Aerobic Exercise Training Attenuates Obesity-Related Hypogonadism in Male Rats

Female and male obese Zucker rats display differential inflammatory mediator and long non-coding RNA profiles

AIMS

The goal of this study was to identify mediators in peri-lymphatic adipose tissue (PLAT) that are altered in obese versus lean Zucker rats, with focus on potential sex differences MAIN METHODS: Mesenteric PLAT was analyzed with protein and lncRNA arrays. Additional RT-PCR confirmation was performed with epididymal/ovarian fat.

KEY FINDINGS

MCP-1, TCK-1, Galectin-1, Galectin-3, and neuropilin-1 were elevated in PLAT from obese rats of both sexes. However, 11 additional proteins were elevated only in obese males while 24 different proteins were elevated in obese females. Profiling of lncRNAs revealed lean males have elevated levels of NEAT1, MALAT1 and GAS5 compared to lean females. NEAT1, MALAT1, and GAS5 were significantly reduced with obesity in males but not in females. Another lncRNA, HOTAIR, was higher in lean females compared to males, and its levels in females were reduced with obesity. Obese rats of both sexes had similar histologic findings of mesenteric macrophage crown-like structures and hepatocyte fat accumulation.

SIGNIFICANCE

While obese male and female Zucker rats both have increased inflammation, they have distinct signals. Future studies of the proteome and lncRNA landscape of obese males vs. females in various animal models and in human subjects are warranted to better guide development of therapeutics for obesity-induced inflammation.

Aerobic physical exercise modifies the prostate tumoral environment

Exercise is recognized for its potential role in reducing the risk of certain cancers. However, the molecular mechanisms behind this risk reduction are not fully understood. Here, we hypothesized that aerobic physical exercise induces cancer attenuating effects through the modulation of oxidative stress and inflammation. To test this hypothesis, twenty male Sprague Dawley rats with chemically induced prostate tumors were divided into two groups: Prostate cancer (PC) in the absence and presence of exercise (PC + Ex). Rats in the PC + Ex group performed exercises on a treadmill for 8 weeks, 5 sessions per week, at an intensity of 60 % of maximum capacity. Weight and feed efficiency, Ki-67, apoptosis, prostatic inflammation, and markers of oxidative stress were analyzed. We found that aerobic physical exercise significantly decreased prostate cell proliferation (p < 0.05) across modulation, tumor size, and prostate weight. The PC + Ex group also significantly reduced anti-apoptosis protein expression (p < 0.05) and increased pro-apoptotic protein expression. Furthermore, physical exercise increased enzymatic antioxidant defenses in the prostate, plasma, and whole blood. Moreover, PC + Ex reduced lipid peroxidation and protein carbonyl levels (p < 0.05). In the prostate, there was an increase in anti-inflammatory cytokines (IL-10), and a reduction in pro-inflammatory cytokines (IL-6, TNF-α, and NF-κB) after 8 weeks of physical exercise. In conclusion, we found that aerobic physical exercise is a functional, beneficial, and applicable approach to control PC progression, because it modifies the systemic environment, including the regulation of glucose and circulating lipids. This modification of the cancer cells environment has anti-inflammatory and antioxidant effects that attenuate tumor growth.

Effects of Moderate-Intensity Continuous Training and High-Intensity Interval Training on Testicular Oxidative Stress, Apoptosis and m6A Methylation in Obese Male Mice

Exercise is an effective way to improve reproductive function in obese males. Oxidative stress and apoptosis are important pathological factors of obesity-related male infertility. Accumulating studies have demonstrated that N6-methyladenosine (m6A) methylation is associated with obesity and testicular reproductive function. Our study aimed to investigate and compare the effect of 8 weeks of moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT) on testicular oxidative stress, apoptosis and m6A methylation in obese male mice. Male C57BL/6 mice were randomly allocated into the four groups: normal diet (ND) group, high-fat diet (HFD) group, high-fat diet with moderate-intensity continuous training (HFD-MICT) group and high-fat diet with high-intensity interval training (HFD-HIIT) group. Mice in the HFD-MICT and HFD-HIIT groups were subjected to 8 weeks of MICT or HIIT treadmill protocols after 12 weeks of HFD feeding. We found that MICT and HIIT increased the protein expression of Nrf2, HO-1 and NQO-1 in the testes of obese mice, and HIIT increased it more than MICT. The Bax/Bcl-2 ratio, Cleaved Caspase-3 protein expression and TUNEL-positive cells were consistently up-regulated in the testes of obese mice, but MICT and HIIT restrained these HFD-induced effects. In addition, HFDs increased m6A levels and the gene expression of METTL3, YTHDF2 and FTO in the testes, but these effects were reversed by MICT and HIIT. However, HIIT was more effective than MICT in reducing m6A methylation in the testes of obese mice. These results demonstrate that both MICT and HIIT protected against HFD-induced oxidative stress, apoptosis and m6A methylation in testicular tissues; as a result, testicular morphological and functional impairment improved. In particular, HIIT was more beneficial than MICT in increasing the mRNA expression of steroidogenic enzymes and testicular antioxidant capacity and decreasing m6A methylation in the testes of HFD-fed mice.

