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Description : Check out this medical presentation on Neurology, which is titled "Dopamine", to know about Dopamine, neurotransmitter of the catecholamine and phenethylamine families.

Tags : Neurology, Dopamine, neurotransmitter, catecholamine, phenethylamine

Published on : Aug 23, 2021 | Views : 3680 | Downloads : 10

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Dopamine By: Kettle, Milner, Doucette
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Dopamine Neurotransmitter of the catecholamine and phenethylamine families Important in the brain and body Major role in the increase of reward-motivated behavior as well as motor control and the release of hormones
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Dopamine Related Disorders Parkinson’s Loss of dopamine secreting neurons in substantia nigra Other disorders: Schizophrenia ADHD RLS
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Dopamine in the Body Paracrine function– Synthesized locally and exerts its effects on cells that are located near the cells that release it Blood vessels Inhibits norepinephrine release and acts as a vasodilator at [normal] Kidneys Increases Na excretion and urine output Pancreas Reduces insulin production Digestive system Reduces gastrointestinal motility and protects intestinal mucosa Immune system Reduces activity of lymphocytes
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Dopamine as Medicine Dopamine Intravenous injection unable to reach brain For treatment of heart failure or shock L-Dopa Able to reach brain Used for Parkinson’s Dopaminergic stimulants ADHD treatment Dopamine hydrochloride Treats acute heart failure, kidney failure, myocardial infarction, and septic shock
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Physiological Effects in Brain Dopaminergic systems– responsible for motor control, motivation, arousal, cognitive control, reinforcement and reward, lactation, sexual gratification, and nausea Dopaminergic neurons– Few in # ( about 400,000 in brain) Confined to small areas but have many projections all over brain areas with powerful effects Dopaminergic areas Substantia nigra– Significant in motor function and learning new motor programs Ventral tegmental area(VTA) – Role in reward and motivation Posterior hypothalamus– Unclear function, possibly involved in RLS Arcuate and Periventricular nuclei of hypothalamus– Influence secretion of prolactin from pituitary gland Zona incerta– Controls gonadotropin releasing hormone involved in puberty Amacrine cells– increase sensitivity to color during bright light conditions
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Physiological Effects in Body Bloodstream Large amounts present with unclear function Primarily dopamine sulphate with is thought to be for detoxifying ingested dopamine Immune system Act upon lymphocyte receptors by reducing activation Kidneys Increases blood supply to the kidney Increases filtration by glomeruli Increases Na excretion in urine Pancreas Exocrine part– Not clear role but possibly to protect mucosa and reduce gastrointestinal motility Endocrine part– Reduce amount of insulin released
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https://en.Wikipedia.org/wiki/Parkinson’s_disease
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Cellular Effects
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Dopamine receptors There are five subtypes of dopamine receptors D1-D5 D1 and D5 increase the intracellular levels of cAMP by activating adenylate cyclase. D2, D3, D4 decrease the intracellular levels of cAMP by inhibiting adenylate cyclase. The effect the dopamine on a neuron depends on the receptor that is one the particular neroun.
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Tonic vs. Phasic dopamine transmission Tonic transmission occurs when dopamine is released independently of neuron activity. Phasic transmission deals with dopamine containing cells themselves. In this form of transmission large amounts of dopamine are released in spikes.
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Substania Nigra dopamine system and motor control The Substania Nigra is a group of basal that is thought to have a major role in motor control. It is described as the “response selection” ganglia; this is where a human and/or animal can have a few possible behaviors when completing a task, and the basal ganglia determine which behavior is expressed. Dopamine modulates the response selection in two different ways “effort threshold” and the “teaching” signal. Effort threshold deals with the amount of “effort” it takes to carry out a behavior. The teaching signal deals with adaptation to carrying out behaviors.
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Anatomy and physiology The anatomy of the basal ganglia is very complex. On the simple level there is one major dopamine projection in the brain. But when looked at on a smaller scale dopamine effects many different neurons based on the receptors that are on each of the neurons. There are two types of signal flow that deal with dopamine indirect and direct. Upregulation of direct and suppression of indirect.
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Vertebral tegmental area and reward Contains the largest group of dopamine neurons on the human brain. The VTA dopamine system is strongly associated with the reward system in the brain. The mouse pushing the lever for the cheese. A large amount of research backs up the idea of VTA and dopamine relating to reward system. But there is also arguments that go against this idea based on dopamine being expressed in an arousal situation like pain for example.
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Role in Cognition In simple terms Dopamine helps maintain proper memory function on the D1 receptor by not having to much or to little dopamine resulting in loss of memory.
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Pharmacology Basically dopamine's use in the medical field is to increase cardiac output by forcing the heart to pump harder and faster. Toxicity- it can be fatal if to much is taken in pharmaceutical forms. No one has ever died of being overly happy. Don’t do drugs like cocaine they can kill you and they will cause you to never have emotions if you take them for to long. Some drugs are used to suppress dopamine levels in treatment of diseases like schizophrenia
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Disease and disorders Parkinson’s- stiffness of the body, slow movements, and trembling of the limbs. It is caused by massive loss of dopamine cells. L-Dopa is used to treat this disease. Dopamine drugs help treat ADHD by increasing the levels of dopamine in the brain. Pain and nausea can be increased with decreased dopamine levels in the brain.
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Dopamine in PD
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Psychosis High levels of dopamine have been observed in patients with schizophrenia. Primary pathways affected by dopamine include an influx of levels in the mesolimbic pathway and a decrease in levels in the esocortical pathway.
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Dopamine in Micro While there is no known Archaea with detected dopamine levels there are some types of bacteria that have traces of dopamine and others the utilize orthologs. Dopamine seen in a protozoan called Tetrahymena. Possible correlation to dopamine in animals coming from bacteria through horizontal gene transfer throughout the evolutionary process.
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Dopamine in Animals Mediates reward learning in animals. Seen sometimes as a modifier to motor behavior. Modifies motor behavior in Nematodes reducing locomotion and increases food exploratory movements. Functions as a neurotransmitters in animals.
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Plants Bananas are seen to have high levels of Dopamine. Synthesized from the amino acid called Acid Tyrosine. This is similar to the process seen in animals. Dopamine consumed by food cannot be utilized in the brain because it cannot cross the blood brain barrier. Melanin close relative to Dopamine is seen in some systems.
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Biosynthesis Synthesized in a specific cell type seen in neurons and in the medulla of the Adrenal Glands. Pathway L-Phenylalanine-> L-Tyrosine-> L-DOPA-> Dopamine
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Degradation Dopamine is utilized when broken down in a process called degradation. Broken down into metabolites which are inactive by a few enzymes such as Monoamine Oxidase, ALDH, and COMT. The metabolites excluding only a couple are filtered through the bloodstream by the kidneys and disposed of through urine.