Effect of carnosine, methylprednisolone and their combined application on irisin levels in the plasma and brain of rats with acute spinal cord injury

Effects of grape seed proanthocyanidin extract on side effects of high-dose methylprednisolone administration in male rats

In this study, we investigated the effects of grape seed proanthocyanidin extract (GSPE) against the side effects of high-dose administration of methylprednisolone (MP) in male rats. A total of 32 adult Wistar male albino rats were divided into four groups: (1) control (CON), received standard food only; (2) MP, received standard food + intraperitoneal injection of 60 mg/kg MP on day 7; (3) GSPE, received standard food + 200 mg/kg/day GSPE; and (4) MP + GSPE, received standard food + 200 mg/kg/day of GSPE + intraperitoneal injection of 60 mg/kg MP on day 7. All animals in the GSPE and GSPE + MP groups were treated once a day by oral gavage for 14 consecutive days. The feed intake of rats in the MP and MP + GSPE groups decreased significantly by 24.14% and 13.52%, respectively (p < 0.05). Administration of MP resulted in significant increases in serum concentrations of blood urea nitrogen (p < 0.001), glucose (p < 0.01), alkaline phosphatase, and adrenocorticotropic hormone (p < 0.05). High-dose MP administration significantly reduced catalase (p < 0.001) and glutathione peroxidase (p < 0.05) concentrations in the liver and kidney tissues of rats, while glutathione concentrations were only reduced in liver tissue (p < 0.05). The expression levels of Bcl-2 and TNF-α in liver, kidney, and testicular tissue were significantly increased, while the expression levels of caspase-3 were reduced (p < 0.001). Furthermore, sperm concentration was significantly affected by GSPE in rats induced by high-dose MP, and sperm loss was significantly reduced in MP + GSPE (p < 0.05). These findings suggest that GSPE could be useful as a supplement to alleviate MP-induced toxicity in rats.

Move Your Body toward Healthy Aging: Potential Neuroprotective Mechanisms of Irisin in Alzheimer's Disease

Alzheimer's disease (AD) is the leading cause of dementia in older adults, having a significant global burden and increasing prevalence. Current treatments for AD only provide symptomatic relief and do not cure the disease. Physical activity has been extensively studied as a potential preventive measure against cognitive decline and AD. Recent research has identified a hormone called irisin, which is produced during exercise, that has shown promising effects on cognitive function. Irisin acts on the brain by promoting neuroprotection by enhancing the growth and survival of neurons. It also plays a role in metabolism, energy regulation, and glucose homeostasis. Furthermore, irisin has been found to modulate autophagy, which is a cellular process involved in the clearance of protein aggregates, which are a hallmark of AD. Additionally, irisin has been shown to protect against cell death, apoptosis, oxidative stress, and neuroinflammation, all of which are implicated in AD pathogenesis. However, further research is needed to fully understand the mechanisms and therapeutic potential of irisin in AD. Despite the current gaps in knowledge, irisin holds promise as a potential therapeutic target for slowing cognitive decline and improving quality of life in AD patients.

Trehalose-Carnosine Prevents the Effects of Spinal Cord Injury Through Regulating Acute Inflammation and Zinc(II) Ion Homeostasis

Spinal cord injury (SCI) leads to long-term and permanent motor dysfunctions, and nervous system abnormalities. Injury to the spinal cord triggers a signaling cascade that results in activation of the inflammatory cascade, apoptosis, and Zn(II) ion homeostasis. Trehalose (Tre), a nonreducing disaccharide, and L-carnosine (Car), (β-alanyl-L-histidine), one of the endogenous histidine dipeptides have been recognized to suppress early inflammatory effects, oxidative stress and to possess neuroprotective effects. We report on the effects of the conjugation of Tre with Car (Tre-car) in reducing inflammation in in vitro and in vivo models. The in vitro study was performed using rat pheochromocytoma cells (PC12 cell line). After 24 h, Tre-car, Car, Tre, and Tre + Car mixture treatments, cells were collected and used to investigate Zn²⁺ homeostasis. The in vivo model of SCI was induced by extradural compression of the spinal cord at the T6-T8 levels. After treatments with Tre, Car and Tre-Car conjugate 1 and 6 h after SCI, spinal cord tissue was collected for analysis. In vitro results demonstrated the ionophore effect and chelating features of L-carnosine and its conjugate. In vivo, the Tre-car conjugate treatment counteracted the activation of the early inflammatory cascade, oxidative stress and apoptosis after SCI. The Tre-car conjugate stimulated neurotrophic factors release, and influenced Zn²⁺ homeostasis. We demonstrated that Tre-car, Tre and Car treatments improved tissue recovery after SCI. Tre-car decreased proinflammatory, oxidative stress mediators release, upregulated neurotrophic factors and restored Zn²⁺ homeostasis, suggesting that Tre-car may represent a promising therapeutic agent for counteracting the consequences of SCI.

