Neuronal nuclear calcium signaling suppression of microglial reactivity is mediated by osteoprotegerin after traumatic brain injury.

BACKGROUND: Traumatic brain injury (TBI) is characterized by massive changes in neuronal excitation, from acute excitotoxicity to chronic hyper- or hypoexcitability. Nuclear calcium signaling pathways are involved in translating changes in synaptic inputs and neuronal activity into discrete transcriptional programs which not only affect neuronal survival and synaptic integrity, but also the crosstalk between neurons and glial cells. Here, we report the effects of blunting neuronal nuclear calcium signals in the context of TBI. METHODS: We used AAV vectors to express the genetically encoded and nuclear-targeted calcium buffer parvalbumin (PV.NLS.mCherry) or the calcium/calmodulin buffer CaMBP4.mCherry in neurons only. Upon TBI, the extent of neuroinflammation, neuronal death and synaptic loss were assessed by immunohistochemistry and targeted transcriptome analysis. Modulation of the overall level of neuronal activity was achieved by PSAM/PSEM chemogenetics targeted to parvalbumin interneurons. The functional impact of neuronal nuclear calcium buffering in TBI was assessed by quantification of spontaneous whisking. RESULTS: Buffering neuronal nuclear calcium unexpectedly resulted in a massive and long-lasting increase in the recruitment of reactive microglia to the injury site, which was characterized by a disease-associated and phagocytic phenotype. This effect was accompanied by a substantial surge in synaptic loss and significantly reduced whisking activity. Transcriptome analysis revealed a complex effect of TBI in the context of neuronal nuclear calcium buffering, with upregulation of complement factors, chemokines and interferon-response genes, as well as the downregulation of synaptic genes and epigenetic regulators compared to control conditions. Notably, nuclear calcium buffering led to a substantial loss in neuronal osteoprotegerin (OPG), whereas stimulation of neuronal firing induced OPG expression. Viral re-expression of OPG resulted in decreased microglial recruitment and synaptic loss. OPG upregulation was also observed in the CSF of human TBI patients, underscoring its translational value. CONCLUSION: Neuronal nuclear calcium signals regulate the degree of microglial recruitment and reactivity upon TBI via, among others, osteoprotegerin signals. Our findings support a model whereby neuronal activity altered after TBI exerts a powerful impact on the neuroinflammatory cascade, which in turn contributes to the overall loss of synapses and functional impairment.

[Sleep disorders and impaired sleep as adverse drug reactions of psychotropic drugs: an evaluation of data of summaries of product characteristics]. / Schlafstörungen und Beeinträchtigungen des Schlafs als Nebenwirkungen von Psychopharmaka: eine Bewertung der Daten aus Fachinformationen.

OBJECTIVE: Psychopharmacotherapy is essential in the treatment of many mental disorders. Adverse drug reactions (ADR) have impact on compliance and tolerability. Sleep disorders or impaired sleep may occur as ADRs of psychopharmacotherapy. Sleep disorders are associated with an increased risk for physical and mental illness and may impair cognition, impulse control, emotion regulation and mood. Objective of the following study was the systematic presentation of type and risk of sleep disorders/impairments of sleep of frequently prescribed psychotropic drugs. METHODS: Psychotropic agents that are most frequently prescribed in Germany were identified by using the Arzneiverordnungs-Report 2016. Summaries of product characteristics (SmPC) of corresponding original products were analyzed regarding presence and frequency of sleep disorders/impairments of sleep according to the International Classification of Sleep Disorders 3 (ICSD-3). RESULTS: N = 64 SmPCs were analyzed. In most of the analyzed SmPCs, at least one sleep disorder (50/64; 78 %) was listed. At least one SmPC with a corresponding ADR was found in the categories insomnia (52 %), parasomnias (33 %), and sleep-related movement disorders (20 %); sleep-related breathing disorders (6 %) and central disorders of hypersomnolence (5 %) were rarely listed; circadian rhythm sleep-wake disorder was not found. The SmPCs of the four most frequently prescribed agents (citalopram > venlafaxine > mirtazapine > sertraline) listed insomnia as an ADR. Nearly all analysed hypnotics (except chloral hydrate) were associated with nightmares. CONCLUSION(S): Most of the psychotropic agents frequently prescribed in Germany may induce sleep disorders/impairments of sleep. The four most frequently prescribed agents were antidepressants and all of the corresponding SmPCs listed insomnia as a possible ADR. Sleep disorders should be taken seriously as possible ADRs of psychopharmacotherapy.