Biology - Neurotransmitters?

Question

What do neurotransmitter do? How do neurotransmitters relate to addiction? What happens when someone is addicted?

Answer 1

Neurotransmitters as a class of molecules are related by where they work and not by mechanism or structure.  They range from peptides (short amino acid sequences) to hormones to gases like NO (nitric oxide).  Certain neurotransmitters, like dopamine, are involved in feelings of happiness reward, and certain drugs either trigger a release of dopamine or inhibit its re-uptake, basically keeping it around longer.