Blockade of neurotensin receptors during amphetamine discontinuation indicates individual variability.
Psychostimulant-induced locomotor sensitization has been related to changes within the mesolimbic dopamine system and has been suggested to be useful to study mechanisms underlying drug craving. Neurotensin is a neuropeptide co-localized with dopamine in the mesolimbic system. The response to novelty has been suggested to be a predictor of enhanced vulnerability to behavioral sensitization. The effects of repeated treatment with the neurotensin antagonist SR48692 after amphetamine discontinuation were investigated in mice previously classified as high responders (HRs) or low responders (LRs) to novelty. Mice were repeatedly treated with 2.0mg/kg amphetamine, every other day for 11 days. During the first 7 days after amphetamine discontinuation, the animals received a daily injection of saline or 0.3mg/kg SR48692. On the eighth day after amphetamine discontinuation all subjects received a 2.0mg/kg amphetamine challenge injection. Then, mice were tested for an open field behavior and after 90min, were sacrificed for Fos expression quantification in the nucleus accumbens. Both HRs and LRs expressed amphetamine-induced sensitized locomotor activation and increased expression of Fos protein. Treatment with SR48692 prevented behavioral sensitization and Fos protein expression enhancement in LRs but not in HRs mice. These data suggest that neurotensin plays a role in individual variability to amphetamine-induced sensitization.
Costa
Fabiana G
FG
Departamento de Patologia, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, Av. Orlando Marques Paiva 87, Cidade Universitária, 05508-900 São Paulo, SP, Brazil.
Frussa-Filho
Roberto
R
Canteras
Newton S
NS
Valera
Adriana G
AG
Felicio
Luciano F
LF
D000661:Amphetamine / Q000009:adverse effects*; D019969:Amphetamine-Related Disorders / Q000503:physiopathology*; D000818:Animals; D000697:Central Nervous System Stimulants / Q000009:adverse effects*; D005106:Exploratory Behavior / Q000187:drug effects; D007150:Immunohistochemistry; D008032:Limbic System / Q000187:drug effects / Q000503:physiopathology; D008297:Male; D051379:Mice; D009043:Motor Activity / Q000187:drug effects; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology; D011804:Quinolines / Q000494:pharmacology; D018028:Receptors, Neurotensin / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013375:Substance Withdrawal Syndrome / Q000503:physiopathology*
D000697:Central Nervous System Stimulants; D016760:Proto-Oncogene Proteins c-fos; D011720:Pyrazoles; D011804:Quinolines; D018028:Receptors, Neurotensin; C079087:SR 48692; D000661:Amphetamine