Alterations in MicroRNA-132/212 Expression Impairs Fear Memory in Goldfish Carassius auratus .

Background: Earlier, we showed that nicotinamide (NAM) treatment impairs spatial memory through the downregulation of CREB-Sirt 1-brain-derived neurotrophic factor ( Bdnf ) signaling cascade.

Purpose: In this study, we examine whether NAM treatment alters CREB-regulated genes through -microRNAs.

Method: To test this hypothesis, goldfish ( Carassius auratus ) were divided into 2 groups: (i) vehicle group (VEH; double distilled water intra-peritoneally [i.p.]) (ii) nicotinamide group (NAM, 1,000 mg/kg, i.p.) and again divided into VEH untrained/trained, NAM untrained/trained. One hour after receiving VEH or NAM, individuals were subject to contextual fear conditioning (CFC) training. After 24 h, both the groups were tested for contextual fear memory. Subsequently, miR-132/212 levels, regulated immediate-early genes (IEGs: C-fos and EGR-1) and Bdnf but not its receptor. -TrkB1were examined following 0' and 60' min after training, and compared with the untrained group.

Results: We observed that NAM treatment significantly impaired fear memory. Further, the analysis showed that miR-132 level was not altered, but miR-212 level was significantly upregulated after CFC training only in NAM-treated fish. We also found that NAM treatment downregulated IEGs and Bdnf but not its receptor TrkB1.

Conclusions: Present study suggests that NAM-treatment impaired fear memory and control IEGs, Bdnf and TrkB1 expression by differentially regulating miR-132 and 212.