Injury-induced functional plasticity in the peripheral gustatory system

Area of Science:

• Neuroscience
• Physiology
• Sensory Biology

Background:

• Dietary sodium restriction enhances sensitivity to salt taste.
• Unilateral denervation of anterior tongue taste buds combined with a low-sodium diet attenuates neurophysiological sodium taste responses.
• The epithelial sodium channel (ENaC) is a key pathway for sodium taste transduction.

Purpose of the Study:

• To investigate the effects of experimentally induced injury on taste responses from anterior tongue taste receptors in sodium-restricted rats.
• To determine the role of local, diffusible factors in regulating sodium salt sensation following neural and/or epithelial damage.

Main Methods:

• Experiments involved sodium-restricted rats with sectioned gustatory nerves (chorda tympani, glossopharyngeal, greater superficial petrosal) or a nongustatory nerve (trigeminal) innervating the anterior tongue.
• A group received thermal injury to the anteroventral tongue.
• Functional salt taste responses were measured from the intact chorda tympani nerve.

Main Results:

• Substantial and selective suppression of sodium salt responses was observed.
• Suppression occurred in a graded manner, related to the proximity of the injury to anterior tongue taste buds.
• The order of effectiveness for suppression was: chorda tympani section > trigeminal section > thermal injury = glossopharyngeal section > greater superficial petrosal section.

Conclusions:

• Local, diffusible factors liberated from immune-derived cells following neural/epithelial damage regulate the sodium salt sensation transduction pathway.
• Dietary sodium restriction may reveal the influence of these factors on salt taste perception.