Acetyl-L-carnitine Improves Depressive-like Behaviors Through Nitric Oxide Modulation in the Cuprizone Intoxication Mouse Model of Multiple Sclerosis

Abstract

Background: Demyelination and inflammation are the most common pathobiological manifestations contributing to depression in multiple sclerosis (MS). Objectives: The current study aimed to evaluate the effects of acetyl-L-carnitine (ALC) in attenuating depressive-like symptoms in the cuprizone intoxication mouse model. Methods: C57BL/6 mice were categorized into three groups (n = 6 each) as follows: The control animals (CTL), the cuprizone-intoxicated mice (CPZ), and the group that received cuprizone and acetyl-L-carnitine (CPZ+ALC). Depressive-like behaviors were evaluated by the forced swim test (FST) and the tail suspension test (TST). The prefrontal cortex (PFC) and corpus callosum (CC) areas were assessed in terms of histopathology, biochemistry, and gene expression. Results: Following oral gavage of ALC, the immobility time, which represents the despairing time, significantly decreased compared to the CPZ group. Histopathological evaluation showed that remyelination in the CC increased significantly in animals receiving ALC compared to the CPZ mice. Acetyl-L-carnitine considerably decreased the nitric oxide (NO) level in the PFC of the brain in the demyelinated mice compared to the CPZ group. The qRT-PCR results revealed that ALC significantly increased neuronal nitric oxide synthase (nNOS) expression but decreased inducible nitric oxide synthase (iNOS) gene expression compared to the CPZ group. Conclusions: ALC attenuated depressive-like behaviors in the cuprizone demyelination mouse model of MS. These neuroprotective effects of ALC may be exerted by facilitating the remyelination process and modulating the NO level in the PFC.