Restraint stress exacerbates cardiac and adipose tissue pathology via β-adrenergic signaling in rats with metabolic syndrome

Macrophage NLRP3 inflammasome mediates the effects of sympathetic nerve on cardiac remodeling in obese rats

Obesity-associated cardiac remodeling is characterized by cardiac sympathetic nerve over-activation and pro-inflammatory macrophage infiltration. We identified norepinephrine (NE), a sympathetic neurotransmitter, as a pro-inflammatory effector to activate macrophage NLRP3 inflammasome, which contributed to cardiac inflammation. In vivo, Sprague-Dawley (SD) rats were fed a high-fat diet (HFD) for 12 weeks to establish obese rat models. Obese rats exhibited marked cardiac hypertrophy compared to normal rats. The expression of NLRP3 and interleukin (IL)-1β was upregulated, accompanied by CD68+NLRP3+ macrophage infiltration in the hearts of the obese rats. The obese rats also showed increased sympathetic nerve activity. β-adrenergic receptor (AR) inhibition mitigated these changes. In vitro, sympathetic neurotransmitter NE significantly exacerbated palmitic acid (PA)-induced macrophage polarization toward pro-inflammatory type and NLRP3 inflammasome activation in THP-1 macrophages. It was further found that the pro-inflammatory role of NE is dependent on the activation of protein kinase A (PKA) and subsequently inhibition of β-arrestin2, which is an important regulator of the nuclear factor-kappa B (NF-κB) pathway. This study identifies the neuro-immune axis as an important mediator in obesity-associated cardiac remodeling. Targeting the neuro-immune system may open therapeutic opportunities for the treatment of cardiac remodeling in obesity.

Insights into the mechanisms of angiogenesis in infantile hemangioma

Infantile hemangioma (IH) is the most common benign tumor in infants and usually resolves on its own. However, a small portion of IH cases are accompanied by serious complications and other problems, impacting the physical and psychological health of the children affected. The pathogenesis of IH is highly controversial. Studies have shown that abnormal blood vessel formation is an important pathological basis for the development of IH. Compared with that in normal tissues, the equilibrium of blood vessel growth at the tumor site is disrupted, and interactions among other types of cells, such as immune cells, promote the rapid proliferation and migration of vascular tissue cells and the construction of vascular networks. Currently, propranolol is the most common systemic drug used to inhibit the growth of IHs and accelerate their regression. The purpose of this review is to provide the latest research on the mechanisms of angiogenesis in IH. We discuss the possible roles of three major factors, namely, estrogen, hypoxia, and inflammation, in the development of IH. Additionally, we summarize the key roles of tumor cell subpopulations, such as pericytes, in the proliferation and regression of IH considering evidence from the past few years, with an emphasis on the possible mechanisms of propranolol in the treatment of IH. Angiogenesis is an important event during the development of IH, and an in-depth understanding of the molecular mechanisms of angiogenesis will provide new insights into the biology and clinical treatment of IH.

Activation of P2X7 Receptor Mediates the Abnormal Ovulation Induced by Chronic Restraint Stress and Chronic Cold Stress

Chronic stress has become a major problem that endangers people's physical and mental health. Studies have shown that chronic stress impairs female reproduction. However, the related mechanism is not fully understood. P2X7 receptor (P2X7R) is involved in a variety of pathological changes induced by chronic stress. Whether P2X7R is involved in the effect of chronic stress on female reproduction has not been studied. In this study, we established a chronic restraint stress mouse model and chronic cold stress mouse model. We found that the number of corpora lutea was significantly reduced in the two chronic stress models. The number of corpora lutea indirectly reflects the ovulation, suggesting that chronic stress influences ovulation. P2X7R expression was significantly increased in ovaries of the two chronic stress models. A superovulation experiment showed that P2X7R inhibitor A-438079 HCL partially rescued the ovulation rate of the two chronic stress models. Further studies showed that activation of P2X7R signaling inhibited the cumulus expansion and promoted the expression of NPPC in granulosa cells, one key negative factor of cumulus expansion. Moreover, sirius red staining showed that the ovarian fibrosis was increased in the two chronic stress models. For the fibrosis-related factors, TGF-β1 was increased and MMP2 was decreased. In vitro studies also showed that activation of P2X7R signaling upregulated the expression of TGF-β1 and downregulated the expression of MMP2 in granulosa cells. In conclusion, P2X7R expression was increased in the ovaries of the chronic restraint-stress and chronic cold-stress mouse models. Activation of P2X7R signaling promoted NPPC expression and cumulus expansion disorder, which contributed to the abnormal ovulation of the chronic stress model. Activation of P2X7R signaling is also associated with the ovarian fibrosis changes in the chronic stress model.

Preventive effects of melatonin on periodontal tissue destruction due to psychological stress in rats with experimentally induced periodontitis

OBJECTIVE AND BACKGROUND

Psychological stress is a potential modifiable environmental risk factor causally related to the exacerbation of periodontitis and other chronic inflammatory diseases. This animal study aimed to investigate comprehensively the preventive efficacy of systemic melatonin administration on the possible effects of restraint stress on the periodontal structures of rats with periodontitis.

METHODS

Forty-eight male Sprague Dawley rats were randomly divided into six groups: control, restraint stress (S), S-melatonin (S-Mel), experimental periodontitis (Ep), S-Ep, and S-Ep-Mel. Periodontitis was induced by placing a 3.0 silk suture in a sub-paramarginal position around the cervix of the right and left lower first molars of the rats and keeping the suture in place for 5 weeks. Restraint stress was applied simultaneously by ligation. Melatonin and carriers were administered to the control, S, Ep, and S-Ep groups intraperitoneally (10 mg/body weight/day, 14 days) starting on day 21 following ligation and subjection to restraint stress. An open field test was performed on all groups on day 35 of the study. Periodontal bone loss was measured via histological sections. Histomorphometric and immunohistochemical (RANKL and OPG) evaluations were performed on right mandibular tissue samples and biochemical (TOS (total oxidant status), TAS (total antioxidant status), OSI (oxidative stress index), IL-1β, IL-10, and IL-1β/IL-10) evaluations were performed on left mandibular tissue samples.

