The Dopamine System Plays A Critical Role Of Psychostimulant Induced Locomotor Activity ( Hall, Powers )

This research paper will evaluate the biological aspects of addictive substance or behavior and how it affects the brain and organs. Biological aspects include dopamine levels that are replaced in the brain due to the reward system being overtaken and the absorption rate of the drug once it is ingested will be discussed. The biological aspects are extensive and permanent if the individual does not get the help they need. Furthermore the clinical issues of addictive substance or behavior will be discussed along with medical treatments and ethical issues. This includes treatments such as counseling

According to the biological perspective, drug use may start off as casual, but through continued use, it produces changes in the brain that influences the onset and maintenance of drug addiction. (Horvath et al., 2013). Drugs have their most prominent effects on the function of neurotransmitters. Almost all major drugs of abuse activate the reward system and cause a flood in the levels of dopamine which is a neurotransmitter that is involved in pleasure. As a result, not only do people learn to associate drug use with pleasure, but the brain also starts to reduce its own natural dopamine production in adjustment to the levels of dopamine produced by the drugs. This is called tolerance, and the consequences of tolerance are highly influential

Cocaine influences dopamine, norepinephrine and serotonin neurotransmission by inhibiting their reuptake. Pimozide, alpha-flupenthixol, perphenazine and chlorpromazine, all dopamine antagonists, were used to pre-treat rats in an attempt to demonstrate the reinforcing effects of dopamine.

The addictive properties of cocaine are a dopamine D2-receptor researchers “indicate that these dopaminergic neural systems play an important part in rewarding effects” (Miller, Gold, Smith, 1997, p.64).

Methamphetamine takes the form of a white, odorless, bitter tasting1, crystalline powder. Methamphetamine increases the amount of dopamine (involved in reward, pleasure, motor function,compulsion, and perseveration). The drug produces this effect because it has a similar molecular compound as dopamine. Methamphetamine is a powerful central nervous system stimulant. The drug works directly on the brain and spinal cord by interfering with normal neurotransmission. When taken repeatedly over time, methamphetamine can produce lasting damage in the nerve cells located in the brain’s pleasure center, as well as nerve cells in other locations.

The major support and refutation of the dopamine hypothesis has come from the examination of dopamine receptors in these regions of the brain. There are two main types of dopamine receptors, D1 and D2. However, within the category of D2 receptors, there are three subtypes, D2, D3, and D4. (5) Through PET scan analysis of dopamine usage in the brain and post-mordum molecular analysis of brain tissue, researcher were able to determine relative levels of dopamine receptors in patients with schizophrenia compared to non-schizophrenics. Overall analysis of dopamine

Over the years, experiments have produced evidence to suggest that dopamine plays a role in the development of Schizophrenia (Howes, McCutcheon, & Stone, 2015). Dopamine is a neurotransmitter that is produced in the substantia nigra and ventral tegmental regions of the brain. The belief that dopamine was involved in Schizophrenia arose after multiple studies performed with compounds produced an increase in extracellular concentrations of dopamine (Lieberman, Kane, & Alvir, 1987). The patients that were administered these compounds had similar symptoms to those observed from patients who were diagnosed with Schizophrenia (Lieberman et al., 1987).

This reversal process is responsible for the return of a neurotransmitter to the synaptic cleft, which would otherwise be metabolised. This increases the chemical messages found at receptors. The psychostimulant action of methamphetamine occurs through its ability to reverse the dopamine transporter. This action can increase locomotor activity in its users (Swanson, Heath, Stratford, & Kelley, 1997). Based on this, it would be expected that a dopamine receptor antagonist would reduce the motor effect of methamphetamine administration. The aim of this report is to identify if the administration of methamphetamine and it’s stimulant effect play a role in locomotor activity, the possible increase of motor behaviour, and whether or not this effect occurs

What do schizophrenia, Parkinson’s disease, bipolar disorder, and cocaine all have in common? It turns out they are all linked to the role of the dopamine transporter (DAT), which is an integral membrane protein responsible for the reuptake of dopamine from the synapse. Drugs that bind to DAT to prevent the reuptake of dopamine are used to treat the diseases mentioned above, among others. However, cocaine, which is also a DAT blocker, leads to profoundly negative effects, such as addiction and psychomotor stimulation. Understanding how different DAT blockers produce distinct behavioral and chemical responses could be the key to developing better drugs to treat dopaminergic disorders and also addiction to DAT blockers like cocaine.

