New Delhi: Medical College of Georgia researchers have discovered that age dramatically delays the time it takes to recover the sense of taste following a significant nerve injury.
In the study, Dr. Lynnette McCluskey, neuroscientist in the MCG Schools of Graduate Studies and Medicine, found that 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.
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.
They also have proportionately fewer subsequent macrophages moving in which she suspects may be part of the reason for the significantly delayed recovery.
The study has been published this month in Neuroscience .