Compare and Contrast how Cocaine, Ecstasy, Heroin and Cannabis Work in the Brain

Drugs of abuse, such as cocaine, ecstasy, heroin and cannabis, are of natural or synthetic origin, which can alter the emotional state, perception, body functioning and behaviour of an individual. Drugs are known to work in the brain by activating certain brain circuits via different mechanisms, and stimulate or inhibit different neurons in the pathway. However, due to the effects of each drug being different, a drug will affect either different pathways and neurons in the brain to that of another, or through a different process, i.e. direct or indirect activity. This essay will discuss the different mechanisms of action that cocaine, ecstasy, heroin and …show more content…

There are believed to be three different types of opioid receptors in the brain; mu, delta, and kappa, and endorphin, enkephalin, and dynorphin neurons naturally bind to these. When heroin enters the body, it is quickly turned to morphine and binds to opiod receptors, imitating the body’s natural endogenous opiods (Klein & Thorne, 2006).

While all drugs have different mechanisms of action, each drug increases the activity of certain neurotransmitters. Like cocaine and ecstasy, heroin and cannabis have been found to have an effect upon increasing dopamine activity. However, unlike cocaine, which increases dopamine activity through direct action at dopamine transporters, heroin and cannabis appear to increase the levels of the neurotransmitter by indirectly stimulating dopamine neurons. This is due to the drugs activating the mesolimbic reward system, which generates a signal in ventral tegmental area (VTA). This, in turn, triggers the release of dopamine in the nucleus accumbens (N-Ac), and therefore causes feelings of pleasure. Research has shown that when heroin binds to opiate receptors, activation of these receptors decreases GABA release within the nucleus accumbems, which normally inhibits dopamine release. Therefore, dopamine activity is increased, affecting the pleasure pathway (Johnson & North, 1992).
Similarly with cannabis, GABA release is decreased resulting in elevated dopamine levels. However, Poddar