title: Interplay between glutamate and serotonin within the dorsal periaqueductal gray modulates anxiety-related behavior of rats exposed to the elevated plus-maze.
abstract: Several neurotransmitters, including glutamate and serotonin, modulate defensive behaviors related to anxiety in the rat dorsal periaqueductal gray (PAG). Although both glutamate N-methyl-d-aspartic acid (NMDA) and serotonin type 1-A (5-HT(1A)) receptors have been shown to interfere with these subtle responses, such as inhibitory avoidance, a possible interaction between them remains to be examined. To address this issue, the present study investigated whether the activation or the blockage of 5-HT(1A) receptors located in the dorsal PAG would interact with NMDA function in animals exposed to the elevated plus-maze task. The effect of the NMDA (25 pmol) was evaluated in rats pretreated with the 5-HT(1A) receptor antagonist WAY-100135 (2.0 or 5.0 nmol). In addition, the effect of the NMDA (100 pmol) was evaluated in rats pretreated with the 5-HT(1A) receptor agonist 8-OH-DPAT (2.0 or 8.0 nmol). Intra-dorsal PAG injection of NMDA (25 pmol) increased inhibitory avoidance behavior. This anxiogenic-like effect of the NMDA was counteracted by the pretreatment with WAY-100135 (5.0 nmol). Although 100 pmol of NMDA failed to increase inhibitory avoidance in the vehicle-pretreated group, in rats pretreated with 8-OH-DPAT this NMDA dose produced an anxiogenic-like effect. These results suggest that 5-HT(1A) and NMDA receptors interact in the dorsal PAG to modulate the anxiety-related behavior.
authors.affiliation: Departamento de Farmacologia, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, 88040-900, Brazil.
authors.forename: Cladis L K
authors.initials: CL
authors.lastname: Moraes
authors.forename: Leandro J
authors.initials: LJ
authors.lastname: Bertoglio
authors.forename: Antonio P
authors.initials: AP
authors.lastname: Carobrez
mesh_terms: D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D001007:Anxiety / Q000378:metabolism / Q000473:pathology*; D001522:Behavior, Animal / Q000187:drug effects; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism*; D008297:Male; D018782:Maze Learning / Q000187:drug effects / Q000502:physiology*; D016202:N-Methylaspartate / Q000494:pharmacology; D010487:Periaqueductal Gray / Q000187:drug effects / Q000378:metabolism*; D010879:Piperazines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000378:metabolism*; D012702:Serotonin Antagonists / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology
chemical_list: D018690:Excitatory Amino Acid Agonists; D010879:Piperazines; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; C081293:WAY 100135; D012701:Serotonin; D018698:Glutamic Acid; D016202:N-Methylaspartate; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin