title: Neural substrates of amphetamine-induced behavioral sensitization: unconditioned (zero context) and conditioned (switch versus same context) components in c-fos overexpression.
abstract: The neural substrates of the unconditioned and conditioned components of amphetamine (AMPH)-induced behavioral sensitization remain unknown. The present study examines the brain activation of rats in response to an AMPH challenge with augmented locomotion in groups receiving chronic AMPH under chloral hydrate anesthetization (i.e., the 'zero context') or when tested in the 'same context' as a chronic treatment, or when tested in a 'different context'. The neural activations of the three groups reveal fairly consistent patterns: (a) The substantia nigra is activated in the same context condition and the pure AMPH effect (i.e., the zero context with the unconditioned component), but not in the switch context condition. (b) The ventral pallidum showed Fos expression in the switch context and the same context, but not in the zero context condition. (c) The other nuclei, including the medial prefrontal cortex, nucleus accumbens, caudate putamen, medial thalamus, hippocampus, amygdala, and ventral tegmental area, are activated in all contextual conditions and the pure AMPH effect (the zero context). The context exerts definable effects on the mesocorticolimbic dopamine system on AMPH-induced behavioral sensitization. (d) The ventral pallidum and the substantia nigra activations dissociate the unconditioned component from the conditioned component in behavioral sensitization. Further studies are needed to determine how these two nuclei mediate the effect in terms of primary and conditioned rewards.
authors.affiliation: Department of Clinical Psychology, Fu Jen Catholic University, New Taipei City, Taipei, Taiwan, ROC.
authors.forename: Ying-Chou
authors.initials: YC
authors.lastname: Wang
authors.forename: Yu-Chi
authors.initials: YC
authors.lastname: Yeh
authors.forename: Chia-Chuan
authors.initials: CC
authors.lastname: Wang
authors.forename: Sigmund
authors.initials: S
authors.lastname: Hsiao
authors.forename: Chin-Cheng
authors.initials: CC
authors.lastname: Lee
authors.forename: Andrew Chih Wei
authors.initials: AC
authors.lastname: Huang
mesh_terms: D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D059333:Central Nervous System Sensitization / Q000502:physiology; D003213:Conditioning, Psychological / Q000187:drug effects*; D059290:Dopaminergic Neurons / Q000187:drug effects / Q000502:physiology; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D016760:Proto-Oncogene Proteins c-fos; D000661:Amphetamine