Tobacco is a public health problem. Thousands of people die every year from smoking-related illnesses, so it is important to understand what causes this addiction and the elements that make it up. The good news is that a group of researchers at the State University of South Dakota are working on the subject. and reached interesting preliminary conclusions.
"When you smoke, the nicotine is converted into a metabolite, which is called cotinine ", says Professor Brady Phelps.
Even passive smokers (those who receive smoke from smokers may have cotinine in their bodies). The metabolite is measured in urine, saliva, or blood.
"Cotinine remains in the body for much longer than nicotine" says Phelp. Half the life span, that is, the time for half of the substance to leave a person's system, is about 15 hours for cotinine and for nicotine for only a few hours. This is a fact investigated by Mayo Medical Laboratories.
Phelps and associate professor Tyler M. Miller worked with Professor Shafiqur Rahman of the Department of Pharmaceutical Sciences to study how cotinine affects the behavior of planar worms. Professor Pharmacologist Scott M. Rawls of Temple University's Substance Abuse Research Center also served on this team.
"Preliminary evidence suggests that nicotine dependence may involve more than", Indicates Phelps and adds "Cotinine may amplify or contribute to the addictive properties of nicotine".
The studies carried out were published online in March and will be printed in the Letters of Neuroscience of June 2019.
"Planarians are commonly used in animal models to study the effects of a drug with potential for addiction," says Phelps. "If given a choice, these aquatic worms prefer a dark environment. Their behavior is described as very phobic in light or a response to photons."
To test the additive nature of the metabolite, the researchers plunged the worms into a solution containing three levels of cotinine under light for 10 minutes. Concentration levels were similar to those used by worms responses to nicotine, in a study by Rawls.
With adequate light and exposure to the drug, there is the potential to change the behavior of planners, which is called a site preference technique conditionally. If the phobic light behavior is reversed and the worms acquire a preference for this kind of light environment, it is clear that a conditioned preference of the place was made, Phelps explains.
This conditioned preference has been used by many other animal species, including mammals, and this is a way of measuring reward or dependency properties. With some exceptions, drugs that have established a site-specific preference could serve as a reward for administering the self-supplied drug, which is another technique widely used to measure the potential for dependence.
The study shows that planters, exposed to cotinine, regardless of concentration, spend more time in the light than the control group..
"This is the first demonstration that cotinine will set a conditioned preference on planners," says Phelps. "There may be more dependence on nicotine and cotinine may be a contributing factor." However, the researcher is wary: "These data are preliminary and should be part of the following studies in this field."