Can be Safe Cigarettes?

As it is known cigarette makers have marked cigarettes, which contain less nicotine, so called light cigarettes. For to attract smokers to buy them, tobacco makers reported that light cigarettes are less harmful to smokers' health. But a new University of California at Los Angeles (UCLA) study shows, however, that they deliver nearly as much nicotine to the brain as regular cigarettes.

Dr. Arthur L. Brody, UCLA psychiatry professor, and his colleagues found that low-nicotine cigarettes act similarly to regular cigarettes, occupying a significant percentage of the brain's nicotine receptors. They found that light cigarettes have nicotine levels of 0.6 to 1 milligrams, while regular cigarettes contain between 1.2 and 1.4 milligrams. The researchers also tested denicotinized cigarettes, which contain only a trace amount of nicotine (0.05 milligrams), and they found that even this low a nicotine level is enough to occupy a sizeable percentage of receptors.

Mr. Brody said: "The two take-home messages are that very little nicotine is needed to occupy a substantial portion of brain nicotine receptors, and cigarettes with less nicotine than regular cigarettes, such as 'light' cigarettes, still occupy most brain nicotine receptors. Thus, low-nicotine cigarettes' function almost the same as regular cigarettes in terms of brain nicotine-receptor occupancy." According to a new study denicotinized cigarettes still deliver a considerable amount of nicotine to the brain. Researchers, clinicians and smokers themselves should consider that fact when trying to quit.

Scientists showed in a study that in the brain, nicotine binds to specific molecules on nerve cells called nicotinic acetylcholine receptors, or nAChRs. Nicotinic acetylcholine receptors are present in many tissues in the body. When nerve cells communicate, nerve impulses jump chemically across gaps between cells called synapses by means of neurotransmitters. The neurotransmitters then bind to the receptor sites on nerve cells - in the case acetylcholine resulting in the release of a pleasure-inducing chemical called dopamine. Nicotine mimics acetylcholine, but it lasts longer, releasing more dopamine.

Brody added: "It can cause specific neurons to communicate and thus increases dopamine for an extended period of time. Most scientists believe that is one key reason why nicotine is so addictive." Researchers in an earlier study determined that smoking a regular, non-light cigarette resulted in the occupancy of 88 percent of these nicotine receptors. However, that study did not determine whether inhaling nicotine or any of the thousands of other chemical found in cigarette smoke resulted in this receptor occupancy.

In a study fifteen smokers participated. Each was given positron emission tomography (PET) scans, a brain-imaging technique that uses minute amounts of radiation-emitting substances to tag specific molecules. In this case, the tracer was designed to bind to the nicotine receptors in the brain. The researchers could then measure what percentage of the tracer was displaced by nicotine when the research subjects smoked. In total, 24 PET scans were taken of participants' brains before and after three different conditions: not smoking, smoking a denicotinized cigarette and smoking a low-nicotine cigarette.

The PET data showed that smoking a denicotinized cigarette and a low-nicotine cigarette occupied 26 percent and 79 percent of the receptors, respectively, which was very close to what the researchers had originally estimated. Researchers want to achieve their aim that's why they continue to study the detrimental effect of cigarettes smoking. In a previous study they studied the regular and light cigarettes but in the present study they showed people that inhaling nicotine during smoking is solely responsible for occupancy of brain nicotine receptors.