title: Medial prefrontal cortex TRPV1 channels modulate the baroreflex cardiac activity in rats.
abstract: OBJECTIVE
  The ventral portion of the medial prefrontal cortex (vMPFC) comprises the infralimbic (IL), prelimbic (PL) and dorsopenducular (DP) cortices. The IL and PL regions facilitate the baroreceptor reflex arc. This facilitatory effect on the baroreflex is thought to be mediated by vMPFC glutamatergic transmission, through NMDA receptors. The glutamatergic transmission can be modulated by other neurotransmitters, such as the endocannabinoids, which are agonists of the TRPV1 receptor. TRPV1 channels facilitate glutamatergic transmission in the brain. Thus, we hypothesized that TRPV1 receptors in the vMPFC enhance the cardiac baroreflex response.
  
  
  METHODS
  Stainless steel guide cannulae were bilaterally implanted into the vMPFC of male Wistar rats. Afterwards, a catheter was inserted into the femoral artery, for recording MAP and HR, and into the femoral vein for assessing baroreflex activation.
  
  
  RESULTS
  Microinjections of the TRPV1 receptor antagonists capsazepine and 6-iodo-nordihydrocapsaicin (6-IODO) into the vMPFC reduced the cardiac baroreflex activity in unanaesthetized rats. Capsaicin microinjected into the vMPFC increased the cardiac baroreflex activity in unanaesthetized rats. When an ineffective dose of the TRPV1 receptor antagonist 6-IODO was used, the capsaicin-induced increase in the cardiac baroreflex response was abolished. The higher doses of capsaicin administered into the vMPFC after the ineffective dose of 6-IODO displaced the dose-response curve of the baroreflex parameters to the right, with no alteration in the maximum effect of capsaicin.
  
  
  CONCLUSIONS
  The results of the present study show that stimulation of the TRPV1 receptors in the vMPFC increases the cardiac baroreceptor reflex response.
authors.affiliation: Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: D C
authors.initials: DC
authors.lastname: Lagatta
authors.affiliation: Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: N C
authors.initials: NC
authors.lastname: Ferreira-Junior
authors.affiliation: Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: L B M
authors.initials: LB
authors.lastname: Resstel
mesh_terms: D000818:Animals; D017704:Baroreflex / Q000502:physiology*; D002211:Capsaicin / Q000031:analogs & derivatives / Q000494:pharmacology; D006321:Heart / Q000502:physiology*; D008297:Male; D017397:Prefrontal Cortex / Q000502:physiology*; D017208:Rats, Wistar; D050916:TRPV Cation Channels / Q000037:antagonists & inhibitors / Q000502:physiology*
chemical_list: D050916:TRPV Cation Channels; C493922:Trpv1 protein, rat; C071423:capsazepine; C517386:nordihydrocapsaicin; D002211:Capsaicin