Overexpression of microRNA-301b accelerates hippocampal microglia activation and cognitive impairment in mice with depressive-like behavior through the NE-κB signaling pathway

Depression is a condition with a complex etiological pattern, whose effective treatments are highly limited. MicroRNAs (miRNAs) have been investigated in intensive studies owing to their involvement in pathophysiology of mood disorders. The current study aimed to elucidate the role of miR-301b in hippocampus in mouse models of depressive-like behavior. Microarray-based prediction identified the differentially expressed gene neuronal pentraxin II (NPTX2) related to mental depression. Next, the putative miR-301b binding sites on the 3'UTR of NPTX2 were verified. Then the effect of miR-301b on cognitive function of mice with depressive-like behavior was analyzed using the Morris water maze test. In addition, the regulation of miR-301b to NPTX2 and activation of NF-kappa B signaling pathway was assessed. Following that, the microglia activation and inflammation in hippocampus were evaluated, with the expressions of inflammatory factors being examined. At last, microglia were flow cytometrically sorted and the inflammatory reaction was also assessed in vitro. The obtained findings revealed that miR-301b targeted and negatively regulated NPTX2. Moreover, overexpressed miR-301b activated the NF-kappa B signaling pathway, as reflected by increasing protein expressions of p-NF-kappa B. Upregulated miR-301b accelerated cognitive impairment in mice with depressive-like behavior. In addition, overexpression of miR-301b activated microglia and stimulated inflammation in hippocampus, accompanied by enhanced release of tumor necrosis factor-alpha (TNIF-alpha), interleukin-1 beta (IL-1 beta) and cyclooxygenase-2(COX-2). Taken together, the evidence provided by the current study indicated that overexpression of miR-301b augmented hippocampal microglia activation, thus exacerbating cognitive impairment and inflammation in mice with depressive-like behavior by activating the NF-kappa B signaling pathway.