Physical activity ameliorates the function of organs via adipose tissue in metabolic diseases

Adipose tissue is a dynamic organ in the endocrine system that can connect organs by secreting molecules and bioactive. Hence, adipose tissue really plays a pivotal role in regulating metabolism, inflammation, energy homeostasis, and thermogenesis. Disruption of hub bioactive molecules secretion such as adipokines leads to dysregulate metabolic communication between adipose tissue and other organs in non-communicable disorders. Moreover, a sedentary lifestyle may be a risk factor for adipose tissue function. Physical inactivity leads to fat tissue accumulation and promotes obesity, Type 2 diabetes, cardiovascular disease, neurodegenerative disease, fatty liver, osteoporosis, and inflammatory bowel disease. On the other hand, physical activity may ameliorate and protect the body against metabolic disorders, triggering thermogenesis, metabolism, mitochondrial biogenesis, β-oxidation, and glucose uptake. Furthermore, physical activity provides an inter-organ association and cross-talk between different tissues by improving adipose tissue function, reprogramming gene expression, modulating molecules and bioactive factors. Also, physical activity decreases chronic inflammation, oxidative stress and improves metabolic features in adipose tissue. The current review focuses on the beneficial effect of physical activity on the cardiovascular, locomotor, digestive, and nervous systems. In addition, we visualize protein-protein interactions networks between hub proteins involved in dysregulating metabolic induced by adipose tissue.

Swimming exercise versus L-carnosine supplementation for Alzheimer's dementia in rats: implication of circulating and hippocampal FNDC5/irisin

Recent studies have suggested that irisin may act as a potential neurokine. Exercise and L-carnosine supplementation showed neuroprotective effects in Alzheimer's disease (AD)-like conditions. However, the regulation of irisin in the hippocampus of streptozotocin (STZ)-induced memory impairment and its relation to insulin signalling remain to be investigated. This study was designed to compare the effect of swimming exercise and L-carnosine intake on serum, CSF and hippocampal irisin in rats received intracerebroventricular (ICV) injection of STZ. Rats were recruited in swimming paradigm, received oral carnosine (100 mg/kg/day) or vehicle treated. After 5 weeks, rats were sacrificed after neurobehavioural testing. CSF and serum irisin were determined. Hippocampal tissues were used to assess expression of FNDC5/irisin, BDNF and proteins related to insulin signalling, in addition to β-amyloid peptide and phosphorylated tau protein levels. We observed decreased hippocampal, but not CSF or serum, irisin in ICV-STZ-injected rats. Exercise and carnosine intake almost normalized hippocampal FNDC5/irisin expression which was associated with reduced soluble β-amyloid peptide and phosphorylated tau protein, improved BDNF and insulin signalling proteins, with corresponding mitigated cognitive impairments. However, hippocampal FNDC5/irisin was not correlated with serum or CSF irisin levels. Histologically, both interventions ameliorated the hippocampal damage in STZ-injected rats. The current study reveals that carnosine is equivalent to exercise in reversing cognitive decline and Alzheimer's biomarkers. In both interventions, enhancement of hippocampal FNDC5/irisin and insulin signalling may be involved in mediating these neuroprotective effects.

Irisin levels in the serum and cerebrospinal fluid of patients with multiple sclerosis and the expression and distribution of irisin in experimental autoimmune encephalomyelitis

Irisin is a novel hormone-like myokine that plays an important role in central nervous system (CNS) diseases, such as cerebral ischaemia and Alzheimer's disease. However, irisin is rarely investigated in multiple sclerosis (MS), a typical inflammatory demyelinating disease of the CNS, and in experimental autoimmune encephalomyelitis (EAE), a typical model of MS. We determined the levels of irisin in the serum and cerebrospinal fluid in patients with MS. The expression and histological distribution of irisin were determined in EAE. Serum irisin levels in patients with MS and in EAE mice were increased, and the levels of FNDC5/irisin mRNA were decreased in the spinal cord and brain regardless of the onset, peak or chronic phase of EAE. Immunofluorescence staining showed co-localization of irisin and neurones. The levels of irisin fluctuated with disease progression in MS and EAE. Irisin may be involved in the pathological process of MS/EAE.

Molecular identification of FNDC5 and effect of irisin on the glucose metabolism in common carp (Cyprinus carpio L.)

Irisin, encoded by fibronectin type III domain-containing protein 5 (FNDC5) gene, plays a role in energy expenditure and insulin sensitivity in mice. In fish, the function of irisin related to glucose metabolism is less reported. It may increase glucose utilization in fish. The aim of the present study was to characterize the regulatory role of irisin in glucose metabolism in common carp (Cyprinus carpio L.). In this study, FNDC5a and FNDC5b were isolated from common carp. The cDNA of FNDC5a and FNDC5b were 722 bp and 714 bp, encoding 221 and 207 amino acids, respectively. FNDC5a was abundantly expressed in the brain and gonad. FNDC5b was mainly expressed in brain. Different expression pattern of FNDC5a and FNDC5b under fasting/refeeding and OGTT experiment were identified. The recombinant common carp irisinA and irisinB were prepared by prokaryotic expression system. Glucose concentration was decreased in treatment with irisinA or irisinB in the in vitro and in vivo experiments. The mRNA expression levels of gluconeogenesis-related genes were significantly down-regulated, while the mRNA expression of glycolysis-related genes were significantly up-regulated after treatment with recombinant irisinA or irisinB in liver in vivo and in primary hepatocytes in vitro. Our research shows that irisin inhibits hepatic gluconeogenesis and promotes hepatic glycolysis. Taken together, this study for the first time revealed the two subtypes of FNDC5 and explored the function and mechanisms of irisinA and irisinB in fish glucose homeostasis.

