The hippocampus and prefrontal cortex are the main region of brain that involve in memory and learning. In the brain, hyperglycemia give rise to reduction or extension of oxidative stress, reactive oxygen species (ROS), inflammation and TAU phosphorylation which are major risk factors for neurodegenerative disease (Hokama et al. 2013; Zhao et al. 2012; Prasad et al. 2014; Caberlotto et al. 2019; Zhao et al. 2016; Revsin et al. 2005; Amin et al. 2013; Matsuura et al. 2018; Pamidi and Satheesha 2012). These factors affects the expression level of lncRNAs (Jacob 2006; Krishnan 2011; Jonathan 2013; Ghasemi 2016; Lin et al. 2018; Sami 2009). In this study, we evaluated the effect of diabetes on physiological parameters and expression level of lncRNAs with highest expression in HP and PFC of diabetic mice.
Our results showed that the expression of lncRNAs in mouse brain changes after diabetes induction. In general, the change in the expression level of the lncRNAs were more significant in PFC than HP. In HP the expression levels of Gas5, Gm20417, 6330403k07Rik, and Gm20463 were decreased. In contrast, the expression of these lncRNAs were significantly increased in PFC. However, the Rian was the sole lncRNA that its expression in both tissues of DM with memory loss was increased compared to DM with normal memory and healthy mice.
It is possible that overexpression of Rian protects neuronal cells from further injuries of diabetes. The Rian (RNA imprinted and accumulated in nucleus) is a maternally-expressed imprinted lncRNA that highly expresses in brain, heart and ovary. Rian negatively regulates nearby genes such as Dlk1 and Mirg in the brain (Han et al. 2014). It has been reported that lncRNA Rian protects neuronal cells from injuries through GATA3 regulation (Wolska et al. 2020). For example, overexpression of Rian protects hippocampal neurons against anesthesia induced cognitive dysfunction (Yu et al. 2021). Also, Rian improves neurological score and inhibits cell apoptosis induced by cerebral ischemia–reperfusion injury (Yao et al. 2020).
Our results showed that Rian expression dramatically increases in HP and PFC of diabetic mice.
In conclusion, our data demonstrated that several lncRNAs expression have changed in HP and PFC of diabetic mice suggesting the potential therapeutic targets for alleviation of diabetes-induced neuronal toxicity.