Photobiomodulation therapy alleviates repeated closed head injury-induced anxiety-like behaviors

Repeated closed head injury (rCHI) is one of the most common brain injuries. Although extensive studies have focused on how to treat rCHI-induced brain injury and reduce the possibility of developing memory deficits, the prevention of rCHI-induced anxiety has received little research attention. The current study was designed to assess the effects of photobiomodulation (PBM) therapy in preventing anxiety following rCHI. The rCHI disease model was constructed by administering three repeated closed-head injuries within an interval 5 days. 2-min daily PBM therapy using an 808 nm continuous wave laser at 350 mW/cm2 on the scalp was implemented for 20 days. We found that PBM significantly ameliorated rCHII-induced anxiety-like behaviors, neuronal apoptosis, neuronal injury, promotes astrocyte/microglial polarization to anti-inflammatory phenotype, preserves mitochondrial fusion-related protein MFN2, attenuates the elevated mitochondrial fission-related protein DRP1, and mitigates neuronal senescence. We concluded that PBM therapy possesses great potential in preventing anxiety following rCHI.

Methylene Blue Pretreatment Protects Against Repeated Neonatal Isoflurane Exposure-Induced Brain Injury and Memory Loss

Perioperative neurocognitive impairment (PND) is a common medical complication in the postoperative period. General anesthesia through volatile anesthetics poses a high risk of POCD. Moreover, the developing brain is especially vulnerable to anesthesia-induced neurotoxicity. Therefore, finding a practical approach to prevent or alleviate neonatal isoflurane (ISO) exposure-induced brain injury and cognitive decline is essential for reducing medical complications following major surgery during the early postnatal period. Using a repeated neonatal ISO exposure-induced PND rat model, we investigated the effects of methylene blue (MB) pretreatment on repeated neonatal isoflurane exposure-induced brain injury and memory loss. Intraperitoneal injection of low-dose MB (1 mg/kg) was conducted three times 24 h before each ISO exposure. The Barnes maze and novel objection test were conducted to assess learning and memory. Immunofluorescence staining, F-Jade C staining, TUNEL staining, and Western blot analysis were performed to determine mitochondrial fragmentation, neuronal injury, degeneration, and apoptosis. Evans blue extravasation assay, total antioxidant capacity assay, MDA assay kit, and related inflammatory assay kits were used to test blood-brain barrier (BBB) disruption, antioxidant capacity, and neuroinflammation. Behavioral tests revealed that MB pretreatment significantly ameliorated ISO exposure-induced cognitive deficits. In addition, MB pretreatment alleviates neuronal injury, apoptosis, and degeneration. Furthermore, the BBB integrity was preserved by MB pretreatment. Additional studies revealed that ISO-induced excessive mitochondrial fragmentation, oxidative stress, and neuroinflammation were significantly attenuated by MB pretreatment in the PND rat model. Our findings suggest that MB pretreatment alleviates ISO exposure-induced brain injury and memory loss for the first time, supporting MB pretreatment as a promising approach to protect the brain against neonatal ISO exposure-induced postoperative cognitive dysfunction.

Oligodendrocyte progenitor cells in Alzheimer's disease: from physiology to pathology