Substance addiction can hugely impact on a person’s thinking, functioning and behaviour. Whilst depressant drugs such as alcohol and opioids slow down your central nervous system (CNS), stimulants such as cocaine or amphetamine increase the activity of the CNS, leading to higher blood pressure, heart rate and increased alertness. Repeated abuse of the substance leads to tolerance and withdrawal, in turn this leads to the user showing signs of irrational behaviour. Another form of substance abuse is hallucinogens; they can cause powerful changes in sensory perceptions. It works by binding to the serotonin receptors, these neurons control visual information and emotions, and this can lead to various effects on the user. Neurobiology can help us understand the reasons for addiction and the effects they have on us. Groman and Jentsch (2012) discuss key issues of differentiating the causes and consequences of addiction through neuroimaging and behavioural research on monkeys, they found that the dysfunction of the dopamine

An individual’s behavior and emotion becomes chemically altered often resulting in dependency, aggression, onset of diseases and poor judgement. This poses a dangerous threat to the neurotransmitters since they have multiple jobs in different parts of the brain. Drugs of abuse are able to exert influence over the brain reward pathway either by directly influencing the action of dopamine within the system, or by altering the activity of other neurotransmitters that exert a modulatory influence over this pathway. These drugs are often powerful and have been known to trigger schizophrenic behavior and can also cause a person to cease breathing, for example hallucinogens such as LSD, mescaline, and psilocybin are able to artificially stimulate the serotonin receptor (Sapolsky, 2005).

Cocaine, on the other hand, has been found to have a profound effect on increased dopamine activity. Kennedy & Hanbauer (1983; cited in Karch, 2007) found a strong correlation between cocaine binding and the inhibition of dopamine uptake, and therefore proposed that dopamine transporters are binding sites for cocaine. Such research, which correlates strong reinforcing properties of cocaine with inhibition of dopamine transporters, suggests that cocaine has a more significant affect upon dopamine, than than it has upon serotonin and noradrenaline. The excessive role of dopamine can explain the high degree of pleasure that users of cocaine experience, as well as depression and cravings, which follow.

In the article “Dopamine and Teenage Logic” by Daniel Siegel he states that “Dopamine is a neurotransmitter central in creating our drive for reward” (Source B). This indicates that dopamine is one of the key causes of risk-taking. Teens often take risks because they are focused on the reward they get after they take it, rather than what would actually happen to them during and after they take the risk. There are two significant ways that dopamine affects our brains; increased impulsiveness, and the susceptibility to addiction by the release of dopamine.

The complexity of the human brain creates mystery when determining the influence of neurophysiological factors and their role in the process of addiction. There is a proposed relationship between drug addiction and the mesolimbic dopamine system, with the mesolimbic pathway from the ventral tegmental area to the nucleus accumbens considered the ‘reward centre’ of the human brain (Alcohol Rehab, 2011). A release of dopamine is necessary for ‘reward’ which is hypothesised to initiate the addiction cycle by providing positive reinforcement for drug self-administration (Feltenstein & See, 2009). Methamphetamine triggers the release of dopamine from synaptic vesicles which flood the synaptic cleft activating feelings of euphoria, well-being

“The overstimulation of this reward system, which normally responds to natural behaviors linked to survival (eating, spending time with loved ones, etc.), produces euphoric effects in response to psychoactive drugs. This reaction sets in motion a reinforcing pattern that “teaches” people to repeat the rewarding behavior of abusing drugs ”(“Understanding Drug Abuse). Using addictive drugs floods the limbic brain with dopamine, taking it up to as much as five or ten times the normal level. A person with elevated dopamine levels now has a brain that begins to associate the substance with an outside neurochemical reward (“Your Brain on Drugs”). As a person continues to abuse drugs, the brain adapts to the overwhelming surges in dopamine by producing less dopamine or by reducing the number of dopamine receptors in the reward circuit. The result is a lessening of dopamine’s impact on the reward circuit, which reduces the abuser’s ability to enjoy the drugs, as well as the events in life that previously brought pleasure. The decrease in normal dopamine levels encourages the addict to keep abusing drugs in an attempt to bring the dopamine function back to normal, except now larger amounts of the drug are required to achieve the same dopamine high, an effect known as tolerance (“Understanding Drug Abuse ). That is what leads to the state of addiction, which leaves the person in a cycle of craving, using, withdrawal, and relapse.