Irisin Protects Against Motor Dysfunction of Rats with Spinal Cord Injury via Adenosine 5'-Monophosphate (AMP)-Activated Protein Kinase-Nuclear Factor Kappa-B Pathway

The aim of the present research was to investigate the effects of irisin, a skeletal muscle-derived myokine, on spinal cord injury (SCI) in rats and explore the possible mechanisms. SCI model was constructed in male SD rats. The effects of irisin on SCI rats were assessed via behavior tests including Basso, Beattie, and Bresnahan (BBB) scoring method and inclined plane test, followed by histomorphology tests including HE staining, Nissl staining, and transmission electron microscope examination. Biochemical analyses including PCR, Western blots and ELISA were employed to further evaluate the changes at molecular level of SCI rats. In addition, lipopolysaccharide (LPS)-induced cell damage model was established in PC12 cells to verify the mechanism of irisin's effect on nerve cells in vitro. Results showed that the BBB score and the angle of incline significantly decreased after SCI surgery, however, chronic irisin treatment improved SCI-induced motor dysfunction. HE and Nissl staining assays showed that SCI surgery induced histological injury of spinal cord, which could be reversed by irisin treatment. Morphological abnormality of nerve cells caused by SCI also could be alleviated by irisin. Further biochemical analyses showed that irisin inhibited SCI-induced overexpression of Interleukin-1β (IL-1β), Interleukin- 6 (IL-6), tumor necrosis factor alpha (TNF-α), inducible nitricoxidesynthase (iNOS) and Cyclooxygenase-2 (COX-2)], as well as nuclear factor kappa-B (NF-κB)p65 in rats, and the positive function of irisin could be reversed by Compound C treatment. In our in vitro study, LPS-induced declines of cell viability and neurite length of PC12 cell were inhibited by irisin treatment, and irisin inhibited LPS-induced overexpression of NF-κBp65, IL-1β, IL-6, TNF-α, iNOS and COX-2. These changes could be reversed by activated protein kinase (AMPK) siRNA pre-treatment. Taken together, irisin could protect the rats from SCI, and its protection is associated with the regulation of adenosine 5'-monophosphate-activated protein kinase (AMPK)- NF-κB signaling pathway.

Effects of Carnosine, Ankaferd, and Silver Sulfadiazine on an Experimental Burn Model: Roles of Irisin and HSP70

In this study, the effects of carnosine, ankaferd, and 1% silver sulfadiazine applied topically on second-degree burns were investigated and the roles of irisin and Heat shock protein 70 (HSP70) in this healing process were evaluated. Ninety male albino rats were used and divided into five groups. The groups were classified as control, burn, burn + carnosine (CAR), burn + ankaferd (ABS), and burn + silver sulfadiazine (SS). It was found that level of irisin increased in the first week and decreased in the second week in the burn and CAR groups. In the ABS and SS groups, the level of irisin was determined that started to increase in the first week and continued to increase in the second week. The level of HSP70 was found to increased in the first week in burn and CAR groups and decreased in the second week, but started to increase in the second week in ABS and SS groups. Both levels of irisin and HSP70 were observed to decreased in all treatment groups in the third week. In this study, it was shown that ankaferd and silver sülfadiazine treatments cause an increase in the irisin levels in the early period and a gradually increase in HSP70 levels in the later period in burns. The inflammatory response was observed to be limited in the early period in the ankaferd and sulfadiazin groups. It was concluded that these findings were effective in early wound healing in burns.

Irisin Protects Brain against Ischemia/Reperfusion Injury through Suppressing TLR4/MyD88 Pathway

BACKGROUND

Inflammatory response exerts an important role in ischemia/reperfusion (I/R) injury. TLR4 and myeloid differentiation factor 88 (MyD88) are key components in inflammation and are involved in the cerebral I/R injury. Irisin is a skeletal muscle-derived myokine produced after exercise, which was found to suppress inflammation. In this study, we investigated whether irisin could protect the brain from I/R injury through the TLR4/MyD88 pathway.

METHODS

Male Sprague Dawley rats (20 months, 190 ∼ 240 g) were pretreated with irisin at 10, 50, or 100 mg/kg for consecutive 3 days and then subjected to surgery of middle cerebral artery occlusion or sham operation. Infarct size and neuron loss were measured to evaluate brain damage. The mRNA and protein levels of TLR4 and MyD88 were measured by in situ hybridization and immunohistochemistry, respectively. NF-κB activation was assessed by electrophoretic mobility shift assay. Neurological function was evaluated by neurobehavior score test and passive avoidance test.