Oligodendrocyte progenitor cells (OPCs) play pivotal roles in myelin formation and phagocytosis, communicating with neighboring cells and contributing to the integrity of the blood-brain barrier (BBB). However, under the pathological circumstances of Alzheimer's disease (AD), the brain's microenvironment undergoes detrimental changes that significantly impact OPCs and their functions. Starting with OPC functions, we delve into the transformation of OPCs to myelin-producing oligodendrocytes, the intricate signaling interactions with other cells in the central nervous system (CNS), and the fascinating process of phagocytosis, which influences the function of OPCs and affects CNS homeostasis. Moreover, we discuss the essential role of OPCs in BBB formation and highlight the critical contribution of OPCs in forming CNS-protective barriers. In the context of AD, the deterioration of the local microenvironment in the brain is discussed, mainly focusing on neuroinflammation, oxidative stress, and the accumulation of toxic proteins. The detrimental changes disturb the delicate balance in the brain, impacting the regenerative capacity of OPCs and compromising myelin integrity. Under pathological conditions, OPCs experience significant alterations in migration and proliferation, leading to impaired differentiation and a reduced ability to produce mature oligodendrocytes. Moreover, myelin degeneration and formation become increasingly active in AD, contributing to progressive neurodegeneration. Finally, we summarize the current therapeutic approaches targeting OPCs in AD. Strategies to revitalize OPC senescence, modulate signaling pathways to enhance OPC differentiation, and explore other potential therapeutic avenues are promising in alleviating the impact of AD on OPCs and CNS function. In conclusion, this review highlights the indispensable role of OPCs in CNS function and their involvement in the pathogenesis of AD. The intricate interplay between OPCs and the AD brain microenvironment underscores the complexity of neurodegenerative diseases. Insights from studying OPCs under pathological conditions provide a foundation for innovative therapeutic strategies targeting OPCs and fostering neurodegeneration. Future research will advance our understanding and management of neurodegenerative diseases, ultimately offering hope for effective treatments and improved quality of life for those affected by AD and related disorders.

An electrical stimulation intervention protocol to prevent disuse atrophy and muscle strength decline: an experimental study in rat

BACKGROUND

Skeletal muscle is negatively impacted by conditions such as spaceflight or prolonged bed rest, resulting in a dramatic decline in muscle mass, maximum contractile force, and muscular endurance. Electrical stimulation (ES) is an essential tool in neurophysiotherapy and an effective means of preventing skeletal muscle atrophy and dysfunction. Historically, ES treatment protocols have used either low or high frequency electrical stimulation (LFES/HFES). However, our study tests the use of a combination of different frequencies in a single electrical stimulation intervention in order to determine a more effective protocol for improving both skeletal muscle strength and endurance.

METHODS

An adult male SD rat model of muscle atrophy was established through 4 weeks of tail suspension (TS). To investigate the effects of different frequency combinations, the experimental animals were treated with low (20 Hz) or high (100 Hz) frequency before TS for 6 weeks, and during TS for 4weeks. The maximum contraction force and fatigue resistance of skeletal muscle were then assessed before the animals were sacrificed. The muscle mass, fiber cross-sectional area (CSA), fiber type and related protein expression were examined and analyzed to gain insights into the mechanisms by which the ES intervention protocol used in this study regulates muscle strength and endurance.

RESULTS

After 4 weeks of unloading, the soleus muscle mass and fiber CSA decreased by 39% and 58% respectively, while the number of glycolytic muscle fibers increased by 21%. The gastrocnemius muscle fibers showed a 51% decrease in CSA, with a 44% decrease in single contractility and a 39% decrease in fatigue resistance. The number of glycolytic muscle fibers in the gastrocnemius also increased by 29%. However, the application of HFES either prior to or during unloading showed an improvement in muscle mass, fiber CSA, and oxidative muscle fibers. In the pre-unloading group, the soleus muscle mass increased by 62%, while the number of oxidative muscle fibers increased by 18%. In the during unloading group, the soleus muscle mass increased by 29% and the number of oxidative muscle fibers increased by 15%. In the gastrocnemius, the pre-unloading group showed a 38% increase in single contractile force and a 19% increase in fatigue resistance, while in the during unloading group, a 21% increase in single contractile force and a 29% increase in fatigue resistance was observed, along with a 37% and 26% increase in the number of oxidative muscle fibers, respectively. The combination of HFES before unloading and LFES during unloading resulted in a significant elevation of the soleus mass by 49% and CSA by 90%, with a 40% increase in the number of oxidative muscle fibers in the gastrocnemius. This combination also resulted in a 66% increase in single contractility and a 38% increase in fatigue resistance.

CONCLUSION

Our results indicated that using HFES before unloading can reduce the harmful effects of muscle unloading on the soleus and gastrocnemius muscles. Furthermore, we found that combining HFES before unloading with LFES during unloading was more effective in preventing muscle atrophy in the soleus and preserving the contractile function of the gastrocnemius muscle.