Sex, Drugs and ... More Sex and Drugs

Since the 1990s when methamphetamine became more widespread, researchers have wondered what made users of the drug so vulnerable to STDs. Many meth users report the drug enhances the sexual experience. While reducing inhibitions, meth also makes abusers more likely to engage in risky sexual behavior. HIV transmission appears to be far more likely among meth users than nonusers. Some researchers speculated that those with a risk-taking propensity were more likely to try the stimulant.

In a new study, male rats introduced to methamphetamine and a sexually receptive female at the same time wanted more of both. In fact, the meth-dosed rats continued to seek sex weeks later, even when it was paired with a nausea-inducing drug. And they returned again and again to the place where they first obtained meth. The rats' behavior suggested compulsion in seeking the drug and sex.

Off the drug, addicted rats were unmotivated by a receptive female compared with rats given a saline placebo. High doses of meth were not necessary to induce compulsive drug- and sex-seeking behavior. Relatively low doses were more potent than a steadily higher dose.

The US and Canadian study authors suggest that methamphetamine paves the way for risk-taking behavior by revving up the brain regions involved in reward-seeking and suppressing activity in brain regions that would normally curb risky behavior.

The full study, "Concurrent Exposure to Methamphetamine and Sexual Behavior Enhances Subsequent Drug Reward and Causes Compulsive Sexual Behavior in Male Rats," was published in the Journal of Neuroscience (2011;31(45):16473-16482).

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