RESULTS

Melatonin significantly limited serum corticosterone elevation related to restraint stress (p < .05). Restraint stress aggravated alveolar bone loss in rats with periodontitis, while systemic melatonin administration significantly reduced stress-related periodontal bone loss. According to the biochemical analyses, melatonin significantly lowered IL-1β/IL-10, OSI (TOS/TAS), and RANKL/OPG rates, which were significantly elevated in the S-Ep group.

CONCLUSION

Melatonin can significantly prevent the limited destructive effects of stress on periodontal tissues by suppressing RANKL-related osteoclastogenesis and oxidative stress.

Stress-induced changes in cognitive function and intestinal barrier integrity can be ameliorated by venlafaxine and synbiotic supplementations

Stress profoundly impacts various aspects of both physical and psychological well-being. Our previous study demonstrated that venlafaxine (Vlx) and synbiotic (Syn) treatment attenuated learned fear-like behavior and recognition memory impairment in immobilized-stressed rats. In this study, we further investigated the physical, behavior, and cellular mechanisms underlying the effects of Syn and/or Vlx treatment on brain and intestinal functions in stressed rats. Adult male Wistar rats, aged 8 weeks old were subjected to 14 days of immobilization stress showed a decrease in body weight gain and food intake as well as an increase in water consumption, urinary corticosterone levels, and adrenal gland weight. Supplementation of Syn and/or Vlx in stressed rats resulted in mitigation of weight loss, restoration of normal food and fluid intake, and normalization of corticosterone levels. Behavioral analysis showed that treatment with Syn and/or Vlx enhanced depressive-like behaviors and improved spatial learning-memory impairment in stressed rats. Hippocampal dentate gyrus showed stress-induced neuronal cell death, which was attenuated by Syn and/or Vlx treatment. Stress-induced ileum inflammation and increased intestinal permeability were both effectively reduced by the supplementation of Syn. In addition, Syn and Vlx partly contributed to affecting the expression of the glial cell-derived neurotrophic factor in the hippocampus and intestines of stressed rats, suggesting particularly protective effects on both the gut barrier and the brain. This study highlights the intricate interplay between stress physiological responses in the brain and gut. Syn intervention alleviate stress-induced neuronal cell death and modulate depression- and memory impairment-like behaviors, and improve stress-induced gut barrier dysfunction which were similar to those of Vlx. These findings enhance our understanding of stress-related health conditions and suggest the synbiotic intervention may be a promising approach to ameliorate deleterious effects of stress on the gut-brain axis.

Antioxidant action of xanthine oxidase inhibitor febuxostat protects the liver and blood vasculature in SHRSP5/Dmcr rats

BACKGROUND

Xanthine oxidase (XO) generates reactive oxygen species during uric acid production. Therefore, XO inhibitors, which suppress oxidative stress, may effectively treat non-alcoholic steatohepatitis (NASH) and atherosclerosis via uric acid reduction. In this study, we examined the antioxidant effect of the XO inhibitor febuxostat on NASH and atherosclerosis in stroke-prone spontaneously hypertensive 5 (SHRSP5/Dmcr) rats.

METHODS

SHRSP5/Dmcr rats were divided into three groups: SHRSP5/Dmcr + high-fat and high-cholesterol (HFC) diet [control group, n = 5], SHRSP5/Dmcr + HFC diet + 10% fructose (40 ml/day) [fructose group, n = 5], and SHRSP5/Dmcr + HFC diet + 10% fructose (40 ml/day) + febuxostat (1.0 mg/kg/day) [febuxostat group, n = 5]. Glucose and insulin resistance, blood biochemistry, histopathological staining, endothelial function, and oxidative stress markers were evaluated.

RESULTS

Febuxostat reduced the plasma uric acid levels. Oxidative stress-related genes were downregulated, whereas antioxidant factor-related genes were upregulated in the febuxostat group compared with those in the fructose group. Febuxostat also ameliorated inflammation, fibrosis, and lipid accumulation in the liver. Mesenteric lipid deposition decreased in the arteries, and aortic endothelial function improved in the febuxostat group.

CONCLUSIONS

Overall, the XO inhibitor febuxostat exerted protective effects against NASH and atherosclerosis in SHRSP5/Dmcr rats.

The sex-dependent response to psychosocial stress and ischaemic heart disease

Stress is an important risk factor for modern chronic diseases, with distinct influences in males and females. The sex specificity of the mammalian stress response contributes to the sex-dependent development and impacts of coronary artery disease (CAD). Compared to men, women appear to have greater susceptibility to chronic forms of psychosocial stress, extending beyond an increased incidence of mood disorders to include a 2- to 4-fold higher risk of stress-dependent myocardial infarction in women, and up to 10-fold higher risk of Takotsubo syndrome-a stress-dependent coronary-myocardial disorder most prevalent in post-menopausal women. Sex differences arise at all levels of the stress response: from initial perception of stress to behavioural, cognitive, and affective responses and longer-term disease outcomes. These fundamental differences involve interactions between chromosomal and gonadal determinants, (mal)adaptive epigenetic modulation across the lifespan (particularly in early life), and the extrinsic influences of socio-cultural, economic, and environmental factors. Pre-clinical investigations of biological mechanisms support distinct early life programming and a heightened corticolimbic-noradrenaline-neuroinflammatory reactivity in females vs. males, among implicated determinants of the chronic stress response. Unravelling the intrinsic molecular, cellular and systems biological basis of these differences, and their interactions with external lifestyle/socio-cultural determinants, can guide preventative and therapeutic strategies to better target coronary heart disease in a tailored sex-specific manner.

