Activity-dependent regulation of the BAX/BCL-2 pathway protects cortical neurons from apoptotic death during early development.

During early brain development, homeostatic removal of cortical neurons is crucial and requires multiple control mechanisms. We investigated in the cerebral cortex of mice whether the BAX/BCL-2 pathway, an important regulator of apoptosis, is part of this machinery and how electrical activity might serve as a set point of regulation. Activity is known to be a pro-survival factor; however, how this effect is translated into enhanced survival chances on a neuronal level is not fully understood. In this study, we show that caspase activity is highest at the neonatal stage, while developmental cell death peaks at the end of the first postnatal week. During the first postnatal week, upregulation of BAX is accompanied by downregulation of BCL-2 protein, resulting in a high BAX/BCL-2 ratio when neuronal death rates are high. In cultured neurons, pharmacological blockade of activity leads to an acute upregulation of Bax, while elevated activity results in a lasting increase of BCL-2 expression. Spontaneously active neurons not only exhibit lower Bax levels than inactive neurons but also show almost exclusively BCL-2 expression. Disinhibition of network activity prevents the death of neurons overexpressing activated CASP3. This neuroprotective effect is not the result of reduced caspase activity but is associated with a downregulation of the BAX/BCL-2 ratio. Notably, increasing neuronal activity has a similar, non-additive effect as the blockade of BAX. Conclusively, high electrical activity modulates BAX/BCL-2 expression and leads to higher tolerance to CASP3 activity, increases survival, and presumably promotes non-apoptotic CASP3 functions in developing neurons.

Chronic running-wheel exercise from adolescence leads to increased anxiety and depression-like phenotypes in adulthood in rats: Effects on stress markers and interaction with BDNF Val66Met genotype.

Exercise has been shown to be beneficial in reducing symptoms of affective disorders and to increase the expression of brain-derived neurotrophic factor (BDNF). The BDNF Val66Met polymorphism is associated with reduced activity-dependent BDNF release and increased risk for anxiety and depression. Male and female Val66Met rats were given access to running wheels from 3 weeks of age and compared to sedentary controls. Anxiety- and depression-like behaviors were measured in adulthood using the elevated plus maze (EPM), open field (OF), and forced swim test (FST). Expression of BDNF and a number of stress-related genes, the glucocorticoid receptor (Nr3c1), serum/glucocorticoid-regulated kinase 1 (Sgk1), and FK506 binding protein 51 (Fkbp5) in the hippocampus were also measured. Rats given access to running wheels developed high levels of voluntary exercise, decreased open-arm time on the EPM and center-field time in the OF, reduced overall exploratory activity in the open field, and increased immobility time in the FST with no differences between genotypes. Chronic exercise induced a significant increase in Bdnf mRNA and BDNF protein levels in the hippocampus with some of these effects being genotype specific. Exercise decreased the expression of Nr3c1 and Sgk1, but increased the expression of Fkbp5. These results suggest that chronic running-wheel exercise from adolescence increased anxiety and depression-like phenotypes in adulthood, independent of BDNF Val66Met genotype. Further studies are required to confirm that increased indices of anxiety-like behavior are independent from reduced overall locomotor activity.

Is Dual Mobility Total Hip Arthroplasty Surgery More Aggressive than Hemiarthroplasty when Treating Femoral Neck Fracture in the Elderly? A Multicentric Retrospective Study on 302 Hips.

INTRODUCTION: Bipolar hemiarthroplasty (BHA) and total hip arthroplasty (THA) are validated treatments for displaced femoral neck fractures (DFNFs). BHA seldomly needs conversion to THA, but the latter has higher dislocation rate in FNFs. Dual Mobility THA offers a reduced dislocation rate and eliminates the risk of conversion. This study looks for differences between BHA and DMTHA in terms of surgical time, blood loss and transfusion, dislocation rate, mortality, and thromboembolic events. MATERIAL AND METHODS: All patients were ≥75yo. Recorded data included use of anticoagulant/antiplatelet drugs, ASA, operative time, intra-operative complications, pre/post-operative hemoglobin values, transfusions, hospitalization time, DVT/PE, glomerular filtration rate, Charlson Comorbidity Index (CCI), dislocation at 60 days, and mortality at 30 days and 6 months. A secondary analysis compared the subgroups in different age range (75-85 and ≥ 86yo). RESULTS: In the cohort of 302 DFNF (93 BHA and 209 DMTHA) differences in mean age, CCI, and ASA score were significant. Once divided by age, the subgroups resulted comparable in terms of age and CCI, with no significant difference. A significant difference in surgical times showed DMTHA being an average 12 minutes longer than BHA. Significant was the ΔHB in the DMTHA subgroup which resulted lower compared to the BHA one. Difference in mean number of post-operative transfusion were not statistically significant. CONCLUSIONS: From our data, DMTHA did not lead to an increase in mortality, morbidity, bleeding, or dislocation rate when compared to BHA and could be considered as treatment of choice for DFNFs especially in healthy and active patients.

Behavioral phenotyping of a rat model of the BDNF Val66Met polymorphism reveals selective impairment of fear memory.

The common brain-derived neurotrophic factor (BDNF) Val66Met polymorphism is associated with reduced activity-dependent BDNF release and increased risk for anxiety disorders and PTSD. Here we behaviorally phenotyped a novel Val66Met rat model with an equivalent valine to methionine substitution in the rat Bdnf gene (Val68Met). In a three-day fear conditioning protocol of fear learning and extinction, adult rats with the Met/Met genotype demonstrated impaired fear memory compared to Val/Met rats and Val/Val controls, with no genotype differences in fear learning or extinction. This deficit in fear memory occurred irrespective of the sex of the animals and was not seen in adolescence (4 weeks of age). There were no changes in open-field locomotor activity or anxiety measured in the elevated plus maze (EPM) nor in other types of memory measured using the novel-object recognition test or Y-maze. BDNF exon VI expression in the dorsal hippocampus was higher and BDNF protein level in the ventral hippocampus was lower in female Val/Met rats than female Val/Val rats, with no other genotype differences, including in total BDNF, BDNF long, or BDNF IV mRNA. These data suggest a specific role for the BDNF Met/Met genotype in fear memory in rats. Further studies are required to investigate gene-environment interactions in this novel animal model.