Background Cognitive impairment in humans with Alzheimer's disease (AD) and in animal models of Aβ-pathology can be ameliorated by treatments with the nuclear receptor peroxisome proliferator-activated receptor-gamma (PPARγ) agonists, such as rosiglitazone (RSG). Previously, we demonstrated that in the Tg2576 animal model of AD, RSG treatment rescued cognitive deficits and reduced aberrant activity of granule neurons in the dentate gyrus (DG), an area critical for memory formation. Methods We used a combination of mass spectrometry, confocal imaging, electrophysiology and split-luciferase assay and in vitro phosphorylation and Ingenuity Pathway Analysis. Results Using an unbiased, quantitative nano-LC-MS/MS screening, we searched for potential molecular targets of the RSG-dependent rescue of DG granule neurons. We found that S226 phosphorylation of fibroblast growth factor 14 (FGF14), an accessory protein of the voltage-gated Na+ (Nav) channels required for neuronal firing, was reduced in Tg2576 mice upon treatment with RSG. Using confocal microscopy, we confirmed that the Tg2576 condition decreased PanNav channels at the AIS of the DG, and that RSG treatment of Tg2576 mice reversed the reduction in PanNav channels. Analysis from previously published data sets identified correlative changes in action potential kinetics in RSG-treated T2576 compared to untreated and wildtype controls. In vitro phosphorylation and mass spectrometry confirmed that the multifunctional kinase GSK–3β, a downstream target of insulin signaling highly implicated in AD, phosphorylated FGF14 at S226. Assembly of the FGF14:Nav1.6 channel complex and functional regulation of Nav1.6-mediated currents by FGF14 was impaired by a phosphosilent S226A mutation. Bioinformatics pathway analysis of mass spectrometry and biochemistry data revealed a highly interconnected network encompassing PPARγ, FGF14, SCN8A (Nav 1.6), and the kinases GSK–3 β, casein kinase 2β, and ERK1/2. Conclusions These results identify FGF14 as a potential PPARγ-sensitive target controlling Aβ-induced dysfunctions of neuronal activity in the DG underlying memory loss in early AD.

Key pointsr Currently, no animal model exists in which selective deletion of α7 nAChRs from a specific cell type or tissue is possible through genetic manipulation.r We have generated mice in which the fourth exon of the α7 nAChR gene (Chrna7) is flanked by loxP sites (B6-Chrna7LBDEx4007Ehs ) which we refer to as floxed α7 nAChR conditional knockout or α7nAChR flox . Abstract There is much interest in α7 nicotinic acetylcholine receptors (nAChRs) in CNS function since they are found throughout peripheral tissues as well as being highly expressed in brain regions implicated in attention, learning and memory. As such, the role of these receptors in many aspects of CNS function and disease is being actively investigated. To date, only one null mouse model (A7KO) is available which is non-conditional and constitutive. Since α7 nAChRs are present on neurons and glia (including astrocytes), as well as being developmentally regulated, there is an unmet need for the technical capability to control α7 nAChR gene expression. Therefore we have generated mice in which the fourth exon of the α7 nAChR gene (Chrna7) is flanked by loxP sites (B6-Chrna7 LBDEx4007Ehs ) which we refer to as floxed α7 nAChR conditional knockout or α7nAChR flox . We validated the chosen approach by mating α7nAChR flox with mice expressing Cre recombinase driven by the glial acidic fibrillary protein (GFAP)-Cre promoter (GFAP-A7KO) to test whether α7nAChR flox , GFAP-A7KO and appropriate littermate controls performed equally in our standard Rodent In Vivo Assessment Core battery to assess general health, locomotion, emotional and cognitive behaviours. Neither α7nAChR flox nor GFAP-A7KO exhibited significant differences from littermate controls in any of the baseline behavioural assessments we conducted, similar to the 'first generation' non-conditional A7KO mice. We also determined that α7 nAChR binding sites were absent on GFAP-positive astrocytes in hippocampal slices obtained from GFAP-A7KO offspring from α7nAChR flox and GFAP-Cre crosses. Finally, we validated that Cre recombinase (Cre)-mediated excision led to functional, cell-and tissue-specific loss of α7 nAChRs by demonstrating that choline-induced α7 nAChR currents were present in Cre-negative, but not synapsin promoter-driven Cre-positive, CA1 pyramidal neurons. Additionally, electrophysiological characterization of α7 nAChR-mediated current traces was similar in terms of amplitude and time constants of decay (during desensitization) for the α7nAChR flox and wild-type (WT) mice. Thus, we have in vivo and in vitro evidence that the Chrna7 exon 4 targeting strategy does not alter behavioural, cognitive, or electrophysiological properties compared to WT and that Cre-mediated excision is an effective approach to delete α7 nAChR expression in a cell-specific manner.

Historically, most alcohol neurotoxicity studies were conducted in young adult males and focused on chronic intake. There has been a shift towards studying the effects of alcohol on the adolescent brain, due to alcohol consumption during this formative period disrupting the brain’s developmental trajectory. Because the most typical pattern of adolescent alcohol intake is heavy episodic (binge) drinking, there has also been a shift towards the study of binge alcohol-induced neurobehavioral toxicity. It has thus become apparent that binge alcohol damages the adolescent brain and there is increasing attention to sex-dependent effects. Significant knowledge gaps remain in our understanding of the effects of binge alcohol on the female brain, however. Moreover, it is unsettling that population-level studies indicate that the prevalence of binge drinking is increasing among American women, particularly those in older age groups. Therefore, although study of adolescents has made it apparent that binge alcohol disrupts ongoing brain maturational processes, we know almost nothing about how it impacts the aging brain, as studies of its effects on the aged brain are relatively scarce, and the study of sex-dependent effects is just beginning. Given the rapidly increasing population of older Americans, it is crucial that studies address age-dependent effects of binge alcohol, and given the increase in binge drinking in older women who are at higher risk for cognitive decline relative to men, studies must encompass both sexes. Because adolescence and older age are both characterized by age-typical brain changes, and because binge drinking is the most common pattern of alcohol intake in both age groups, the knowledge that we have amassed on binge alcohol effects on the adolescent brain can inform our study of its effects on the aging brain. In this review, we therefore cover the current state of knowledge of sex and age-dependent effects of binge alcohol, as well as statistical and methodological considerations for studies aimed at addressing them.

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