Vitamin D injection into the dorsal-CA1 hippocampus improves short-term sleep deprivation induced cognitive impairment in male rats

Abstract

This study was conducted with aim of investigating the consequences of sleep deprivation (SD) on cognitive functions. For this purpose, adult male rats were subjected to SD protocol for 5 h. The SD and the control rats were trained in the Morris water maze (MWM) to assess spatial behavioral deficits due to the SD protocol. To determine the role of astrocytes in spatial navigation deficits associated with SD, an inhibitor of astrocyte activation, fluorocitrate (FC), or a suppressor of astrocyte activation, vitamin D, was injected into the dorsal-CA1 hippocampus before subjecting rats to the SD protocol and the effects of these compounds on spatial navigation deficits associated with SD in the MWM were assessed. As expected, 5 h of SD impaired the Morris water navigation task in rats. FC injection into the dorsal-CA1 hippocampus before the SD protocol did not prevent the SD-induced cognitive deficits. Interestingly, injection of vitamin D into the dorsal-CA1 hippocampus prior to the SD protocol alleviated the SD-induced severe spatial navigation deficit in the MWM. Sequential injection of FC and vitamin D prior to the SD protocol did not reduce the SD-induced spatial memory impairment, suggesting a role for astrocytes. In sum, vitamin D can improve cognitive dysfunction associated with sleep deprivation, possibly dependent on astrocyte function. The results show that maintaining adequate levels of vitamin D offers a promising avenue to improve cognitive function in sleep-deprived conditions.

Keywords

• Hippocampus
• Learning and memory
• Sleep deprivation
• Astrocytes
• Glial metabolic inhibitor
• Glial activation suppressor