Voluntary wheel running from early adolescence reduces disease progression, and anxiety- and depression-related symptoms in an adult male mouse model of rheumatoid arthritis

Rheumatoid arthritis (RA) is a multifactorial autoimmune disease that progressively destroys synovial joints and leads to chronic systemic inflammation. This autoimmune disorder is associated with increased anxiety- and depression-related symptoms, which reduces quality of life. Clinical and experimental evidence suggests that higher physical activity from early adolescence may prevent chronic diseases and reduce the risk of mental health problems in adulthood. This study aimed to assess whether voluntary wheel running from early adolescence can decrease clinical symptoms, anxiety- and depression-related behaviors in adult mice with rheumatoid arthritis. Adolescent male mice were exposed to voluntary wheel running until adulthood and got collagen-induced arthritis. We measured body weight, the thickness of the hind paw and knee joint (clinical signs), anxiety- and depression-related behaviors, serum testosterone, and cytokines (IFN-γ IL-1β, IL-6, TNF-α, IL-10). The findings showed that collagen-induced arthritis resulted in anxious-like behavior, increased anhedonia, elevated IL-6, IL-1β, TNF-α, and IFN-γ, and decreased testosterone levels in the serum of mice. However, no change was observed in behavioral despair. We found that higher physical activity from early adolescence significantly reduced the severity of clinical signs, anxiety- and anhedonia-like behaviors, and decreased behavioral despair in RA-induced mice. In addition, the running wheel exposure normalized RA-induced abnormalities in testosterone and inflammatory cytokines in mice. Altogether, this study suggests that higher physical activity from early adolescence may make mice less vulnerable or resistant to RA-induced clinical symptoms and anxiety- and depression-related behaviors by changing testosterone and inflammatory cytokines productions in adulthood.

Fluoxetine combined with swimming exercise synergistically reduces lipopolysaccharide-induced depressive-like behavior by normalizing the HPA axis and brain inflammation in mice

Major depression disorder is a debilitating psychiatric disease affecting millions of people worldwide. This disorder is the leading cause of morbidity and mortality in high-income countries. Selective serotonin reuptake inhibitors such as fluoxetine are first-line drugs for treating depression-related disorders, but not all patients respond well to these antidepressants. This study aimed to evaluate whether fluoxetine combined with aerobic exercise can affect lipopolysaccharide (LPS)-induced depressive-like behavior, hypothalamic-pituitary-adrenal (HPA) axis dysregulation, and brain inflammation in mice. Male mice were exposed to fluoxetine, swimming exercise, or a combination of both and finally treated with LPS. We measured depression-related symptoms such as anhedonia, behavioral despair, weight gain, and food intake. Hormones (corticosterone and testosterone) and cytokines (IL-1β, IL-6, TNF-α, IL-10) were also measured in serum and brain (hippocampus and prefrontal cortex), respectively. The findings indicated that LPS induced anhedonia and behavioral despair and increased corticosterone, hippocampal IL-1β, TNF-α, and decreased testosterone and hippocampal IL-10 in mice. Fluoxetine and exercise separately reduced LPS-induced depressive-like behavior, while their combination synergistically reduced these symptoms in LPS-treated mice. We found fluoxetine alone increased food intake and body weight in LPS-treated mice. Fluoxetine and exercise combination reduced corticosterone, hippocampal TNF-α, and prefrontal IL-6 and TNF-α levels and increased testosterone and hippocampal and prefrontal IL-10 levels more effectively than fluoxetine alone in LPS-treated mice. This study suggests that swimming exercise combined with fluoxetine can affect depression-related behavior, HPA axis, and brain inflammation more effectively than when they are used separately.

