Nicotinamide Adenine Dinucleotide Supplementation Improves Cuprizone-Induced Multiple Sclerosis-Related Behavioral Changes in C57BL/6J Mice

Abstract

Objective: To investigate whether nicotinamide adenine dinucleotide (NAD+) supplementation can improve behavioral changes in a cuprizone-intoxicated mouse model. Methods: Six-week-old C57BL/6J mice were divided into three groups: two were fed 0.2% cuprizone chow (cuprizone and cuprizone + NAD+ groups), and the other group was fed normal rodent chow (control group) for 4 weeks. The mice in the cuprizone + NAD+ group received 250 mg/kg/day NAD+ intraperitoneally once a day, while the other mice were administered saline simultaneously. Behavioral tests for spatial memory (Morris water maze and Y maze), locomotor ability (grip test and rotarod test), depression-like behavior (open field test and tail suspension test), and exploratory behavior (open field test) were conducted. Results: In the probe test of the Morris water maze, the cuprizone group spent a significantly smaller proportion of time in the target quadrant than the control group did (16.32% vs. 31.66%, p = 0.006). However, supplementation with NAD+ increased the value (28.78% vs. 16.32%, p = 0.023). Similarly, in the Y maze test, the cuprizone group demonstrated a notably lower ratio of effective alterations compared to the control group (0.543 vs. 0.648, p < 0.001), and the cuprizone + NAD+ group presented an improved ratio compared with the cuprizone group (0.613 vs. 0.543, p = 0.021). Compared with the control group, cuprizone toxicity resulted in a decreased time to fall (169.10 vs. 247.60 s, p = 0.015) in the grip test, but NAD+ supplementation mitigated this effect (261.60 vs. 169.10 s, p = 0.003). There were no significant differences in the immobile time among groups in both the tail suspension test and the open field test, and there were also no significant differences in center distance in the open field test. Conclusions: Direct NAD+ supplementation improves the locomotor ability and spatial memory of cuprizone-intoxicated C57BL/6J mice. However, NAD+ supplementation does not show significant effects on depressive and exploratory behavior of experimental mice.