Although dopaminergic system represents the cornerstone in rewarding, other neurotransmitters can modulate
both the reward system and the psychomotor effects of addictive drugs. Many hypotheses have been proposed for a better
understanding of the reward system and its role in drug addiction. However, after many years of investigation, no single
theory can completely explain the neural basis of drug addiction. Recent reports introduce novel neurotransmitters into the
game e.g. dynorphins, orexins, histamine, gheralin and galanin. The interacting functions of these neurotransmitters have
shown that the reward system and its role in drug dependence, is far more complicated than was thought before.
Individual variations exist regarding response to drug exposure, vulnerability for addiction and the effects of different
cues on reward systems. Consequently, genetic variations of neurotransmission are thought to influence reward processing
that in turn may affect distinctive social behavior and susceptibility to addiction. However, the individual variations can
not be based mainly on genetics; environmental factors seem to play a role too. Here we discuss the current knowledge
about the orquestic regulation of different neurotransmitters on reward-seeking behavior and their potential effect on drug
Keywords: Dopamine, orexin, ghrelin, galanin, histamine, reward-seeking behavior, synaptic plasticity, signaling, individual
variations, drug addiction.
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