A study on CaMKII involvement in behavioral and molecular alterations in iNOS knockout mice

• Grant number: 24/05428-3
• Support Opportunities: Scholarships in Brazil - Master
• Start date: September 01, 2024
• End date: January 31, 2026
• Field of knowledge: Biological Sciences - Pharmacology - Neuropsychopharmacology
• Principal Investigator: Sabrina Francesca de Souza Lisboa
• Grantee: Thales Andrade da Silva
• Host Institution: Faculdade de Ciências Farmacêuticas de Ribeirão Preto (FCFRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil
• Associated research grant: 17/19731-6 - Identification of epigenetic mechanisms induced by stress which modulate endocannabinoid signaling and neuroimmunological mechanisms as new therapeutic targets to treat the posttraumatic stress disorder (PTSD), AP.JP

Abstract

Stressful stimuli play a crucial role in the pathogenesis of psychiatric disorders such as Post-Traumatic Stress Disorder (PTSD). The isoforms of the nitric oxide synthase (NOS) enzyme-neuronal (nNOS), inducible (iNOS), and endothelial (eNOS)-are responsible for nitric oxide (NO) production, a critical factor in fear responses. In the central nervous system (CNS), the primary NO synthesis occurs via nNOS, triggered by stress-related stimuli. These stimuli also activate the endocannabinoid system (eCB), modulating behavioral phenotypes. Previous studies by our group demonstrated that mice with the iNOS gene deletion (iNOS knockout) exhibit greater difficulty in memory extinction during the contextual fear conditioning protocol (CFC) and dysregulation of the eCB system in the prefrontal cortex (PFC) due to increased nNOS expression. This suggests that this animal model can be used to study PTSD and the involvement of NO in its features. Recent studies by our group also have highlighted the role of type 1 vanilloid receptors (TRPV1) in fear extinction in iNOS knockout animals, with receptor inhibition partially mitigating the observed deficits. The enzyme calmodulin kinase II (CaMKII) can undergo nitrosylation by NO and may be involved in TRPV1 sensitization in iNOS KO animals through phosphorylation. Therefore, this study aims to investigate whether CaMKII is activated by nitrosylation and sensitizes TRPV1 receptors in the medial PFC of iNOS KO animals, thereby altering the observed phenotype. To achieve this, we will assess CaMKII expression and nitrosylation activation, as well as TRPV1 phosphorylation in the PFC of wild-type (WT) and iNOS KO animals subjected to CFC paradigm. Subsequently, a reversible inhibitor of this enzyme (KN-93) will be administered directly to the medial PFC to observe its potential to attenuate the observed alterations.