Overtraining is a condition characterized by various functional disorders or pathological states caused by continuous fatigue, which occurs after a persisting imbalance between training-related load and physical function and recovery. Generally speaking, it’s a state of imbalance between training and recovery, exercise and exercise performance, and stress and stress tolerance. Overtraining can cause various phenotypic changes or pathological remodeling, such as decreased skeletal muscle strength and exhaustive exercise endurance, skeletal muscle fatigue damage and dysfunction, skeletal muscle atrophy and loss, skeletal muscle glycogen depletion, skeletal muscle soreness and stiffness, skeletal muscle glucose intolerance, inattention, memory decline, anxiety, depression, abnormal emotions and behaviors, sleep disorders, cognitive function impairment, poor appetite, weight loss, liver/heart fat deposition, compensatory increase of liver/heart insulin signaling and glycogen storage, cardiac pathological hypertrophy, exercise-induced arrhythmias, myocardial fibrosis, ectopic and visceral fat deposition, and increased risk of injury. Unfortunately, its underlying mechanism is largely unclear. Recently, the enrichment of molecular and cellular signal pathway theory offers us a new explanatory paradigm for revealing its internal mechanisms. Based on the traditional explanation mechanisms and molecular and cellular signal pathway theory, we thoroughly analyzed the key mechanisms of health damage caused by overtraining from the perspective of oxidative stress, mitochondrial quality control disorder, inflammatory response, endoplasmic reticulum stress, cell apoptosis, and so forth. Specifically, overtraining-induced excessive reactive oxygen species (ROS) leads to serious oxidative stress damage in organisms at least via depressing Kelch like ECH associated protein 1(Keap1)/nuclear factor erythroid-2-related factor (Nrf2)/antioxidant response element (ARE) antioxidant pathway and activating p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway. Overtraining induces mitochondrial quality control disorder and mitochondrial dysfunction, and thus triggers health impairment through inhibiting mitochondrial biogenesis and fusion, stimulating mitochondrial fission, and over-activating autophagy/mitophagy. Overtraining can also produce muscle, skeletal and joint trauma, then circulating monocytes are abundantly activated by injury-related cytokines, and in turn generate large quantities of proinflammatory IL-1β, IL-6, TNF‑α, causing systemic inflammation and inflammatory health injury. Overtraining induces excessive pathological endoplasmic reticulum stress (ERS) and severe health damage via PERK-eIF2α, IRE1α-XBP1 and ATF6 pathways which activated by proinflammatory signals. Overtraining also induces excessive apoptosis and harmful health consequences via Bax/Bcl2-Caspase 3-mediated mitoptosis which activated by oxidative stress and inflammation or even CHOP and Caspase 12-dependent ERS apoptosis. Nonetheless, it should be importantly emphasized that oxidative stress and inflammation are the central and pre-emptive mechanisms of overtraining and its health damage. Although the efficient strategies for preventing and controlling overtraining are scientifically and reasonably arranging and planning training intensity, training volume, and recovery period, as well as accurately assessing and monitoring physical function status in the early stage, yet various anti-inflammatory, anti-oxidant, anti-apoptotic, or anti-aging drugs such as curcumin, astaxanthin, oligomeric proanthocyanidins, silibinin, hibiscus sabdariffa, dasatinib, quercetin, hydroxytyrosol, complex probiotics, astragalus polysaccharides, semaglutide and fasudil also have an irreplaceable positive effect on preventing overtraining and its relevant health damage via depressing oxidative stress, mitochondrial quality control disorder, proinflammatory signals, endoplasmic reticulum stress, apoptosis and so on. We hope that this review can help us further grasp the features, mechanisms and regularity of overtraining, and provide an important reference for athletes and sports fan to conduct scientific training, improve training effectiveness, extend exercise lifespan, and promote physical and mental health.

