EXAMPLES OF NEUROTRANSMITTERS
There are many neurotransmitters in the nervous system. Some examples of common neurotransmitters are norepinephrine, dopamine, serotonin, -aminobutyric acid (GABA), glutamate, glycine, enkephalins, endorphins, substance P, nitric oxide (yes, a gas!), among many others. Some neurotransmitters are predomi-nant in certain areas of the nervous system. If production of these neurotransmitters is affected, the func-tioning of this region of the nervous system is affected.
Many drugs affect the nervous system at the synapse level. For example, symptoms of strychnine poisoning (spasm of skeletal muscles) is a result of the blocking of glycine receptors. Glycine is the neurotransmitter in neurons that inhibits motor neurons to muscle. If these neurons don’t function, the motor neurons fire continuously, causing muscles to spasm. Similarly, cocaine causes euphoria by blocking dopamine removal from certain areas of the brain. Increased levels of dopamine in these synapses result in change in feeling. Valium (diazepam), an antianxiety drug, enhances the effects of GABA (an inhibitory neurotransmitter). Viagra (sildenafil) produces its action by facilitating the action of nitric oxide, and Prozac (fluoxetine), the drug pre-scribed for attention deficit disorder (ADD) and de-pression, acts by slowing down the removal of sero-tonin in synapses.