Cuprizone‐mediated demyelination reversibly degrades voiding behavior in mice while sparing brainstem reflex

Abstract

Multiple sclerosis (MS) is a chronic, progressively debilitating demyelinating disease of the central nervous system (CNS). Nearly 80% of MS patients experience lower urinary tract dysfunction early in their diagnosis. This significantly affects the quality of life, and in latter stages of disease is a leading cause of hospitalization. Previously, animal models have shown that inflammatory demyelination in the CNS causes profound bladder dysfunction, but the confounding influence of systemic inflammation limits the potential interpretation of the contribution of CNS demyelination to bladder dysfunction. Since the micturition circuit has myelinated neuronal connections in the cortex, brainstem, and spinal cord, we examined alterations in bladder function in the cuprizone model characterized by demyelinating lesions in the cortex and corpus callosum that are independent of T‐cell–mediated autoimmunity. Herein, we report that a 4‐week dietary cuprizone treatment in C57Bl/6J mice induced alterations in voiding behavior with increased micturition frequency and reduced volume voided, similar to human MS bladder dysfunction. Subsequently, recovery from cuprizone treatment restored normal bladder function. Demyelination and remyelination were confirmed by Luxol Fast Blue staining of the corpus callosum. Additionally, we also determined that an 8‐week cuprizone treatment, resulting in chronic demyelination lacking spontaneous remyelination potential, is associated with an exacerbated voiding phenotype. Interestingly, while cuprizone‐induced CNS demyelination severely affected conscious (cortical) urinary behavior, the brainstem and spinal cord reflex remained unchanged, as confirmed by urethane‐anesthetized cystometry. This is the first study to show that cortical demyelination independent of inflammation can negatively impact urinary function.

Orosomucoid-1 Arises as a Shared Altered Protein in Two Models of Multiple Sclerosis

“…On the other hand, the cuprizone model primarily affects the white matter of the brain (Sen et al, 2019), but our findings demonstrate glial, synaptic, and dendritic changes in the cortex of cuprizone-treated mice (Sen et al, 2020). Additionally, a decrease in cortical myelination in cuprizone mice suggests altered neuronal activity in this region (Dubey et al, 2022;Hashem et al, 2022), whereas no such changes were observed in the spinal cord of this model (Ramasamy et al, 2022).…”

“…A milder positive regulation of projection extension is also evident in the response of the cortex in EAE mice. These regional differences in the strength of responses can be expected considering the symptoms in the EAE animals, which were assigned a clinical score between 1.5 and 2.5 that is characterized by motor disability in a caudalrostral direction (Shahi et al, 2019) Interestingly, and consistent with the minimal effect of cuprizone on the spinal cord (Ramasamy et al, 2022), neither the glial response nor the regulation of synaptic remodeling or neuron projection development is observed in the spinal cord of cuprizone-treated mice. This region is characterized by negative regulation of hemostasis and blood coagulation, and it has an enriched humoral immune response similar to that seen in the other studied tissues.…”

“…However, inflammatory lesions have also been reported in the cortex of EAE mice after the peak of the disease (Koutsoudaki et al, 2010;Barriola et al, 2020). In contrast, CPZ-induced demyelination is independent of T-cell-mediated autoimmunity and affects both the white and gray matter of the brain (Ramasamy et al, 2022). Notably, cuprizone has minimal effect on the spinal cord (Herder et al, 2011;Ramasamy et al, 2022).…”

“…In contrast, CPZ-induced demyelination is independent of T-cell-mediated autoimmunity and affects both the white and gray matter of the brain (Ramasamy et al, 2022). Notably, cuprizone has minimal effect on the spinal cord (Herder et al, 2011;Ramasamy et al, 2022). To gain insights into the common and specific molecular changes occurring regionally in these two models, we compared the proteomic profiles of cortical and spinal cord tissues using Sequential Window Acquisition of All Theoretical Mass Spectra (SWATH-MS) (Collins et al, 2017).…”