Background: Oropharyngeal dysphagia (OD) is a major gastrointestinal motility disorder that causes severe nutritional and respiratory complications in elderly and neurological patients. In an earlier study, we found that stimulation of pharyngeal sensory neurons by capsaicinoids acting on transient receptor potential vanilloid 1 (TRPV1) improved the swallow response of dysphagic patients. The aim of this study was to explore the effect of piperine, a dual TRPV1/TRPA1 agonist, on the swallow response of dysphagic patients.
Methods: A videofluoroscopic study was performed to assess the signs of impaired safety and efficacy of swallow and the swallow response of 40 dysphagic patients while swallowing one series of nectar control boluses and two series of nectar boluses supplemented with piperine. Patients were randomized into two groups: one group received 150 μM piperine and the other group received 1 mM.
Results: Piperine improved the safety of swallow by: (a) reducing the prevalence of unsafe swallows by -34.48% (P = 0.004) at 150 μM and -57.19% (P < 0.001) at 1 mM, and the severity score of the penetration-aspiration scale from 3.25 ± 0.51 to 1.85 ± 0.27 (P = 0.003, 1 mM); and (b) shortening the time to laryngeal vestibule closure from 0.366 ± 0.024 to 0.270 ± 0.022 s with 150 μM piperine (P < 0.001) and from 0.380 ± 0.032 to 0.306 ± 0.028 s with 1 mM piperine (P < 0.05).
Conclusions: Supplementing the alimentary bolus with piperine speeds swallow response and strongly improves safety of swallow in patients with OD, with a maximal therapeutic effect at 1 mM. Our results suggest that activation of TRPV1/A1 in oropharyngeal sensory neurons is a very promising neurostimulation strategy for dysphagic patients.