Effects of limonene on tracheal and vascular reactivity in a mouse model of asthma

Abstract

Animal models of asthma have shown that limonene (terpene in citrus fruits) reduces inflammation and airway reactivity. We have shown a role for A2A adenosine receptors (A2AAR) in mediating these effects in asthma. We investigated the effects of limonene (in vivo administration) on isolated tracheal and aortic rings to determine tissue‐specific reactivity using organ bath experiments. Mice were divided into control (CON) and allergen sensitized‐challenged (SEN) groups, and were sensitized i.p. on days 1, 6 with 20μg ovalbumin (OVA) followed by 5% OVA aerosol challenges on days 11–13 (n=4–6 mice per group). Limonene was administered as an inhalation prior to allergen challenges in one group of allergic (SEN+LIM). Response (contraction) to methacholine (MCh; 0.1μM) in isolated trachea was significantly higher in SEN tissues (225.99±67.34% vs 5.57±19.74% in CON). Treatment with limonene significantly reduced the tracheal reactivity (80.68±20% in SEN+LIM vs SEN; p<0.05). For isolated aorta, we found a significant difference in endothelial‐mediated relaxation as measured by response to acetylcholine in SEN (12.74±13%) compared to controls (53.94±.26). Limonene treated groups showed significant increase in endothelial response compared to non‐treated groups. No difference was observed in aortic smooth muscle responses (measured against sodium nitroprusside) for any group. These data suggest that limonene reduces tracheal reactivity and improves endothelial response in asthmatic mice. Further experiments are needed to identify the exact mechanisms of these effects.Support or Funding InformationInstitutional Research Grant, LIU (DSP)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.