Navegando por Palavras-chave "Generalized anxiety"
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- ItemSomente MetadadadosEffects of medial amygdala inactivation on a panic-related behavior(Elsevier B.V., 2006-09-25) Herdade, Karina Costa Paes; Strauss, Christiana Villela de Andrade; Zangrossi Junior, Helio; Viana, Milena de Barros [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP); Pontificia Univ CatolicaIn the last years, the role played by the medial nucleus of the amygdala (MeA) in the modulation of fear- and anxiety-related behaviors has been increasingly investigated. This nucleus plays an important role in the processing of predator odor-induced defensive reactions, i.e. freezing and risk-assessment behaviors. Immunohistochemical evidence also indicates that the MeA may be involved in the regulation of escape, a defensive behavior related to panic attacks. in this study, we further addressed this question by investigating the effects of the reversible inactivation of the nucleus on escape behavior generated in male Wistar rats by two different aversive stimuli, electrical stimulation of the dorsal periaqueductal gray matter (dPAG) and exposure to one of the open arms of the elevated T-maze. Results showed that intra-MeA administration of either the reversible sodium channel blocker lidocaine (34 nmol/0.2 mu l) or the GABA(A) receptor agonist muscimol (0.22 nmol/0.2 mu l) raised the threshold of aversive electrical stimulation, increasing the amount of current that applied to the dPAG evokes escape, an antiaversive effect. Local microinjection of muscimol (0.22 nmol/0.2 mu l) inhibited escape behavior in the elevated T-maze, also suggesting an antiaversive effect. in this latter test, muscimol did not affect inhibitory avoidance, a behavior associated with generalized anxiety disorder. Muscimol effect in the elevated T-maze was independent of changes in general exploratory activity as measured in an open-field. Taken together, our data corroborate previous evidences suggesting that the MeA is involved in the modulation of escape. Dysfunction of this regulatory mechanism may be of relevance in the genesis/maintenance of panic disorder. (c) 2006 Elsevier B.V. All rights reserved.
- ItemSomente MetadadadosFacilitation of 5-HT2A/2C-mediated neurotransmission in the ventromedial hypothalamic nucleus decreases anxiety in the elevated T-maze(Elsevier B.V., 2011-01-20) Silva, E. S. da [UNIFESP]; Poltronieri, Selma Conceição; Nascimento, Juliana Olivetti Guzman [UNIFESP]; Zangrossi Junior, Helio; Viana, Milena de Barros [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Ctr Univ Votuporanga UNIFEV; Universidade de São Paulo (USP)Previous evidence has shown that facilitation of GABA/benzodiazepine-mediated neurotransmission in the ventromedial hypothalamus (VMH) inhibits both escape and inhibitory avoidance responses generated in the elevated T-maze test of anxiety (ETM). These defensive behaviors have been associated with panic and generalized anxiety, respectively. Aside from GABA/benzodiazepine receptors, the VMH also contains a significant number of serotonin (5-HT) receptors, including 1A, 2A and 2C subtypes. the purpose of the present study was to investigate the effect of the activation of 5-HT1A and 5-HT2A/2C receptors in the VMH on defensive behavioral responses in rats submitted to the ETM. for that, male Wistar rats were treated intra-VMH with the 5-HT1A agonist 8-OH-DPAT, with the 5-HT2A/2C agonist DOI, with the 5-HT2C selective agonist MK-212, or with the 5-HT2A/2C antagonist ketanserin and 10 min after were submitted to the ETM. Results showed that both DOI and MK-212 significantly decreased avoidance measurements, an anxiolytic-like effect, without altering escape. 8-OH-DPAT and ketanserin were without effect, although the last drug attenuated the effects of DOI. None of the drugs altered locomotor activity in an open field. These results suggest that 5-HT2A/2C receptors of the VMH are involved in the regulation of inhibitory avoidance and might be of relevance to the physiopathology of generalized anxiety. (C) 2010 Elsevier B.V. All rights reserved.
- ItemSomente MetadadadosGABA/benzodiazepine receptors in the ventromedial hypothalamic nucleus regulate both anxiety and panic-related defensive responses in the elevated T-maze(Elsevier B.V., 2007-09-14) Bueno, Cintia Heloina; Zangrossi Junior, Helio; Viana, Milena de Barros [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP)It has been shown that facilitation of GABA-mediated neurotransmission in the medial nucleus of the amygdala and the dorsal periaqueductal gray (dPAG) inhibits the escape, but not the inhibitory avoidance response generated in the elevated T-maze test of anxiety (ETM). These defensive behaviors have been associated with panic and generalized anxiety, respectively. Previous evidence indicates that the dorsomedial part of the ventromedial hypothalamus (VMHdm), which is interconnected with these two brain areas, is also part of the neurobiological substrate controlling escape behavior. in the present study, we investigated in male Wistar rats whether the intra-VMHdm injection of GABA-modulating drugs differently affect the two defensive tasks measured in the ETNI. the results showed that the microinjection of the benzodiazepine (BZD) receptor agonist midazolam (10, 20 and 40 nmol), the GABA(A) receptor agonist muscimol (2, 4 and 8 nmol) or the GABA(B) receptor agonist baclofen (2, 4 and 8 nmol) impaired inhibitory avoidance and escape performance, an anxiolytic and panicolytic-like effect, respectively. On the other hand, local administration of the BZD inverse agonist FG 7142 (20, 40 and 80 pmol) facilitated both behaviors, suggesting anxiogenic and panicogenic-like effects. These results were not due to motor alterations, since the drugs did not affect exploratory behavior in an open field. the data suggest that GABA(A)/BZD and GABAB receptors within the VMHdm are involved not only in the control of panic-related, but also of anxiety-related behaviors. (c) 2007 Elsevier Inc. All fights reserved.