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Enhanced dorsolateral periaqueductal gray activity counteracts the anxiolytic response to midazolam on the elevated plus-maze Trial 2 in rats.
Behav Brain Res. 2005 Jul 01; 162(1):99-107.BB

Abstract

Rodents previously (Trial 1) experienced in the elevated plus-maze (EPM) apparatus no longer respond to anxiolytic-like drugs during retesting (Trial 2). In view of the fact that the dorsolateral periaqueductal gray (dlPAG) modulates fear/anxiety-like behavior, the present study sought to determine its role in this phenomenon. In order to address this issue, EPM-experienced rats that had received lidocaine, a drug which produces a reversible functional deactivation, intra-dlPAG pre-Trial 1, post-Trial 1 or pre-Trial 2, were systemically injected with the benzodiazepine midazolam and submitted to the EPM apparatus. According to the results, 0.25 mg/kg midazolam increased open arms exploration and reduced risk assessment behavior, suggesting an anxiolytic-like effect in EPM-naive rats, regardless of the intra-dlPAG treatment. EPM-experienced rats administered with midazolam only displayed a similar pattern of behavior when lidocaine was administered intra-dlPAG pre-Trial 2, but not pre- or post-Trial 1. These effects were observed in the absence of changes in enclosed arms entries, an EPM general exploratory activity index. The present results suggest that an increased activity of the dlPAG during Trial 2 would explain the lack of anxiolytic-like effect of drugs elicited by prior EPM test experience.

Authors+Show Affiliations

Departamento de Farmacologia, FMRP-USP, Av. Bandeirantes, 3900, Ribeirão Preto, SP 14049-900, Brazil.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

15922070

Citation

Bertoglio, Leandro José, et al. "Enhanced Dorsolateral Periaqueductal Gray Activity Counteracts the Anxiolytic Response to Midazolam On the Elevated Plus-maze Trial 2 in Rats." Behavioural Brain Research, vol. 162, no. 1, 2005, pp. 99-107.
Bertoglio LJ, Anzini C, Lino-de-Oliveira C, et al. Enhanced dorsolateral periaqueductal gray activity counteracts the anxiolytic response to midazolam on the elevated plus-maze Trial 2 in rats. Behav Brain Res. 2005;162(1):99-107.
Bertoglio, L. J., Anzini, C., Lino-de-Oliveira, C., & Carobrez, A. P. (2005). Enhanced dorsolateral periaqueductal gray activity counteracts the anxiolytic response to midazolam on the elevated plus-maze Trial 2 in rats. Behavioural Brain Research, 162(1), 99-107.
Bertoglio LJ, et al. Enhanced Dorsolateral Periaqueductal Gray Activity Counteracts the Anxiolytic Response to Midazolam On the Elevated Plus-maze Trial 2 in Rats. Behav Brain Res. 2005 Jul 1;162(1):99-107. PubMed PMID: 15922070.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Enhanced dorsolateral periaqueductal gray activity counteracts the anxiolytic response to midazolam on the elevated plus-maze Trial 2 in rats. AU - Bertoglio,Leandro José, AU - Anzini,Cláudia, AU - Lino-de-Oliveira,Cilene, AU - Carobrez,Antônio Pádua, Y1 - 2005/04/18/ PY - 2005/02/25/received PY - 2005/03/04/revised PY - 2005/03/07/accepted PY - 2005/6/1/pubmed PY - 2005/8/13/medline PY - 2005/6/1/entrez SP - 99 EP - 107 JF - Behavioural brain research JO - Behav Brain Res VL - 162 IS - 1 N2 - Rodents previously (Trial 1) experienced in the elevated plus-maze (EPM) apparatus no longer respond to anxiolytic-like drugs during retesting (Trial 2). In view of the fact that the dorsolateral periaqueductal gray (dlPAG) modulates fear/anxiety-like behavior, the present study sought to determine its role in this phenomenon. In order to address this issue, EPM-experienced rats that had received lidocaine, a drug which produces a reversible functional deactivation, intra-dlPAG pre-Trial 1, post-Trial 1 or pre-Trial 2, were systemically injected with the benzodiazepine midazolam and submitted to the EPM apparatus. According to the results, 0.25 mg/kg midazolam increased open arms exploration and reduced risk assessment behavior, suggesting an anxiolytic-like effect in EPM-naive rats, regardless of the intra-dlPAG treatment. EPM-experienced rats administered with midazolam only displayed a similar pattern of behavior when lidocaine was administered intra-dlPAG pre-Trial 2, but not pre- or post-Trial 1. These effects were observed in the absence of changes in enclosed arms entries, an EPM general exploratory activity index. The present results suggest that an increased activity of the dlPAG during Trial 2 would explain the lack of anxiolytic-like effect of drugs elicited by prior EPM test experience. SN - 0166-4328 UR - https://www.unboundmedicine.com/medline/citation/15922070/Enhanced_dorsolateral_periaqueductal_gray_activity_counteracts_the_anxiolytic_response_to_midazolam_on_the_elevated_plus_maze_Trial_2_in_rats_ DB - PRIME DP - Unbound Medicine ER -