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Role of the insular cortex in control of the cardiovascular and anxiogenic responses to stress in rats: evaluation of functional topography and involvement of corticotropin-releasing factor (CRF) neurotransmission

Grant number: 19/24478-3
Support type:Regular Research Grants
Duration: September 01, 2020 - August 31, 2022
Field of knowledge:Biological Sciences - Pharmacology - Neuropsychopharmacology
Principal Investigator:Carlos Cesar Crestani
Grantee:Carlos Cesar Crestani
Home Institution: Faculdade de Ciências Farmacêuticas (FCFAR). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil

Abstract

Stress is identified as a prominent factor involved in the pathogenesis of various diseases. Despite the relevance of the theme, the neurobiological mechanisms related to stress-induced cardiovascular and behavioral changes are still poorly understood. In this sense, the insular cortex (IC) has been implicated in the integration and processing of limbic information in humans and animals. In fact, an involvement of IC in cardiovascular and behavioral responses to stress has been reported. However, a possible rostro-caudal organization in control of stress responses by IC has never been investigated. This is a relevant aspect, since studies in humans and animals have reported functional dissociation along the rostro-caudal axis of the IC in control of cardiovascular function and sensory responses. Thus, a first proposal of the present study is to evaluate the functional topography of the IC in control of cardiovascular and anxiogenic responses to acute restraint stress. Another relevant aspect is that the local neurochemical mechanisms involved in control of stress responses by the IC was poorly explored. In this sense, corticotropin-releasing factor (CRF) neurotransmission has been reported to be an important mechanism in the central nervous system involved in the etiology of behavioral changes and physiological adjustments observed during exposure to aversive threats. However, the specific brain sites whereby CRF neurotransmission acts to control stress responses are still poorly understood. CRF-containing terminals as well as the CRF1 receptor were identified within the IC. However, a possible involvement of this IC neurochemical mechanism in control of stress-induced physiological and behavioral responses has never been investigated. Thus, a second proposal of the present study is to evaluate the participation of CRF in the IC, acting through local CRF1 receptor activation, in control of the cardiovascular and anxiogenic responses evoked by acute restraint stress in rats. Finally, it has also been reported that repeated exposure to aversive events alters CRF and CRF1 receptor expression in various limbic structures. However, a possible effect of chronic stress on CRFergic neurotransmission within the IC has never been investigated. Thus, a final proposal of the present project is to investigate whether repeated exposure to restraint stress causes changes in IC CRFergic neurotransmission, and whether these changes affect the control of restraint-evoked cardiovascular and anxiogenic responses by this neurochemical mechanism in the IC. (AU)