The correlation of pericoronary adipose tissue with coronary artery disease and left ventricular function

OBJECTIVE

We sought to investigate the correlation of pericoronary adipose tissue with coronary artery disease and left ventricular (LV) function.

METHODS

Participants with clinically suspected coronary artery disease were enrolled. All participants underwent coronary computed tomography angiography (CCTA) and echocardiography followed by invasive coronary angiography (ICA) within 6 months. Pericoronary adipose tissue (PCAT) was extracted to analyze the correlation with the Gensini score and LV function parameters, including IVS, LVPW, LVEDD, LVESD, LVEDV, LVESV, FS, LVEF, LVM, and LVMI. The correlation between PCAT and the Gensini score was assessed using Spearman's correlation analysis, and that between the PCAT volume or FAI and LV function parameters was determined using partial correlation analysis.

RESULTS

One hundred and fifty-nine participants (mean age, 64.55 ± 10.64 years; men, 65.4% [104/159]) were included in the final analysis. Risk factors for coronary artery disease, such as hypertension, diabetes, dyslipidemia, and a history of smoking or drinking, had no significant association with PCAT (P > 0.05), and there was also no correlation between PCAT and the Gensini score. However, the LAD-FAI was positively correlated with the IVS (r = 0.203, P = 0.013), LVPW (r = 0.218, P = 0.008), LVEDD (r = 0.317, P < 0.001), LVESD (r = 0.298, P < 0.001), LVEDV (r = 0.317, P < 0.001), LVESV (r = 0.301, P < 0.001), LVM (r = 0.371, P < 0.001), and LVMI (r = 0.304, P < 0.001). Also, the LCX-FAI was positively correlated with the LVEDD (r = 0.199, P = 0.015), LVESD (r = 0.190, P = 0.021), LVEDV (r = 0.203, P = 0.013), LVESV (r = 0.197, P = 0.016), LVM (r = 0.220, P = 0.007), and LVMI (r = 0.172, P = 0.036), and the RCA-FAI was positively correlated with the LVEDD (r = 0.258, P = 0.002), LVESD (r = 0.238, P = 0.004), LVEDV (r = 0.266, P = 0.001), LVESV (r = 0.249, P = 0.002), LVM (r = 0.237, P = 0.004), and LVMI (r = 0.218, P = 0.008), respectively. Finally, the total volume was positively correlated with FS (r = 0.167, P = 0.042).

CONCLUSION

The FAI was positively correlated with the LV function but was not associated with the severity of coronary artery disease.

Pharmacological inhibition of the lipid phosphatase PTEN ameliorates heart damage and adipose tissue inflammation in stressed rats with metabolic syndrome

Phosphatidylinositol 3-kinase (PI3K) signaling promotes the differentiation and proliferation of regulatory B (Breg) cells, and the lipid phosphatase phosphatase and tensin homolog deleted on chromosome 10 (PTEN) antagonizes the PI3K-Akt signaling pathway. We previously demonstrated that cardiac Akt activity is increased and that restraint stress exacerbates hypertension and both heart and adipose tissue (AT) inflammation in DS/obese rats, an animal model of metabolic syndrome (MetS). We here examined the effects of restraint stress and pharmacological inhibition of PTEN on heart and AT pathology in such rats. Nine-week-old animals were treated with the PTEN inhibitor bisperoxovanadium-pic [bpV(pic)] or vehicle in the absence or presence of restraint stress for 4 weeks. BpV(pic) treatment had no effect on body weight or fat mass but attenuated hypertension in DS/obese rats subjected to restraint stress. BpV(pic) ameliorated left ventricular (LV) inflammation, fibrosis, and diastolic dysfunction as well as AT inflammation in the stressed rats. Restraint stress reduced myocardial capillary density, and this effect was prevented by bpV(pic). In addition, bpV(pic) increased the proportions of Breg and B-1 cells as well as reduced those of CD8+ T and B-2 cells in AT of stressed rats. Our results indicate that inhibition of PTEN by bpV(pic) alleviated heart and AT inflammation in stressed rats with MetS. These positive effects of bpV(pic) are likely due, at least in part, to a reduction in blood pressure, an increase in myocardial capillary formation, and an altered distribution of immune cells in fat tissue that result from the activation of PI3K-Akt signaling.

Surgical ablation of whitened interscapular brown fat ameliorates cardiac pathology in salt-loaded metabolic syndrome rats

Brown adipose tissue (BAT) is an endocrine organ that contributes to thermogenesis and energy consumption. We investigated the effects of salt loading and surgical removal of whitened interscapular BAT (iBAT) on cardiac and adipose tissue pathology in DahlS.Z-Lepr^fa /Lepr^fa (DS/obese) rats, an animal model of metabolic syndrome (MetS). DS/obese rats were subjected to surgical removal of iBAT or sham surgery at 8 weeks of age and were provided with drinking water containing or not containing 0.3% NaCl for 4 weeks beginning at 9 weeks of age. Removal of iBAT suppressed the salt-induced exacerbation of left ventricular inflammation, fibrosis, and diastolic dysfunction, but not that of hypertension development, in DS/obese rats. Salt loading attenuated adipocyte hypertrophy but enhanced inflammation in both visceral white adipose tissue (WAT) and iBAT. Although iBAT removal did not affect visceral WAT pathology in salt-loaded DS/obese rats, it attenuated the elevation of circulating interleukin-6 levels in these animals. Downregulation of uncoupling protein-1 expression in iBAT of DS/obese rats was not affected by salt loading. Our results suggest that the conversion of iBAT to WAT-like tissue contributes to a salt-induced elevation of circulating proinflammatory cytokine levels that leads to exacerbation of cardiac pathology in this model of MetS.

