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NEWS & INFO
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Study finds Lobeline reduces self-administration
of methamphetamine in rats.
Public release date: 2-May-2003
Contact: Michelle Person
mperson@mail.nih.gov
NIH/National Institute on Drug Abuse
Lobeline, a drug with a long history of use in smoking cessation programs, may be a potential treatment for methamphetamine abuse. In a previous study using rats, researchers from the University of Kentucky found that lobeline decreased the animals' self-administration of d-methamphetamine (METH). They concluded that lobeline acted by decreasing the animal's perception of METH- induced pleasure (reward).
The researchers conducted a series of experiments with male rats that were trained to self-administer METH by pressing a lever. In a group of rats that consistently self-administered METH, the researchers exchanged METH with lobeline to determine whether lobeline would serve as a substitute for METH. When METH was exchanged with lobeline, the number of times the rats pressed the lever decreased daily over the course of the experiment, indicating that lobeline did not serve as substitute for METH.
In a different experiment, the researchers investigated whether lobeline would cause rats to resume drug-seeking behavior after a period of abstinence or if it alters METH-induced reinstatement of drug-seeking behavior. They found that lobeline did not restore drug-seeking behavior nor did it alter METH-induced reinstatement. These findings indicate that lobeline appears to alter the mechanisms mediating METH reward, but not the mechanisms mediating the reinstatement of drug-seeking behavior.
In another experiment, the effects of lobeline on dopamine levels in the brains of rats were examined. It was found that lobeline had no effect on dopamine levels, the brain chemical that regulates feelings of pleasure. This finding indicates that lobeline does not induce the same feelings of reward as METH and that lobeline did not act as a substitute reinforcer. This finding would indicate that lobeline, unlike some other pharmacological agents used to treat addiction, does not itself pose a risk for abuse.
WHAT IT MEANS: The ability of lobeline to decrease METH self-administration without inducing reward itself suggests that lobeline may be a useful pharmacological treatment without risk of abuse.
Dr. Steven Harrod and colleagues published the study in the February 23 issue of the journal Psychopharmacology.
Our assessment: This is all very nice, but the article does not say what effect the drug Lobeline does have on the user's brain. It just seems inconclusive to me. In the first experiment, if the subject (rat) is taking Lobeline instead of meth and the starts to press the lever less, it could be because the rat is just not getting the meth that it wants. Why should it keep pressing some stupid lever to get something fake.
In the second experiment it seems that they are testing to see if Lobeline is addictive. OK lots of things are not addictive. It further states Lobeline "appears to alter the mechanisms mediating METH reward." So, what good nutrition might aslo mediate the mechanisms of meth reward. Was lobeline given at the same time as the meth, and causing the meth to be less effective. The article does not say.
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