Drug abuse is influenced by genetic and environmental factors, and acute drug‑induced locomotor responses serve as useful endophenotypes. This dissertation investigates the role of nicotinic acetylcholine receptors and a quantitative trait locus (QTL) on mouse chromosome 9 in locomotor stimulation by ethanol, cocaine, and methamphetamine. Pharmacological studies show that neuronal nicotinic receptors contribute to ethanol‑induced, but not psychostimulant‑induced, locomotor activation. Genetic analyses confirm a chromosome 9 QTL influencing responses to all three drugs. Molecular findings implicate Chrna3 as a candidate gene for ethanol sensitivity, highlighting distinct genetic mechanisms underlying drug responses.