Alleviation of salt-induced exacerbation of cardiac, renal, and visceral fat pathology in rats with metabolic syndrome by surgical removal of subcutaneous fat

OBJECTIVES

Evidence suggests that visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) should be considered as distinct types of white fat. Although VAT plays a key role in metabolic syndrome (MetS), the role of subcutaneous adipose tissue (SAT) has been unclear. DahlS.Z-Lepr^fa/Lepr^fa (DS/obese) rats, an animal model of MetS, develop adipocyte hypertrophy and inflammation to similar extents in SAT and VAT. We have now investigated the effects of salt loading and SAT removal on cardiac, renal, and VAT pathology in DS/obese rats.

METHODS

DS/obese rats were subjected to surgical removal of inguinal SAT or sham surgery at 8 weeks of age. They were provided with a 0.3% NaCl solution as drinking water or water alone for 4 weeks from 9 weeks of age.

RESULTS

Salt loading exacerbated hypertension, insulin resistance, as well as left ventricular (LV) hypertrophy, inflammation, fibrosis, and diastolic dysfunction in DS/obese rats. It also reduced both SAT and VAT mass but aggravated inflammation only in VAT. Although SAT removal did not affect LV hypertrophy in salt-loaded DS/obese rats, it attenuated hypertension, insulin resistance, and LV injury as well as restored fat mass and alleviated inflammation and the downregulation of adiponectin gene expression in VAT. In addition, whereas salt loading worsened renal injury as well as upregulated the expression of renin-angiotensin-aldosterone system-related genes in the kidney, these effects were suppressed by removal of SAT.

CONCLUSIONS

SAT removal attenuated salt-induced exacerbation of MetS and LV and renal pathology in DS/obese rats. These beneficial effects of SAT removal are likely attributable, at least in part, to inhibition of both VAT and systemic inflammation.

Effects of occlusal disharmony on cardiac fibrosis, myocyte apoptosis and myocyte oxidative DNA damage in mice

Occlusal disharmony leads to morphological changes in the hippocampus and osteopenia of the lumbar vertebra and long bones in mice, and causes stress. Various types of stress are associated with increased incidence of cardiovascular disease, but the relationship between occlusal disharmony and cardiovascular disease remain poorly understood. Therefore, in this work, we examined the effects of occlusal disharmony on cardiac homeostasis in bite-opening (BO) mice, in which a 0.7 mm space was introduced by cementing a suitable applicance onto the mandibular incisior. We first examined the effects of BO on the level of serum corticosterone, a key biomarker for stress, and on heart rate variability at 14 days after BO treatment, compared with baseline. BO treatment increased serum corticosterone levels by approximately 3.6-fold and the low frequency/high frequency ratio, an index of sympathetic nervous activity, was significantly increased by approximately 4-fold by the BO treatment. We then examined the effects of BO treatment on cardiac homeostasis in mice treated or not treated with the non-selective β-blocker propranolol for 2 weeks. Cardiac function was significantly decreased in the BO group compared to the control group, but propranolol ameliorated the dysfunction. Cardiac fibrosis, myocyte apoptosis and myocyte oxidative DNA damage were significantly increased in the BO group, but propranolol blocked these changes. The BO-induced cardiac dysfunction was associated with increased phospholamban phosphorylation at threonine-17 and serine-16, as well as inhibition of Akt/mTOR signaling and autophagic flux. These data suggest that occlusal disharmony might affect cardiac homeostasis via alteration of the autonomic nervous system.

The impact of chronic stress on energy metabolism

The brain is exceptionally demanding in terms of energy metabolism. Approximately 20% of the calories consumed are devoted to our cerebral faculties, with the lion's share provided in the form of glucose. The brain's stringent energy dependency requires a high degree of harmonization between the elements responsible for supplying- and metabolizing energetic substrates. However, chronic stress may jeopardize this homeostatic energy balance by disruption of critical metabolic processes. In agreement, stress-related mental disorders have been linked with perturbations in energy metabolism. Prominent stress-induced metabolic alterations include the actions of hormones, glucose uptake and mitochondrial adjustments. Importantly, fundamental stress-responsive metabolic adjustments in humans and animal models bear a striking resemblance. Here, an overview is provided of key findings, demonstrating the pervasive impact of chronic stress on energy metabolism. Furthermore, I argue that medications, aimed primarily at restoring metabolic homeostasis, may constitute a novel approach to treat mental disorders.

The pretreatment of chronic restraint stress exerts little impact on the progression of heart failure in mice

Stress is a potent risk factor for depression. Chronic stress can exacerbate and induce symptoms of depression. Clinical studies suggested that depressive patients are more likely to develop coronary artery diseases. However, the causal relationship between depression and heart failure progression remains unclear. In this study, we aimed to explore the relevance between stress and heart failure (HF) in a mouse model subjected to chronic restraint stress and left anterior descending coronary artery (LAD) ligation. Mice were restrained for 3 h daily for 21 days and the processes were repeated once 3 months later. After the repeated chronic restraint stress, mice showed dramatically increased immobility time in the forced swim test, indicating a state of despair. Restrained and control mice were further subjected to LAD ligation surgery. Echocardiography was conducted 1 week, 2 weeks, and 1 month afterward. LAD-operated mice showed a significant decrease in the values of left ventricular ejection fraction (LVEF), and there was no difference in the LVEF values between the restrained and control mice. Relevant gene expression, neurotransmitter system, glial activation, and morphology of the heart-brain axis were comprehensively evaluated. We found no overall differences between the restrained and control mice with HF. Our results revealed that the repeated chronic restraint stress may have little effects on the progression of heart failure.

