Addiction is primarily fueled by abnormal neurotransmission, biomolecular mechanisms enabling nerve cells (neurons) to send impulses or signal to other nerve cells. The more accelerated neurotransmission rates, the more powerful the feeling of arousal and euphoria experienced by drug addicts. People experiencing drug-sustained states of pleasure and arousal are compelled to continually seek addictive substances or risk-taking activities (gambling, racing cars or skydiving, for example) that elevate neurotransmission rates in brain regions responsible for that particular kind of sensation. Alternately, individuals addicted to opioids and depressants crave activities that dramatically reduce the rate of neurotransmission while slowing down central nervous system functioning.
Once modification of normal neurotransmission occurs, the brain instinctively tries to reestablish normal neurotransmission rates, which causes the addict to develop a tolerance for their drug of choice. To achieve a desired state of arousal, the addict must now increase the amount of drugs they use to compensate for disturbances in the brain and CNS. This is a basic definition of the “cycle of addiction” and why withdrawal symptoms emerge when addicts abstain from consuming drugs.
Biomolecular Mechanisms of Neurotransmission
Neurotransmission involves nerve cells connecting to the central nervous system via dendrites, or fibrous tentacles that send and receive signals to other neurons. Between neurons exist tiny areas called synaptic junctions where neurotransmitters (dopamine, serotonin, norepinephrine, GABA) are released from pre-synaptic terminals. Once a neurotransmitter is released into a synaptic junction, they are either assimilated into a post-synaptic membrane or weakened by enzymes and rendered inactive.
When a neurotransmitter is “taken up” by a post-synaptic nerve cell in sufficient quantities, membranes within the nerve cell depolarize, a process involving the cell’s negative internal charge changing to a positive charge. It is during depolarization that a signal can be transmitted containing information about a feeling, thought, sensation or mood.
How Drugs Disrupt Neurotransmission
Within pre-synaptic terminals are enzymes that degrade neurotransmitters before being released into synaptic junctions. Upon degradation by enzymes, neurotransmitters cannot reach post-synaptic nerve terminals and impulses cease their transmission. This degradation may also happen within synaptic junctions, meaning that enzymes remaining in junctions can exist in overabundance or under-abundance. Addictive drug molecules that occupy receptors may or may not present similar effects exhibited by neurotransmitters but can overfill receptors at post-synaptic terminals.
In addition, the cAMP pathway (cAMP is a chemical messenger needed for intracellular signal transduction) may be interrupted, a change that results in delayed or reduced impulse transmission.
When less cAMP is manufactured, neurotransmission activity is inhibited and strong mood changes affect the addict. It is the cAMP system that connects withdrawal symptoms to the biochemistry of tolerance and addiction. Consequently, abstaining from drugs causes massive decreases in cAMP production, which leads to classic withdrawal symptoms such as pain, panic and cravings.
Endorphins and Enkephalins in Biomolecular Mechanisms
Barbiturates and opioids decrease neurotransmission while releasing huge amounts of endorphins or enkephalins. Acting as natural opiates made by the body, enkephalins readily attach to pre-synaptic terminals, decreasing the release of neurotransmitters and slowing neurotransmission. In attempting to counteract this effect, the body increases levels of a chemical called adenylate cyclase that, in turn, elevates cAMP levels and neurotransmission rates. As tolerance builds, the addict will need to increase drug use to “keep up” with increasing cAMP and cell signaling activity or suffer withdrawal symptoms.
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By understanding basic biomolecular mechanisms that reinforce the disease of addiction, patients and their loved ones seeking assistance from treatment centers learn to accept the fact that addiction is not a lifestyle choice but a serious, chronic disease that requires the same caring and insightful medical attention given to people with diabetes, heart disease or cancer. Take the quiz today and let us help you achieve the goal of living a sober, productive life.