Answer: Dopamine
Step-by-step explanation:
Drugs of abuse such as methamphetamine and morphine increase the levels of dopamine in the central nervous system. Dopamine has a variety of functions but functions mainly in motivation and reward mechanism. People doing drugs of abuse create a pleasurable sensation in which there is a dopamine surge every time they use drugs. In the absence of drugs, the body "looks" for the pleasure thereby causing the person to be drug-dependent and addicted.
Drugs of abuse that are commonly abused by people are alcohol, cocaine, MA, heroin, marijuana, nicotine.
Most of these drugs increase the level of dopamine in the brain.
Dopamine is an amine neurotransmitter which generates feelings of pleasure and thus creates a sense of euphoria.
Further, this neurotransmitter is also responsible for reward behavior and thus generates a feeling of satisfaction in the abuser.
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