RESULTS

Irisin could reduce neuronal damage and neurofunctional impairment after I/R injury. This effect was mediated by downregulating the TLR4/MyD88 and inhibiting NF-κB activation.

CONCLUSION

Irisin plays a beneficial effect in I/R injury through regulating the TLR4/MyD88 pathway.

Valproic acid-labeled chitosan nanoparticles promote recovery of neuronal injury after spinal cord injury

Chitosan nanoparticles have been recognized as a new type of biomaterials for treatment of spinal cord injury (SCI). To develop a novel treatment method targeted delivery injured spinal cord, valproic acid labeled chitosan nanoparticles (VA-CN) were constructed and evaluated in the treatment of SCI. Our results demonstrated that administration of VA-CN significantly promoted the recovery of the function and tissue repair after SCI. Moreover, we found treatment of VA-CN inhibited the reactive astrocytes after SCI. Furthermore, administration of VA-CN enhanced immunoreactions of neuronal related marker NF160, which suggested that VA-CN could promote the neuroprotective function in rats of SCI. The production of IL-1β, IL-6 and TNF-α were significantly decreased following treatment of VA-CN. Meanwhile, administration of VA-CN effectively improved the blood spinal cord barrier (BSCB) disruption after SCI. Administration of VA-CN could enhance the recovery of neuronal injury, suppress the reactive astrocytes and inflammation, and improve the blood spinal cord barrier disruption after SCI in rats. These results provided a novel and promising therapeutic manner for SCI.

Mechanistic complexities of bone loss in Alzheimer's disease: a review

Purpose/Aim: Alzheimer's disease (AD), the primary cause of dementia in the elderly, is one of the leading age-related neurodegenerative diseases worldwide. While AD is notorious for destroying memory and cognition, dementia patients also experience greater incidence of bone loss and skeletal fracture than age-matched neurotypical individuals, greatly impacting their quality of life. Despite the significance of this comorbidity, there is no solid understanding of the mechanisms driving early bone loss in AD. Here, we review studies that have evaluated many of the obvious risk factors shared by dementia and osteoporosis, and illuminate emerging work investigating covert pathophysiological mechanisms shared between the disorders that may have potential as new risk biomarkers or therapeutic targets in AD.Conclusions: Skeletal deficits emerge very early in clinical Alzheimer's progression, and cannot be explained by coincident factors such as aging, female sex, mobility status, falls, or genetics. While research in this area is still in its infancy, studies implicate several potential mechanisms in disrupting skeletal homeostasis that include direct effects of amyloid-beta pathology on bone cells, neurofibrillary tau-induced damage to neural centers regulating skeletal remodeling, and/or systemic Wnt/Beta-catenin signaling deficits. Data from an increasing number of studies substantiate a role for the newly discovered "exercise hormone" irisin and its protein precursor FNDC5 in bone loss and AD-associated neurodegeneration. We conclude that the current status of research on bone loss in AD is insufficient and merits critical attention because this work could uncover novel diagnostic and therapeutic opportunities desperately needed to address AD.

Swimming Training Attenuates Allodynia and Hyperalgesia Induced by Peripheral Nerve Injury in an Adult Male Rat Neuropathic Model: Effects on Irisin and GAD65

Objective

The analgesic mechanism of long-lasting exercise on neuropathic pain is not well understood. This study explored the effects of swimming training on neuropathic pain and the expression of irisin, GAD65, and P2X3 after chronic constriction injury (CCI) of the sciatic nerve.

Methods

Thirty-five male rats were randomly assigned to one of the following five groups: 1) no CCI or swimming (control); 2) swimming without CCI (SW); 3) swimming with CCI (CCISW); 4) CCI without swimming (CCI); and 5) sham CCI surgery (sham CCI). Behavioral responses to mechanical, cold, and heat stimuli were tested before and after CCI surgery, as well as each week throughout the four weeks of swimming training. The expression of irisin, GAD65, and P2X3 proteins in L4-L6 spinal cord segment, ipsilateral to the nerve injury, were evaluated by western blotting.

Results

Mechanical hyperalgesia was alleviated between the second and fourth weeks of training in the CCISW group. In the tactile allodynia and heat hyperalgesia tests, withdrawal thresholds of the CCISW group were significantly higher than the CCI group at the third and fourth week of training (P < 0.05), while cold allodynia showed delayed improvement occurring by the fourth week of training. The expression of irisin was lower in the CCISW and SW groups compared with the CCI group at day 33 post-CCI surgery. Moreover, CCI surgery significantly decreased the protein expression of GAD65 in L4-L6 spinal cord segments (P = 0.018), whereas swimming training prevented the decline of GAD65 in the CCISW group.

Conclusions

Our findings showed that four weeks of swimming training produce beneficial rehabilitative effects on neuropathic pain symptoms. The analgesic effect of swimming training is partially related to the increase of GAD65. The beneficial role of irisin in neuropathic pain will require further investigation.

