Dopamine D-2 receptors regulate unconditioned fear in deep layers of the superior colliculus and dorsal periaqueductal gray

Autor(es)

Muthuraju, Sangu ^{[1, 2]} ; Talbot, Teddy ^{[2, 3]} ; Brandao, Marcus Lira ^{[1, 2]}

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, FFCLRP, Lab Neuropsychopharmacol, BR-14049901 Ribeirao Preto, SP - Brazil

^[2] Inst Neurociencias & Comportamento, BR-14050000 Sao Paulo - Brazil

^[3] Univ Sao Paulo, Ribeirao Preto Sch Med, Dept Neurosci & Behav, BR-14049901 Ribeirao Preto, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Behavioural Brain Research; v. 297, p. 116-123, JAN 15 2016.
• Citações Web of Science: 7

Resumo

Rationale: Electrical and chemical stimulation of the dorsal periaqueductal gray (dPAG), deep layers of the superior colliculus (dISC), and inferior colliculus (IC) causes freezing and escape behavior in rodents. Systemic injections of the selective dopamine D-2 receptor antagonist sulpiride increased the number of switch-off responses (SORs) to light and auditory evoked potentials in response to loud sounds. Dopamine D-2 receptor inhibition in the IC was shown to enhance unconditioned fear. Nevertheless, the role of dopamine receptors in the dISC and dPAG in the mediation of unconditioned fear has not yet been demonstrated. Objectives: The purpose of the present study was to characterize the effects of sulpiride injections (4 and 8 mu g/0.2 mu l) in the dISC and dPAG in rats that were subjected to unconditioned fear paradigms. Methods: Switch-off responses to light and exploratory behavior in the elevated plus maze were used to evaluate unconditioned fear in rats. Results: Intra-d1SC microinjections of sulpiride increased the number of SORs to light. Intra-d1SC and intra-dPAG injections of sulpiride reduced the number of entries into and time spent on the open arms and decreased end-arm exploration and head dipping in the elevated plus maze. Conclusion: These findings suggest that dopamine, through D-2 receptors in the dISC and dPAG, is involved in defense reactions that are organized in the midbrain tectum. (C) 2015 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 14/02000-0 - Caracterização do papel da dopamina na mediação de tipos distintos de medo
• Beneficiário: Sangu Muthuraju
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 11/00041-3 - Neurobiologia do estresse: a interface sensório-motora
• Beneficiário: Marcus Lira Brandão
• Modalidade de apoio: Auxílio à Pesquisa - Temático