Non-alcoholic steatohepatitis aggravates nitric oxide synthase inhibition-induced arteriosclerosis in SHRSP5/Dmcr rat model

Non-alcoholic steatohepatitis (NASH) is linked to increased cardiovascular risk, independent of the broad spectrum of metabolic syndrome risk factors. Stroke-prone (SP) spontaneously hypertensive rats (SHRSP5/Dmcr) fed a high-fat and high-cholesterol (HFC) diet developed hepatic lesions similar to those in human NASH pathology. These rats simultaneously developed lipid deposits in the mesenteric arteries, cardiac fibrosis, endothelial dysfunction and left ventricle (LV) diastolic dysfunction. However, the intermediary factors between NASH and cardiovascular disease are still unknown. We investigated whether NASH aggravates nitric oxide (NO) synthase inhibition-induced arteriosclerosis in SHRSP5/Dmcr rats. Wistar Kyoto and SHRSP5/Dmcr rats were divided into 4 groups of 5 and fed the stroke-prone (SP) or HFC diets for 8 weeks. To induce NO synthase inhibition, N^ω -nitro-L-arginine methyl ester hydrochloride (L-NAME) mixed with drinking water was administered in the final 2 weeks. The NASH+L-NAME group demonstrated the following characteristics related to arteriosclerosis and myocardial ischaemia: (a) LV systolic dysfunction with asynergy, (b) replacement fibrosis caused by the shedding of cardiomyocytes and (c) arterial lipid deposition and coronary occlusion secondary to endothelial dysfunction. These characteristics were not observed in the NASH or non-NASH+L-NAME groups. The SHRSP5/Dmcr rat model demonstrates that NASH significantly aggravates cardiovascular risk.

β2-AR regulates the expression of AKR1B1 in human pancreatic cancer cells and promotes their proliferation via the ERK1/2 pathway

Psychological stress has been recognized as a well-documented risk factor associated with β2-adrenergic receptor (β2-AR) in the development of pancreatic cancer. Aldo-keto reductase 1 member B1 (AKR1B1) is a potential interacting partner of β2-AR, but the effect of their interaction on pancreatic cancer cells is not known at present. We found a positive correlation between AKR1B1 and β2-AR expression in pancreatic cancer tissue samples, and co-localization of these proteins in the human pancreatic cancer BXPC-3 cell line. Compared to the controls, the CFPAC-1 and PANC-1 pancreatic cancer cells overexpressing β2-AR and AKR1B1 respectively showed significantly higher proliferation rates, which is attributed to higher proportion of cells in the S phase and decreased percentage of early apoptotic cells. Furthermore, overexpression of β2-AR led to a significant increase in the expression of AKR1B1 and phosphorylated extracellular signal-regulated kinase (p-ERK1/2). Overexpression of AKR1B1 significantly decreased β2-AR levels and increased that of p-ERK1/2. Taken together, β2-AR directly interacted with and up-regulated AKR1B1 in pancreatic cancer cells, and promoted their proliferation and inhibited apoptosis via the ERK1/2 pathway. Our findings also highlight the β2-AR-AKR1B1 axis as a potential therapeutic target for pancreatic cancer.

Phyllanthus emblica leaf extract ameliorates testicular damage in rats with chronic stress

Stress affects the male reproductive system and can cause sub-fertility or infertility. Although Phyllanthus emblica L. (PE) extract has been shown to have high antioxidant capacity and protective properties in damaged tissue, the preventive effects of PE extract on testicular function from stress-related impairment have never been demonstrated. This study aimed to investigate the effects of PE aqueous leaf extract on testicular impairment and protein marker changes in rats suffering from chronic stress. Adult male rats were divided into four groups: a control group, a chronic stress (CS) group, and two groups with CS that received different doses of PE extract (50 or 100 mg/kg body weight (BW)). In the treatment groups, the animals were given PE extract daily before stress induction for 42 consecutive days. Stress was induced through immobilization (4 h/d) followed by forced cold swimming (15 min/d). Sperm quality and the histology of the testes and caudal epididymis were examined, as were levels of serum corticosterone, testosterone, and malondialdehyde (MDA). The expressions of testicular steroidogenic acute regulatory (StAR) and tyrosine-phosphorylated proteins were investigated using immuno-Western blot analysis, as these proteins are assumed to play important roles in spermatogenesis and androgen synthesis. The results showed that PE (50 mg/kg BW) significantly increased sperm concentration and testosterone levels, while decreasing corticosterone levels, MDA levels, sperm head abnormalities, and acrosome-reacted sperm in CS rats. In addition, PE at both doses was found to diminish testicular histopathology in the CS rats. We also found that 50 mg/kg BW of PE significantly improved StAR protein expression and altered the intensities of some tyrosine-phosphorylated proteins in testis. We conclude that PE leaf extract at 50 mg/kg BW can prevent testicular damage in rats with CS.