Poor Diet, Stress, and Inactivity Converge to Form a "Perfect Storm" That Drives Alzheimer's Disease Pathogenesis

North American incidence of Alzheimer's disease (AD) is expected to more than double over the coming generation. Although genetic factors surrounding the production and clearance of amyloid-β and phosphorylated tau proteins are known to be responsible for a subset of early-onset AD cases, they do not explain the pathogenesis of the far more prevalent sporadic late-onset variant of the disease. It is thus likely that lifestyle and environmental factors contribute to neurodegenerative processes implicated in the pathogenesis of AD. Herein, we review evidence that (1) excess sucrose consumption induces AD-associated liver pathologies and brain insulin resistance, (2) chronic stress overdrives activity of locus coeruleus neurons, leading to loss of function (a common event in neurodegeneration), (3) high-sugar diets and stress promote the loss of neuroprotective sex hormones in men and women, and (4) Western dietary trends set the stage for a lithium-deficient state. We propose that these factors may intersect as part of a "perfect storm" to contribute to the widespread prevalence of neurodegeneration and AD. In addition, we put forth the argument that exercise and supplementation with trace lithium can counteract many of the deleterious consequences associated with excessive caloric intake and perpetual stress. We conclude that lifestyle and environmental factors likely contribute to AD pathogenesis and that simple lifestyle and dietary changes can help counteract their effects.

Increasing hypothalamic nucleobindin 2 levels and decreasing hypothalamic inflammation in obese male mice via diet and exercise alleviate obesity-associated hypogonadism

To explore the role of nesfatin-1 in regulating male reproductive function during energy balance variation, we employed an obese mouse model which was first induced by a high-fat diet (HFD) and followed by interventions of a normal diet (ND) and/or moderate exercise, and then serum reproductive hormones of male mice, hypothalamic nucleobindin 2 (NUCB2)/nesfatin-1, inflammatory factors, and gonadotropin-releasing hormone (GnRH) levels were tested. Our findings showed that both serum nesfatin-1, follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone (T) levels and hypothalamic NUCB2/nesfatin-1 and Gnrh mRNA levels were reduced, whereas, the mRNA and protein levels of hypothalamic tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, inhibitor kappa B kinase β (IKKβ), and nuclear factor (NF)-κB were increased in obese male mice. Diet, exercise, and diet combined with exercise interventions reversed the decreases in serum nesfatin-1, FSH, LH, and T levels; increased hypothalamic NUCB2/nesfatin-1 and Gnrh mRNA levels; and reduced hypothalamic TNF-α, IL-1β, IKKβ, and NF-κB levels. These changes were accompanied by reduced adiposity, and these effects were more obvious in the diet combined with exercise group. Overall, our findings suggested that the hypogonadotropic hypogonadism associated with obesity may be induced by reduced hypothalamic NUCB2/nesfatin-1 levels, which attenuated the stimulatory effect on GnRH directly or indirectly by suppressing its anti-inflammatory effect in the brain. Diet and/or exercise interventions were able to alleviate the hypogonadotropic hypogonadism associated with obesity, potentially by increasing hypothalamic NUCB2/nesfatin-1 levels.

Effects of obesity and exercise on testicular leptin signal transduction and testosterone biosynthesis in male mice

