Fish oil consumption prevents glucose intolerance and hypercorticosteronemy in footshock-stressed rats

X chromosome dosage drives statin-induced dysglycemia and mitochondrial dysfunction

Statin drugs lower blood cholesterol levels for cardiovascular disease prevention. Women are more likely than men to experience adverse statin effects, particularly new-onset diabetes (NOD) and muscle weakness. Here we find that impaired glucose homeostasis and muscle weakness in statin-treated female mice are associated with reduced levels of the omega-3 fatty acid, docosahexaenoic acid (DHA), impaired redox tone, and reduced mitochondrial respiration. Statin adverse effects are prevented in females by administering fish oil as a source of DHA, by reducing dosage of the X chromosome or the Kdm5c gene, which escapes X chromosome inactivation and is normally expressed at higher levels in females than males. As seen in female mice, we find that women experience more severe reductions than men in DHA levels after statin administration, and that DHA levels are inversely correlated with glucose levels. Furthermore, induced pluripotent stem cells from women who developed NOD exhibit impaired mitochondrial function when treated with statin, whereas cells from men do not. These studies identify X chromosome dosage as a genetic risk factor for statin adverse effects and suggest DHA supplementation as a preventive co-therapy.

Protein Intake from Various Foods Sources Is Negatively Associated with Cardiometabolic Risk Markers in Italian Older Adults

OBJECTIVES

To examine the relationships between protein intake from various food sources and cardiometabolic risk markers in Italian older adults.

DESIGN

Cross-sectional study.

SETTING

Unconventional settings across Italy (e.g., exhibitions, health promotion campaigns).

PARTICIPANTS

People 65+ years who provided a written informed consent.

MEASUREMENTS

Blood pressure (BP), blood glucose, total blood cholesterol, and anthropometric indices were assessed. Daily protein intake was estimated for 12 food items listed in a food frequency questionnaire.

RESULTS

Three-thousand four-hundred twenty-four older adults (mean age: 72.7 ± 5.7 years; 55% women) were included in the study. Results of linear regression analysis indicated that protein intake from several food sources was negatively associated with BP, waist and hip circumferences, and waist-to-hip ratio in both sexes. Blood glucose levels were inversely associated with many protein sources in women. Positive associations were observed between some protein sources and total blood cholesterol in both men and women.

CONCLUSION

Our findings suggest that dietary protein is differentially associated with cardiometabolic risk factors depending on sex and food sources.

Effect of the dietary intake of fish oil on psycho-social behavioral disorder caused by social-defeat stress

Exposure to psychosocial stress is a risk factor for human diseases such as depression. Social defeat stress (SDS) is a well-known rodent model of human psychosocial stress, and animals exposed to SDS show social avoidance behavior. Fish oil, which is rich in docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), is expected to decrease the risk of depressive disorders. In this study, we determined whether fish oil affects the social behavior of SDS-exposed mice and measured serotonin levels and expression of genes related to tryptophan (TRP) metabolism in the hippocampus. The experimental animals were fed a diet containing fish oil during SDS exposure. For the fish oil treatment, experimental mice were fed a diet containing fish oil at low (L-FO), middle (M-FO), and high (H-FO) concentrations. The control group was supplemented with an equivalent amount of canola oil (no fish oil: N-FO). After the SDS protocol, we performed a social interaction test and assessed the sociality of experimental mice. In the N-FO group, SDS-exposed mice showed negative social interactions compared with non-stressed mice. The L-FO and H-FO groups showed negative social interactions after SDS exposure; however, the M-FO group did not exhibit negative social behavior. The serotonin levels of SDS-exposed mice were lower than those of non-stressed mice in the N-FO group. In contrast with these results in the N-FO group, there was no difference in serotonin levels between SDS-exposed and non-stressed mice in the FO groups. In addition, the expression of genes related to TRP metabolism in SDS-exposed mice increased in the N-FO group, but not in the FO group. These results suggest that fish oil improves the psychosocial behavioral disorders caused by SDS. This improvement could be explained by the increase in serotonin synthesis in the hippocampus.

Early postnatal stress impairs insulin secretion in response to psychological stress in adult rats

PURPOSE

Adversity in early life can induce metabolic defects in exposure to stress in adulthood. Therefore, the exploration of involving mechanisms can be helpful in the treatment of metabolic disorders. So, the present study was conducted in terms of exploring the effects of interaction between early postnatal stress and young adulthood psychological stress on insulin secretion and pancreatic GLUT-2 levels in male rats.

