Research code: .......
Ethics code: IR.IAU.SARI.REC.1401.236
Clinical trials code: IR.IAU.SARI.REC.1401.236
sari , parvin.farzanegi@gmail.com
Abstract: (616 Views)
Background & Aims: One of the most common metabolic disorders in the world is diabetes, which brings various complications and problems. This disease affects many people every year and is one of the main causes of death in many countries (1). The incidence of type 2 diabetes (T2D), largely driven by the obesity epidemic, is increasing at alarming rates. It was estimated that in 2030, the number of people suffering from this disease will increase to 578 million patients worldwide (2). Diabetes is generally associated with mild chronic inflammation, which activates pro-inflammatory elements and releases inflammatory cytokines through some signaling pathways. In recent decades, chronic low-grade “metabolic” inflammation has been identified as contributing to insulin resistance and progression to T2D. In this way, inflammation is associated with both insulin dysfunction and secretion (3). Gut microbiota plays an important role as an immune modulator in human metabolism. Although this property is vital for human health, it can also have harmful consequences. Based on this, gut microbiota has been determined as a driver of inflammation in obesity and T2D, which are characterized by altered gut microbiota composition (6, 5). TLR4 has been suggested to be involved in beta-cell failure during diet-induced obesity in mice, as HFD-fed TLR4 mice have preserved insulin secretory function, lower inflammatory markers, and no macrophage infiltration of pancreatic islets (10). Thus, TLR4 may be an interesting therapeutic target and an important mediator of insulin resistance, inflammation, and beta-cell failure. On the other hand, the activation of Toll-like receptor 4 (TRL4) is an important process in understanding how diabetes initiates inflammation, and the TLR4/NF-κB signaling pathway is one of the most important signal transmission pathways in the initiation and development of inflammation (12). TLR4-mediated signaling leads to the activation of nuclear transcription factor kappa B (NF-κB) and the production of pro-inflammatory cytokines (13). In numerous studies, the benefits and anti-inflammatory effects of regular exercise and medicinal herbs have been shown. Regular aerobic exercises reduce the release of pro-inflammatory cytokines and also regulate anti-inflammatory cytokines (17). The main anti-inflammatory effect of exercise may be due to the effects on the activation of the TLR pathway. Exercise training can reduce the circulating levels of TLR ligands that are increased in metabolic diseases. It seems that licorice plant has anti-inflammatory effects due to the presence of effective substances and phenolic and antioxidant compounds (21).The purpose of this research was to investigate the effect of licorice extract and selected swimming exercise on signaling pathway of gene expression of the TLR4/NF-Kb in the intestinal tissue of diabetic male rats.
Methods: 30 male Wistar rats were randomly divided into 6 healthy controls, diabetic sham, saline diabetic, diabetic + supplement, diabetic + exercise, diabetic + exercise + supplement. To induce diabetes, a single dose of streptozotocin was used as an intraperitoneal injection. 500 mg of licorice extract was injected intraperitoneally to rats. In order to induce diabetes, a single dose of streptozotocin at the rate of 50 mg/kg of body weight was used as an intraperitoneal injection one week before the start of training (22). Daily, 500 mg of licorice powder prepared with 6 cc of normal saline was diluted and injected intraperitoneally to rats. The main training program included swimming for 6 weeks and 5 sessions per week, which started with 5 minutes of training in the first week and gradually increased the swimming time to 30 minutes at the beginning of the fourth week and continued until the eighth week. 48 hours after the last training session, the studied rats in each group were anesthetized by intraperitoneal injection of a mixture of 10% ketamine at a dose of 50 mg/kg and 2% xylazine at a dose of 10 mg/kg, followed by Intestinal tissue extraction was performed. The expression levels of TLR4 and NF-κB genes were measured using Real-Time PCR method. After collecting the raw data, in order to check the normality of the data, the Shapiro-Wilk test was used. After determining the normality of data distribution and establishing the assumption of equality of variances, one-way analysis of variance and Tukey's post hoc test were used for statistical analysis of data and comparison between groups. All statistical calculations were done using SPSS23 statistical software at a significance level of P˂ 0.05.