Irisin Contributes to the Hepatoprotection of Dexmedetomidine during Intestinal Ischemia/Reperfusion

Intestinal ischemia/reperfusion (I/R), which is associated with high morbidity and mortality, is also accompanied with abnormal energy metabolism and liver injury. Irisin, a novel exercise-induced hormone, can regulate adipose browning and thermogenesis. The following study investigated the potential role of dexmedetomidine in liver injury during intestinal I/R in rats. Adult male Sprague-Dawley rats underwent occlusion of the superior mesenteric artery for 90 min followed by 2 h of reperfusion. Dexmedetomidine or irisin-neutralizing antibody was intravenously administered for 1 h before surgery. The results demonstrated that severe intestine and liver injuries occurred during intestinal I/R as evidenced by pathological scores and an apparent increase in serum diamine oxidase (DAO), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) levels. In addition, the hepatic irisin, cleaved caspase-3, Bax, and NLRP3 inflammasome components (including NLRP3, ASC, and caspase-1), protein expressions, apoptotic index, reactive oxygen species (ROS), malondialdehyde (MDA), myeloperoxidase (MPO), tumor necrosis factor- (TNF-) α, and interleukin- (IL-) 6 levels increased; however, the serum irisin level and hepatic Bcl-2 protein expression and superoxide dismutase (SOD) activity decreased after intestinal I/R. Interestingly, dexmedetomidine could reduce the above listed changes and increase the irisin levels in plasma and the liver in I/R rats. Dexmedetomidine-mediated protective effects on liver injury and NLRP3 inflammasome activation during intestinal I/R were partially abrogated via irisin-neutralizing antibody treatment. The results suggest that irisin might contribute to the hepatoprotection of dexmedetomidine during intestinal ischemia/reperfusion.

The Role of PGC-1α/UCP2 Signaling in the Beneficial Effects of Physical Exercise on the Brain

In understanding the pathology of neurological diseases, the role played by brain energy metabolism is gaining prominence. Animal models have demonstrated that regular physical exercise improves brain energy metabolism while also providing antidepressant, anxiolytic, antioxidant and neuroprotective functions. This review summarizes the latest evidence on the roles played by peroxisome proliferator-activated receptor gamma (PPAR-γ) coactivator 1-alpha (PGC-1α) and mitochondrial uncoupling protein (UCP) in this scenario. The beneficial effects of exercise seem to depend on crosstalk between muscles and nervous tissue through the increased release of muscle irisin during exercise.

The Role of Irisin in Alzheimer's Disease

Alzheimer’s disease (AD) is characterized by progressive memory dysfunction, oxidative stress, and presence of senile plaques formed by amyloid beta (Aβ) accumulation in the brain. AD is one of the most important causes of morbidity and mortality worldwide. AD has a variety of risk factors, including environmental factors, metabolic dysfunction, and genetic background. Recent research has highlighted the relationship between AD and systemic metabolic changes such as glucose and lipid imbalance and insulin resistance. Irisin, a myokine closely linked to exercise, has been associated with glucose metabolism, insulin sensitivity, and fat browning. Recent studies have suggested that irisin is involved in the process in central nervous system (CNS) such as neurogenesis and has reported the effects of irisin on AD as one of the neurodegenerative disease. Here, we review the roles of irisin with respect to AD and suggest that irisin highlight therapeutic important roles in AD. Thus, we propose that irisin could be a potential future target for ameliorating AD pathology and preventing AD onset.

Fibronectin type III domain-containing protein 5 interacts with APP and decreases amyloid β production in Alzheimer's disease

The deposition of Amyloid-beta peptides (Aβ) is detected at an earlier stage in Alzheimer’s disease (AD) pathology. Thus, the approach toward Aβ metabolism is considered to play a critical role in the onset and progression of AD. Mounting evidence suggests that lifestyle-related diseases are closely associated with AD, and exercise is especially linked to the prevention and the delayed progression of AD. We previously showed that exercise is more effective than diet control against Aβ pathology and cognitive deficit in AD mice fed a high-fat diet; however, the underlying molecular mechanisms remain poorly understood. On the other hand, a report suggested that exercise induced expression of fibronectin type III domain-containing protein 5 (FNDC5) in the hippocampus of mice through PGC1α pathway. Thus, in the current study, we investigated a possibility that FNDC5 interacts with amyloid precursor protein (APP) and affects Aβ metabolism. As a result, for the first time ever, we found the interaction between FNDC5 and APP, and forced expression of FNDC5 significantly decreased levels of both Aβ₄₀ and Aβ₄₂ secreted in the media. Taken together, our results indicate that FNDC5 significantly affects β-cleavage of APP via the interaction with APP, finally regulating Aβ levels. A deeper understanding of the mechanisms by which the interaction between APP and FNDC5 may affect Aβ production in an exercise-dependent manner would provide new preventive strategies against the development of AD.