METHODS

Footshock as a model of early life stress (at 2 weeks of age) and psychological stress induced by communication box as a model of young adulthood stress (at 8-10 weeks of age) were induced in male Wistar rats for five consecutive days (2 times/day). Blood samples were drawn to measure glucose, insulin, homeostatic model assessment of insulin resistance (HOMA-IR) and homeostasis model assessment of β-cell dysfunction (HOMA-B), before and after stress protocol in young adult rats. Corticosterone was measured on days 1 and 5 of stress induction. The day after the stress period, factors including glucose tolerance, TNF-alpha, isolated islets' insulin output and levels of pancreatic GLUT-2 protein via western blotting were determined.

RESULTS

The combination of early footshock exposure and psychological stress during adulthood did not affect plasma corticosterone, but increased plasma insulin, HOMA-IR, HOMA-B and TNF-alpha levels. Plasma TNF was not only increased by the combination of both stressors, but also after only E STR exposure. HOMA-IR was increased in both Psy STR and E + Psy-STR groups. Plasma glucose just increased in Psy STR group. The combination of these two life stressors further increased the in vitro insulin secretion from isolated islets in response to 16.7-mM glucose. The level of Glut2 was increased in Psy STR and decreased in both E STR and E + Psy STR groups. Finally, glucose tolerance was impaired and glucose-stimulated insulin secretion was increased in E + Psy STR group.

CONCLUSIONS

In conclusion, inducing stress in early life makes the organism more susceptible to metabolic defects in exposure to psychological stress later in life.

Early postnatal hypothalamic-pituitary-adrenal axis activity and reduced insulin sensitivity in adult rats

OBJECTIVE

Early life stress influences the development of metabolic disorders, including functional changes in the developing of pancreas mediated hypothalamic-pituitary-adrenal (HPA) axis. In the present study, the role of an early postnatal stress on corticosterone, glucose, and insulin levels was investigated during young adulthood.

METHODS

Two groups of pups were studied, including control group (pups not receiving foot shock by communication box), and early stress group (pups receiving foot shock by communication box 2 times/day for 5 consecutive days). In rats, concentration of plasma corticosterone, glucose, and insulin was detected before and after placing them into the communication box at 2 weeks of age. At 8-10 weeks of age, concentrations of plasma corticosterone, glucose, and insulin and glucose tolerance were measured in young adult rats.

RESULTS

Our results showed that early postnatal foot shock stress increased the corticosterone, insulin, and glucose levels in the postnatal age (p<0.01) that did not last until young adult age, but it caused a significant increase in plasma glucose and insulin levels (p<0.05) following the intraperitoneal glucose tolerance test (IPGTT) in young adult rats.

CONCLUSIONS

These results suggest that impaired IPGTT in young adult rats who experienced early postnatal stress can indicate insulin resistance or reduced insulin sensitivity that make it at risk of the type 2 diabetes later in life.

Impact of chronic exercise on counteracting chronic stress-induced functional and morphological pancreatic changes in male albino rats

Chronic stress has been linked to many diseases resulted from dysfunction of both the nervous system and peripheral organ systems. Yet, the effects of chronic stress on the pancreas have received relatively little attention. This work aims to investigate the influence of chronic stress exposure on both the endocrine and exocrine pancreatic function and morphology and its possible mechanism of action, and also to evaluate the impact of chronic exercise with moderate intensity on ameliorating the stress-induced pancreatic changes. Forty adult male albino rats were used and divided into four groups: control group, exercised group (3 weeks of swimming exercise), stressed group (3 weeks of immobilization stress), and stressed group practicing exercise (3 weeks of exercise, concomitant with 21 daily sessions of stress). On the final day of the experiment, all rats were sacrificed. Biochemical, immunohistochemical, and histological studies were conducted. The results showed that chronic immobilization stress produced hyperglycemia, hyperinsulinemia, and increased homeostatic model assessment of insulin resistance index (HOMA-IR) with increasing exocrine pancreatic injury markers by increasing oxidative and inflammatory status of the pancreatic tissue. Histological study showed the injurious effect of stress on the morphology of pancreatic tissue. Physical exercise protected the pancreas from the negative effects of stress through its anti-inflammatory and anti-oxidative effects, evidenced by increasing pancreatic interleukin 10 and total antioxidant capacity and decreasing pancreatic tumor necrosis factor-alpha, and malondialdehyde with ameliorating most of the histological changes induced by stress exposure. Physical exercise effectively counteracts chronic stress-induced pancreatic changes through different mechanisms.

