Rafael Calais Gaspar

The role of physical exercise on Sestrin1 and 2 accumulations in the skeletal muscle of mice

Aims: Sestrins, a class of stress‐related proteins, is involved in the control of aging‐induced organic dysfunctions and metabolic control. However, the factors that modulate the levels of Sestrins are poorly studied. Here, we evaluated the effects of acute and chronic aerobic exercise on Sestrin 1 (Sesn1) and Sesn2 protein contents in the skeletal muscle of mice. Main methods: Male C57BL/6 J mice performed an acute or chronic (4 weeks) exercise protocols on a treadmill running at 60% of the peak workload. Then, the quadriceps muscle was removed and analyzed by Western blot. Bioinformatics analysis was also performed to evaluate Sesn1 and Sesn2 mRNA in the skeletal muscle and phenotypic pattern in a large panel of isogenic strains of BXD mice. Key findings: While acute aerobic exercise increased Sesn1 accumulation and induced a discrete augment of Sesn2 protein content and AMPK threonine phosphorylation, chronic exercise reduced the basal levels of Sesn1 and Sesn2 as well as of AMPK threonine phosphorylation in the quadriceps muscles of C57BL/6 J mice. In accordance with these experimental approaches, transcriptomic analysis revealed that Sesn1 and Sesn2 mRNA levels in the skeletal muscle were inversely correlated with the locomotor activity in several strains of BXD mice. Significance: Our data suggest that physical exercise has role on Sestrin1 and Sestrin2 expression on skeletal muscle, providing new insights into the mechanism by which physical exercise affects stress‐related proteins in skeletal muscles.

Acute physical exercise increases the adaptor protein APPL1 in the hypothalamus of obese mice

Graphical abstract The acute physical exercise was able to increase serum adiponectin levels, reducing the glucose intolerance in obese mice. Interestingly, this phenomenon was associated with increased hypothalamic APPL1 and increased Akt phosphorylation, which improved the food intake control. Figure. No Caption available. HighlightsHypothalamic APPL1 protein content is reduced in obese and glucose intolerant mice induced by high‐fat diet.Acute physical exercise restored the serum adiponectin, hypothalamic APPL1 protein content and increased Akt phosphorylation.Physical exercise improved the food intake control. &NA; Adiponectin is considered an adipokine that has essential anti‐inflammatory and insulin‐sensitivity actions. The adaptor protein containing the pleckstrin homology domain, the phosphotyrosine‐binding domain, and leucine zipper motif 1 (APPL1) is a protein involved in adiponectin signaling that plays a role in many physiological and pathophysiological processes. In the central nervous system, adiponectin can potentiate the effects of leptin in the arcuate proopiomelanocortin (POMC) neurons. However, the role of APPL1 in the hypothalamus is not well understood. Therefore, in this study, we explored the effects of acute physical exercise on APPL1 protein content in the hypothalamus and food intake control in leptin stimulated‐obese mice. Here we show that acute exercise increased serum adiponectin levels and APPL1 content in the hypothalamus, which were followed by reduced food intake in obese mice. Further, at the molecular level, the exercised obese mice increased the protein kinase B (Akt) signaling in the hypothalamus and attenuated the mammalian homolog of Drosophila tribbles protein 3 (TRB3) levels. In conclusion, the results indicate physical exercise is capable of increasing APPL1 protein content in the hypothalamus of leptin stimulated‐obese mice and modulating food intake.

High Dosage of Vitamin D Regulates the Energy Metabolism and Increases Insulin Sensitivity, but are Associated with High Levels of Kidney Damage

Preclinical Research

Exercise increases Rho-kinase activity and insulin signaling in skeletal muscle

The effects of physical exercise on insulin signaling and glycemic homeostasis are not yet fully understood. Recent findings elucidated the positive role of Rho‐kinase (Rock) in increasing the glucose uptake through insulin receptor substrate‐1 (IRS1) phosphorylation in the skeletal muscle. Here, we explored the effects of short‐term exercise on Rock activity and insulin signaling. Fischer 344 rats (3 months old) were subjected to a short‐term swimming exercise for 2 hr per day for 5 days, with an overload corresponding to 1.5% of body weight. As expected, the exercised group had a reduced glycemia and increased insulin sensitivity. The contents of Rock1, Rock2, and Rock activity were improved in the skeletal muscle of the exercised rats. The contents of RhoA and RhoGEF, which are proteins involved in the Rock metabolism, were also increased in the skeletal muscle after exercise. These changes in the protein contents were accompanied by an increase in the insulin signaling pathway (pIRS1/pPDK/pAkt/pGSK3β/pAS160/GLUT4), Rock activity, and IRS1 phosphorylation at the 632/635 serine residues. On the other hand, when Rock was inhibited with the Y‐27632, the insulin sensitivity in response to exercise was impaired. Based on these findings, we conclude that the short‐term exercise increased both insulin sensitivity and glucose tolerance, through the increased Rock activity and pIRS1 (serine 632/635) mediated by Rock, in the skeletal muscle of Fischer 344 rats. These data represent an exercise‐mediated novel mechanism, suggesting an essential role of Rock activity in the insulin signaling and glucose homeostasis improvement.

Impaired insulin signaling and spatial learning in middle-aged rats: The role of PTP1B

Abstract The insulin and Brain‐Derived Neurotrophic Factor (BDNF) signaling in the hippocampus promotes synaptic plasticity and memory formation. On the other hand, aging is related to the cognitive decline and is the main risk factor for Alzheimers Disease (AD). The Protein‐Tyrosine Phosphatase 1B (PTP1B) is related to several deleterious processes in neurons and emerges as a promising target for new therapies. In this context, our study aims to investigate the age‐related changes in PTP1B content, insulin signaling, &bgr;‐amyloid content, and Tau phosphorylation in the hippocampus of middle‐aged rats. Young (3 months) and middle‐aged (17 months) Wistar rats were submitted to Morris‐water maze (MWM) test, insulin tolerance test, and molecular analysis in the hippocampus. Aging resulted in increased body weight, and insulin resistance and decreases learning process in MWM. Interestingly, the middle‐aged rats have higher levels of PTP‐1B, lower phosphorylation of IRS‐1, Akt, GSK3&bgr;, mTOR, and TrkB. Also, the aging process increased Tau phosphorylation and &bgr;‐amyloid content in the hippocampus region. In summary, this study provides new evidence that aging‐related PTP1B increasing, contributing to insulin resistance and the onset of the AD. HighlightsMiddle‐aging is associated with increased PTP1B content in the hippocampus.The PTP1B is one of the major tyrosine phosphatases of IR, IRS1, and TrkB.This process disrupts the hippocampal insulin signaling, impairing the spatial learning.

Overexpression of Mitogen-activated protein kinase phosphatase-3 (MKP-3) reduces FoxO1 phosphorylation in mice hypothalamus

The mitogen-activated kinase phosphatase-3 (MKP-3) has gained great importance in the scientific community by acting as a regulator of the cell cycle through dephosphorylation of FoxO1, an important transcription factor involved in the insulin intracellular signaling cascade. When dephosphorylated and translocated to the nuclei, FoxO1 can promote the transcription of orexigenic neuropeptides (NPY/AgRP) in the hypothalamus, whereas insulin signaling is responsible for the disruption of this process. However, it is not understood if the hypothalamic activation of MKP-3 affects FoxO1 phosphorylation, and we hypothesized that MKP-3 overexpression reduces the capacity of the insulin signal to phosphorylate FoxO1. In the present study, we overexpressed the DUSP6 gene through an injection of adenovirus directly into the hypothalamic third ventricle of Swiss mice. The colocalization of the adenovirus was confirmed by the immunofluorescence assay. Then, MKP-3 overexpression resulted in a significant reduction of hypothalamic FoxO1 phosphorylation after insulin stimulation. This effect was independent of changes in Akt phosphorylation. Thus, the role of MKP-3 in the hypothalamus is closely associated with FoxO1 dephosphorylation and may provide a potential therapeutic target against hypothalamic disorders related to obesity and unbalanced food intake control.

The reversal effect of physical exercise on aging-related increases in APPL2 content in skeletal muscle

Aims: The aim of this study was to evaluate the effects of aging on intracellular adiponectin signaling and the possible therapeutic effect of physical exercise. Main methods: Fischer 344 rats were distributed in the following groups: Young (3 months old); Sedentary Old (Old, 27 months old); and Old Exercised (Old‐Exe, 27 months old), which were subjected to a short‐term exercise training protocol. Key findings: The results showed that the old rats presented glucose intolerance without increased adiposity. However, short‐term exercise training reversed this disorder, which was associated with a decrease in the pleckstrin homology domain, phosphotyrosine‐binding domain, and leucine zipper motif (APPL) isoform 2 (APPL2) content. The APPL isoform 1 (APPL1) and TRB3 (Tribbles homolog 3) contents were not altered. Akt phosphorylation was only increased in the old exercised rats. There was a reduction in the content of adiponectin receptor 1 in the old rats. Significance: The short‐term exercise training protocol was able to decrease APPL2 content in the skeletal muscle, which was accompanied by an improvement in the glucose tolerance of the old Fischer 344 rats. These findings provide new evidence supporting the role of physical exercise as a non‐pharmacological therapeutic intervention to attenuate age‐related deficits.

Immune-endocrine responses and physical performance of master athletes during the sports season : MINUZZI et al.

The purpose of this study was to investigate the impact of a training season (approximately 7 months) on physiological and salivary immune‐endocrine markers in master athletes. Nine male master athletes were evaluated at the beginning of the season (M1) and a week after the main official competition at the end of the sports season (M2). The controlled variables included Maximal oxygen consumption, anthropometric, physiological, and salivary immune‐endocrine markers. Master athletes presented a reduced percentage of fat mass and increased lean body mass at the end of the season. VO2max values were similar at M1 and M2, while the maximal heart rate and lactate were lower at M2. No differences were observed in Immunoglobulin A and cortisol levels between moments, whereas testosterone levels and the testosterone/cortisol ratio were significantly lower at the end of the season. The results suggest that maintaining regular training throughout life has positive effects on body composition and improves physiological fitness. However, care should be taken to avoid fatigue as indicated by lower testosterone levels at the end of the season.

Acute physical exercise increases leptin-induced hypothalamic extracellular signal-regulated kinase1/2 phosphorylation and thermogenesis of obese mice: GASPAR et al.

The obesity is a result of energy imbalance and the increase in thermogenesis seems an interesting alternative for the treatment of this disease. The mechanism of energy expenditure through thermogenesis is tightly articulated in the hypothalamus by leptin. The hypothalamic extracellular signal‐regulated kinase‐1/2 (ERK1/2) is a key mediator of the thermoregulatory effect of leptin and mediates the sympathetic signal to the brown adipose tissue (BAT). In this context, physical exercise is one of the main interventions for the treatment of obesity. Thus, this study aimed to verify the effects of acute physical exercise on leptin‐induced hypothalamic ERK1/2 phosphorylation and thermogenesis in obese mice. Here we showed that acute physical exercise reduced the fasting glucose of obese mice and increased leptin‐induced hypothalamic p‐ERK1/2 and uncoupling protein 1 (UCP1) content in BAT ( P < 0.05). These molecular changes are accompanied by an increased oxygen uptake (VO 2) and heat production in obese exercised mice ( P < 0.05). The increased energy expenditure in the obese exercised animals occurred independently of changes in spontaneous activity. Thus, this is the first study demonstrating that acute physical exercise can increase leptin‐induced hypothalamic ERK1/2 phosphorylation and energy expenditure of obese mice.

Exercise decreases CLK2 in the liver of obese mice and prevents hepatic fat accumulation

The accumulation of fatty acids in the liver associated with obesity condition is also known as nonalcoholic fatty liver disease (NAFLD). The impaired fat oxidation in obesity condition leads to increased hepatic fat accumulation and increased metabolic syndrome risk. On the other hand, physical exercise has been demonstrated as a potent strategy in the prevention of NAFLD. Also, these beneficial effects of exercise occur through different mechanisms. Recently, the Cdc2‐like kinase (CLK2) protein was associated with the suppression of fatty acid oxidation and hepatic ketogenesis. Thus, obese animals demonstrated elevated levels of hepatic CLK2 and decreased fat acid oxidation. Here, we explored the effects of chronic physical exercise in the hepatic metabolism of obese mice. Swiss mice were distributed in Lean, Obese (fed with high‐fat diet during 16 weeks) and Trained Obese group (fed with high‐fat diet during 16 weeks and exercised (at 60% exhaustion velocity during 1 h/5 days/week) during 8 weeks. In our results, the obese animals showed insulin resistance, increased hepatic CLK2 content and increased hepatic fat accumulation compared to the Lean group. Otherwise, the chronic physical exercise improved insulin resistance state, prevented the increased CLK2 in the liver and attenuated hepatic fat accumulation. In summary, these data reveal a new protein involved in the prevention of hepatic fat accumulation after chronic physical exercise. More studies can evidence the negative role of CLK2 in the control of liver metabolism, contributing to the improvement of insulin resistance, obesity, and type 2 diabetes.