Answer: ACTIVITY OF ITS TARGET NEURONS.
stimulating receiving-neuron receptors more copiously and producing much greater dopamine impact on the receiving neurons than occurs naturally.
Explanation: Dopamine is a neurotransmitter that produces feelings of pleasure when released by the brain reward system,it has multiple functions depending on where in the brain it acts,it is the primary neurotransmitter of the reward system.
When an individual uses a drug,the drug reflects the functional roles of the particular neurotransmitter (s)it disrupts or stimulates.
Each individual neuron manufactures one or more neurotransmitters: dopamine, glutamate, serotonin, acetylcholine etc.Each neurotransmitter is associated with particular effects depending on its distribution among the brain’s various functional areas.Dopamine, for example, is highly concentrated in regions that regulate motivation and feelings of reward, and is a strong motivator for drug use. A neurotransmitter’s impact also depends on whether it stimulates or dampens activity of its target neurons.
Certain drugs affect one neurotransmitter or class of neurotransmitters primarily. example, prescription opioids and heroin produce effects that are similar to but more pronounced than those produced by the neurotransmitters endorphin and enkephalin: they produce increased analgesia, decreased alertness, and slowed respiration.
Other drugs disrupt more than one type of neurotransmitter. Cocaine, for example, attaches to structures that regulate dopamine, leading to increases in dopamine activity and producing euphoria; it also produces changes in norepinephrine and glutamate systems that cause stimulant effects.Nicotine binds to the presynaptic receptors exciting the neurons to fire more action potentials causing an increase in dopamine release.