| Abstract— Many studies have shown a close relationship between obesity and asthma
severity. In the present study, the effects of diet-induced obesity were examined on airway
responsiveness to methacholine in addition to visfatin level in female Wistar rats’ tracheae
after sensitization with ovalbumin. 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 OVA-sensitized with 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. 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. According to results, diet-induced obesity
caused airway hyperresponsiveness to methacholine and enhanced visfatin protein levels in
the tracheae of ovalbumin-sensitized female rats. Our results suggested that, in obese
ovalbumin-sensitized conditions 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 obesity-ovalbumin sensitization
conditions in female rats. |