Anion size modulates salt taste in rats

Area of Science:

• Neuroscience
• Sensory Biology
• Physiology

Background:

• Sodium taste perception is vital for survival.
• The roles of specific ion channels, like epithelial sodium channels (ENaC) and transient receptor potential vanilloid-1 (TRPV1), in processing sodium taste are not fully understood.
• Anion size is known to influence taste perception, but its specific impact on sodium taste via ENaC and TRPV1 requires further investigation.

Purpose of the Study:

• To investigate the influence of anion size on sodium-taste responses.
• To determine the contribution of epithelial sodium channel (ENaC) and transient receptor potential vanilloid-1 (TRPV1) channels to sodium taste perception.
• To analyze the responses of rat chorda tympani (CT) neurons to various salt stimuli.

Main Methods:

• Recorded multiunit and single-cell responses from rat chorda tympani (CT) nerve and geniculate ganglion neurons.
• Utilized pharmacological antagonists benzamil (for ENaC) and SB-366791/cetylpyridinium chloride (for TRPV1).
• Applied various stimuli including NaCl and Na-gluconate at different concentrations, dissolved in artificial saliva.

Main Results:

• CT nerve responses were significantly higher for NaCl compared to Na-gluconate, particularly in broadly tuned neurons.
• Narrowly tuned neurons showed similar but temporally distinct responses to NaCl and Na-gluconate.
• Benzamil inhibited NaCl responses in narrowly tuned neurons, while TRPV1 antagonists had no effect on NaCl responses.

Conclusions:

• Apical ENaCs in fungiform papillae are critical for peripheral gustatory neurons to process sodium taste information.
• The involvement of TRPV1 channels in sodium taste perception remains uncertain.
• Anion size influences sodium taste detection, with ENaC playing a key role in this process.