The main characteristics of neurodegenerative diseases represented by Alzheimer’s disease (AD) and Parkinson’s disease (PD) is the progressive irreversible loss of neurons, leading to varying degrees of pathological changes and loss of cognitive function. There is still no effective treatment. With the acceleration of global aging society, the incidence of neurodegenerative diseases is rapidly increasing, becoming a serious global public health concern that urgently requires the development of effective therapeutic strategies. The Hippo signaling pathway, a highly evolutionarily conserved pathway, consists of the core components MST1/2, LATS1/2, and downstream effectors, transcriptional co-activators YAP and TAZ. It plays a crucial role in the regulation of various biological processes such as cell proliferation, differentiation, development, and apoptosis. Dysregulation of the Hippo pathway contributes to the development of many diseases, including cancer, cardiovascular diseases, immune disorders, etc. Therefore, targeting the dysregulated components of the Hippo pathway may be an effective strategy for treating various diseases. Increasing evidence indicates that the Hippo pathway is excessively activated in the development of neurodegenerative diseases, manifested by increased expression of MST1 and downregulation of YAP. Stabilizing the Hippo pathway levels has shown improvements in AD and PD. However, most studies on the Hippo pathway in AD and PD focus on changes in the expression levels of Hippo pathway components, and research in other neurodegenerative diseases is still lacking. Therefore, further investigation is needed to fully understand the mechanistic role of the Hippo pathway in neurodegenerative diseases. Meanwhile, miRNA, similarly dysregulated in neurodegenerative diseases and serving as biomarkers, is a primary target for miRNA therapy in neurodegenerative diseases, including AD and PD. Activating or inhibiting dysregulated miRNAs is the main strategy of miRNA therapy during the neurodegenerative disease development. Evidence suggests that the interaction between the Hippo pathway and miRNA can result in widespread biological effects and crosstalk in the occurrence of different types of diseases. However, studies on the interplay between the Hippo pathway and miRNA in neurodegenerative diseases are relatively scarce. In this paper, we predicted the miRNAs related to Hippo pathway through bioinformatics database, and further screened the miRNAs with crosstalk relationship with Hippo signaling pathway through experiments in combination with PubMed. Then, the mechanism of action of Hippo signaling pathway related miRNAs in AD and PD is further elucidated. It is reported that the Hippo pathway and its related miRNA may exert neuroprotective effects by reducing oxidative stress, improving neuroinflammation, stabilizing autophagy levels, maintaining neuronal mitochondrial function, and ameliorating blood-brain barrier dysfunction, thereby delaying the progression of AD and PD. However, research on miRNA directly regulating the Hippo pathway to improve AD and PD is limited, and observations of the Hippo pathway and its related miRNA in other neurodegenerative diseases are scarce. However, considering the regulatory relationship between the Hippo pathway and miRNA in multiple diseases and their respective roles in key mechanisms of neurodegenerative diseases, such as oxidative stress and neuroinflammation, the crosstalk between miRNA and the Hippo pathway holds a crucial regulatory role in the development of neurodegenerative diseases. Thus, the interaction pathways of the Hippo pathway and its related miRNA may be a pivotal avenue for exploring effective therapeutic strategies for neurodegenerative diseases in the future.

Cognitive dysfunction is one of the serious complications of type 2 diabetes.Exercise interven-tion has a certain effect on improving diabetes cognition,but the exact process remains ambiguous.This research aims to explore the impact and molecular processes of treadmill exercises in enhancing cognitive impairments in type 2 diabetic mice.Ten m/m 8-week-old male mice were used as the control group.Forty db/db mice,each 8 weeks old and male,were categorized into four distinct groups with each group containing 10 mice,including the db/db group(model group),db+Exe group(exercise group),db+Exe+SB203580 group(exercise combined with the p38 MAPK inhibitor group),db+SB203580 group(p38 MAPK inhibitor group).db+Exe group and db+Exe+SB203580 group were subjected to treadmill running intervention(40 min/time,5 times/week,a total of 8 weeks).db+Exe+SB203580 and db+SB203580 group were intraperitoneally injected with SB203580(5 mg/kg,5 times/week,8 weeks)2 hours before treadmill exercise.The results of body weights and fasting blood glucose measurement showed that 8-week treadmill exercise could significantly reduce the body mass and fasting blood glucose levels(P＜0.01);the results of water maze showed that treadmill exercise improved cognitive dysfunction in diabetic mice(P＜0.05).Immunofluorescence staining revealed that treadmill exercise diminished the fluorescence intensity of NLRP3 in hippocampus,and there was a significant difference in CA1 and CA3 regions(P＜0.05).Treadmill exercise reduced the fluorescence intensity of PI in the hippocampus,and there was a significant difference in the DG region(P＜0.01).The results of qRT-PCR revealed that treadmill exercise decreased IL-1β and IL-18 mRNA levels in hippocampus,with a notable difference in IL-1β mRNA levels(P＜0.05).Western blotting analysis revealed that treadmill exercise reduced the concentrations of Caspase3,Caspase9 and Bax in hippocampus(P＜0.01),reduced the concentrations of TXNIP,NLRP3,GSDMD-N,IL-1β,IL-18,Cleaved Caspase1 and Caspasel(P＜0.05),decreased the levels of p-RIPK1,RIPK1,p-RIPK3 and RIPK3(P＜0.05).After adding p38 inhibitors,treadmill ex-ercise combined with p38 inhibitor intervention further inhibited the expression of Caspase3,TXNIP,GS-DMD-N and IL-18(P＜0.05),and the expression levels of Caspase9,Bax,NLRP3,IL-1β,Cleaved Caspase 1 and Caspase 1 also showed a downward trend.The expression of RIPK1 and p-RIPK3 in-creased significantly(P＜0.05),and the protein expression levels of p-p38,p-RIPK1 and RIPK3 showed an upward trend.In conclusion,treadmill running intervention can effectively improve the cogni-tive dysfunction in type 2 diabetic mice,and its mechanism is partly through the p38 MAPK signaling pathway to regulate PANoptosis.

