title: A single cocaine exposure disrupts actin dynamics in the cortico-accumbal pathway of adolescent rats: modulation by a second cocaine injection.
abstract: Among the changes caused by repeated exposure to drugs of abuse, structural rearrangements play a critical role, setting the stage for maladaptive responses to environmental challenges and sustaining drug-taking and drug-seeking behaviors. Given that adolescents are more vulnerable to drug abuse than adults and based on our recent data showing that a single exposure to cocaine during adolescence is sufficient to change the adolescent brain, we decided to investigate whether acute cocaine exposure may alter actin remodeling in reward-related brain regions.
  
  
  
  Accordingly, we decided to evaluate if F-actin/G-actin ratio was altered by a single injection of cocaine (20 mg/kg) at postnatal day 35. We also evaluated whether the first administration of cocaine influences such a ratio in response to a second injection (10 mg/kg) provided 24 h or 7 days later.
  
  
  
  Within the medial prefrontal cortex, a single cocaine injection increases the F-actin/G-actin ratio. This effect lasts 1 week, and it is not affected by the second injection of cocaine, indicating a persistent effect of the first exposure. In the nucleus accumbens, cocaine reduces the F-actin/G-actin ratio 24 h later. Seven days later, instead, such a ratio is markedly increased: notably, the additional exposure to the psychostimulant normalizes the F-actin/G-actin ratio.
  
  
  
  These results suggest that a single cocaine injection during adolescence causes possible changes in actin dynamics and influences the response to a second challenge of the psychostimulant, indicating that early cocaine priming might affect mechanisms regulating synaptic structural plasticity in specific brain regions.
authors.affiliation: Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Via Balzaretti 9, 20133, Milan, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Caffino
authors.affiliation: Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Via Balzaretti 9, 20133, Milan, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Giannotti
authors.affiliation: Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Via Balzaretti 9, 20133, Milan, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Racagni
authors.affiliation: Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Via Balzaretti 9, 20133, Milan, Italy. Fabio.Fumagalli@unimi.it.
authors.forename: Fabio
authors.initials: F
authors.lastname: Fumagalli
mesh_terms: D000199:Actins / Q000187:drug effects*; D000704:Analysis of Variance; D000818:Animals; D000697:Central Nervous System Stimulants / Q000494:pharmacology; D003042:Cocaine / Q000008:administration & dosage / Q000494:pharmacology*; D019970:Cocaine-Related Disorders / Q000378:metabolism; D004195:Disease Models, Animal; D008297:Male; D009473:Neuronal Plasticity / Q000187:drug effects; D009714:Nucleus Accumbens / Q000187:drug effects; D017397:Prefrontal Cortex / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012201:Reward
chemical_list: D000199:Actins; D000697:Central Nervous System Stimulants; D003042:Cocaine
keywords: Actin dynamics; Adolescence; Cocaine