Findings: The level of NF-κB and TLR4 gene expression in the sham and saline groups increased significantly compared to the control group (p=0.012, p=0.023, respectively). While the expression of NF-κB gene in the exercise and supplement groups was significantly decreased compared to the sham group (p=0.012, p=0.011, respectively). Also, the level of TLR4 gene expression in the sham and saline groups increased significantly compared to the control group (p<0.001, p=0.006, respectively). Also, the expression level of TLR4 decreased in the experimental groups compared to the sham group; this decreasing trend was significant only in the combined group (p=0.002). However, TLR4 gene expression values in the experimental groups were still at a higher level compared to the control group.
Conclusion: The results of the present study also showed that the induction of diabetes caused a significant increase in TLR4 and NF-κB in the patient group (sham and saline) compared to the healthy control group. Also, the results of the present study showed that swimming training caused a decrease in TLR4 and NF-κB gene expression in diabetic rats. In line with the results of the current research, Kaki et al.(2019) investigated the effect of aerobic exercise on the expression of Toll-like receptor 4 gene and inflammatory mediators in diabetic rats. The results showed that aerobic exercise can reduce the expression of TLR4 gene (27). Also, Kawanishi et al showed that sixteen weeks of aerobic exercise decreased TLR4 gene expression in mice fed a high-fat diet (17). Also, in a research, Marta et al investigated the effect of intense interval training on TLR4 gene expression in people with high body mass index. The results showed that 2 weeks of high-intensity interval training caused a significant increase in TLR4 gene expression in monocytes in inactive men, which is not consistent with the results of the present study. The reason for the inconsistency of the present study with Marta et al.'s research can be related to the type and intensity of the exercise as well as the subjects. In the current research, swimming aerobic exercise was used in animal subjects; While in Marta et al.'s research, the effect of high-intensity interval training has been done on human subjects. It has been shown in the research that long-term and regular exercise can produce inflammatory cytokines and also the expression of TLR4 and NF-κB in the surface reduce monocytes. The mechanism involved in reducing the expression of TLR4 and NF-κB as a result of exercise can be related to the role of aerobic activity in increasing the levels of anti-inflammatory cytokines, heat shock proteins and glucocorticoids, which can inhibit TLR4 and NF-κB (28, 29). The phenolic compounds present in the root of licorice plant by regulating the expression of cyclooxygenase, nitric oxide synthase and tumor necrosis factor (TNF-α) and interleukin 6 as anti-inflammatory agents may reduce free radicals in the cellular space and reduce the inflammation process (38). Results of present study showed that induction of cancer caused the activation of the TLR4/NF-κB signaling pathway and increased regulation of factors in the cancer group compared to the healthy control. Also, licorice extract along with endurance exercises caused a decrease in TLR4 and NF-κB gene expression in the experimental groups compared to the cancer group. According to the results of the research, it is possible that the consumption of licorice extract along with endurance training can be effective in reducing the inflammatory process through the negative regulation of the TLR4/NF-κB signaling pathway.