The Diagnostic Value of Irisin in Pediatric Patients with Acute Abdominal Pain

Objectives

Diagnosis of pediatric patients presenting to the Emergency Department with acute abdominal pain is not always easy. The purpose of this study was to investigate the effectiveness of irisin, a peptide hormone with reactivity shown in the appendix and neutrophils, in the differential diagnosis of pediatric patients with acute abdominal pain.

Methods

162 subjects consenting to participate, including 112 patients presenting to the Pediatric Emergency and Pediatric Surgery clinics with acute abdominal pain and 50 controls, were enrolled in the study. Blood was collected from all patients following initial examination for irisin, WBC, and CRP investigation.

Results

Mean irisin levels in cases of acute appendicitis (AA) and perforated appendicitis (PA) were statistically significantly higher compared to nonspecific abdominal pains and the control group. No statistically significant difference was observed in irisin levels between AA and PA cases. WBC and CRP levels were also significantly higher in cases of AA and PA compared to nonspecific abdominal pains.

Conclusions

Differential diagnosis of acute abdominal pains in children and deciding on surgery are a difficult and complex process. Our study shows that irisin can be a useful biomarker in differentiating AA and PA from other acute abdominal pains in children.

An update on the role of irisin in the regulation of endocrine and metabolic functions

Irisin is a novel myokine and adipokine that has gained much attention recently due to its mechanisms of action. Irisin is secreted following proteolytic cleavage of its precursor fibronectin type III domain containing 5 (FNDC5). Following its release, irisin exerts its major action by increasing the expression of mitochondrial uncoupling protein 1 (UCP 1), which facilitates the conversion of white adipose tissue (WAT) into beige adipose tissue. Irisin is distributed in various body tissues and several actions have been attributed to its presence in those tissues. It has been suggested that it plays a role in metabolic diseases, ageing, inflammation and neurogenesis. However, the circulating levels of irisin are modulated by several factors such as diet, obesity, exercise, pharmacological agents and different pathological conditions. In this review, we have discussed the mechanisms by which irisin influences the functions of different body systems and how external factors in turn affect the circulating level of irisin. In conclusion, modification of circulating irisin level may help in the management of a variety of endocrine and metabolic disorders.

Spatiotemporal expression of Ski after rat spinal cord injury

Ski is an evolutionarily conserved protein and widely participates in the regulation of various pathological and physiological processes such as wound healing, liver regeneration, development of the embryonic nervous system, muscle differentiation, and progression of many kinds of tumors. However, the distribution and function of Ski in central nervous system lesion and disease remain unclear. In this study, we investigated the spatiotemporal expression of Ski in a spinal cord injury (SCI) model in adult rats. Western Blot analysis indicated that Ski was expressed in both normal and injured spinal cord, and showed a significant upregulation after SCI compared with the sham group. Double-labeled immunofluorescence staining showed that Ski was significantly expressed in astrocytes, but not in the neurons. Western Blot analyses of glial fibrillary acidic protein (GFAP) and BBB scores were carried out and correlation analysis showed a positive correlation between them. In addition, the relative expression level of Ski was also positively correlated with the relative expression level of GFAP. Moreover, the conspicuous co-expression band of Ski and GFAP at the lesion border was found in the results of immunofluorescence staining combined with the pattern of glial scar formation reflected by H&E staining; in addition, it was found that Ski was also highly associated with glial scar. On the basis of our data, we speculated that Ski might play an important role in the process of reactive astrogliosis after SCI and our study might provide a basis for further study on the detailed role of Ski in astrocytes.

The treatment of spinal cord injury in rats using bone marrow-derived neural-like cells induced by cerebrospinal fluid

This study aimed to evaluate the effect of bone mesenchymal stem cells (BMSCs) and BMSC neural-like cells (BMSC-Ns) on the spinal cord injury (SCI) in the rat model of SCI. BMSC-Ns were prepared from the third passage of BMSCs by induction of healthy cerebrospinal fluid (CSF) of an adult human. The SCI rat model was established through a surgical procedure, and after 7 days the rats were randomly divided into 3 (A, B and C) groups. Groups A (BMSC-Ns) and B (BMSCs) were treated with 1 × 10⁶/20 μl cells, while group C (saline) was treated with saline, all via intracerebroventricular injection. After transplantation, the BBB score of group A was significantly higher than that of group B, which in turn was significantly higher than that of group C (P < .05). The levels of Bdnf, Ngf, Ntf3 were statistically significantly higher in group A than those in groups B and C (P < .05). The levels of 5-HT, NA, Ach, DA, GABA in group A were significantly higher than those in groups B and C, whereas the level of Glu was significantly lower in group A than that in groups B and C (P < .05). The histopathological data showed remarkably less necrosis of the spinal cord in group A, compared to that in groups B and C. Transplanting BMSC-Ns or BMSCs into the lateral ventricles improved the neurological function of rats with SCI. Moreover, BMSC-Ns were significantly more effective than BMSCs, which provides a possible approach for the treatment of SCI.

