Chronic stress induces strain-dependent sensitization to the behavioral effects of amphetamine in the mouse.
Following 10 days of daily restraint stress, sensitization developed to the stimulatory effect of amphetamine on locomotion in DBA/2 but not in C57BL/6 mice tested 24 h after the last stressful experience regardless of their being naive or habituated to the test cages. Saline-injected C57BL/6 mice, however, showed an increase of locomotion 24 h after chronic stress treatment. Chronically stressed mice of the two strains did not exhibit any alteration of dopamine and metabolites (3-4-dihydroxphenylacetic acid, homovanillic acid, and 3-methoxytyramine) levels in the frontal cortex, caudatus putamen, or nucleus accumbens septi, thus ruling out that stress-induced alteration of basal dopamine metabolism affected the behavioral response to amphetamine challenging in DBA/2 mice. Ten daily amphetamine injections (5 mg/kg) did not significantly modify the behavioral response to amphetamine in either strain of mice tested 24 h after the  end of the chronic treatment and did not increase locomotion in saline-injected C57BL/6 mice. Finally, chronically stressed hybrids B6D2F1 did not show sensitization to the locomotor effects of amphetamine, suggesting a dominant mode of inheritance in the response to chronic stress of the C57BL/6 strain.
Badiani
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Istituto di Psicobiologia e Psicofarmacologia (CNR), Roma, Italy.
Cabib
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S
Puglisi-Allegra
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S
D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D001923:Brain Chemistry / Q000187:drug effects; D005838:Genotype; D006185:Habituation, Psychophysiologic / Q000187:drug effects; D006719:Homovanillic Acid / Q000378:metabolism; D008297:Male; D008781:Methyltyrosines / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D009043:Motor Activity / Q000187:drug effects; D011954:Receptors, Dopamine / Q000187:drug effects; D012149:Restraint, Physical; D013045:Species Specificity; D013315:Stress, Psychological / Q000523:psychology*
D008781:Methyltyrosines; D011954:Receptors, Dopamine; D015102:3,4-Dihydroxyphenylacetic Acid; C032745:methyl-3-tyrosine; D000661:Amphetamine; D006719:Homovanillic Acid