Neuroscience
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Activity-dependent transcription factors critically coordinate the gene expression program underlying memory formation. The tumor suppressor gene, MEN1, encodes a ubiquitously expressed transcription regulator required for synaptogenesis and synaptic plasticity in invertebrate and vertebrate central neurons. ⋯ In vivo knockdown of MEN1 prevented LTM formation and conditioning-induced changes in neuronal activity in the identified pacemaker neuron RPeD1. Our findings suggest the involvement of a new pathway in LTM consolidation that requires MEN1-mediated gene regulation.
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The present study is the first to explore the multigenerational effects of mammalian paternal cocaine intake on offspring (F1) circadian clock regulation. Parental cocaine use poses significant health risks to the offspring, through both maternal and paternal drug influences. With respect to the latter, recent evidence suggests that a paternal mode of cocaine inheritance involves epigenetic germ line actions that can ultimately disrupt offspring behavior. ⋯ In contrast, F1 cocaine-sired females, but not males, had suppressed circadian phase advance shifting responses to two non-photic stimuli: acute i.p. injections of cocaine and the serotonin agonist ([+]8-OH-DPAT). The reduced cocaine shifting in females was not due to suppressed cocaine-induced behavioral arousal. Collectively, these results reveal that a father's cocaine use can disrupt major circadian entrainment mechanisms in his adult progeny in a sex-dependent manner.
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Dendritic spines have stable filamentous actin (F-actin) and dynamic F-actin. The formation of stable F-actin plays a pivotal role in spine formation. Drebrin binds to and stabilizes F-actin in dendritic spines. ⋯ In addition, F-actin depolymerization with latrunculin A significantly reduced the stable GFP-DA fraction. These findings indicate that preferential binding of drebrin A to F-actin than drebrin E causes higher stable fraction of drebrin A in dendritic spines, although the F-actin-binding ability of purified drebrin E and drebrin A are comparable. Therefore, we suggest that a drebrin isoform conversion from drebrin E to drebrin A in dendritic spines results in the accumulation of drebrin-bound stable F-actin, which plays a pivotal role in synapse formation.
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Cortices are non-uniform in their capacity for adaptive changes. In cat area 17, pinwheel centers of the orientation map demonstrated much greater selectivity shifts after the orientation adaptation than the iso-orientation domains (Dragoi et al., 2001a). However, whether this heterogeneity exists in other visual cortical regions remains unclear. ⋯ However, at either pinwheel centers or iso-orientation domains, the selectivity shifts in area 21a were all consistently greater than those in area 17, even though the heterogeneity in the orientation distribution was similar in the two areas. More importantly, in our short-term adaptation protocol, orientation adaptation in area 17 resulted in mostly repulsive shifts at the pinwheel center region, while in area 21a, it induced both repulsive and attractive effects. These results suggest that both common and distinct strategies exist for orientation adaptation across cortices and sub-regions.
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Comparative Study
Sex Differences and Estrous Cycle Changes in Synaptic Plasticity-related microRNA in the Rat Medial Amygdala.
The posterodorsal medial amygdala (MePD) is a sex steroid-sensitive and sexually dimorphic subcortical area that dynamically modulates social behaviors in rats. As different microRNA (miRNA) can act as post-transcriptional regulators of synaptic processing, we addressed changes that occur in miRNA expression in the MePD of males and females along the estrous cycle. The expression of miR25-3p, miR132-3p, miR138-5p, miR181a-5p, miR195-5p, and miR199a-5p, involved in neuronal cytoskeleton remodeling and synaptic plasticity, were evaluated by RT-qPCR. ⋯ In addition, diestrus females showed higher values of miR25-3p, miR181a-5p, and miR195-5p when compared to estrus females. These miRNA expression profiles indicate a variable and fine-tuned protein regulation in the adult MePD. It is likely that these miRNA can be involved in structural and functional synaptic features and plasticity characteristic of males and cycling females and for the MePD regulation of mammalian reproduction.