Age dramatically delays the time if takes to recover the sense of taste following a significant nerve injury, Medical College of Georgia researchers said.
When old rats received nerve injuries similar to ones that can occur in ear or dental surgery, their taste buds took essentially twice as long to recover function as their younger counterparts, Dr. Lynnette McCluskey, neuroscientist in the MCG Schools of Graduate Studies and Medicine reported during the Association for Chemoreception Sciences annual meeting April 21-25.
"This is probably something that has a huge quality-of-life impact," said McCluskey, who uses taste buds to study regeneration of sensory nerves that enable touch, vision and hearing as well as taste. Similar studies have shown that age only slightly delays recovery time for neurons that enable movement.
"We did not expect that much of a difference based on the literature for motor neurons so these changes are way more severe than anybody predicted," McCluskey said. "Now we need to find out why before we can start to address ways to improve it."
In younger rats, injury to the chorda tympani nerve, which innervates the front of the tongue, typically prompts an infusion of immune cells called neutrophils to the injury site as well as surrounding tissue. Short-term, the neutrophils, which are like a front-line demolition crew pulverizing tissue for removal, can actually hinder the function of nearby nerves. But soon a similar number of white blood cells called macrophages move in to call off the neutrophils and start cleaning things up. Within 45 days, the witherd taste bud is regenerated, the nerve has recovered and taste is intact. "The nerve grows back, stimulates those cells to regenerate and it hooks up perfectly," McCluskey said.
But older rats experience a much bigger invasion of neutrophils although McCluskey notes it doesn't seem to impact nearby nerve function as with younger rats. "T
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Medical College of Georgia