Persistent structural modifications in nucleus accumbens and prefrontal cortex neurons produced by previous experience with amphetamine.
Experience-dependent changes in behavior are thought to involve structural modifications in the nervous system, especially alterations in patterns of synaptic connectivity. Repeated experience with drugs of abuse can result in very long-lasting changes in behavior, including a persistent hypersensitivity (sensitization) to their psychomotor activating and rewarding effects. It was hypothesized, therefore, that repeated treatment with the psychomotor stimulant drug amphetamine, which produces robust sensitization, would produce structural adaptations in brain regions that mediate its psychomotor activating and rewarding effects. Consistent with this hypothesis, it was found that amphetamine treatment altered the morphology of neurons in the nucleus accumbens and prefrontal cortex. Exposure to amphetamine produced a long-lasting (>1 month) increase in the length of dendrites, in the density of dendritic spines, and in the number of branched spines on the major output cells of the nucleus accumbens, the medium spiny neurons, as indicated by analysis of Golgi-stained material. Amphetamine treatment produced similar effects on the apical (but not basilar) dendrites of layer III pyramidal neurons in the prefrontal cortex. The ability of amphetamine to alter patterns of synaptic connectivity in these structures may contribute to some of the long-term behavioral consequences of repeated amphetamine use, including amphetamine psychosis and addiction.
Robinson
T E
TE
Department of Psychology and Neuroscience Program, The University of Michigan, Ann Arbor, Michigan 48109, USA.
Kolb
B
B
D019969:Amphetamine-Related Disorders / Q000473:pathology*; D000818:Animals; D001925:Brain Damage, Chronic / Q000139:chemically induced / Q000473:pathology; D000697:Central Nervous System Stimulants / Q000494:pharmacology* / Q000633:toxicity; D003712:Dendrites / Q000187:drug effects / Q000648:ultrastructure; D003913:Dextroamphetamine / Q000494:pharmacology* / Q000633:toxicity; D008297:Male; D009474:Neurons / Q000187:drug effects* / Q000648:ultrastructure; D009714:Nucleus Accumbens / Q000187:drug effects* / Q000648:ultrastructure; D009778:Occipital Lobe / Q000187:drug effects / Q000648:ultrastructure; D010296:Parietal Lobe / Q000187:drug effects / Q000648:ultrastructure; D017397:Prefrontal Cortex / Q000187:drug effects* / Q000648:ultrastructure; D011605:Psychoses, Substance-Induced / Q000473:pathology; D011618:Psychotic Disorders; D017966:Pyramidal Cells / Q000187:drug effects / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley; D013569:Synapses / Q000187:drug effects* / Q000648:ultrastructure
D000697:Central Nervous System Stimulants; D003913:Dextroamphetamine