Study of the participation of the ventromedial hypothalamus and periaqueductal gray matter on nociceptive processes mediated by the anterior cingulate cortex

• Grant number: 21/13219-7
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date until: April 30, 2022
• End date until: April 29, 2023
• Field of knowledge: Health Sciences - Medicine - Psychiatry
• Principal Investigator: Norberto Cysne Coimbra
• Grantee: Luiz Luciano Falconi Sobrinho
• Supervisor: Filipa Santos Costa Pinto Ribeiro de Lacerda
• Host Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil
• Institution abroad: Universidade do Minho (UMinho), Portugal
• Associated to the scholarship: 19/05255-3 - Study of the role of glutamatergic pathways from the anterior cingulate cortex on nitrergic mechanisms of the ventromedial hypothalamus and periaqueductal grey matter involved in the genesis of defensive responses evoked in mice threatened by snakes, BP.PD

Abstract

The rostromedial region of the frontal lobe cortex (mPFC; medial prefrontal cortex) has been implicated in the modulation of fear- and anxiety-related defensive responses, organised in diencephalic and mesencephalic structures. Recent studies have shown that the anterior cingulate cortex (ACC), a structure that also integrates the mPFC, has glutamatergic neurons that play a relevant role in the regulation of defensive behaviours and fear-induced antinociception, organised by anterior and posterior hypothalamic neurons. In addition, data referring to the postdoctoral internship, but not yet published, suggest that ACC activation with NMDA, an excitatory amino acid, appears to modulate defensive responses organised by dorsomedial division of the ventromedial hypothalamus (dmVMH) and dorsal periaqueductal gray matter (dPAG) neurons. However, for the modulatory role of ACC on nociceptive processes we hypothesize that the ACC glutamatergic pathways recruit dmHMH and dPAG as relays before reaching the dorsal horn of the spinal cord (DHSC), but it remains unclear. Thus, to better understand the role of both dmVMH and dPAG in CCA-mediated nociceptive processes, electrophysiological techniques combined with pharmacological approaches will be performed in our study. Male C57/BL6 mice, anesthetised, and exposed to heat stimulation in the paw, will be subjected to electrophysiological recordings in the DHSC to record the activity of local nociceptive neurons, after chemical stimulation of ACC with NMDA, preceded by microinjections of either lidocaine or LY235959, a NMDA receptor antagonist, in the dmVMH and dPAG. (AU)