Long-Term Pharmacological Inhibition of the Activity of All NOS Isoforms Rather Than Genetic Knock-Out of Endothelial NOS Leads to Impaired Spatial Learning and Memory in C57BL/6 Mice

Abstract

Increasing epidemiological and experimental evidence points to a link between arterial stiffness and rapid cognitive decline. However, the underlying mechanism linking the two diseases is still unknown. The importance of nitric oxide synthases in both diseases is well-defined. In this study, we introduced arterial stiffness in both genetic (eNOS−/−, endothelial nitric oxide synthase knockout) and pharmacological (N(G)-nitro-L-arginine methyl ester (L-NAME) treatment) NO dysfunction models to study their association with cognitive decline. Our findings demonstrate that the non-selective inhibition of NOS activity with L-NAME induces cardiac dysfunction, arterial stiffness, and a decline in hippocampal-dependent learning and memory. This outcome demonstrates the importance of neuronal NOS (nNOS) in both cardiovascular and neurological pathophysiology and its potential contribution in the convergence between arterial stiffness and cognitive decline.

Proteomic Assessment of C57BL/6 Hippocampi after Non-Selective Pharmacological Inhibition of Nitric Oxide Synthase Activity: Implications of Seizure-like Neuronal Hyperexcitability Followed by Tauopathy

“…As expected, we found significantly increased PWV values in L-NAME-treated animals compared to controls after 2, 8, and 16 weeks of treatment, which was progressively significant over time. Moreover, we found that long-term L-NAME treatment led to impaired visuospatial learning and memory [ 21 ]. The goal of this study was to further explore the observed progressive cognitive decline because of L-NAME treatment via proteomic analysis of hippocampal tissue.…”

“…After sixteen weeks of NOS inhibition with L-NAME and the point reached of significantly deteriorated visuospatial learning and memory of treated C57BL/6 mice [ 21 ], 120 DEPs were found in their hippocampi. In accordance with our findings of 2-week L-NAME-treated hippocampi, we observed the downregulation of the Gabbr2, GABA B receptor subunit 2, alongside a downregulation of Sfn, 14-3-3 protein sigma.…”

“…This manuscript was prepared in accordance with the Animal Research: Reporting of In Vivo Experiments (ARRIVE) Guidelines [ 24 ]. After a 2-week experimental battery as previously reported [ 21 ], mice were humanely killed by perforation of the diaphragm while under deep anesthesia (sodium pentobarbital, Sanofi, Diegem, Belgium), 250 mg/kg, i.p. [ 25 ]).…”

“…Moreover, we found that this long-term non-selective inhibition of all NOS isoform activity with L-NAME led to deteriorated hippocampal-dependent visuospatial learning and memory in C57BL/6 mice as assessed with a Morris water maze test. This outcome therefore highlights the potential contribution of NOS activity in the convergence between AS and cognitive decline [ 21 ]. In the present study, we aimed to further investigate the progressive generation of molecular signatures in degenerating hippocampal tissue of previously characterized L-NAME-treated C57Bl/6 mice [ 21 ] via LC–MS/MS proteomic analysis.…”

“…This outcome therefore highlights the potential contribution of NOS activity in the convergence between AS and cognitive decline [ 21 ]. In the present study, we aimed to further investigate the progressive generation of molecular signatures in degenerating hippocampal tissue of previously characterized L-NAME-treated C57Bl/6 mice [ 21 ] via LC–MS/MS proteomic analysis.…”