Cocaine, an illegal substance used recreationally by many Americans, has proved highly addictive. Researchers see case after case of cocaine addicts that lose their homes, their jobs and their spouses because of the drug yet continue to seek it on a regular basis. Eric J. Nestler, M.D., PhD reports in his article, "The neurobiology of cocaine addiction," that cocaine has effects on specific parts of the brain that initiate and prolong the addiction.
Cocaine's Effects
Cocaine produces an elevation of mood and euphoria in its users. Energy increases for short durations and the drug's effects wear off quickly. Because of its addictive properties, the cocaine user seeks to purchase and use this expensive street drug over and over. The need for money to buy the drug becomes the source of trouble in relationships and families as the user spends money allocated for bills and such. This lapse in judgment shows up in many studies, according to University of Texas Southwestern Medical Center, 2010.
Mechanism of Cocaine High
Scientists identified the specific mechanism in the brain that underlies the cocaine high. The isolated chemical, dopamine, one of many neuroreceptors in the central and peripheral nervous system, succumbs to cocaine. The neurorecptor has the job of leaving a neuron and traveling to another neuron to stimulate it. This mechanism becomes excessively stimulated by cocaine. An increase in the amount and frequency of dopamine leaves these neurotransmitters in a state of limbo with no target cells available to receive their stimulation. Consequently, the extra dopamine settles into the nerve synapse, the connection between two nerves. This causes the excitation and exaltation of the cocaine high.
Mechanism of Cocaine Addiction
The part of the brain that responds to cocaine, the mesolimbic system, controls the release of good feelings that act as a reward and keep humans and other mammals functioning. For example, hunger tells the body to eat. When it eats it feels pleasure and satisfaction. Those rewards come from the mesolimbic system and reinforce in us the desire to eat again. Addiction Science.net, 2000 reports that repeated use of cocaine depletes dopamine in the brain. When dopamine depletes, normal rewards lose their motivational significance. Then dopamine becomes even more sensitive to cocaine. The cycle of addiction establishes itself as the dopamine adapts to the stimulant.
Cocaine's Long-Term Effects
Scientists have found that cocaine alters gene expression. As the cocaine user makes the transition from drug abuse to addiction, changes occur in the mesolimbic system to the genes. The changes involve turning on or turning off the expression of those genes. One of the genes involved affects an important neurotransmitter chemical called glutamate. According to University of Texas Southwestern Medical Center, 2010, the effects of cocaine on a specific nerve structure can alter the nerve for many months after the last cocaine exposure. The reporting doctors feel this change has a part in the craving that remains after cessation of the drug.
On the Horizon
Most efforts to develop a drug to break the cycle of addiction aim at preventing cocaine from getting to the brain by stimulating antibodies that intercept it, according to Eric J. Nestler, MD, Ph.D., the Department of Psychiatry and Center for Basic Neuroscience at the University of Texas Southwestern Medical Center. Subsidized by three grants from the National Institute on Drug Abuse, Nestler offers insights as to what developments lie ahead. He says another avenue of exploration involves a chemical that suppresses or prevents cocaine's pleasure properties by interfering with the transport of dopamine's normal functions. The methods under study act on the initial phase of cocaine addiction but do not address the long term changes that occur in the brain. Nestler states that a medication that would reverse these changes holds promise as a treatment for cocaine addiction as well. Regardless of the outcome, Nestler's research has led him to believe that the eventual discovery of effective cocaine addiction lies in the pursuit of the neurobiological mechanisms of the addiction.