Methods: 30 male Wistar rats were randomly divided into 6 healthy controls, diabetic sham, saline diabetic, diabetic + supplement, diabetic + exercise, diabetic + exercise + supplement. To induce diabetes, a single dose of streptozotocin was used as an intraperitoneal injection. 500 mg of licorice extract was injected intraperitoneally to rats. In order to induce diabetes, a single dose of streptozotocin at the rate of 50 mg/kg of body weight was used as an intraperitoneal injection one week before the start of training (22). Daily, 500 mg of licorice powder prepared with 6 cc of normal saline was diluted and injected intraperitoneally to rats. The main training program included swimming for 6 weeks and 5 sessions per week, which started with 5 minutes of training in the first week and gradually increased the swimming time to 30 minutes at the beginning of the fourth week and continued until the eighth week. 48 hours after the last training session, the studied rats in each group were anesthetized by intraperitoneal injection of a mixture of 10% ketamine at a dose of 50 mg/kg and 2% xylazine at a dose of 10 mg/kg, followed by Intestinal tissue extraction was performed. The expression levels of TLR4 and NF-κB genes were measured using Real-Time PCR method. After collecting the raw data, in order to check the normality of the data, the Shapiro-Wilk test was used. After determining the normality of data distribution and establishing the assumption of equality of variances, one-way analysis of variance and Tukey's post hoc test were used for statistical analysis of data and comparison between groups. All statistical calculations were done using SPSS23 statistical software at a significance level of P˂ 0.05.
Findings: The level of NF-κB and TLR4 gene expression in the sham and saline groups increased significantly compared to the control group (p=0.012, p=0.023, respectively). While the expression of NF-κB gene in the exercise and supplement groups was significantly decreased compared to the sham group (p=0.012, p=0.011, respectively). Also, the level of TLR4 gene expression in the sham and saline groups increased significantly compared to the control group (p<0.001, p=0.006, respectively). Also, the expression level of TLR4 decreased in the experimental groups compared to the sham group; this decreasing trend was significant only in the combined group (p=0.002). However, TLR4 gene expression values in the experimental groups were still at a higher level compared to the control group.
Conclusion: The results of the present study also showed that the induction of diabetes caused a significant increase in TLR4 and NF-κB in the patient group (sham and saline) compared to the healthy control group. Also, the results of the present study showed that swimming training caused a decrease in TLR4 and NF-κB gene expression in diabetic rats. In line with the results of the current research, Kaki et al.(2019) investigated the effect of aerobic exercise on the expression of Toll-like receptor 4 gene and inflammatory mediators in diabetic rats. The results showed that aerobic exercise can reduce the expression of TLR4 gene (27). Also, Kawanishi et al showed that sixteen weeks of aerobic exercise decreased TLR4 gene expression in mice fed a high-fat diet (17). Also, in a research, Marta et al investigated the effect of intense interval training on TLR4 gene expression in people with high body mass index. The results showed that 2 weeks of high-intensity interval training caused a significant increase in TLR4 gene expression in monocytes in inactive men, which is not consistent with the results of the present study. The reason for the inconsistency of the present study with Marta et al.'s research can be related to the type and intensity of the exercise as well as the subjects. In the current research, swimming aerobic exercise was used in animal subjects; While in Marta et al.'s research, the effect of high-intensity interval training has been done on human subjects. It has been shown in the research that long-term and regular exercise can produce inflammatory cytokines and also the expression of TLR4 and NF-κB in the surface reduce monocytes. The mechanism involved in reducing the expression of TLR4 and NF-κB as a result of exercise can be related to the role of aerobic activity in increasing the levels of anti-inflammatory cytokines, heat shock proteins and glucocorticoids, which can inhibit TLR4 and NF-κB (28, 29). The phenolic compounds present in the root of licorice plant by regulating the expression of cyclooxygenase, nitric oxide synthase and tumor necrosis factor (TNF-α) and interleukin 6 as anti-inflammatory agents may reduce free radicals in the cellular space and reduce the inflammation process (38). Results of present study showed that induction of cancer caused the activation of the TLR4/NF-κB signaling pathway and increased regulation of factors in the cancer group compared to the healthy control. Also, licorice extract along with endurance exercises caused a decrease in TLR4 and NF-κB gene expression in the experimental groups compared to the cancer group. According to the results of the research, it is possible that the consumption of licorice extract along with endurance training can be effective in reducing the inflammatory process through the negative regulation of the TLR4/NF-κB signaling pathway.
Type of Study: Research |
Subject:
Exercise Physiology
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