The BrainMarijuana, Cocaine, And The Opiates Part 4Localization Of THC Binding SitesWhen a person smokes marijuana, the active ingredient, cannabinoids or THC, travels quickly to the brain. Areas where THC (magenta) concentrates, the VTA, nucleus accumbens, caudate nucleus, hippocampus, and cerebellum are highlighted.
 A Picture Of Localization Of THC Binding Sites THC binds to THC receptors that are concentrated in areas within the reward system as well as these other areas. The action of THC in the hippocampus explains its ability to interfere with memory and actions in the cerebellum are responsible for its ability to cause incoordination and loss of balance. THC Binding To THC ReceptorsNote to scientists - the interaction of THC with the reward system is not fully understood at this point. The following discussion is based on recent data, but additional theories may emerge as we obtain more data. Scientists know the least about THC. Over the last few years, there has been intense study to discover where and how THC works. One theory is that it acts in a similar way to opiates. The same 3 neurons are probably involved; the dopamine terminal, another terminal (on the right) containing a different neurotransmitter (probably GABA), and the post-synaptic cell containing dopamine receptors.
 A Picture Of THC Binding To THC Receptors THC binds to THC receptors (magenta) on the neighboring terminal and this sends a signal to the dopamine terminal to release more dopamine. Again, it is probably a presynaptic receptor on GABA interneurons that controls dopamine release. Increased cAMP produced in post-synaptic cell In a closer view, show how this affects the function of the post-syanaptic cell. Since there is more dopamine released, there is increased activation of dopamine receptors. This causes increased production of cAMP inside the post-synaptic cell which alters the normal activity of the neuron. As a result of THC actions in the nucleus accumbens, there are increased impulses leaving the nucleus accumbens to activate the reward system. Scientists still don't know how the continued use of marijuana alters the reward system. Indicate that this is an area of intense research by neuroscientists. These drugs all activate the reward system via increasing dopamine neurotransmission Each drug increases the activity of the reward pathway by increasing dopamine transmission. This happens even though the drugs act by different mechanisms. Because of the way our brains are designed, and because these drugs activate a particular brain pathway for reward, they have the ability to be abused. Books Buzzed: |