Why does prenatal alcohol exposure up addiction risk?

One of the many negative consequences when foetuses are exposed to alcohol in the womb is an increased risk for drug addiction later in life. Neuroscientists are discovering why.

Researcher Roh-Yu Shen from the University at Buffalo Research Institute on Addictions is studying how prenatal alcohol exposure alters the reward system in the brain and how this change continues through adulthood.

The key appears to lie with endocannibinoids, cannabis-like chemicals that are produced by the brain itself.

"By understanding the role endocannibinoids play in increasing the brain's susceptibility to addiction, we can start developing drug therapies or other interventions to combat that effect and, perhaps, other negative consequences of prenatal alcohol exposure," Shen said.

"After the prenatal brain is exposed to alcohol, the endocannibinoids have a different effect on certain dopamine neurons which are involved in addicted behaviors than when brain is not exposed to alcohol," Shen says. "The end result is that the dopamine neurons in the brain become more sensitive to a drug of abuse's effect. So, later in life, a person needs much less drug use to become addicted."

Specifically, in the ventral tegmental area (VTA) of the brain, endocannibinoids play a significant role in weakening the excitatory synapses onto dopamine neurons. The VTA is the part of the brain implicated in addiction, attention and reward processes. However, in a brain prenatally exposed to alcohol, the effect of the endocannabinoids is reduced due to a decreased function of endocannabinoid receptors. As a result, the excitatory synapses lose the ability to be weakened and continue to strengthen, which Shen believes is a critical brain mechanism for increased addiction risk.

The study appears in Journal of Neuroscience.

-ANI