A single intrategmental amphetamine exposure induces transient behavioral sensitization in the rats.
Repeated treatment with psychostimulant drugs induces enduring behavioral sensitization and neuroadaptations which may play an important role in the development of drug addiction. However, different number and time course in drug administration and various lengths of drug withdrawal were employed in the literature, and there were inconsistent findings in the profile of extracellular dopamine level related to behavioral sensitization. Therefore, the effects of the number of drug exposure and the length of drug withdrawal period on the sensitized behavioral response were investigated in this study. Various lengths of amphetamine (AMPH) withdrawal (1, 3 and 5 days) after a single local administration of AMPH to bilateral ventral tegmental area (VTA) were used to observe the locomotor activity response. Besides, different amounts of administration of intra-VTA AMPH were given (1, 2 and 3 times of injection) to monitor the profile of travel distance and stereotypic movements of rats after 7 days of drug withdrawal. An early and short-lived behavioral sensitization to the single intra-VTA AMPH administration was induced. In the repeated treatment group, more drug exposures were associated with escalating and robust levels of travel distance after 7 days of drug withdrawal. The authors speculated that the transient and, a later augmented locomotor activity response might represent respective phases in the development of behavioral sensitization, which in turn contributed to the formation of more lasting behavioral and neuroplastic changes associated with drug addiction.
Wu
Hsiao-Hua
HH
Institute of Pharmacology, School of Medicine, National Yang-Ming University, Taipei, Taiwan, ROC.
Lee
Chang-Ru
CR
Lin
Shi-Kwang
SK
Yeh
Pen-Ho
PH
Pan
Wynn H T
WH
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D003913:Dextroamphetamine / Q000008:administration & dosage / Q000494:pharmacology*; D004334:Drug Administration Schedule; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013239:Stereotyped Behavior / Q000187:drug effects*; D013375:Substance Withdrawal Syndrome / Q000503:physiopathology; D017557:Ventral Tegmental Area / Q000187:drug effects* / Q000502:physiology
D003913:Dextroamphetamine