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Serotonergic regulation of inhibitory avoidance and one-way escape in the rat elevated T-maze.
Neurosci Biobehav Rev. 2001 Dec; 25(7-8):637-45.NB

Abstract

It has been proposed that distinct 5-HT pathways modulate different types of anxiety. Activation of the ascending dorsal raphe (DR)-5-HT pathway, innervating the amygdala and frontal cortex, would facilitate learned defensive behaviors. On the other hand, activation of the DR-periventricular 5-HT pathway, which innervates the dorsal periaqueductal gray matter (DPAG), would inhibit innate flight or fight reactions. Dysfunction of these pathways has been suggested to relate to generalized anxiety disorder (GAD) and panic disorder (PD) in humans, respectively. The elevated T-maze has been developed to separate conditioned (inhibitory avoidance) from unconditioned (escape) defensive responses in the same rat. Pharmacological validation of this model has shown that the GAD-effective serotonergic anxiolytic buspirone or the putative anxiolytic ritanserin selectively impaired inhibitory avoidance while leaving one-way escape unchanged. Chronic injection of the 5-HT/noradrenaline reuptake inhibitor imipramine impaired inhibitory avoidance and prolonged escape, an effect that may be related to the therapeutic action of this drug on both GAD and PD. Like imipramine, intra-DPAG injection of the 5-HT(1A) agonist 8-OH-DPAT impaired both inhibitory avoidance and one-way escape. Intra-DPAG administration of the 5-HT(2A/2C) agonist DOI prolonged escape, without affecting inhibitory avoidance. The reversible inactivation of the DRN by muscimol impaired inhibitory avoidance, while facilitating escape from the open arm. Taken together, these results suggest that 5-HT exerts differential control on inhibitory avoidance and escape response in the elevated T-maze, mobilizing different types of 5-HT receptors in key structures implicated in fear/anxiety.

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Authors+Show Affiliations

Zangrossi H
Department of Pharmacology, School of Medicine, University of São Paulo, 14049-901, SP, Ribeirão Preto, Brazil. zangross@fmrp.usp.br
Viana MB
No affiliation info available
Zanoveli J
No affiliation info available
Bueno C
No affiliation info available
Nogueira RL
No affiliation info available
Graeff FG
No affiliation info available

MeSH

AnimalsAnxietyAvoidance LearningEscape ReactionRatsSerotoninSerotonin Agents

Pub Type(s)

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

Language

eng

PubMed ID

11801289

Citation

Zangrossi, H, et al. "Serotonergic Regulation of Inhibitory Avoidance and One-way Escape in the Rat Elevated T-maze." Neuroscience and Biobehavioral Reviews, vol. 25, no. 7-8, 2001, pp. 637-45.
Zangrossi H, Viana MB, Zanoveli J, et al. Serotonergic regulation of inhibitory avoidance and one-way escape in the rat elevated T-maze. Neurosci Biobehav Rev. 2001;25(7-8):637-45.
Zangrossi, H., Viana, M. B., Zanoveli, J., Bueno, C., Nogueira, R. L., & Graeff, F. G. (2001). Serotonergic regulation of inhibitory avoidance and one-way escape in the rat elevated T-maze. Neuroscience and Biobehavioral Reviews, 25(7-8), 637-45.
Zangrossi H, et al. Serotonergic Regulation of Inhibitory Avoidance and One-way Escape in the Rat Elevated T-maze. Neurosci Biobehav Rev. 2001;25(7-8):637-45. PubMed PMID: 11801289.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Serotonergic regulation of inhibitory avoidance and one-way escape in the rat elevated T-maze. AU - Zangrossi,H,Jr AU - Viana,M B, AU - Zanoveli,J, AU - Bueno,C, AU - Nogueira,R L, AU - Graeff,F G, PY - 2002/1/22/pubmed PY - 2002/5/1/medline PY - 2002/1/22/entrez SP - 637 EP - 45 JF - Neuroscience and biobehavioral reviews JO - Neurosci Biobehav Rev VL - 25 IS - 7-8 N2 - It has been proposed that distinct 5-HT pathways modulate different types of anxiety. Activation of the ascending dorsal raphe (DR)-5-HT pathway, innervating the amygdala and frontal cortex, would facilitate learned defensive behaviors. On the other hand, activation of the DR-periventricular 5-HT pathway, which innervates the dorsal periaqueductal gray matter (DPAG), would inhibit innate flight or fight reactions. Dysfunction of these pathways has been suggested to relate to generalized anxiety disorder (GAD) and panic disorder (PD) in humans, respectively. The elevated T-maze has been developed to separate conditioned (inhibitory avoidance) from unconditioned (escape) defensive responses in the same rat. Pharmacological validation of this model has shown that the GAD-effective serotonergic anxiolytic buspirone or the putative anxiolytic ritanserin selectively impaired inhibitory avoidance while leaving one-way escape unchanged. Chronic injection of the 5-HT/noradrenaline reuptake inhibitor imipramine impaired inhibitory avoidance and prolonged escape, an effect that may be related to the therapeutic action of this drug on both GAD and PD. Like imipramine, intra-DPAG injection of the 5-HT(1A) agonist 8-OH-DPAT impaired both inhibitory avoidance and one-way escape. Intra-DPAG administration of the 5-HT(2A/2C) agonist DOI prolonged escape, without affecting inhibitory avoidance. The reversible inactivation of the DRN by muscimol impaired inhibitory avoidance, while facilitating escape from the open arm. Taken together, these results suggest that 5-HT exerts differential control on inhibitory avoidance and escape response in the elevated T-maze, mobilizing different types of 5-HT receptors in key structures implicated in fear/anxiety. SN - 0149-7634 UR - https://www.unboundmedicine.com/medline/citation/11801289/Serotonergic_regulation_of_inhibitory_avoidance_and_one_way_escape_in_the_rat_elevated_T_maze_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0149763401000471 DB - PRIME DP - Unbound Medicine ER -