In a paper published this month in Neuroscience, she and co-authors suggest that a balanced response between neutrophils and macrophages enhance recovery. In adult rats, they documented the usual, rapid neutrophil response at the immediate site of a taste system injury and in nearby tissue. When they blocked the neutrophil response, nearby nerve function was unaffected and when they increased neutrophils, it decreased function at least initially in injured and nearby uninjured nerves.
"It's a really tightly controlled interplay between these populations of neutrophils and macrophages. If you mess with it, you are going to change nerve function," McCluskey said. "Ultimately we have to look upstream at some of the adhesion molecules that get upregulated and tell neutrophils to come in."
She knows neutrophils are bad for nerve function when they are present but wants to determine if they have some lasting impact as well, particularly when there are a lot of them. She also wants to know why they are not nearly as mobile in the older rats.
Most old rats eventually recovered their sense of taste but not until at least 85 days after injury. Interestingly taste buds and nerves were present much earlier but apparently not functioning. "That was the really surprising part," McCluskey said. "We don't know if the nerve is completely normal in terms of morphology but it's there." The problem may be that the nerve and taste bud are slower to reconnect, so one of her follow-up studies will be looking at affected nerves as well as well as the form and function of axons, or arms, nerves use to reach out to another cell.
Several studies indicate that taste perception declines with age, even though taste bud numbers hold fairly steady. "
|Contact: Toni Baker|
Medical College of Georgia