Nicotine causes selective degeneration in brain, UCLA neuroscientists report

November 05, 2000

Nicotine causes degeneration in a region of the brain that affects emotional control, sexual arousal, REM sleep and seizures, UCLA neuroscientists report in the current issue of the journal Neuropharmacology.

"Nicotine causes the most selective degeneration in the brain that I have ever seen," said UCLA neuroscientist Gaylord Ellison, a professor of psychology and member of UCLA's Brain Research Institute. "Only one tract of the brain is affected."

The part of the brain that is affected by nicotine is called fasciculus retroflexus, which has two halves. In previous research conducted over more than two decades, Ellison's research team has shown that such drugs as amphetamines, cocaine and ecstasy damage one half of fasciculus retroflexus. In the journal Neuropharmacology and at the Society for Neuroscience's annual meeting in New Orleans this month, Ellison's research team reports for the first time that nicotine causes degeneration in the other half of fasciculus retroflexus. The neuroscientists further report that the drugs that damage one half of fasciculus retroflexus do not damage the other half that nicotine affects.

"Our findings suggest that this (fasciculus retroflexus) is the brain's weak link for stimulant addictive drugs," Ellison said. "This tract is affected more by chronic drug use than any other tract in the brain.

"It seems likely that fasciculus retroflexus is linked to drug addiction and relapse," Ellison said. "In chronic smokers, this tract may well play a major role in the addiction to nicotine."

Fasciculus retroflexus is a pathway that emerges from the brain's habenula, which is above the thalamus. (The habenula is the chief relay nucleus of the descending dorsal diencephalic conduction system.) This pathway is a part of the brain that is not well understood.

The researchers administered nicotine to rats for five days through a mini-pump inserted under their skin. At high doses of nicotine, the degeneration was almost complete in the pathway.

"We initially gave relatively high doses of nicotine, and then reduced it to a dose that induces plasma levels of nicotine in rats comparable to those of two-pack-a-day smokers," Ellison said. "Even at this much lower dose, we still found degeneration in the tract. We measured the degeneration and found that the larger the dose, the more damage."
Ellison's research team includes his UCLA graduate students Janice Carlson and Brian Armstrong, and Robert Switzer of NeuroScience Associates.

Ellison has studied the effects of drugs on the brain for more than 20 years. His research is funded by the National Institute of Drug Abuse and the Tobacco Related Disease Research Program, which is funded by California's tobacco tax.

University of California - Los Angeles

Related Nicotine Articles from Brightsurf:

Nicotine vapour more rewarding for adolescents than adults
University of Guelph researchers are the first to discover that adolescents react differently to e-cigarette vapour than adults.

Understanding the link between nicotine use and misuse of 'benzos'
Lately, misuse of prescription benzodiazepines (such as alprazolam or Xanax, and diazepam or Valium) has been linked to nicotine use.

Popular electronic cigarette may deliver nicotine more effectively than others
When it comes to nicotine delivery, not all electronic cigarettes are created equally, according to Penn State researchers.

Fetal nicotine exposure harms breathing in infants
Exposure to nicotine during development inhibits the function of neurons controlling the tongue, according to research in newborn rats recently published in eNeuro.

Diabetes drug relieves nicotine withdrawal
A drug commonly used to treat Type II diabetes abolishes the characteristic signs of nicotine withdrawal in rats and mice, according to new research published in JNeurosci.

The nicotine in e-cigarettes appears to impair mucus clearance
E-cigarette vaping with nicotine appears to hamper mucus clearance from the airways, according to new research published online in the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine.

Truth telling about tobacco and nicotine
In 'Truth Telling about Tobacco and Nicotine,' PRC researchers explain that, although there is agreement among researchers about evidence that vaping can be less harmful than combustible cigarettes, the tobacco control community remains divided about how to communicate -- or even whether to communicate -- information about the relative risks of tobacco and nicotine products.

This is a neuron on nicotine
Newly developed sensors visually illustrate how nicotine affects cells from the inside out.

New data suggests nicotine while pregnant alters genes
A University of Houston biomedical research team is reporting that a possible cure for addiction may be found by following the pathways of significantly altered dopamine neurons in newborns who were chronically exposed to nicotine in utero.

Ex-smokers might be better off with high rather than low nicotine e-cigs
Vapers using low rather than high nicotine e-cigarettes may be using their devices more intensely, potentially increasing the risk of exposure to toxins in the vapour, according to new research funded by Cancer Research UK and published in Addiction today.

Read More: Nicotine News and Nicotine Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to