Effects of dexmedetomidine on pain threshold, memory ability, and neurological function in sleep-deprived rats through expression of PSD95 protein and the phosphorylation level of the PI3K/AKT pathway

Introduction
The study aimed to observe the effects of different doses of dexmedetomidine (Dex) on pain threshold, memory, and neurological ability in rats with sleep deprivation.

Material and methods
Forty-eight SD rats were divided into a control group (n = 12), model group (n = 12), sleep deprivation + Dex low dose injection group (DEX low dose group), and sleep deprivation + Dex high dose injection group (high dose DEX group). The rats in the model group, DEX low dose group, and DEX high dose group were subjected to sleep deprivation for 3 hours, and the DEX low dose group and DEX high dose group were injected with Dex (6 µg/kg, 60 µg/kg, 10 min, respectively). The neurological function scores of rats in each group were compared, and the contents of PSD95 and PI3K/AKT protein were detected.

Results
The food intake of rats in groups B, C, and D was lower than in group A (p < 0.05), and the food intake in group D was higher than in groups B and C (p < 0.05). The escape latency of the Morris water maze test in all groups decreased gradually from day 1 to day 3 (p < 0.05). On days 2 and 3, the escape latency of group B was longer than that of group A (p < 0.05), while the escape latency of groups C and D was shorter than that of group B (p < 0.05). The target quadrant residence time of group B was shorter than that of group A (p < 0.05), while the target quadrant residence time of group C and D was longer than that of group B (p < 0.05). The neurological function score of the group B was increased (p < 0.05), while the neurological function score of groups C and D was lower than that of group B in a dose-dependent manner (p < 0.05). The PSD95 protein content and PI3K/AKT phosphorylation level in group B were lower (p < 0.05), while these values in groups C and D were higher than in group B in a dose-dependent manner (p < 0.05).

Conclusions
Different doses of Dex can effectively reduce the pain threshold, enhance memory ability, and improve neurological function in sleep-deprived rats. The mechanism may be mediated by regulation of PSD95 expression and phosphorylation of the PI3K/AKT pathway.