Dopamine A Placebo Mediator

Of the six most common neurotransmitters, dopamine is probably the one people know the most about. Dopamine is involved in controlling the reward and pleasure system in the brain. It allows us to recognize rewards and helps give us the ability to go after them. Learning, behavior, and cognition are also affected by dopamine levels. As with anything, if you have an imbalance, then bad things can happen. Parkinson’s disease can be caused by low dopamine amounts. People who have low dopamine levels can be addicted to substances easier.

Some dopaminergic (i.e., dopamine-releasing) neurons run from the substantia nigra to the corpus striatum; their loss gives rise to the clinical manifestations of Parkinson's Disease (Korczyn 1994); others, involved in the rewarding effects of drugs and natural stimuli, run from the mesencephalon to the nucleunucleus accumbens.

Furthermore Parkinson’s disease, which is associated with a depletion of dopamine display behaviours characteristic of schizophrenia when given too much L-DOPA, a dopamine stimulant (Gershon, Angrist, and Shopsin, 1977 as cited in Kalat, 1992). In addition if schizophrenics are given drugs such as L-DOPA their symptoms are heightened. (Kalat, 1992).

Dopamine (DA) for many years has been understood to be a key neurotransmitter governing the reward response in regards to drug addiction. Dopamine is a catecholamine neurotransmitter which is known to act on five know types of receptors ranging from D1-D5, and is produced is multiple locations of the brain with DA release from the midbrain having a central role in reward and drug dependence (Kim, Inoue et al. 2007) . It has been found that DA levels rapidly change after substance abuse, in which levels of DA are up regulated after administration of a large array of drugs, including that of cocaine, which leads to eventual blunting of the DA levels after prolonged use and onset of the cocaine addiction. A study performed by Martinez and Narendran (2007) had found that individuals who were cocaine dependent had marked reductions in the D2 and D3 receptors binding sites available, with individuals who had more blunted receptors have a positive correlation in selecting a cocaine of a higher dosage. Within the same study it was also found that when subjects were offered a voucher of five dollars or cocaine with a street level less than five dollars, individuals with greater levels of dopamine deficits would still select the cocaine. Findings show the relationship and importance of dopamine and control of maladaptive behaviors related to addiction and inability to change behavior despite understanding

Dopamine is one of the main hypothesized physiological causes of schizophrenia (Brisch et. al., 2014). It is involved in movement, pleasure, and cognition: all of which are impacted in schizophrenia. Dopamine is a neurotransmitter or a chemical messenger. It is in the neurotransmitter class of catecholamine and has both inhibitory and excitatory effects (Carlson, 2013). These effects are seen on the postsynaptic neuron, depending on the neuron dopamine can either be inhibitory or excitatory. Within the brain, there are three main systems that use dopamine as their neurotransmitter. These three systems are the nigrostriatal system, mesolimbic system, and the mesocortical system (Carlson, 2013).

This first video called, The Mechanisms of Drug Addiction in the Brain (Alila Medical Media, 2014), was a very informative video of the brain structure. It showed us how different drugs react in our brain and showed us a great visual of how these drugs interact and lead to more production of dopamine (e.g. over stimulation of dopamine levels leading to euphoria/good feelings). The video explains this process as, the major reward pathways involved in the transmission of the neurotransmitter dopamine from the ventral tegmental area – the VTA - of the midbrain to the limbic system and the frontal cortex (Alila Medical Media, 2014). The text also explained this process as directly or indirectly targeting the brain’s rewards system by releasing

Nicotine, the primary psychoactive chemical in tobacco, is a very powerful drug. When nicotine enters the body, it travels through the bloodstream to bind with nicotinic acetylcholine receptors throughout the body and brain, causing physiological and psychological changes in functioning. Among the many effects nicotine has in the body, perhaps its most powerful is its ability to stimulate the release of dopamine in the mesolimbic dopaminergic pathway. It is thought that increased levels of dopamine in the brain are a major contributor to the euphoric, relaxing, and addictive properties of nicotine (Fagerstom et al. 1990). It has been proposed that this effect might be especially powerful and rewarding to individuals who suffer from mental illnesses caused by dysfunctions in the dopamine system, like schizophrenia, depression, and addictive disorders (Maté 2010). For these people, the burst of dopamine cause by ingesting nicotine could be having a more powerful effect, making it more addictive. This same mechanism could also explain why attempting to quit smoking, and thereby further upsetting an already unbalanced dopamine response, could be especially difficult for people with a mental

The placebo effect is a widely known phenomenon where patients are given some form of dummy medication in place of actual medication that produces the same effect as the real medication would have. They intend to help stimulate areas of the brain that may prompt the release of chemicals such as endorphins to aid in the relief of the symptom. Tests have shown that forms such as injections psychologically perform better than pills, because of the slight pain that injections bring ( Freeman, Shanna. "How the Placebo Effect Works." HowStuffWorks. HowStuffWorks.com, 13 Jan. 2009. Web.). Because of the pain, people tend to believe that the medication would work better. Placebos can be used to treat multiple different diseases, but has been