Irisin protects against neuronal injury induced by oxygen-glucose deprivation in part depends on the inhibition of ROS-NLRP3 inflammatory signaling pathway

Recent studies found that irisin, a newly discovered skeletal muscle-derived myokine during exercise, is also synthesized in various tissues of different species and protects against neuronal injury in cerebral ischemia. The NOD-like receptor pyrin 3 (NLRP3) inflammasome play an important role in detecting cellular damage and mediating inflammatory responses to aseptic tissue injury during ischemic stroke. However, it is unclear whether irisin is involved in the regulation of NLRP3 inflammasome activation during ischemic stroke. In the present study, PC12 neuronal cells were exposed to oxygen-glucose deprivation (OGD), exogenous irisin (12.5, 25, 50nmol/L) or NLRP3 inhibitor glyburide (50, 100, 200μmol/L) were used as an intervention reagent, NLRP3 was over-expressed or suppressed by transfection with a NLRP3 expressing vector or NLRP3-specifc siRNA, respectively. Our data showed that both irisin and its precursor protein fibronectin type III domain containing 5 (FNDC5) expression were significantly down-regulated (p<0.05); but oxidative stress and ROS-NLRP3 inflammasome signaling were activated by OGD (p<0.05); treatment with irisin or inhibition of NLRP3 reversed OGD-induced oxidative stress and inflammation (p<0.05). However, these irisin-mediated effects were blunted by over-expression NLRP3 (p<0.05). Taken together, our results firstly revealed that irisin mitigated OGD-induced neuronal injury in part via inhibiting ROS-NLRP3 inflammatory signaling pathway, suggesting a likely mechanism for irisin-induced therapeutic effect in ischemic stroke.

The regulatory effect of electro-acupuncture on the expression of NMDA receptors in a SCI rat model

BACKGROUND

In early spinal cord injury (SCI), glutamate receptors, including N-methyl-d-aspartate (NMDA) receptors (NMDARs), are over-stimulated by excessively released glutamate. The enhanced activity of NMDARs may cause cell death by overloading calcium (Ca²⁺) into cells based on their high permeability to Ca²⁺. Studies in SCI animals have shown that treatment with electro-acupuncture (EA) is able to reduce cell death and to improve functional recovery. One possible mechanism of this neuroprotective effect is that EA has regulatory effect on NMDARs.

AIMS

To test whether EA could protect the spinal cord after SCI by decreasing the expression levels of NR1 and NR2A.

MAIN METHODS

We conducted EA treatment on a rat SCI model produced with a New York University (NYU) Impactor and measured hindlimb locomotor function by Basso, Beattie and Bresnahan Locomotor Rating Scale (BBB Scale). The expression of NR1 and NR2, the subunits of NMDARs, in the injured spinal cord was measured by Immunofluorescence stainings, western blot and real-time quantitative PCR (RT-qPCR).

KEY FINDING

Our results showed that two days after the SCI the expression of NR1 and NR2 were dramatically enhanced at both protein and mNRA levels, which were significantly reduced by EA treatment at two specific acupoints, Dazhui (DU14) and Mingmen (DU4).

SIGNIFICANCE

EA is a potential therapeutic method for treating early SCI in human.

Can irisin be a linker between physical activity and brain function?

Irisin was initially discovered as a novel hormone-like myokine released from skeletal muscle during exercise to improve obesity and glucose dysfunction by stimulating the browning of white adipose tissue. Emerging evidence have indicated that irisin also affects brain function. FNDC5 mRNA and FNDC5/irisin immunoreactivity are present in various regions of the brain. Central irisin is involved in the regulation of neural differentiation and proliferation, neurobehavior, energy expenditure and cardiac function. Elevation of peripheral irisin level stimulates hippocampal genes related to neuroprotection, learning and memory. In this brief review, we summarize the current understanding on neuronal functions of irisin. In addition, we discuss the pros and cons for this molecule as a potential messenger mediating the crosstalk between skeletal muscle and central nervous system during exercise.

The combined application of human adipose derived stem cells and Chondroitinase ABC in treatment of a spinal cord injury model

BACKGROUND

Although stem cell therapy has become a major focus as a new option for management of spinal cord injury (SCI), its effectiveness should be promoted. In this study, we investigated the effects of co-administrating human adipose-derived stem cells (hADSCs) and Chondroitinase ABC (ChABC) in a rat model of spinal cord injury.

MATERIAL AND METHODS

hADSCs derived from superficial layer of abdominal adipose tissue were used to treat a contusion-induced SCI. Animals were randomly allocated to five equal groups including sham (only laminectomy), SCI (SCI+vehicle injection), hADSCs (1×10⁶ hADSCs/10μl intra-spinal injection), ChABC (10μl of 100U/ml ChABC intra-spinal injection injection), and hADSCs+ChABC. Basso, Beattie and Bresnahan tests were used to evaluate locomotor function. 8weeks after treatment, cavity size, myelination, cell differentiation (neuron and astrocyte), and chondroitin sulfate amount were analyzed.