Effects of adipokine zinc-α2-glycoprotein on adipose tissue metabolism after dexamethasone treatment

Zinc-α2-glycoprotein (ZAG) has been demonstrated to play a role in stimulating lipid mobilization under normal conditions. However, further studies are required to determine whether ZAG overexpression can alleviate the reduction in plasma lipid levels under stress conditions. In the present study, we investigated the effects of ZAG on lipometabolism in white adipose tissue (WAT) after dexamethasone (DEX) stimulation using C57BL/6 male mice as the experimental models. Transcript and protein levels of genes associated with the β-adrenoreceptor (β-AR)/cyclic adenosine monophosphate/protein kinase a (PKA) pathway, lipid mobilization, and energy metabolism were determined by quantitative real-time polymerase chain reaction and Western blotting. Plasma levels of nonesterified fatty acid (NEFA) were measured using an automatic biochemical analyzer. Results indicated that plasma NEFA levels were decreased in the DEX group, but NEFA levels were rescued by ZAG overexpression. ZAG overexpression resulted in the upregulation of β3-AR and phosphorylated PKA protein relative to those of the DEX group. Analysis of lipometabolism showed that protein levels of phosphorylated hormone-sensitive lipase was reduced upon DEX treatment but were restored by ZAG overexpression. For energy metabolism, ZAG significantly upregulated the protein expression of carnitine palmitoyltransferase1a and cytochrome c oxidase subunit 1 relative to those of the DEX group. In conclusion, ZAG could alleviate DEX-induced decrease in plasma NEFA levels and this could be associated with the promoting lipid mobilization in WAT.

Linalyl acetate restores endothelial dysfunction and hemodynamic alterations in diabetic rats exposed to chronic immobilization stress

Although stress is one of the risk factors of diabetes, few studies have assessed the effects of stress on diabetic rats. This study, therefore, analyzed differences in cardiovascular-related factors among control, nonstressed diabetic, and stressed diabetic rats as well as assessed the effects of linalyl acetate (LA) on stressed diabetic rats. Male Sprague-Dawley rats were subjected to immobilization stress throughout the experimental period, and diabetes was induced on day 15 by a single injection of streptozotocin. After confirming the induction of diabetes, stressed diabetic rats were administered LA (10 or 100 mg/kg) or metformin (500 mg/kg) for the last 7 days. Compared with nonstressed diabetic rats, stressed diabetic rats had significantly lower body weight, body fat percentage, ACh-induced vasorelaxation, systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), and NF-κB expression as well as increased serum nitrite concentration. Although metformin increased serum insulin concentration significantly, 100 mg/kg LA showed only an increasing tendency. However, treatment with 100 mg/kg LA not only reduced serum glucose and NF-κB expression, but also restored ACh-induced vasorelaxation, SBP, DBP, HR, AMP-activated protein kinase expression, and serum nitrite almost to control levels. Importantly, 100 mg/kg LA was more effective than metformin in ameliorating serum glucose, endothelial nitric oxide synthase expression, HR, and serum nitrite. These findings suggest that chronic stress can aggravate endothelial dysfunction and hemodynamic alterations in diabetes and that LA may have potent therapeutic efficacy in diabetic patients with cardiovascular disease complications or chronic stress.

NEW & NOTEWORTHY To our knowledge, this is the first study to assess the effects of linalyl acetate (LA) on cardiovascular-related factors in diabetic rats exposed to chronic stress. Treatment with LA restored acetylcholine-induced vasorelaxation, blood pressure, heart rate, and AMP-activated protein kinase and serum nitrite levels. The present results suggest that LA may have potent therapeutic efficacy in diabetic patients with complications of cardiovascular disease or chronic stress.

In the View of Endothelial Microparticles: Novel Perspectives for Diagnostic and Pharmacological Management of Cardiovascular Risk during Diabetes Distress

Acute or chronic exposure to diabetes-related stressors triggers a specific psychological and behavior stress syndrome called diabetes distress, which underlies depressive symptoms in most diabetic patients. Distressed and/or depressive diabetic adults exhibit higher rates of cardiovascular mortality and morbidity, which have been correlated to macrovascular complications evoked by diabetic behavior stress. Recent experimental findings clearly point out that oxidative stress accounts for the vascular dysfunction initiated by the exposure to life stressors in diabetic conditions. Moreover, oxidative stress has been described as the main autocrine and paracrine mechanism of cardiovascular damage induced by endothelial microparticles (anuclear ectosomal microvesicles released from injured endothelial cells) in diabetic subjects. Such robust relationship between oxidative stress and cardiovascular diseases strongly suggests a critical role for endothelial microparticles as the primer messengers of the redox-dependent vascular dysfunction underlying diabetes distress. Here, we provide novel perspectives opened in the view of endothelial microparticles as promising diagnostic and pharmacotherapeutic biomarkers of cardiovascular risk in distressed diabetic patients.

A High-Fat and High-Cholesterol Diet Induces Cardiac Fibrosis, Vascular Endothelial, and Left Ventricular Diastolic Dysfunction in SHRSP5/Dmcr Rats

AIM

Non-alcoholic steatohepatitis (NASH) increases cardiovascular risk regardless of risk factors in metabolic syndrome. However, the intermediary factors between NASH and vascular disease are still unknown because a suitable animal model has never been established. The stroke-prone (SP) spontaneously hypertensive rat, SHRSP5/Dmcr, simultaneously develops hypertension, acute arterial lipid deposits in mesenteric arteries, and NASH when feed with a high-fat and high-cholesterol (HFC) diet. We investigated whether SHRSP5/Dmcr affected with NASH aggravates the cardiac or vascular dysfunction.

METHOD

Wister Kyoto and SHRSP5/Dmcr rats were divided into 4 groups of 5 rats each, and fed with a SP or HFC diet. After 8 weeks of HFC or SP diet feeding, glucose and insulin resistance, echocardiography, blood biochemistry, histopathological staining, and endothelial function in aorta were evaluated.

