In a study published this month in the Journal of Neuroscience, scientists reported on a new receptor target that
distinguishes those actively addicted to methamphetamine from non-addicted controls. The images of a variant of a dopamine receptor present a new target for possible drugs to reduce cravings for meth.
The study, discussed here, used a chemical probe that specifically bound to D3 (dopamine subtype 3) receptors. Dopamine is a neurotransmitter known to be involved in the reward system. Using a PET scanner to examine the brains of active addicts allowed scientists to see where the chemical probe was most concentrated. Because the number of receptors has increased in addicts, and because dopamine is associated with cravings, the idea is to block the D3 subtype and switch off cravings.
This could be a key development because it gives a biological mechanism underlying the almost irresistible cravings that meth addicts endure. It is those cravings which drive them to seek out more of the drug, even when they know it is harming them. Until now, the neurological basis for these feelings was unknown, although some type of dopamine involvement was suspected.
The study doesn’t clear up all the mysteries, nor will it necessarily lead to a “cure.” However, it is a step along the path. With a target to shoot for, pharmaceutical companies can now investigate possible drugs to counteract the activity at the D3 receptor. It is likely that other behavioral cues will also remain important and treatment that addresses life issues will still be needed, even if a drug therapy eventually emerges.
The research is also thought to apply to other stimulant style drugs, like cocaine. It is probably not a window into cravings for narcotics however. Morphine and derivatives are marked by significant physical addictions and while cravings are associated with all forms of addiction, opiates probably have a different mechanism.
