Neurotransmitters and Drugs First I'll define what exactly neurotransmitters are and give you a example of a few: First of all, the primary monoamine neurotransmitters are Dopamine, Norepinephine, and Serotonin. Neurotransmitters are the chemicals which account for the transmission of singnals from one neuron to the next across the synapses within the brain. They are also found at the axon endings of motor neurons, which is where they simulate the muscle fibers to conctract. Neurotransmitters: Acetylcholine- Acetylcholine is imporant to know, becuase it was the first neurotransmitter to ever be discovered. It was first isolated in 1921 by the German biologist, Otto Loewi. Otto Lewoi actually later won the Nobel Prize for his discovery and hard work. Acetylcholine has many different functions such as, it is responsible for much of the stimulation of muscules, including the muscles of the gastro-intestinal system. It is also found in the sensory neurons and in the autonomic nervous system, and has a part in the schedule of REM sleep. Norepinephrine- Norepinephrine was discovered in 1946 by the Swedish biologist Ulf Von Euler, who also won a Nobel Prize for his work. Norepinphrine is strongly associated with bringing our nervous system into a 'high-alert'. It is prevalent in the sympathetic nervous system and it also increases our blood pressure along with our heart rate. Our adernal glands release it into our blood stream, along with it's colse relative adernalin. Norepinephrine is very important when it comes to forming memories. Amphetamines work by causing the release of Norepinephrine. Dopamine- Dopamine was discovered by the Swedish biologist Arvid Carlsson. It is an inhibitory neurotransmitter which means that when it finds its way to it's receptor sites, it then blocks the tendenct of that neuron to fire. Dopamine is strongly associated with the reward mechanisms in the brain. Drugs such as cocaine, opium, heroin,alcohol, and nicotine increase the levels of dopamine. Another thing to note is that schizophrenia has been shown to invlove excessive amounts of dopamine in the frontal lobes and drugs that block dopamine are used to help schizophrenics. But also, too little dopamine in the motor areas of the brain are the cause of the illness Parkinson's disease. Serotonin- Serotonin is mainly involved in emotion and mood. Too little serotonin has been shown to lead to depression, behavioral problems, obessive-compulsive disorder, and even suicide. Too little also leads to an increased appetite for carbohydrates and trouble sleeping. SSRI's, which are also known as Selective Serotonin Reuptake Inhibitors are drugs that help people with depression by preventing the neurons from taking up excess serotonin, so that there is more floating around in the synapses. An interesting fact is that a little warm mile before bedtime also increases the levels of serotonin. Serotonin also plays a role in perception. All hallucinogens, such as LSD-25 work by attaching to serotonin receptor sites. Drugs work on Neurotransmitters in one or more of these ways: 1. Drugs can stop the chemical reactions that create neurotransmitters. 2. Drugs can empty neurotransmitters form the vesicles where they are normally stored and protected from breakdowns by enzymes. 3. Drugs can block neurotransmitters from entering or leaving vesicles. 4. Drugs can bind to receptors in place of neurotransmitters. 5. Drugs can prevent neurotransmitters from returning to their reuptake system 6. Drugs can interfere with second messengers, the chemical and electrical changes that take place in a receiving neuron.