GAINESVILLE, Fla. (WTXL) - University of Florida neuroscientists have made what they describe as a significant finding that holds the potential to break the cycle of addiction for methamphetamine users.
They say they have identified a novel way to use on-the-market medicines to preventively decrease the reward effects of methamphetamine on the brain.
"Our data show that there are drugs already approved for other conditions by the Food and Drug Administration that can help methamphetamine addiction," said Habibeh Khoshbouei, an associate professor of neuroscience and psychiatry at UF’s College of Medicine, part of UF Health.
No federally approved therapeutic medicines are specifically targeted to treat meth addiction.
In the journal Nature Communications, published Wednesday, a multi-university team led by Khoshbouei demonstrates in rodents how preventive use of medications decreases the euphoria that normally results from methamphetamine intake.
The researchers found that, in mice, a low dose of a sigma-1 receptor agonist - medications including the antidepressant Prozac - thwarts the expected increase in firing activity of dopamine neurons in the brain that goes hand-in-hand with meth use. Dopamine is a chemical messenger released during pleasurable activities such as eating and sex.
Methamphetamine, a psychostimulant, greatly interferes with the normal transmission of dopamine in the brain.
Previous findings by the lab show that a meth-induced increase in dopamine lasts for hours as compared with a much shorter time for cocaine.
Meth also interacts with a signaling modulator in the brain called the sigma-1 receptor, which the researchers identified as a potential molecular target to treat meth addiction.
The study found that the use of certain medications has the potential to prevent stimulation of dopamine neurons that normally follows meth use. Sigma-1 receptor agonists include some commonly prescribed antidepressants, such as fluvoxamine, and antihistamines, such as dextromethorphan, that can "turn on" the sigma-1 receptor.
Importantly, the study found that sigma-1 receptor agonists, in the absence of methamphetamine, do not provoke the reverse transport of dopamine through its carrier.
The next step would be future clinical trials in humans.
Khoshbouei draws a parallel to the use of naloxone to block the effect of opioids. One contrast is that the sigma-1 receptor agonist for meth treatment would only be effective when taken prior to meth intake — not to reverse effects afterward. The therapy thus would be suited for people motivated to recover from the addiction.
"Methamphetamine is such a menace because the amount of dopamine released following meth abuse is so huge that after long-term abuse these people experience psychosis,” Khoshbouei said.
If that effect were blocked, she said, "It could really help people to beat their addiction."
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