RESULTS

We demonstrate that SHRSP5/Dmcr rats fed with a HFC diet presented with cardiac and vascular dysfunction caused by cardiac fibrosis, endothelial dysfunction, and left ventricular diastolic dysfunction, in association with NASH and hypertension. These cardiac and vascular dysfunctions were aggravated and not associated with the presence of hypertension, glucose metabolism disorder, and/or obesity.

CONCLUSIONS

SHRSP5/Dmcr rats may be a suitable animal model for elucidating the organ interaction between NASH and cardiac or vascular dysfunction.

Atorvastatin reduces cardiac and adipose tissue inflammation in rats with metabolic syndrome

BACKGROUND

Statins are strong inhibitors of cholesterol biosynthesis and help to prevent cardiovascular disease. They also exert additional pleiotropic effects that include an anti-inflammatory action and are independent of cholesterol, but the molecular mechanisms underlying these additional effects have remained unclear. We have now examined the effects of atorvastatin on cardiac and adipose tissue inflammation in DahlS.Z-Lepr^fa/Lepr^fa (DS/obese) rats, which we previously established as a model of metabolic syndrome (MetS).

METHODS AND RESULTS

DS/obese rats were treated with atorvastatin (6 or 20mgkg^-1day^-1) from 9 to 13weeks of age. Atorvastatin ameliorated cardiac fibrosis, diastolic dysfunction, oxidative stress, and inflammation as well as adipose tissue inflammation in these animals at both doses. The high dose of atorvastatin reduced adipocyte hypertrophy to a greater extent than did the low dose. Atorvastatin inhibited the up-regulation of peroxisome proliferator-activated receptor γ gene expression in adipose tissue as well as decreased the serum adiponectin concentration in DS/obese rats. It also activated AMP-activated protein kinase (AMPK) as well as inactivated nuclear factor-κB (NF-κB) in the heart of these animals. The down-regulation of AMPK and NF-κB activities in adipose tissue of DS/obese rats was attenuated and further enhanced, respectively, by atorvastatin treatment.

CONCLUSIONS

The present results suggest that the anti-inflammatory effects of atorvastatin on the heart and adipose tissue are attributable at least partly to increased AMPK activity and decreased NF-κB activity in this rat model of MetS.

Inhibitory Effects and Mechanisms of Electroacupuncture via Chronically Implanted Electrodes on Stress-Induced Gastric Hypersensitivity in Rats With Neonatal Treatment of Iodoacetamide

BACKGROUND

Stress is considered an independent factor causing and aggravating gastrointestinal symptoms, including visceral pain. The aim of this study was to investigate effects and mechanisms of electroacupuncture (EA) on stress-induced gastric hypersensitivity in rats treated with neonatal iodoacetamide mimicking human functional dyspepsia (FD).

METHODS

Neonatal rats were treated with gavage of 0.2 mL of 0.1% iodoacetamide in 2% sucrose daily for six days starting on tenth day after birth. The control group was given 0.2 mL of 2% sucrose. When the rats were eight weeks old, acute restraint stress was performed on them for 90 min. EA at ST36 (ZuSanLi) was performed during the acute stress or 30 min after the stress. Adrenoceptor blocking drugs (propranolol and phentolamine) were injected intraperitoneally 30 min before acute restraint stress to explore possible sympathetic mechanisms. Visceral-motor responses to gastric distention were assessed by electromyogram (EMG).

RESULTS

1) Stress-induced gastric hypersensitivity was significantly more severe in the FD rats, compared to the control rats. It was blocked by the adrenoceptor antagonists. 2) EA inhibited stress-induced gastric hypersensitivity; the preventive effect of EA (given during stress) was more remarkable than the curative effect (given after stress). Stress resulted in a higher sympathovagal ratio and this was suppressed by EA.

CONCLUSIONS

Rats treated with neonatal iodoacetamide mimicking FD are more vulnerable to stress. Stress-induced gastric hypersensitivity can be prevented or suppressed by EA at ST36 via the restoration of sympathovagal balance.

Effects of various types of anesthesia on hemodynamics, cardiac function, and glucose and lipid metabolism in rats

Anesthesia can affect respiratory, circulatory, and endocrine systems but is necessary for certain experimental procedures such as echocardiography and blood sampling in small animals. We have now investigated the effects of four types of anesthesia [pentobarbital sodium (PENT), ketamine-xylazine (K/X), and low- or high-dose isoflurane (ISO)] on hemodynamics, cardiac function, and glucose and lipid metabolism in Sprague-Dawley rats. Aortic pressure, heart rate, and echocardiographic parameters were measured at various time points up to 45 min after the induction of anesthesia, and blood was then collected for measurement of parameters of glucose and lipid metabolism. Systolic aortic pressure remained constant in the PENT group, whereas it showed a biphasic pattern in the K/X group and a gradual decline in the ISO groups. Marked bradycardia was observed in the K/X group. The serum glucose concentration was increased and the plasma insulin level was reduced in the K/X and ISO groups compared with the PENT group. The concentrations of free fatty acids and norepinephrine in plasma were increased in the K/X group. Despite the metabolic effects of K/X and ISO, our results suggest that the marked bradycardic effect of K-X renders this combination appropriate for measurement of Doppler-derived indexes of left ventricular diastolic function, whereas the relative ease with which the depth of anesthesia can be controlled with ISO makes it suitable for manipulations or data collection over long time periods. On the other hand, PENT may be best suited for experiments that focus on measurement of cardiac function by M-mode echocardiography and metabolic parameters.

