The Effects of Dietary Capsaicin on Ventilation in Aging Mice

Abstract

Capsaicin (CAP), the main pungent component of chili peppers, is a selective agonist for transient receptor potential vanilloid 1 (TRPV1). Stimulation of TRPV1 receptors with low doses of CAP results in augmented ventilatory output in anesthetized mice (Wang, 2006 JAP). We tested the hypothesis that dietary intake of CAP in older mice would augment ventilation compared to a control diet. Male mice were tested using unrestrained barometric plethysmography to quantify ventilation before initiation of a specialized diet and after 4‐weeks of AIN‐93G diet (Harlan Teklad) enhanced with either CAP dissolved in lecithin (50 mg/kg food weight: CAP; n=13) or lecithin only (CON; n=12). Mice were acclimated to the chamber (30 min – 180 min) and a 10‐min baseline was collected with room air. Data were analyzed using a multi‐variate linear model and are presented as MEAN±SEM; p < 0.05. At 23‐mon, mice displayed a similar pattern of quiet breathing (data combined; Freq 124±4 bpm, tidal volume (TV) 0.33±0.01 mL/breath, minute ventilation (MV) 40.7±2.1 mL/min). Following 4 weeks of AIN‐93G diet, CON vs. CAP groups demonstrated no differences when exposed to room air for Freq (119±9 vs. 146±13 bpm), TV (0.34±0.02 vs. 0.32±0.01 mL/breath) or MV (39.3±2.6 vs. 47.1±4.7). These responses indicate that dietary CAP does not alter quiet breathing in aging mice. Both groups were exposed to acute hypoxia (15 minutes; 10% O2); these data may provide additional insight regarding the pattern of breathing following dietary CAP. Funding: LMC Student Research Committee; McDevitt Center Research Fellowships in Natural Science to AL and SR.