Nicotine and the Brain
Posted at 05:29 PM





One of the main ingredients in tobacco has grabbed scientists' attention. A number of studies are showing that the chemical nicotine can trigger a slew of brain mechanisms. Many appear to be positive. Researchers now are weeding out nicotine's behavioral, cognitive and addictive actions and testing nicotine-like drugs that may address some of today's major health problems.

Puff. Puff. Puff. A brew of chemicals enters the body through a cloud of cigarette smoke.
It's known that some of these chemicals ravage the body. Prime ingredients such as tars and carbon monoxide are instigators of cardiovascular diseases and lung ailments. The cigarette's third main component, nicotine, affects the heart, lungs and stomach during its internal travels.
Nicotine, however, doesn't stop there. Starting in the l980s researchers unearthed definitive evidence that this chemical also affects the brain. Today several studies show that nicotine, which can act as either a stimulant or depressant depending on dose and history of use, launches a number of surprisingly different brain mechanisms. And some are beneficial.
Nicotine's two-faced qualities range from boosting memory to promoting the addiction process.

The new understanding is leading to:

Potent compounds that potentially could bypass the chemical's negative qualities and aid in the treatment of health problems.
A clearer picture of why it is so difficult to stop smoking.
Nicotine activates a multitude of brain mechanisms by attaching to specific proteins, known as receptors, which are found on the surface of nerve cells. This interaction leads to the transmission of a chemical message. Nicotine receptors flourish in many areas of the central nervous system and diverse structural variations exist between different nicotine receptor types. Nicotine can exert dramatically different actions depending on the location and type of receptor it sticks to.
Today scientists are conducting research to track the function of each receptor group and type. Some say that a better understanding of nicotine's effects may explain why those who find it hardest to stop smoking often have other ailments such as depression or schizophrenia. These patients may be rebalancing their chemical system by treating themselves with nicotine. Other insights are helping researchers to design new drugs that may mimic specific benefits offered by this chemical.
Some scientists already are testing synthetic new drugs that they believe sidestep the negative effects of nicotine and enhance its positive effects by acting only on specific subtypes of nicotine receptors in the brain. One drug in early human trials is showing promise as a pain medication. The compound appears to act as a more potent pain reliever than current medications. Animal studies suggest that it may cause fewer side effects.
Two additional synthetic drugs that seem specifically to target different nicotine receptor subtypes are being tested in patients with Parkinson's disease and Alzheimer's disease. The hope is that the drugs will help to reverse deficits in motor function and attention, as well as memory.
Ongoing human studies show that administration of nicotine itself through a skin patch improves attention in Parkinson's patients and, at a low dose, enhances memory in Alzheimer's patients.
Scientists also are studying the darker side of nicotine. Nicotine appears to initiate a chemical process of addiction that is similar to that initiated by other drugs of abuse (see illustration). Recent studies in animals may have uncovered the specific nicotine receptor type that is involved in the process. Normally, after mice sample nicotine they become hooked and continue to consume it. But mice bred without a specific component of a major brain type of nicotine receptor snubbed the nicotine. The research suggests that the nicotine receptor types that contain this component are essential for the drug-craving process. Such findings could help researchers develop medications that wean a person off cigarettes and other tobacco products. Furthermore, these studies indicate that compounds acting at other nicotine receptor subtypes may not have the addictive qualities of nicotine itself.

One downside of nicotine is that it appears to create a dependency or addiction. Research shows that nicotine activates neurochemical addiction responses that are similar to other drugs of abuse. Nerve cells release the brain chemical dopamine, which is associated with pleasure, in the brain area known as the nucleus accumbens. Researchers hope that new therapies that target only certain nicotine receptor subtypes will bypass this undesirable effect of nicotine.



-from the wires

Yehey...
Posted at 11:11 AM




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