Exercise training and vascular heterogeneity in db/db mice: evidence for regional- and duration-dependent effects.

Exercise training (ET) has several health benefits; however, our understanding of regional adaptations to ET is limited. We examined the functional and molecular adaptations to short- and long-term ET in elastic and muscular conduit arteries of db/db mice in relation to changes in cardiovascular risk factors. Diabetic mice and their controls were exercised at moderate intensity for 4 or 8 weeks. The vasodilatory and contractile responses of thoracic aortae and femoral arteries isolated from the same animals were examined. Blood and aortic samples were used to measure hyperglycemia, oxidative stress, inflammation, dyslipidemia, protein expression of SOD isoforms, COX, eNOS, and Akt. Short-term ET improved nitric oxide (NO) mediated vasorelaxation in the aortae and femoral arteries of db/db mice in parallel with increased SOD2 and SOD3 expression, reduced oxidative stress and triglycerides, and independent of weight loss, glycemia, or inflammation. Long-term ET reduced body weight in parallel with reduced systemic inflammation and improved insulin sensitivity along with increased SOD1, Akt, and eNOS expression and improved NO vasorelaxation. Exercise did not restore NOS- and COX-independent vasodilatation in femoral arteries, nor did it mitigate the hypercontractility in the aortae of db/db mice; rather ET transiently increased contractility in association with upregulated COX-2. Long-term ET differentially affected the aortae and femoral arteries contractile responses. ET improved NO-mediated vasodilation in both arteries likely due to collective systemic effects. ET did not mitigate all diabetes-induced vasculopathies. Optimization of the ET regimen can help develop comprehensive management of type 2 diabetes.

Sex Differences in Plasma, Adipose Tissue, and Central Accumulation of Cannabinoids, and Behavioral Effects of Oral Cannabis Consumption in Male and Female C57BL/6 Mice.

BACKGROUND: Cannabis edibles are an increasingly popular form of cannabis consumption. Oral consumption of cannabis has distinct physiological and behavioral effects compared with injection or inhalation. An animal model is needed to understand the pharmacokinetics and physiological effects of oral cannabis consumption in rodents as a model for human cannabis edible use. METHODS: Adult male and female C57BL/6 mice received a single dose of commercially available cannabis oil (5 mg/kg Δ9-tetrahydrocannabinol [THC]) by oral gavage. At 0.5, 1, 2, 3, and 6 hours post exposure, plasma, hippocampus, and adipose tissue were collected for THC, 11-OH-THC, and THC-COOH measures. RESULTS: We report delayed time to peak THC and 11-OH-THC concentrations in plasma, brain, and adipose tissue, which is consistent with human pharmacokinetics studies. We also found sex differences in the cannabis tetrad: (1) female mice had a delayed hypothermic effect 6 hours post consumption, which was not present in males; (2) females had stronger catalepsy than males; (3) males were less mobile following cannabis exposure, whereas female mice showed no difference in locomotion but an anxiogenic effect at 3 hours post exposure; and (4) male mice displayed a longer-lasting antinociceptive effect of oral cannabis. CONCLUSIONS: Oral cannabis consumption is a translationally relevant form of administration that produces similar physiological effects as injection or vaping administration and thus should be considered as a viable approach for examining the physiological effects of cannabis moving forward. Furthermore, given the strong sex differences in metabolism of oral cannabis, these factors should be carefully considered when designing animal studies on the effects of cannabis.

Vitamin D modulates hepatic microRNAs and mitigates tamoxifen-induced steatohepatitis in female rats.

