title: 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.
abstract: 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).
  
  
  
  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.
  
  
  
  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.
  
  
  
  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.
authors.affiliation: 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. Electronic address: shimizug@gmail.com.
authors.forename: G S
authors.initials: GS
authors.lastname: Bassi
authors.affiliation: 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.
authors.forename: M C
authors.initials: MC
authors.lastname: Carvalho
authors.affiliation: 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.
authors.forename: R C
authors.initials: RC
authors.lastname: Almada
authors.affiliation: 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.
authors.forename: M L
authors.initials: ML
authors.lastname: Brandão
mesh_terms: D000679:Amygdala / Q000187:drug effects*; D000700:Analgesics / Q000494:pharmacology; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D005239:Fear / Q000187:drug effects* / Q000523:psychology*; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D008845:Microinjections; D064729:Neurokinin-1 Receptor Antagonists / Q000494:pharmacology*; D051381:Rats; D018040:Receptors, Neurokinin-1 / Q000378:metabolism*; D013373:Substance P / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors* / Q000494:pharmacology*; D014828:Vocalization, Animal / Q000187:drug effects
chemical_list: D000700:Analgesics; D064729:Neurokinin-1 Receptor Antagonists; D018040:Receptors, Neurokinin-1; D013373:Substance P; C042867:spantide
keywords: Amygdala; Elevated plus maze; Neurokinin; Rat; Tail-flick; Ultrasonic vocalizations