Nicotine and the taste allure for salty food

Abstract

Smoking has been recognized as one agent that may decrease the effectiveness of the gustatory system to detect salt (Na + ) in foodstuffs. As a consequence, smokers tend to ingest saltier foods than nonsmokers. An increase in sodium intake has been associated with hypertension: thus, smoking may concur to the development of hypertension by impairing salt perception. Understanding the mechanisms underlying the action of smoking on salty taste represents the premise to design proper intervention aiming at restoring normal sensitivity to sodium in smokers. I addressed this issue by studying the effect of nicotine, one of the main components of tobacco smoke, on the sodium detection mechanism in rat taste cells. Electrophysiological analysis of these cells revealed that long-term exposure to nicotine reduced the ion current mediated by the Epithelial Sodium Channel (ENaC), one of the sodium receptors occurring in taste cells. As to the molecular mechanism responsible for such a current decrease, data were consistent with a reduction in the number of functional ENaCs in the membrane of taste cells. Therefore, nicotine reduces the capability of taste cells to respond to sodium ions. This might explain, at least in part, why smokers tend to use salt more abundantly when flavoring their food: they are just boosting the sensory information to be relayed to the brain.