Tamoxifen (TAM) is a life-saving and cost-effective drug widely used in the prevention and treatment of breast cancer. However, the adverse effects of tamoxifen can lead to non-adherence and poor patient outcomes. Therefore, exploring novel strategies to improve TAM safety profile is crucial. Given the key role that vitamin D (VD) plays in modulating lipid metabolism and inflammation, in addition to its benefits in reducing risk and progression of breast cancer, we evaluated the protective potential of VD against TAM-induced hepatotoxicity focusing on lipid metabolism and microRNAs (miRNAs) regulation. Female rats were pretreated with VD as cholecalciferol (500 IU/kg/day, po) for 4 weeks before receiving TAM (40 mg/kg/day, po) concurrently with VD during the fifth and sixth weeks. Liver histology, lipid profile and expression of genes, proteins, and miRNAs involved in lipid metabolism and inflammation were examined. TAM-induced steatohepatitis was evidenced by elevated liver triglycerides and cholesterol contents, increased serum miRNA-122 level, and ALT activity, in parallel with accumulation of lipid droplets, focal necrosis, and inflammatory cells infiltration in hepatocytes. Prophylactic use of VD mitigated TAM-induced steatohepatitis by modulating key transcription factors in the liver: PPAR-α, Srebf1, and NF-κB and their downstream genes/proteins Fas, CPT-1A, and TNF-α resulting in reduced hepatic lipids and suppressed pro-inflammatory signaling. Notably, VD pretreatment mitigated TAM-induced alterations in the expression of serum miRNA-122, hepatic miRNA-21, and miRNA-33. The combination therapy of VD and TAM has complementary benefits in terms of safety and not only efficacy and should be further investigated clinically.

Vitamin D mitigates diabetes-associated metabolic and cognitive dysfunction by modulating gut microbiota and colonic cannabinoid receptor 1.

INTRODUCTION: Obesity is associated with elevated endocannabinoid tone, gut dysbiosis, and inflammation predisposing to diabetes. The endocannabinoid system mediates the effects of gut microbiota and regulates the gut barrier integrity. We examined the effects of vitamin D (VD) on colonic cannabinoid receptor 1(CB1R), tight junction proteins, gut dysbiosis, metabolic and cognitive dysfunction in a model of type 2 diabetes compared with metformin. METHODS: Rats received high-fat, high-sucrose diet (HFSD) and either VD (500 IU/kg/day; p.o.), or metformin (200 mg/kg/day; p.o.) for 8 weeks. After 6 weeks, streptozotocin (STZ) (40 mg/kg; i.p) was injected. Behavioral, cognitive, and metabolic assessments were carried out. Finally, fecal, blood, and tissue samples were collected to examine Bacteroidetes/Firmicutes ratio, colonic CB1R, zonula occludens-1 (ZO-1), occludin, and Toll-like receptor 4 (TLR4); serum lipopolysaccharides (LPS), peptidoglycan (PGN), tumor necrosis factor-alpha (TNF-ɑ), glucagon-like peptide-1 (GLP-1), lipids, and VD; hippocampal brain-derived neurotrophic factor (BDNF) and inflammatory markers. RESULTS: VD ameliorated HFSD/STZ-induced dysbiosis/gut barrier dysfunction as indicated by lower circulating LPS, PGN and TNF-ɑ levels, likely by downregulating colonic CB1R and upregulating ZO-1 and occludin expressions. Additionally, VD suppressed HFSD/STZ-induced hyperglycemia, hyperinsulinemia, dyslipidemia, and hippocampal neuroinflammation. These changes culminated in improved glycemic control and cognitive function. VD was more effective than metformin in decreasing serum LPS and TNF-ɑ levels; whereas metformin resulted in better glycemic control. CONCLUSION: Targeting gut microbiota by VD could be a successful strategy in the treatment of diabetes and associated cognitive deficit. The crosstalk between VD axis and the endocannabinoid system needs further exploration.

Accelerated developmental adipogenesis programs adipose tissue dysfunction and cardiometabolic risk in offspring born to dams with metabolic dysfunction.

