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Bassi GS, Carvalho MC, Almada RC, Brandão ML. Inhibition of substance P-induced defensive behavior via neurokinin-1 receptor antagonism in the central and medial but not basolateral nuclei of the amygdala in male Wistar rats. Prog Neuropsychopharmacol Biol Psychiatry 2017; 77:146-154. [PMID: 28390968 DOI: 10.1016/j.pnpbp.2017.03.026] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 03/08/2017] [Indexed: 10/19/2022]
Abstract
RATIONALE The production of unconditioned defensive behaviors has been related to the amygdala, a key component of the encephalic aversion system. Microinjection of the neuropeptide substance P (SP) in the amygdala elicits defensive behaviors via the activation of type 1 neurokinin (NK-1) receptors. However, no studies have investigated whether intra-amygdala SP/NK-1 mechanisms can elicit other types of defensive responses, such as antinociception and ultrasonic vocalizations (USVs). METHODS The present study investigated the effects of SP-induced activation of the neurokininergic system in three main nuclei of the amygdala-basolateral (BLA), central (CeA), and medial (MeA) nuclei-in rats that were subjected to the elevated plus maze (EPM), tail-flick test, and USV recording. The effects of SP in these amygdaloid nuclei were challenged with combined injections of the NK-1 receptor antagonist spantide. RESULTS The present study showed that SP injections in the CeA and MeA but not BLA exerted anxiogenic-like effects. In contrast to the CeA, the anxiogenic-like effects of SP in the MeA were not dependent on NK-1 mechanisms. In the tail-flick test, SP microinjections produced antinociceptive effects only in the MeA through NK-1 receptor activation. No USV emissions were detected after the SP microinjections. CONCLUSIONS The present study showed that NK-1 receptors in the CeA and MeA but not BLA are involved in defensive reactions to conditions of fear. The present results may provide a better understanding of the neurochemical mediation of fear states.
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Affiliation(s)
- G S Bassi
- Instituto de Neurociências e Comportamento, Av. do Café, 2.450, Ribeirão Preto, SP 14050-220, Brazil; Laboratório de Neuropsicofarmacologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP), Universidade de São Paulo (USP), Av. dos Bandeirantes, 3900, Ribeirão Preto, SP 14040-901, Brazil.
| | - M C Carvalho
- Instituto de Neurociências e Comportamento, Av. do Café, 2.450, Ribeirão Preto, SP 14050-220, Brazil; Laboratório de Neuropsicofarmacologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP), Universidade de São Paulo (USP), Av. dos Bandeirantes, 3900, Ribeirão Preto, SP 14040-901, Brazil
| | - R C Almada
- Instituto de Neurociências e Comportamento, Av. do Café, 2.450, Ribeirão Preto, SP 14050-220, Brazil; Laboratório de Neuropsicofarmacologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP), Universidade de São Paulo (USP), Av. dos Bandeirantes, 3900, Ribeirão Preto, SP 14040-901, Brazil
| | - M L Brandão
- Instituto de Neurociências e Comportamento, Av. do Café, 2.450, Ribeirão Preto, SP 14050-220, Brazil; Laboratório de Neuropsicofarmacologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP), Universidade de São Paulo (USP), Av. dos Bandeirantes, 3900, Ribeirão Preto, SP 14040-901, Brazil
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