title: Behavioral and neuronal recording of the nucleus accumbens in adolescent rats following acute and repetitive exposure to methylphenidate.
abstract: The nucleus accumbens (NAc) has been shown to play a key role in the brain's response to methylphenidate (MPD). The present study focuses on neuronal recording from this structure. The study postulates that repetitive exposure to the same dose of MPD will elicit in some rats behavioral sensitization and in others tolerance. Furthermore, the study postulates that NAc neuronal activity recorded from animals expressing behavioral tolerance after repetitive MPD exposure will be significantly different from NAc neuronal activity recorded from animals expressing behavioral sensitization after repetitive MPD exposure at doses of 0.6, 2.5, 5.0, and 10.0 mg/kg. To test this, behavioral and neuronal activity was recorded concomitantly from the NAc of freely behaving adolescent rats (postnatal day 40) before and after acute and repetitive administration of four different MPD doses. Comparing the acute MPD effect to the repetitive MPD effect revealed that the acute response to MPD exhibited dose-response characteristics: an increase in behavioral activity correlated with increasing MPD doses. On the other hand, following repetitive MPD exposure, some animals exhibited attenuated behavior (tolerance), while others exhibited further increases in the recorded behavior (sensitization). Moreover, the neuronal activity following repetitive MPD exposure recorded in animals exhibiting behavioral sensitization was significantly different from neuronal activity recorded in animals exhibiting behavioral tolerance. This implies that when studying the effects of repetitive MPD administration on adolescent rats, it is advisable to simultaneously record both neuronal and behavioral activity and to evaluate all data based on the animals' behavioral response to the repetitive MPD exposure.
authors.affiliation: Department of Neurobiology and Anatomy, University of Texas Medical School, Houston, Texas; and.
authors.forename: Alexander
authors.initials: A
authors.lastname: Frolov
authors.affiliation: Departmento de Fisiologia, Devivion de Investigacion, Facultad de Medicina, Universidad Nacional Autonoma de Mexico, Mexico City, Mexico.
authors.forename: Cruz
authors.initials: C
authors.lastname: Reyes-Vasquez
authors.affiliation: Department of Neurobiology and Anatomy, University of Texas Medical School, Houston, Texas; and Nachum.Dafny@uth.tmc.edu.
authors.forename: Nachum
authors.initials: N
authors.lastname: Dafny
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004361:Drug Tolerance / Q000502:physiology; D004567:Electrodes, Implanted; D008297:Male; D008774:Methylphenidate / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects* / Q000502:physiology; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D009714:Nucleus Accumbens / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology; D011897:Random Allocation; D017207:Rats, Sprague-Dawley
chemical_list: D000697:Central Nervous System Stimulants; D008774:Methylphenidate
keywords: dose response; freely behaving animal; methylphenidate; neuronal recording