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Involvement of 5-HT1A and 5-HT2 receptors of the dorsal periaqueductal gray in the regulation of the defensive behaviors generated by the elevated T-maze.
Brain Res Bull. 2004 Aug 30; 64(2):181-8.BR

Abstract

Previous studies have shown that serotonin plays an inhibitory role in escape behavior induced by the aversive stimulation of the dorsal periaqueductal gray matter (DPAG). This defensive behavior has been related to panic disorder. Serotonin injected into the DPAG also inhibits escape behavior generated by the elevated T-maze. Besides escape, this test also measures inhibitory avoidance, a behavior associated with generalized anxiety disorder. We presently evaluate the role of the 5-HT1A, 5-HT2A and 5-HT2C receptors of the DPAG in the modulation of inhibitory avoidance and escape responses of rats submitted to the elevated T-maze. The results showed that intra-DPAG administration of the 5-HT1A receptor antagonist WAY-100635 and of the preferential antagonists of 5-HT2A and 5-HT2C receptors, ketanserin and SDZ SER 082, respectively, did not change rat behavior in the elevated T-maze. Intra-DPAG injection of serotonin inhibited escape, an effect blocked by local injection of these three antagonists. Ketanserin and SDZ SER 082, but not WAY-100635 antagonized the effect of serotonin in facilitating inhibitory avoidance. Intra-DPAG injection of the 5-HT1A agonist 8-OH-DPAT and of DOI, a preferential 5-HT2A agonist, also inhibited escape, an effect antagonized by WAY-100635 and ketanserin, respectively. The results indicate that serotonin in the DPAG exerts a phasic regulatory control on inhibitory avoidance and escape behaviors in the elevated T-maze. 5-HT1A and 5-HT2C receptors in the DPAG play an opposite role in inhibitory avoidance: whereas activation of the former receptors inhibits the acquisition of this response, activation of the latter facilitates it. Both 5-HT1A, 5-HT2A and 5-HT2C receptors seem to mediate the inhibitory action of serotonin on escape.

Authors+Show Affiliations

(a)Department of Pharmacology, School of Medicine, University of São Paulo, 14049-900 Ribeirão Preto, SP, Brazil.No affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

15342106

Citation

de Paula Soares, Vanessa, and Hélio Zangrossi. "Involvement of 5-HT1A and 5-HT2 Receptors of the Dorsal Periaqueductal Gray in the Regulation of the Defensive Behaviors Generated By the Elevated T-maze." Brain Research Bulletin, vol. 64, no. 2, 2004, pp. 181-8.
de Paula Soares V, Zangrossi H. Involvement of 5-HT1A and 5-HT2 receptors of the dorsal periaqueductal gray in the regulation of the defensive behaviors generated by the elevated T-maze. Brain Res Bull. 2004;64(2):181-8.
de Paula Soares, V., & Zangrossi, H. (2004). Involvement of 5-HT1A and 5-HT2 receptors of the dorsal periaqueductal gray in the regulation of the defensive behaviors generated by the elevated T-maze. Brain Research Bulletin, 64(2), 181-8.
de Paula Soares V, Zangrossi H. Involvement of 5-HT1A and 5-HT2 Receptors of the Dorsal Periaqueductal Gray in the Regulation of the Defensive Behaviors Generated By the Elevated T-maze. Brain Res Bull. 2004 Aug 30;64(2):181-8. PubMed PMID: 15342106.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Involvement of 5-HT1A and 5-HT2 receptors of the dorsal periaqueductal gray in the regulation of the defensive behaviors generated by the elevated T-maze. AU - de Paula Soares,Vanessa, AU - Zangrossi,Hélio,Jr PY - 2004/02/03/received PY - 2004/06/14/revised PY - 2004/06/16/accepted PY - 2004/9/3/pubmed PY - 2004/12/16/medline PY - 2004/9/3/entrez SP - 181 EP - 8 JF - Brain research bulletin JO - Brain Res Bull VL - 64 IS - 2 N2 - Previous studies have shown that serotonin plays an inhibitory role in escape behavior induced by the aversive stimulation of the dorsal periaqueductal gray matter (DPAG). This defensive behavior has been related to panic disorder. Serotonin injected into the DPAG also inhibits escape behavior generated by the elevated T-maze. Besides escape, this test also measures inhibitory avoidance, a behavior associated with generalized anxiety disorder. We presently evaluate the role of the 5-HT1A, 5-HT2A and 5-HT2C receptors of the DPAG in the modulation of inhibitory avoidance and escape responses of rats submitted to the elevated T-maze. The results showed that intra-DPAG administration of the 5-HT1A receptor antagonist WAY-100635 and of the preferential antagonists of 5-HT2A and 5-HT2C receptors, ketanserin and SDZ SER 082, respectively, did not change rat behavior in the elevated T-maze. Intra-DPAG injection of serotonin inhibited escape, an effect blocked by local injection of these three antagonists. Ketanserin and SDZ SER 082, but not WAY-100635 antagonized the effect of serotonin in facilitating inhibitory avoidance. Intra-DPAG injection of the 5-HT1A agonist 8-OH-DPAT and of DOI, a preferential 5-HT2A agonist, also inhibited escape, an effect antagonized by WAY-100635 and ketanserin, respectively. The results indicate that serotonin in the DPAG exerts a phasic regulatory control on inhibitory avoidance and escape behaviors in the elevated T-maze. 5-HT1A and 5-HT2C receptors in the DPAG play an opposite role in inhibitory avoidance: whereas activation of the former receptors inhibits the acquisition of this response, activation of the latter facilitates it. Both 5-HT1A, 5-HT2A and 5-HT2C receptors seem to mediate the inhibitory action of serotonin on escape. SN - 0361-9230 UR - https://www.unboundmedicine.com/medline/citation/15342106/Involvement_of_5_HT1A_and_5_HT2_receptors_of_the_dorsal_periaqueductal_gray_in_the_regulation_of_the_defensive_behaviors_generated_by_the_elevated_T_maze_ DB - PRIME DP - Unbound Medicine ER -