other groups. Also, maximum response was the highest (P< 0.05 to P< 0.001), EC50 was the lowest (P< 0.05 to P< 0.001), and visfatin protein level was the highest (P< 0.05 to P < 0.01) in S + HFD. Conclusion: According to results, diet-induced obesity caused airway hyperresponsiveness to methacholine and enhanced visfatin protein levels in the tracheae of ovalbuminsensitized female rats. Our results suggested that, in obese ovalbumin-sensitizedconditions in female rats, the local production of adipocytokines, such as visfatin, may be increased, resulting in the deterioration of inflammation in lungs. This finding shows a possible mechanism for the altered phenotype in obesityovalbumin sensitization conditions in female rats.

Keywords:

Airway hyperresponsiveness , Asthma , Obesity , Visfatin , Wistar rats.