Highly purified eicosapentaenoic acid ameliorates cardiac injury and adipose tissue inflammation in a rat model of metabolic syndrome

INTRODUCTION

n-3 Polyunsaturated fatty acids such as eicosapentaenoic acid (EPA), which are abundant in fish oil, have been shown to delay the onset of cardiovascular events. We previously established DahlS.Z-Lepr^fa/Lepr^fa (DS/obese) rats, which are derived from a cross between Dahl salt-sensitive and Zucker rats, as a model of metabolic syndrome. This study has now explored the influence of highly purified EPA on cardiac and adipose tissue pathophysiology in this animal model.

MATERIALS AND METHODS

DS/obese rats were administered EPA (300 or 1,000 mg kg^-1 d^-1, per os) or vehicle from age 9 to 13 weeks. Homozygous lean (DahlS.Z-Lepr⁺/Lepr⁺, or DS/lean) littermates were studied as controls.

RESULTS

Whereas EPA had no effect on body weight, food intake or systolic blood pressure in DS/obese rats, it attenuated cardiac fibrosis, diastolic dysfunction, oxidative stress and inflammation in these animals. In addition, EPA did not affect insulin resistance but reduced adipocyte hypertrophy and inflammation in visceral fat of DS/obese rats. Moreover, EPA increased circulating levels of adiponectin as well as attenuated both the down-regulation of AMP-activated protein kinase phosphorylation and the up-regulation of phosphorylation of the p65 subunit of nuclear factor-kB in the heart of DS/obese rats.

CONCLUSIONS

Treatment of DS/obese rats with EPA did not affect hypertension but reduced cardiac fibrosis and diastolic dysfunction, with the latter effects being accompanied by AMP-activated protein kinase activation and inactivation of nuclear factor-kB signalling in the heart, possibly as a result of an increase in adiponectin secretion. EPA may be suitable for the treatment of cardiac injury associated with metabolic syndrome.

The Dichotomous Effect of Chronic Stress on Obesity

Obesity and metabolic diseases are linked to chronic stress and low socioeconomic status. The mechanistic link between stress and obesity has not been clarified, partly due to the inherent complexity exemplified by the bidirectional effect of stress on eating and body weight. Recent studies focusing on adaptive thermogenesis and brown adipose tissue (BAT) function support a dichotomous relation to explain the impact of stress on obesity: stress promotes obesity in the presence of hyperphagia and unchanged BAT function; stress results in weight loss and/or obesity resistance in the presence of hypophagia, or when hyperphagia is associated with BAT recruitment and enhanced thermogenesis. Mechanistically dissecting the bidirectional effects of stress on metabolic outcomes might open new avenues for innovative pharmacotherapies for the treatment of obesity-associated diseases.

Emotional Stress and Cardiovascular Complications in Animal Models: A Review of the Influence of Stress Type

Emotional stress has been recognized as a modifiable risk factor for cardiovascular diseases. The impact of stress on physiological and psychological processes is determined by characteristics of the stress stimulus. For example, distinct responses are induced by acute vs. chronic aversive stimuli. Additionally, the magnitude of stress responses has been reported to be inversely related to the degree of predictability of the aversive stimulus. Therefore, the purpose of the present review was to discuss experimental research in animal models describing the influence of stressor stimulus characteristics, such as chronicity and predictability, in cardiovascular dysfunctions induced by emotional stress. Regarding chronicity, the importance of cardiovascular and autonomic adjustments during acute stress sessions and cardiovascular consequences of frequent stress response activation during repeated exposure to aversive threats (i.e., chronic stress) is discussed. Evidence of the cardiovascular and autonomic changes induced by chronic stressors involving daily exposure to the same stressor (predictable) vs. different stressors (unpredictable) is reviewed and discussed in terms of the impact of predictability in cardiovascular dysfunctions induced by stress.

Attenuation of cold stress-induced exacerbation of cardiac and adipose tissue pathology and metabolic disorders in a rat model of metabolic syndrome by the glucocorticoid receptor antagonist RU486

OBJECTIVES

Chronic stress affects the central nervous system as well as endocrine, metabolic and immune systems. However, the effects of cold stress on cardiovascular and metabolic disorders in metabolic syndrome (MetS) have remained unclear. We recently characterized DahlS.Z-Lepr(fa)/Lepr(fa) (DS/obese) rats, derived from a cross between Dahl salt-sensitive and Zucker rats, as a new animal model of MetS. We have now investigated the effects of chronic cold stress and glucocorticoid receptor (GR) blockade on cardiac and adipose tissue pathology as well as on metabolic parameters in this model.

METHODS

DS/obese rats were exposed to cold stress (immersion in ice-cold water to a depth of 1-2 cm for 2 h per day) with or without subcutaneous injection of the GR antagonist RU486 (2 mg kg(-1)day(-1)) for 4 weeks beginning at 9 weeks of age. Age-matched homozygous lean (DahlS.Z-Lepr(+)/Lepr(+)) littermates served as a control.

RESULTS

Chronic cold stress exacerbated hypertension as well as left ventricular (LV) hypertrophy, fibrosis and diastolic dysfunction in DS/obese rats in a manner sensitive to RU486 treatment. Cold stress with or without RU486 did not affect body weight or fat mass. In contrast, cold stress further increased cardiac oxidative stress as well as macrophage infiltration and proinflammatory gene expression in LV and visceral fat tissue, with all of these effects being attenuated by RU486. Cold stress also further increased GR and 11β-hydroxysteroid dehydrogenase type 1 mRNA and protein abundance in LV and visceral adipose tissue, and these effects were again inhibited by RU486. In addition, RU486 ameliorated the stress-induced aggravation of dyslipidemia, glucose intolerance and insulin resistance in DS/obese rats.

CONCLUSIONS

Our results implicate GR signaling in cold stress-induced exacerbation of cardiac and adipose tissue pathology as well as of abnormal glucose and lipid metabolism in a rat model of MetS.