ObjectiveTo explore the mechanism of treadmill exercise against type 2 diabetes mellitus (T2DM) with non-alcoholic fatty liver disease (NAFLD) based on the regulator effects of exercise on ferroptosis. MethodsEight 8-week-old male m/m mice were used as control group (Con, n=8), and db/db mice of the matched age were randomly divided into T2DM model group (db/db, n=8), exercise group (db+Exe, n=8), p38 mitogen-activated protein kinase (MAPK) inhibitor group (db+SB203580, n=8) and exercise combined with p38 MAPK inhibitor group (db+Exe+SB203580, n=8). After one-week adaptive feeding, the mice in the db+Exe group and db+Exe+SB203580 group underwent moderate intensity treadmill exercise for 40 min/d, 5 d/week lasting 8 weeks. The db+SB203580 group and db+Exe+SB203580 group were treated with SB203580 (a specific inhibitor of p38 MAPK) with a dose of 5 mg/kg, 5 d/week for 8 weeks. And the exercise intervention was performed 2 h later after the intraperitoneal injection of SB203580. The body weight and fasting blood glucose of mice were measured regularly every week during the experiment. After 24 h of the last intervention, the mice were weighted, the liver tissues were taken, weighted and the liver index was calculated. The pathological changes of liver were determined by Oil Red O and hematoxylin-eosin (HE) staining. The levels of blood lipids, liver function, Fe²⁺ and oxidative stress markers of liver were measured by enzyme linked immunosorbent assay (ELISA). The related mRNA expression levels of lipogenesis and inflammation were evaluated by quantitative reverse transcriptase-mediated PCR (qRT-PCR). The related protein expression levels of lipogenesis and ferroptosis in liver were determined by immunohistochemical (IHC) staining and Western blot. ResultsThe body weight, fasting blood glucose, liver index, blood lipid and transaminase levels in the db/db group were significantly increased compared with the Con group. HE and Oil Red O staining showed severe lipid accumulation and ballooning change in the liver of db/db mice. Biochemical tests showed that Fe²⁺ and MDA level of liver constitution homogenate increased, while GSH level decreased significantly. The results of qRT-PCR showed that the mRNA levels of MCP-1, IL-6, SREBF1 and ACC1 in liver tissue of db/db mice were all significantly increased. Western blot results showed that the expression levels of SREBF1, ACC1 increased, ferroptosis relative proteins were significantly decreased. The 8 weeks of exercise significantly reduced the rise in body weight, blood glucose, liver index and blood lipid levels in db/db mice. Exercise intervention also alleviated hepatic steatosis and reduced the expression levels of Fe²⁺, MDA, MCP-1, IL-6, ACC1 and SREBF1, upregulated the expression levels of GSH, NRF2, HO-1, SLC7A11 and GPX4 in liver tissue of db/db mice. The intervention of exercise combined with SB203580 significantly down-regulated the mRNA expression levels of ACC1, MCP-1, IL-6, reduced the levels of Fe²⁺ and MDA, and up-regulated the level of GSH in db/db mice. Compared with the db+Exe group, the expression of Fe²⁺, MDA, MCP-1, and SREBF1 in the liver of the db+Exe+SB203580 group mice significantly increased, while the expression level of GSH and expression levels of ferroptosis relative proteins also significantly decreased. In addition, compared with db+SB203580 group, the iron accumulation and lipid peroxidation in the liver of db+Exe+SB203580 group were significantly improved. ConclusionThe8-week treadmill exercise can effectively alleviate liver injury and steatosis, and its mechanism may be related to the inhibition of hepatocyte ferroptosis through p38 MAPK signal.