Diazepam and exercise training combination synergistically reduces lipopolysaccharide-induced anxiety-like behavior and oxidative stress in the prefrontal cortex of mice

Anxiety-related disorders are among the most important risks for global health, especially in recent years due to the COVID-19 pandemic. Benzodiazepines like diazepam are generally used to treat anxiety disorders, but the overall outcome is not always satisfactory. This is why psychiatrists encourage patients with anxiety to change their lifestyle habits to decrease the risk of anxiety recurrence. However, the effect of diazepam and exercise in combination is unknown. This study aimed to investigate the effect of diazepam alone or in combination with swimming exercise on lipopolysaccharide (LPS)-induced anxiety-like behavior and oxidative stress in the hippocampus and prefrontal cortex of mice. Mice were exposed to diazepam and swimming exercise alone or in combination with each other and then received LPS. We assessed anxiety-like behavior using open field and light-dark box and measured oxidative markers including glutathione (GSH), malondialdehyde (MDA), and glutathione disulfide (GSSG) in the hippocampus and prefrontal cortex. The findings showed that LPS increased anxiety-related symptoms and oxidative stress by decreasing GSH and increasing MDA and GSSG levels in the prefrontal cortex but not in the hippocampus. Although diazepam alone did not reduce anxiety-like behavior and oxidative stress, it in combination with exercise significantly decreased anxiety-like behavior and oxidative stress in the prefrontal cortex of LPS-treated mice. This drug and exercise combination also displayed a more effective effect in comparison with exercise alone. Overall, this study suggests that diazepam in combination with swimming exercise has higher efficacy on anxiety-like behavior and oxidative stress than when they are used alone.

The role of the oxytocinergic system in the antidepressant-like effect of swimming training in male mice

Increasing evidence shows that higher physical activity such as running and swimming exercises is associated with decreased depression-related symptoms. However, underlying mechanisms are not fully understood. This study aimed to investigate whether oxytocinergic system can mediate the antidepressant effect of swimming exercises in mice. First, male NMRI mice were subjected to swimming training for eight weeks, then animals intraperitoneally received oxytocin antagonist (L-368899) 1hour before behavioral tests. We assessed anhedonia and social behavior and behavioral despair using the sucrose preference test, social interaction test, and tail suspension test. Oxytocin levels in the brain and serum were also measured. The results showed that swimming training decreased anhedonia and behavioral despair, whereas it increased social behavior and oxytocin levels in male mice. On the other hand, a subthreshold dose of oxytocin antagonist treatment in exercised mice prevented the antidepressant effect of swimming exercise via increased anhedonia and behavioral despair and decreased social behavior compared to the swimming training group. However, the blockade of oxytocin receptors did not affect oxytocin levels in exercised mice. Overall, these findings suggest that oxytocinergic system can play a role in mediating the antidepressant-like effect of swimming training in mice.

Exercise During Adolescence Attenuated Depressive-Like Behaviors and Hippocampal Mitochondrial Dysfunction Following Early Life Stress in Adult Male Rats

In this study, we assumed that treating animals with an antidepressant agents or voluntary running wheel exercise (RW) during adolescence may have beneficial outcomes against early life stress (ELS) which could be effective on behavior and mitochondrial function. Evidence indicated that ELS has deleterious impacts on brain and increases the risk of brain disorders such as depression. Maternal separation stress (MS) model to male rats (postnatal day or PND2-PND14) were performed to determination of depressive-like behaviors using the forced swimming test, splash test, and mitochondrial function in the hippocampus. Treating MS rats with both RW and fluoxetine (5 mg/kg/day, i.p) during adolescence (PND30-PND60) produced antidepressant-like effects in animals and attenuated the negative effects of ELS on hippocampal mitochondrial function in adult male rats. The results of the present study showed that (none) pharmacological treatments during adolescence are able to produce therapeutic effects against adverse effects of ELS on behavior and mitochondrial performance. These results showed the importance of adolescence as an important period of life and the long-lasting effects of ELS on hippocampal mitochondrial function which can suggest the possible contribution of abnormal mitochondrial function in pathogenesis of depression following experiencing ELS.