In one case, four adults aged 26-42 who had injected heroin were essentially immobile, unable to speak, had frozen facial expressions and were extremely rigidity in their arms. According to Langston (1984) these symptoms are highly similar to those experienced by an advanced Parkinson’s disease (PD) patient. PD results from substantia nigra cell death which is a region within the basal ganglia. These cells are the main source of dopamine but Langston (1984) was unable to visualise any structural brain damage on CT or MRI scans, however, PET scans confirmed hypo metabolism of dopamine. After a chemical analysis, the drug injected by these four patients actually had little resemblance to heroin but had a similar structure to meperidine (a synthetic opioid) which is now known as MPTP. Lab experiments indicate that MPTP is selectively destructive for dopamine cells. Since this drug discovery, various surgical procedures have been developed to reduce the inhibition in those with PD either by lesioning the output structure of the basal ganglia - which has many limitations or by deep-brain stimulation. Therefore, as a result of studying these four patients suffering from Parkinsonian symptoms, drug discoveries have been made which can thus be used to make advancements in our understanding and effective treatments of Parkinson’s disease which to this date,

During the second world war, medical supplies in the barracks were diminishing and injuries were piling up for American troops. One nurse, unable to face telling a soldier the morphine was gone, assured him the shot of saline water she gave him would alleviate his pain. Incredibly, it did. This nurse was working under a surgeon named Beecher, who eventually published a work called “The Powerful Placebo” (REFwired) that led US Congress to implement placebo control groups. This became the measure of whether a drug went to production worldwide.

The parts of the brain are what make us function in our day to day lives, if one thing were to go wrong it could throw our whole system off. Dopamine is a part of our neurons that control how we feel pleasure and basically what actually makes us feel good. This neuron controls our emotions as well as our movements. Dopamine causes the human being to stay close to the good feeling we have had and makes us move towards them. This part of our neuron can lead us to addictions of these pleasures. Drugs that are used today ignite these receptors of dopamine and continually leads us back to this feeling again and again, this is an addiction. Many people have addictions to drugs, one in particular cocaine. This drug sets off our neurons and reward us for something that actually hurts us and is not good for us. In the article we read of an experiment with mice and rats. The experiment entails targeting the dopamine receptors in these animals by incentives of the electrical sort. The rats feel rewarded for “VTA microinjections”, which they say “can also establish condition-placed preference”. The VTA is very high with the electric stimulations, when eating, drinking, and the use of cocaine. The need for cocaine is increased as the use becomes abuse. They study the effects of this on the system and see how they affect the cholinergic cells. The loss of these cells did not affect the use of cocaine, and was not a factor. They also did this study with heroine and yielded the same

The brain reacts to listening to music by releasing dopamine. The dopamine was released when someone was feeling their best(when listening to their favorite music). Researchers also found out that dopamine was released in response to things like food and money, but also things like love, which cannot be touched. The amount of dopamine raised up 9% when someone was listening to the music they liked, so music was found pleasurable because the brain thought it to be a ‘reward’. This is why we enjoy music so much, but we still don’t really understand why the brain does it. Researchers used a large amount of volunteers to see what music does to the brain, but only eight of them showed any physical sign of dopamine being released. These volunteers

A placebo is a way of testing a medical therapy where one group receives a real treatment and the other group receives a sham. It's like two patients having the same sickness but they only give one of them the real treatment. This is why I am against placebos.

Dopamine is involved in several activities like movement and motivation, and its deficiency or excess will contribute to lots of disorders. Dopamine receptors are categorized into two general groups: D1-like receptors, (D1, and D5) which increase cAMP level, and the activity of PKA, and thus, have a positive effect on the excitability of the cell membrane; and D2-like receptors, (D2, D3, and D4) which decrease cAMP level as well as the activity of PKA, and therefore, have a negative effect on the excitability of the membrane. Several studies have shown that dopamine receptors are widely distributed in the nervous system. So, not surprisingly, dopamine has different effects on the activity of ion channels, and consequently, on the excitability of the cell membrane as well as the shape and the conduction velocity of propagating spikes. For example, dopamine administration in the cultured frog melanotrophs mediates the initiation of action potentials via activating voltage-gated potassium channels as well as inhibiting calcium and sodium channels. (Valentijn, Louiset, Vaudry, & Cazin, 1991) Similarly, in the rat prefrontal cortex, dopamine increases the threshold for spike generation and has an inhibitory effect on the spike initiations. (Geijo-Barrientos & Pastore, 1995) While the majority of studies have emphasized on the inhibitory effects of D1-like receptors versus

What if there was a new drug that’s making you high, but is just a sugar pill? What if you can get drunk with non-alcoholic drinks? What if there was a pill that can cure all your physical and emotional problems? This is known as the placebo effect. The placebo effect is a phenomenon in which some people experience a type of benefit after the use of a placebo. A placebo is any substance with no known medical effects; such as sterile water, saline solution, or a sugar pill. (About.com Psychology) Although it doesn’t have known effects, people exposed to the placebo effect often gets the effect on what it’s supposed to do.