This study determined if a perturbation in in utero adipogenesis leading to later life adipose tissue (AT) dysfunction underlies programming of cardiometabolic risk in offspring born to dams with metabolic dysfunction. Female mice heterozygous for the leptin receptor deficiency (Hetdb) had 2.4-fold higher prepregnancy fat mass and in late gestation had higher plasma insulin and triglycerides compared with wild-type (Wt) females (P < 0.05). To isolate the role of the intrauterine milieu, wild-type (Wt) offspring from each pregnancy were studied. Differentiation potential in isolated progenitors and cell size distribution analysis revealed accelerated adipogenesis in Wt pups born to Hetdb dams, accompanied by a higher accumulation of neonatal fat mass. In adulthood, whole body fat mass by NMR was higher in male (69%) and female (20%) Wt offspring born to Hetdb versus Wt pregnancies, along with adipocyte hypertrophy and hyperlipidemia (all P < 0.05). Lipidomic analyses by gas chromatography revealed an increased lipogenic index (16:0/18:2n6) after high-fat/fructose diet (HFFD). Postprandial insulin, ADIPO-IR, and ex vivo AT lipolytic responses to isoproterenol were all higher in Wt offspring born to Hetdb dams (P < 0.05). Intrauterine metabolic stimuli may direct a greater proportion of progenitors toward terminal differentiation, thereby predisposing to hypertrophy-induced adipocyte dysfunction.NEW & NOTEWORTHY This study reveals that accelerated adipogenesis during the perinatal window of adipose tissue development predisposes to later life hypertrophic adipocyte dysfunction, thereby compromising the buffering function of the subcutaneous depot.

Insulin and endocannabinoids in the mesolimbic system.

Easy access to palatable food and an abundance of food-related cues exacerbate non-homeostatic feeding. The metabolic and economical sequelae of non-homeostatic feeding outweigh those of homeostatic feeding and contribute significantly to the global obesity pandemic. The mesolimbic dopamine system is the primary central circuit that governs the motivation to consume food. Insulin and endocannabinoids (eCBs) are two major, presumably opposing, players in regulating homeostatic and non-homeostatic feeding centrally and peripherally. Insulin is generally regarded as a postprandial satiety signal, whereas eCBs mainly function as pre-prandial orexinergic signals. In this review, we discuss the effects of insulin and eCB-mediated actions within the mesolimbic pathways. We propose that insulin and eCBs have regional- and time course-dependent roles. We discuss their mechanisms of actions in the ventral tegmental area and nucleus accumbens, as well as how their mechanisms converge to finely tune dopaminergic activity and food intake.

Neuroprotective Effects of Telmisartan and Nifedipine Against Cuprizone-Induced Demyelination and Behavioral Dysfunction in Mice: Roles of NF-κB and Nrf2.

Multiple sclerosis is a chronic inflammatory neurodegenerative disease of the central nervous system which injures the myelin sheath. Telmisartan and nifedipine are antihypertensive drugs that recently showed neuroprotective properties against neurodegenerative diseases. This study evaluated the neuroprotective effect of telmisartan or nifedipine in cuprizone-induced demyelination in mice by examining the underlying mechanisms. C57BL/6 mice received a diet containing 0.7% (w/w) cuprizone for 7 days followed by 3 weeks on a 0.2% cuprizone diet. Telmisartan (5 mg/kg/day, p.o.) or nifedipine (5 mg/kg/day, p.o.) was administered for 3 weeks starting from the second week. Telmisartan or nifedipine improved locomotor activity and enhanced motor coordination as demonstrated by open field, rotarod, and grip strength tests. Furthermore, telmisartan or nifedipine restored myelin basic protein mRNA and protein expression and increased luxol fast blue-staining intensity. Telmisartan or nifedipine attenuated cuprizone-induced oxidative stress and apoptosis by decreasing brain malondialdehyde and caspase-3 along with restoring reduced glutathione and brain-derived neurotrophic factor levels. Telmisartan or nifedipine exerted an anti-inflammatory effect by reducing the expression of nuclear factor kappa B (NF-κB p65) as well as pro-inflammatory cytokines and elevating the expression of IκB-α. In parallel, telmisartan or nifedipine upregulated the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and the levels of heme oxygenase-1 and NADPH quinone oxidoreductase 1 enzymes. In conclusion, the current study provides evidence for the protective effect of telmisartan and nifedipine in cuprizone-induced demyelination and behavioral dysfunction in mice possibly by modulating NF-κB and Nrf2 signaling pathways.

