Featured Research

from universities, journals, and other organizations

Age dramatically delays recovery of the sense of taste

Date:
April 22, 2010
Source:
Medical College of Georgia
Summary:
Age dramatically delays the time if takes to recover the sense of taste following a significant nerve injury researchers report. 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.

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. "That was better than we expected," she said. They also have proportionately fewer subsequent macrophages moving in which she suspects may be part of the reason for the significantly delayed recovery.

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. "People say things don't taste like they used to; they start putting on more salt," McCluskey said. Complicating factors may be a decreased sense of smell and medications that can alter taste.

Abstract co-authors include MCG medical student Arkadiy Yagdorov and research assistant Dr. Lianying He.


Story Source:

The above story is based on materials provided by Medical College of Georgia. Note: Materials may be edited for content and length.


Cite This Page:

Medical College of Georgia. "Age dramatically delays recovery of the sense of taste." ScienceDaily. ScienceDaily, 22 April 2010. <www.sciencedaily.com/releases/2010/04/100421102443.htm>.
Medical College of Georgia. (2010, April 22). Age dramatically delays recovery of the sense of taste. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2010/04/100421102443.htm
Medical College of Georgia. "Age dramatically delays recovery of the sense of taste." ScienceDaily. www.sciencedaily.com/releases/2010/04/100421102443.htm (accessed July 31, 2014).

Share This




More Health & Medicine News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

House Republicans Vote to Sue Obama Over Healthcare Law

House Republicans Vote to Sue Obama Over Healthcare Law

Reuters - US Online Video (July 31, 2014) The Republican-led House of Representatives votes to sue President Obama, accusing him of overstepping his executive authority in making changes to the Affordable Care Act. Mana Rabiee reports. Video provided by Reuters
Powered by NewsLook.com
Despite Health Questions, E-Cigs Are Beneficial: Study

Despite Health Questions, E-Cigs Are Beneficial: Study

Newsy (July 31, 2014) Citing 81 previous studies, new research out of London suggests the benefits of smoking e-cigarettes instead of regular ones outweighs the risks. Video provided by Newsy
Powered by NewsLook.com
Dangerous Bacteria Kills One in Florida

Dangerous Bacteria Kills One in Florida

AP (July 31, 2014) Sarasota County, Florida health officials have issued a warning against eating raw oysters and exposing open wounds to coastal and inland waters after a dangerous bacteria killed one person and made another sick. (July 31) Video provided by AP
Powered by NewsLook.com
Health Insurers' Profits Slide

Health Insurers' Profits Slide

Reuters - Business Video Online (July 30, 2014) Obamacare-related costs were said to be behind the profit plunge at Wellpoint and Humana, but Wellpoint sees the new exchanges boosting its earnings for the full year. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



    Save/Print:
    Share:

    Free Subscriptions


    Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

    Get Social & Mobile


    Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

    Have Feedback?


    Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
    Mobile: iPhone Android Web
    Follow: Facebook Twitter Google+
    Subscribe: RSS Feeds Email Newsletters
    Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins