Cardiac Effects of Treadmill Running at Different Intensities in a Rat Model

Exercise ameliorates cardiac injury induced by nandrolone decanoate through downregulation of osteopontin and mTOR expressions

Nandrolone-decanoate (NA), a synthetic anabolic steroid, negatively impacts cardiac function. While exercise is known to benefit cardiovascular health, its effects on individuals misusing anabolic steroids require further study. Osteopontin (OPN) and mammalian target of rapamycin (m-TOR) are crucial in inflammation-related cardiovascular diseases and can be influenced by exercise, though results are inconclusive. This study aims to examine how exercise affects NA's cardiac adverse effects and the potential role of OPN and m-TOR. The study involved 52 male rats divided into four groups: control, exercise-only, NA-treated (15 mg/kg/day S.C for 8 W), and combined exercise and NA treatment. Researchers measured blood pressure, heart rate (HR), serum cardiac enzymes, CRP, IL-1B, IL-6, Brain Natriuretic Peptide (BNP) and conducted macro and micromorphological assessments. Additionally, immunohistochemical analysis of cardiac OPN and mTOR was performed. The NA-treated group showed significant increases in blood pressure, HR, weight, and cardiac enzymes compared to the control group. Exercise significantly improved these parameters in the combined exercise and NA treatment group, except for blood pressure. All groups exhibited an increase in cardiac weight relative to the control. The NA-treated group displayed marked hyaline degeneration and necrosis in cardiac tissues, with increased cell diameter and excess collagen deposition, which was less severe in the combined exercise (EX) and NA treatment group. NA treatment significantly elevated inflammatory mediators and the area percentage of OPN and m-TOR expression. These markers were significantly reduced in the combined exercise and NA treatment group. BNP was remarkably raised in EX+NA group compared to all other groups. Exercise mitigated NA-induced cardiac damage by reducing inflammation, possibly through the downregulation of cardiac OPN and m-TOR expression.

Gestational arsenite exposure alters maternal postpartum heart size and induces Ca2+-handling dysregulation in cardiomyocytes

Cardiovascular disease is the leading cause of mortality in the United States. Studies suggest a role for environmental exposures in the etiology of cardiovascular disease, including exposure to arsenic through drinking water. Arsenic exposure during pregnancy has been shown to have effects on offspring, but few studies have examined impacts on maternal cardiovascular health. Although our prior work documented the detrimental effect of arsenic on the maternal heart during pregnancy, our current study examines the effect of gestational arsenic exposure on the maternal heart postpartum. Timed-pregnant wild-type (C57BL/6J) mice were exposed to 0, 100, or 1,000 µg/L sodium arsenite (NaAsO2) via drinking water from embryonic day 2.5 until parturition. Postpartum heart structure and function was assessed via transthoracic echocardiography and gravimetric measurement. Hypertrophic markers were probed via qRT-PCR and Western blot. Isolated cardiomyocyte Ca2+-handling and contraction were also assessed, along with the expression of with Ca2+-handling and contractile proteins. Interestingly, we found that exposure to either 100 or 1,000 µg/L sodium arsenite increased postpartum heart size at postpartum day 12 vs. nonexposed postpartum controls. At the cellular level, we found altered cardiomyocyte Ca2+-handling and contraction, along with expression changes of key contractile proteins, including α-actin and cardiac myosin binding protein C (cMyBP-c). Together, these findings suggest that gestational arsenic exposure impacts the postpartum maternal heart, possibly inducing long-term cardiovascular changes. Furthermore, these findings highlight the importance of reducing arsenic exposure during pregnancy, and the need for more research on the impact of arsenic on maternal heart health and adverse pregnancy events.NEW & NOTEWORTHY Gestational exposure to sodium arsenite at environmentally relevant doses (100 and 1,000 µg/L) increases postpartum heart size, and induces dysregulated Ca2+ homeostasis and impaired shortening in isolated cardiomyocytes. This is the first study to demonstrate that gestational arsenic exposure impacts postpartum heart structure and function beyond the exposure period.

Mechanosensitive lncRNA H19 promotes chondrocyte autophagy, but not pyroptosis, by targeting miR-148a in post-traumatic osteoarthritis

OBJECTIVE

Investigating whether mechanosensitive lncRNA H19 can directly target miR-148a to alleviate cartilage damage in post-traumatic osteoarthritis (PTOA).

METHODS

Thirty-two female rats were randomly divided into four groups: Sham-operated group (Sham group, n = 8), treadmill running group (R group, n = 8), anterior cruciate ligament transection (ACLT) group (ACLT group, n = 8), and ACLT + treadmill running group (ACLT + R group, n = 8). Histological evaluation was performed to observe the pathological changes in the cartilage of the rat knee. Micro-CT was performed to detect the bone morphological changes in the subchondral bone. RT-qPCR and Western-Blot were performed to detect changes in mRNA and protein levels of metabolic and inflammatory factors as well as changes in the expression of lncRNA H19 and miR-148a in cartilage. The Flexcell 5000™ Tension System was used to further validate that lncRNA H19 has mechanosensitivity in vitro. Finally, cell transfection techniques were used to knock down the expression of lncRNA H19 in chondrocytes to validate the regulatory role of lncRNA H19/miR-148a in cartilage metabolism.

RESULTS

ACLT combined with treadmill running aggravated the abnormal hyperplasia of subchondral bone in the lateral tibial plateau of the rat knee joint, disturbed the balance of cartilage metabolism, induced cartilage inflammatory response and chondrocyte pyroptosis, which eventually led to cartilage damage and PTOA. Importantly, we found that the expression of lncRNA H19 was significantly downregulated in the cartilage of the ACLT + R group. Bioinformatics analysis revealed that miR-148a may be a direct target of lncRNA H19. Subsequently, we focused on the mechanosensitive of lncRNA H19. Subsequently, moderate-intensity mechanical tension stress reversed the expression of lncRNA H19 and autophagy-related factors in inflammatory chondrocytes, while miR-148a showed an opposite expression trend, demonstrating that mechanosensitive lncRNA H19 may be involved in regulating the chondrocyte inflammatory response by targeting miR-148a and activating autophagy. Cell transfection experiments revealed that lncRNA H19 knockdown upregulated miR-148a expression and significantly inhibited the autophagy level of chondrocytes without significant alteration of chondrocyte pyroptosis, which in turn exacerbated the inflammatory response of chondrocytes.

CONCLUSIONS

Mechanosensitive lncRNA H19 can promote chondrocyte autophagy rather than pyroptosis by targeting miR-148a, thus alleviating cartilage damage in PTOA. LncRNA H19 may be a potential therapeutic target for PTOA.

Gestational arsenite exposure alters maternal postpartum heart size and induces Ca 2+ handling dysregulation in cardiomyocytes

Cardiovascular disease is the leading cause of mortality in the US. Studies suggest a role for environmental exposures in the etiology of cardiovascular disease, including exposure to arsenic through drinking water. Arsenic exposure during pregnancy has been shown to have effects on offspring, but few studies have examined impacts on maternal cardiovascular health. While our prior work documented the detrimental effect of arsenic on the maternal heart during pregnancy, our current study examines the effect of gestational arsenic exposure on the maternal heart postpartum. Timed-pregnant wild-type (C57BL/6J) mice were exposed to 0, 100 or 1000 µg/L sodium arsenite (NaAsO2) via drinking water from embryonic day 2.5 (E2.5) until parturition. Postpartum heart structure and function was assessed via transthoracic echocardiography and gravimetric measurement. Hypertrophic markers were probed via qRT-PCR and western blot. Isolated cardiomyocyte Ca 2+ -handling and contraction were also assessed, and expression of proteins associated with Ca 2+ handling and contraction. Interestingly, we found that exposure to either 100 or 1000 µg/L sodium arsenite increased postpartum heart size at P12 vs. non-exposed postpartum controls. At the cellular level, we found altered cardiomyocyte Ca 2+ -handling and contraction. We also found altered expression of key contractile proteins, including α-Actin and cardiac myosin binding protein C (cMyBP-c). Together, these findings suggest that gestational arsenic exposure impacts the postpartum maternal heart, possibly inducing long-term cardiovascular changes. Furthermore, these findings highlight the importance of reducing arsenic exposure during pregnancy, and the need for more research on the impact of arsenic and other environmental exposures on maternal heart health and adverse pregnancy events.

New & Noteworthy

Gestational exposure to sodium arsenite at environmentally relevant doses (100 and 1000 µg/L) increases postpartum heart size, and induces dysregulated Ca 2+ homeostasis and impaired shortening in isolated cardiomyocytes. This is the first study to demonstrate that gestational arsenic exposure impacts postpartum heart structure and function beyond the exposure period.

Exercise promotes osteogenic differentiation by activating the long non-coding RNA H19/microRNA-149 axis

BACKGROUND

Regular physical activity during childhood and adolescence is beneficial to bone development, as evidenced by the ability to increase bone density and peak bone mass by promoting bone formation.

AIM

To investigate the effects of exercise on bone formation in growing mice and to investigate the underlying mechanisms.

METHODS

20 growing mice were randomly divided into two groups: Con group (control group, n = 10) and Ex group (treadmill exercise group, n = 10). Hematoxylin-eosin staining, immunohistochemistry, and micro-CT scanning were used to assess the bone formation-related indexes of the mouse femur. Bioinformatics analysis was used to find potential miRNAs targets of long non-coding RNA H19 (lncRNA H19). RT-qPCR and Western Blot were used to confirm potential miRNA target genes of lncRNA H19 and the role of lncRNA H19 in promoting osteogenic differentiation.

