Navigation Links
Nicotine exposure during development leads to hearing problems

Scientists know that children of women who smoke during pregnancy can develop hearing-related cognitive deficits. For the first time, researchers believe they have evidence that not only implicates nicotine as the culprit, but also shows what the substance does to the brain to cause these deficits.

In a study using rats, Raju Metherate, associate professor of neurobiology and behavior, and colleagues from UC Irvine, showed that nicotine exposure during the equivalent of a human's third trimester led to hearing-related cognitive problems. This is the first time a study has demonstrated this causal link. Further tests then revealed that the probable cause of the deficits was damage to the receptors in the brain that are sensitive to nicotine, which seems to occur when humans or animals are exposed to the substance during development. The study appears this week in the early online issue of the European Journal of Neuroscience.

Children with auditory processing deficits can have a number of hearing-related problems. They may have difficulty understanding speech in a noisy environment, not understand information that is presented verbally, and may not be able to tell the difference between similar sounds.

"This study is significant because it suggests to us precisely what aspect of smoking is so harmful in pregnancy when it comes to cognitive hearing deficits," Metherate said. "Most women who smoke find it difficult to quit during pregnancy. For them, doctors often prescribe a nicotine patch. While that does protect the fetus from the well-known physical under-development related to harmful chemicals in cigarette smoke, exposure to nicotine appears to be enough to cause serious problems on its own, in terms of brain development."

Chemicals known as neurotransmitters act as message carriers between cells and bind with receptors on the cells' surfaces, much like a key fits into the lock. If the receptors are damaged, they can no longer bind properly with the neurotransmitter. Nicotine shares a receptor with the neurotransmitter acetylcholine, which is important for a number of cognitive functions.

Researchers believe that when people are paying attention to something, such as an important sound, acetylcholine is released into the brain. It then interacts with the nicotinic-acetylcholine receptor and, the UCI study showed, thereby enhances sensitivity to that sound. If that receptor is damaged due to prenatal exposure to nicotine, acetylcholine cannot bind with it and increased sensitivity to the important sound is lost.

"While verbal function cannot be measured in an animal, this establishment of a causal relationship between prenatal nicotine exposure and auditory-cognitive deficits is an important step forward in reinforcing these previous findings in humans," Metherate said.

According to the researchers, given the importance of acetylcholine to a number of brain functions, a loss of nicotinic-acetylcholine receptors may have a negative effect on other higher cognitive functions and may also impair vision and other senses.

Nicotine does seem to actually enhance cognitive processing when administered to adults, a finding that has also been shown in previous studies. The researchers found that in this study, nicotine appeared to enhance auditory function in the adult rats, but only if they had not been exposed to the substance during development.

Researchers placed electrodes in the animals' auditory cortex, then exposed them to different frequencies of sound. They found that nicotine made the cortex much more responsive to sound if the rats had not had exposure to nicotine during their early development. In the case of previous exposure, there was no increased sensitivity to sound. According to Metherate, this occurs most likely because the nicotine is mimicking the action of acetylcholine on their shared receptors and increasing responsiveness to sou nd if those receptors had not been previously damaged.


'"/>

Source:University of California - Irvine


Related biology news :

1. Nicotine triggers the same brain reward circuitry as opiates
2. Any exposure to tobacco smoke during pregnancy is risky
3. Scalpel-free surgery could reduce risk of HIV and hepatitis exposure for health care workers
4. Prenatal exposure to famine increases risk of schizophrenia
5. Prenatal exposure to marine toxin causes lasting damage
6. Experimental vaccine protects nonhuman primates when given after exposure to Marburg virus
7. Prenatal nicotine exposure reduces breathing response of newborns...
8. Bird brains shrink from exposure to contaminants
9. Vaccine combined with short-term postexposure antibiotics protects monkeys from inhalational anthrax
10. Solvent exposure linked to birth defects in babies of male painters
11. Early exposure to indoor fungus molecules may protect infants against future allergies
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:11/17/2016)... -- Global Market Watch: Primarily supported by ownership ... and Academics) market is to witness a value of US$37.1 ... highest Compounded Annual Growth Rate (CAGR) of 10.75% is foreseen ... period 2014-2020. North America is not ... Europe at 9.56% respectively. Report Focus: ...
(Date:11/15/2016)... Research and Markets has announced the addition ... report to their offering. ... The global ... from USD 6.21 Billion in 2016, growing at a CAGR of ... bioinformatics market is driven by the growing demand for nucleic acid ...
(Date:6/22/2016)... -- The American College of Medical Genetics and Genomics was once ... one of the fastest-growing trade shows during the Fastest 50 ... Las Vegas . Winners ... each of the following categories: net square feet of paid ... The 2015 ACMG Annual Meeting was ranked 23 out of ...
Breaking Biology News(10 mins):
(Date:12/2/2016)... ... December 01, 2016 , ... Orthogonal, a Chicago-based ... recent FDA Class II 510(k) clearance for their flagship medical device, SimplECG. , ... cardiac monitoring devices that rely on cloth-based nanosensors. While other companies have attempted ...
(Date:12/2/2016)... BC , Dec. 2, 2016 /PRNewswire/ - bioLytical Laboratories, a world leader in ... to Kenya,s Pharmaceutical Association members. (Photo: http://photos.prnewswire.com/prnh/20161201/444905 ... ... , , ... (CHAI) and the Kenya Pharmaceutical Association (KPA) to introduce the INSTI HIV Self Test ...
(Date:11/30/2016)... Fla. , Nov. 30, 2016 Biotest ... products, is pleased to announce the addition of its ... Kearney, Nebraska . The 15,200 square ... on November 29th, 2016 and brings the total number ... Ileana Carlisle , BPC,s Chief Executive Officer ...
(Date:11/30/2016)... 2016   Merck , ein führendes ... einer Reihe von Vereinbarungen mit Evotec AG ... Screeningleistungen für Mercks Palette genetischer Reagenzien wie ... diese Bibliotheken in Kombination mit Evotecs Expertise ... zur Ermittlung und Erforschung neuer Arzneimitteltargets.    ...
Breaking Biology Technology: