THC Exposure from Marijuana Linked to Addiction and Compulsive Behavior in Offspring

It turns out that tetrahydrocannabinol (THC), the primary psychoactive ingredient in marijuana, may have some unforeseen consequences. Scientists have discovered that exposing adolescent rats to THC can lead to molecular and behavioral alterations in the next generation of offspring, even though their children weren't directly exposed to the drug.

In this particular study, the researchers gave male adolescent rats 1.5 mg/kg of THC. That's similar to about one joint in human use. None of the rats had been exposed to THC before, but their parents were exposed to THC as teens and then mated later in life. In the end, the researchers found that the THC-exposed offspring worked harder to self-administer heroin by pressing a level multiple times to get heroin infusion.

"Our study emphasizes that cannabis [marijuana] affects not just those exposed, but has adverse effects on future generations," said Yasmin Hurd, one of the researchers, in a news release. "Finding increased vulnerability to drug addiction and compulsive behavior in generations not directly exposed is an important consideration for legislators considering legalizing marijuana."

In fact, the researchers found that male offspring of individuals exposed to THC exhibited molecular changes in the gultamatergic system. This is the most important excitatory pathway for neurotransmission in the brain. Damage in the glutamate pathway has been linked to disturbances in goal-directed behavior and habit formation.

"What this opens up are many questions regarding the epigenetic mechanisms that mediate cross generational brain effects," said Hurd in a news release.

Currently, the researchers plan to conduct future studies to determine whether THC effects continue to be transmitted even in the subsequent grandchildren and great-grandchildren of these mice. The findings could lend insight into what THC exposure means. In addition, this could help inform policy makers in the future.

The findings are published in the journal Neuropsychopharmacology.