To explore the role of the testicular leptin and JAK-STAT[leptin (LEP)-JAK-STAT] pathway in testosterone biosynthesis during juvenile stages and exercise for weight loss, male C57BL/6J mice were randomly divided into normal-diet and high-fat diet groups. After 10 wk, mice in the high-fat diet-fed group were further divided randomly into obese control, obese moderate-volume exercise, and obese high-volume exercise groups. Mice in the obese moderate-volume exercise group were provided with 2 h/day, 6 days/wk swimming exercise for 8 wk, and mice in the obese high-volume exercise group underwent twice the amount of daily exercise intervention as the obese moderate-volume exercise group. The results showed that a high-fat diet causes obesity, leptin resistance, inhibition of the testicular LEP-JAK-STAT pathway, decreased mRNA and protein expression of steroidogenic factor-1, steroidogenic acute regulatory protein, and the P-450 side-chain cleavage enzyme, a decrease in the serum testosterone-to-estradiol ratio, and declines in sperm quality parameters. Both moderate and high-volume exercise were able to reduce body fat and increase the mRNA and protein expression of LEP-JAK-STAT, but only moderate exercise significantly increased the mRNA and protein expression of steroidogenic factor-1, steroidogenic acute regulatory protein, and P-450 side-chain cleavage enzyme and significantly reversed the serum testosterone-to-estradiol ratio and sperm quality parameters. These findings suggest that by impairing the testicular LEP-JAK-STAT pathway, early-stage obesity inhibits the biosynthesis of testosterone and sexual development and reduces male reproductive potential. Long-term moderate and high-volume exercise can effectively reduce body fat and improve obesity-induced abnormalities in testicular leptin signal transduction, whereas only moderate-volume exercise can reverse the negative impacts of obesity on male reproductive function.

Severe Obesity Shifts Metabolic Thresholds but Does Not Attenuate Aerobic Training Adaptations in Zucker Rats

Severe obesity affects metabolism with potential to influence the lactate and glycemic response to different exercise intensities in untrained and trained rats. Here we evaluated metabolic thresholds and maximal aerobic capacity in rats with severe obesity and lean counterparts at pre- and post-training. Zucker rats (obese: n = 10, lean: n = 10) were submitted to constant treadmill bouts, to determine the maximal lactate steady state, and an incremental treadmill test, to determine the lactate threshold, glycemic threshold and maximal velocity at pre and post 8 weeks of treadmill training. Velocities of the lactate threshold and glycemic threshold agreed with the maximal lactate steady state velocity on most comparisons. The maximal lactate steady state velocity occurred at higher percentage of the maximal velocity in Zucker rats at pre-training than the percentage commonly reported and used for training prescription for other rat strains (i.e., 60%) (obese = 78 ± 9% and lean = 68 ± 5%, P < 0.05 vs. 60%). The maximal lactate steady state velocity and maximal velocity were lower in the obese group at pre-training (P < 0.05 vs. lean), increased in both groups at post-training (P < 0.05 vs. pre), but were still lower in the obese group at post-training (P < 0.05 vs. lean). Training-induced increase in maximal lactate steady state, lactate threshold and glycemic threshold velocities was similar between groups (P > 0.05), whereas increase in maximal velocity was greater in the obese group (P < 0.05 vs. lean). In conclusion, lactate threshold, glycemic threshold and maximal lactate steady state occurred at similar exercise intensity in Zucker rats at pre- and post-training. Severe obesity shifted metabolic thresholds to higher exercise intensity at pre-training, but did not attenuate submaximal and maximal aerobic training adaptations.

Effects of exercise training on indicators of adipose tissue angiogenesis and hypoxia in obese rats

OBJECTIVE

To investigate the effects of obesity and exercise training on regional adipose tissue angiogenesis and hypoxia markers in rats.

METHODS

Lean (Fa/Fa) and obese (fa/fa) male Zucker rats at 2 months of age were randomly assigned to a sedentary or an exercise training group (lean sedentary: n=7, lean exercise: n=8, obese sedentary: n=7, obese exercise: n=8). The exercise group walked on a rat treadmill 5 times per week for 8 weeks. Inguinal and epididymal adipose tissue vascular endothelial growth factor A (VEGF-A) and lactate levels were determined.

RESULTS

There were significant effects of obesity in increasing inguinal (P<0.001) and epididymal (P<0.05) adipose tissue VEGF-A, and a significant effect of exercise training in increasing epididymal adipose tissue VEGF-A (P<0.05). There was a significant effect of obesity in increasing inguinal adipose tissue lactate levels (P<0.001). Compared to lean sedentary animals, obese sedentary animals had significantly higher epididymal adipose tissue lactate levels (P<0.001); compared to obese sedentary animals, obese exercise rats had significantly lower epididymal adipose tissue lactate levels (P<0.05).

CONCLUSIONS

Exercise training increased adipose tissue VEGF-A, an important factor of tissue angiogenesis, and lowered adipose tissue lactate, an indicator of adipose tissue hypoxia in obese rats. However, these effects are depot-specific and only observed in intra-abdominal adipose tissue.