Much like the tiny insects, humans who use methamphetamine also hugely decrease their food intake and ratchet up physical activity. The study used fruit flies (Drosophila melanogaster)as a proxy for humans to track behavioral and metabolic changes resulting from methamphetamine usage.
Methamphetamine, commonly known as meth or speed, is a highly addictive stimulant. The effects of the drug include rapid and irregular heartbeat, increased blood pressure and increased wakefulness. If taken for a long time, it can lead to violent behavior, mood disturbances, insomnia and dental problems, according to the National Institute on Drug Abuse, or NIDA.
It increases the release of dopamine in the brain, a chemical that is involved in causing someone to feel reward, motivation and other good feelings. At the same time, it blocks the reuptake of dopamine, causing it to build up in the brain, a common thread among addictive substances, according to NIDA.
It also is illegal to use and produce, and is a Schedule II substance. This designation means it has a high potential for abuse and can lead to intense physical and psychological dependence.
Previous studies have linked meth use to the alteration of the expression of genes that affect the metabolism and associated proteins or, alternatively, that meth changes feeding and physical activity behaviors, one of the researchers who led the study explained.
To clear it up, researchers monitored the flies’ metabolism, energy reserves, physical activity, respiration and feeding behavior after they were exposed to meth, with and without a glucose dietary supplement.
The results showed that meth exposure decreases the flies’ food intake by 60 to 80 percent while doubling their locomotor activity. At the same time, two key energy storage molecules decreased, which points to meth creating a “negative caloric balance.”
The flies’ metabolic rate decreased when exposed to meth, which indicates metabolic changes weren’t the cause of the decline of energy storage molecules, according to the research.
The flies’ response is similar to what is seen in people who have been exposed to amphetamines, a class of drugs closely related to methamphetamines.
The findings were published in The Journal of Toxicological Sciences.
About 1.2 million people in the U.S. ages 12 and older had used meth at least once in the previous year, according to 2009 figures. A later study showed that 1.2 percent of 8th graders and 1 percent of high school seniors used meth at least once in the previous year, according to NIDA.
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