Effect of early life stress on pancreatic isolated islets' insulin secretion in young adult male rats subjected to chronic stress

Early stressful experiences may predispose organisms to certain disorders, including those of metabolic defects. This study aimed to explore the effects of early life stress on pancreatic insulin secretion and glucose transporter 2 (GLUT2) protein levels in stressed young adult male rats. Foot shock stress was induced in early life (at 2 weeks of age) and/or in young adulthood (at 8-10 weeks of age) for five consecutive days. Blood samples were taken before and after stress exposure in young adult rats. At the end of the experiment, glucose tolerance, isolated islets' insulin secretion, and pancreatic amounts of GLUT2 protein were measured. Our results show that early life stress has no effect on basal plasma corticosterone levels and adrenal weight, either alone or combined with young adulthood stress, but that early life + young adulthood stress could prevent weight gain, and cause an increase in basal plasma glucose and insulin. The homeostasis model assessment of insulin resistance index did not increase, when the rats were subjected to early life stress alone, but increased when combined with young adulthood stress. Moreover, glucose tolerance was impaired by the combination of early life + young adult stress. There was a decrease in islet's insulin secretion in rats subjected to early life stress in response to 5.6 mM glucose concentration, but an increase with a concentration of 16.7 mM glucose. However, in rats subjected to early life + young adulthood stress, islet's insulin secretion increased in response to both the levels of glucose concentrations. GLUT2 protein levels decreased in response to early life stress and early life + young adulthood stress, but there was a greater decrease in the early life stress group. In conclusion, perhaps early life stress sensitizes the body to stressors later in life, making it more susceptible to metabolic syndrome only when the two are in combination.

Effects of probiotic therapy on metabolic and inflammatory parameters of rats with ligature-induced periodontitis associated with restraint stress

BACKGROUND

This study evaluates the effects of probiotic therapy (PT) in rats with ligature-induced periodontitis associated with restraint stress.

METHODS

Sixty-four rats were divided into control, stress (STR), probiotic (PROB), periodontal disease (PD), STR-PROB, STR-PD, STR-PROB-PD, and PROB-PD groups. The probiotic was added to the drinking water for 44 days. PD was induced by a ligature. In STR groups, the animals were subjected to restraint stress for 2.5 hours per day for 30 days.

RESULTS

Rats with PD exhibited increased alveolar bone loss (P <0.05), as well as increased levels of cyclooxygenase-2, serum C-terminal telopeptide (CTX), p38 mitogen-activated protein kinase (p38), and receptor activator of nuclear factor-κB ligand and decreased levels of osteoprotegerin (OPG). Stressed rats presented high levels of C-peptide, corticosterone, and glucose (P <0.05). In general, the presence of stress reduced the expression of CTX and p38 (P <0.05). PT reduced alveolar bone loss in unstressed animals. It also decreased expression of CTX and induced increased expression of OPG in unstressed animals with PD. However, PT was not effective in preventing bone loss or altering the expression of inflammatory markers in stressed animals. PT decreased the number of inflammatory cells in the periodontal tissue (P <0.05). Groups with stress and PD showed decreased villous height and crypt depth. Stress seemed to prevent part of the probiotic beneficial effects on the small intestine.

CONCLUSIONS

Based on the methodology used, PT may reduce tissue breakdown resulting from PD in unstressed rats. The protocol used for restraint stress influenced the immunomodulatory effects of PT in intestinal and periodontal tissues.

Effects of individual glucose levels on the neuronal correlates of emotions

This study aimed to directly assess the effect of changes in blood glucose levels on the psychological processing of emotionally charged material. We used functional magnetic resonance imaging (fMRI) to evaluate the effect of blood glucose levels on three categories of visually presented emotional stimuli. Seventeen healthy young subjects participated in this study (eight females; nine males; body weight, 69.3 ± 14.9 kg; BMI, 22 ± 2.7; age, 24 ± 3 years), consisting of two functional MRI sessions: (1) after an overnight fast under resting conditions (before glucose administration); (2) after reaching the hyperglycemic state (after glucose administration). During each session, subjects were presented with visual stimuli featuring funny, neutral, and sad content. Single-subject ratings of the stimuli were used to verify the selection of stimuli for each category and were covariates for the fMRI analysis. Analysis of the interaction effect of the two sessions (eu- and hyperglycemia), and the emotional categories accounting for the single-subject glucose differences, revealed a single activation cluster in the hypothalamus. Analysis of the activation profile of the left amygdala corresponded to the three emotional conditions, and this profile was obtained for both sessions regardless of glucose level. Our results indicate that, in a hyperglycemic state, the hypothalamus can no longer respond to emotions. This study offers novel insight for the understanding of disease-related behavior associated with dysregulation of glucose and glucose availability, potentially offering improved diagnostic and novel therapeutic strategies in the future.