RESULTS

hADSC transplanted animals, ChABC injected animals (P<0.001), and hADSC+ChABC treated rats (P<0.001) displayed significant motor improvement compared to SCI group. Combination therapy of hADSCs and ChABC led to greater locomotor recovery compared to using hADSCs (P<0.001) or ChABC (P<0.01) alone. Spinal cords in the combined and single therapy groups had cavities filled with myelinated areas and less chondroitin sulfate content in comparison with the control group (P<0.001). hADSCs expressed GFAP, B III tubulin and Map2.

CONCLUSION

Combination therapy with ChABC and hADSCs exhibits more significant functional recovery than single therapy using either. This result may be applicable in selection of the best therapeutic strategy for SCI.

Irisin inhibition of growth hormone secretion in cultured tilapia pituitary cells

Irisin, the product of fibronectin type III domain-containing protein 5 (FNDC5) gene, is well-documented to be a regulator of energy metabolism. At present, not much is known about its biological function in non-mammalian species. In this study, a full-length tilapia FDNC5 was cloned and its tissue expression pattern has been confirmed. Based on the sequence obtained, we produced and purified recombinant irisin which could induce uncoupling protein 1 (UCP1) gene expression in tilapia hepatocytes. Further, the rabbit polyclonal irisin antiserum was produced and its specificity was confirmed by antiserum preabsorption. In tilapia pituitary cells, irisin inhibited growth hormone (GH) gene expression and secretion and triggered rapid phosphorylation of Akt, Erk1/2, and p38 MAPK. Furthermore, irisin-inhibited GH mRNA expression could be prevented by inhibiting PI3K/Akt, MEK1/2, and p38 MAPK, respectively. Apparently, fish irisin can act directly at the pituitary level to inhibit GH transcript expression via multiple signaling pathways.

Serum, Saliva, and Urine Irisin with and Without Acute Appendicitis and Abdominal Pain

A 112-amino-acid protein irisin (IRI) is widely expressed in many organs, but we currently do not know whether appendix tissue and blood cells express it. If appendix tissue and neutrophil cells express IRI, measuring its concentration in biological fluids might be helpful in the diagnosis of acute appendicitis (AA), since neutrophil cells are the currently gold-standard laboratory parameters for the diagnosis of AA. Therefore, the purpose of this study was to investigate the suitability of enzyme-linked immunosorbent assay-based measurements of the proposed myokine IRI for the discrimination of patients with AA from those with acute abdominal pain (AP) and healthy controls. Moreover, immunoreactivity to IRI was investigated in appendix tissues and blood cells. Samples were collected on admission (T1), 24 hours (T2), and 72 hours (T3) postoperatively from patients with suspected AA and from patients with AP corresponding to T1–T3, whereas control subject blood was once corresponding to T1. IRI was measured in serum, saliva, and urine by using enzyme-linked immunosorbent assay, whereas in appendix tissue and blood cells, IRI was detected by immunohistohcemistry. Appendix tissue and blood cells (except for erythrocytes) are new sources of IRI. Basal saliva, urine, and serum levels were higher in children with AA compared with postoperative levels (T2) that start to decline after surgery. This is in line with the finding that IRI levels are higher in children with AA when compared with those with AP or control subject levels, most likely due to a large infiltration of neutrophil cells in AA that release its IRI into body fluids. Measurement of IRI in children with AA parallels the increase or decrease in the neutrophil count. This new finding shows that the measurement of IRI and neutrophil count can together improve the diagnosis of AA, and it can distinguish it from AP. IRI can be a candidate marker for the diagnosis of AA and offers an additional parameter to neutrophil count. The promising receiving operating curve results indicate the following sensitivities and specificities, respectively, for IRI: serum 90% and 55%, saliva 90% and 60%, and urine 90% and 50%. Serum neutrophil count gave a sensitivity of 90% and a specificity of 90%. This promising result now needs to be confirmed in a larger group of patients.

Panax notoginseng saponins improve recovery after spinal cord transection by upregulating neurotrophic factors

Saponins extracted from Panax notoginseng are neuroprotective, but the mechanisms underlying this effect remain unclear. In the present study, we established a rat model of thoracic (T₁₀) spinal cord transection, and injected Panax notoginseng saponins (100 mg/kg) or saline 30 minutes after injury. Locomotor functions were assessed using the Basso, Beattie, and Bresnahan (BBB) scale from 1 to 30 days after injury, and immunohistochemistry was carried out in the ventral horn of the spinal cord at 1 and 7 days to determine expression of nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF). Our results show that at 7–30 days post injury, the BBB score was higher in rats treated with Panax notoginseng saponins than in those that received saline. Furthermore, at 7 days, more NGF- and BDNF-immunoreactive neurons were observed in the ventral horn of the spinal cord of rats that had received Panax notoginseng saponins than in those that received saline. These results indicate that Panax notoginseng saponins caused an upregulation of NGF and BDNF in rats with spinal cord transection, and improved hindlimb motor function.