RESULTS

Compared with the Con group, the expression of bone morphogenetic protein 2 was also significantly increased. The micro-CT results showed that 8 wk moderate-intensity treadmill exercise significantly increased bone mineral density, bone volume fraction, and the number of trabeculae, and decreased trabecular segregation in the femur of mice. Inhibition of lncRNA H19 significantly upregulated the expression of miR-149 and suppressed the expression of markers of osteogenic differentiation. In addition, knockdown of lncRNA H19 significantly downregulated the expression of autophagy markers, which is consistent with the results of autophagy-related protein changes detected in mouse femurs by immunofluorescence.

CONCLUSION

Appropriate treadmill exercise can effectively stimulate bone formation and promote the increase of bone density and bone volume in growing mice, thus enhancing the peak bone mass of mice. The lncRNA H19/miR-149 axis plays an important regulatory role in osteogenic differentiation.

The Roles of Aerobic Exercise and Folate Supplementation in Hyperhomocysteinemia-Accelerated Atherosclerosis

Background

Hyperhomocysteinemia (HHcy) is an independent risk factor for atherosclerosis. Effective interventions to reduce HHcy-accelerated atherosclerosis are required.

Objectives

This study aimed to investigate the effects of aerobic exercise (AE) and folate (FA) supplementation on plasma homocysteine (Hcy) level and atherosclerosis development in a mouse model.

Methods

Six-week-old female apoE-/- mice were grouped into five groups (N = 6-8): HHcy (1.8 g/L DL-homocysteine (DL-Hcy) in drinking water), HHcy + AE (1.8 g/L DL-Hcy and aerobic exercise training on a treadmill), HHcy + FA (1.8 g/L DL-Hcy and 0.006% folate in diet), HHcy + AE + FA (1.8 g/L DL-Hcy, 0.006% folate, and aerobic exercise training on a treadmill), and a control group (regular water and diet). All treatment was sustained for 8 weeks. Triglyceride, cholesterol, lipoprotein, and Hcy levels were determined enzymatically. Plaque and monocyte chemoattractant protein-1 (MCP-1) expression levels in mouse aortic roots were evaluated by immunohistochemistry.

Results

Compared to the HHcy group (18.88 ± 6.13 μmol/L), plasma Hcy concentration was significantly reduced in the HHcy + AE (14.79 ± 3.05 μmol/L, p = 0.04), HHcy + FA (9.4 ± 3.85 μmol/L, p < 0.001), and HHcy + AE + FA (9.33 ± 2.21 μmol/L, p < 0.001) groups. Significantly decreased aortic root plaque area and plaque burden were found in the HHcy + AE and HHcy + AE + FA groups compared to those in the HHcy group (both p < 0.05). Plasma MCP-1 level and MCP-1 expression in atherosclerotic lesions were significantly decreased in the HHcy + AE and HHcy + AE + FA groups compared to the HHcy group (all p < 0.05).

Conclusions

AE reduced atherosclerosis development in HHcy apoE-/- mice independently of reducing Hcy levels. FA supplementation decreased plasma Hcy levels without attenuating HHcy-accelerated atherosclerosis. AE and FA supplementation have distinct mechanisms in benefiting atherosclerosis.

A low-intensity lifelong exercise routine changes miRNA expression in aging and prevents osteosarcopenic obesity by modulating inflammation

Osteosarcopenic obesity (OSO) has been associated with increase immobility, falls, fractures, and other dysfunctions, which could increase mortality risk during aging. However, its etiology remains unknown. Recent studies revealed that sedentarism, fat gain, and epigenetic regulators are critical in its development. One effective intervention to prevent and treat OSO is exercise. Therefore, in the present study, by keeping rats in conditions of sedentarism and others under a low-intensity exercise routine, we established an experimental model of OSO. We determined the degree of sarcopenia, obesity, and osteopenia at different ages and analyzed the miRNA expression during the lifespan using miRNA microarrays from gastrocnemius muscle. Interestingly microarrays results showed that there is a set of miRNAs that changed their expression with exercise. The pathway enrichment analysis showed that these miRNAs are strongly associated with immune regulation. Further inflammatory profiles with IL-6/IL-10 and TNF-α/IL-10 ratios showed that exercised rats presented a lower pro-inflammatory profile than sedentary rats. Also, the body fat gain in the sedentary group increased the inflammatory profile, ultimately leading to muscle dysfunction. Exercise prevented strength loss over time and maintained skeletal muscle functionality over time. Differential expression of miRNAs suggests that they might participate in this process by regulating the inflammatory response associated with aging, thus preventing the development of OSO.