ABSTRACT
This chapter focuses on the neurobiology and pharmacology of drug action and addiction. The use of drugs to affect conscious states in humans goes back almost to the origins of humanity. As drug abuse expanded, repressive laws flourished without regard its social origins. Nicotine and cannabis have been primarily used as recreational drugs in Western societies for centuries. There are increasing indications that nicotine and its derivatives act as cognitive enhancers and that cannabis functions as a painkiller in severe diseases. Receptors for other drugs and neurotransmitters look rather similar, even those that display an "inhibitory" action responding in a direction opposite to that of nicotine. In some instances, the distance between the release site and the target of the neurotransmitter becomes relatively large—on a scale of millimeters or even centimeters. In midbrain sections, clusters of cell bodies discretely stain for a particular group of neurotransmitters that play a crucial role in drug addiction: dopamine, norepinephrine, acetylcholine and serotonin.