Redox Signaling and Regional Heterogeneity of Endothelial Dysfunction in db/db Mice.

The variable nature of vascular dysfunction in diabetes is not well understood. We explored the functional adaptation of different arteries in db/db mice in relation to increased severity and duration of diabetes. We compared endothelium-dependent and -independent vasodilation in the aortae, as well as the carotid and femoral arteries, of db/db mice at three ages in parallel with increased body weight, oxidative stress, and deterioration of glycemic control. Vascular responses to in vitro generation of reactive oxygen species (ROS) and expression of superoxide dismutase (SOD) isoforms were assessed. There was a progressive impairment of endothelium-dependent and -independent vasorelaxation in the aortae of db/db mice. The carotid artery was resistant to the effects of in vivo and in vitro induced oxidative stress, and it maintained unaltered vasodilatory responses, likely because the carotid artery relaxed in response to ROS. The femoral artery was more reliant on dilation mediated by endothelium-dependent hyperpolarizing factor(s), which was reduced in db/db mice at the earliest age examined and did not deteriorate with age. Substantial heterogeneity exists between the three arteries in signaling pathways and protein expression of SODs under physiological and diabetic conditions. A better understanding of vascular heterogeneity will help develop novel therapeutic approaches for targeted vascular treatments, including blood vessel replacement.

17ß-Estradiol augments the neuroprotective effect of agomelatine in depressive- and anxiety-like behaviors in ovariectomized rats.

RATIONALE AND OBJECTIVE: Estradiol decline has been associated with depression and anxiety in post-menopausal women. Agomelatine (Ago) is an agonist of the melatonergic MT1/MT2 receptors and an antagonist of the serotonergic 5-HT2c receptors. The present study aimed to evaluate the effects of combining Ago with 17ß-estradiol (E2) on ovariectomy (OVX)-induced depressive- and anxiety-like behaviors in young adult female rats. METHODS: OVX rats were treated with Ago (40 mg/kg/day, p.o.) for 10 days starting 1 week after surgery alone or combined with two doses of E2 (40 µg/kg/day, s.c.) given before behavioral testing. RESULTS: Co-administration of E2 enhanced the anti-depressant and anxiolytics effects of Ago as evidenced by decreased immobility time in the forced swimming test, as well as increased time spent in the open arms and number of entries to open arms in the elevated plus-maze. In parallel, Ago increased hippocampal norepinephrine, dopamine, melatonin, and brain-derived neurotrophic factor (BDNF). Meanwhile, Ago-treated rats exhibited reduced hippocampal nuclear factor kappa beta (NF-kB) P65 expression and pro-inflammatory cytokine level. Ago upregulated estrogen receptor (ER α and ß) mRNA expression in the hippocampus of OVX rats and elevated serum estradiol levels. Co-administration of E2 with Ago synergistically decreased NF-kB P65 expression and pro-inflammatory cytokines, and increased BDNF levels. CONCLUSION: E2 augmented the neuroprotective effect of Ago in OVX rats via its anti-inflammatory and neurotrophic effects. The combined treatment of E2 and Ago should be further investigated as a treatment of choice for depression, anxiety, and sleep disturbances associated with menopause.

Gastroprotective effect of cilostazol against ethanol- and pylorus ligation-induced gastric lesions in rats.

Despite the availability of effective antiulcer medications, their suboptimal safety profile ignites the search for alternative/complementary treatments. Drug repositioning is an attractive, efficient, and low-risk strategy. Cilostazol, a clinically used phosphodiesterase 3 inhibitor, has pronounced anti-inflammatory and vasodilatory effects suggesting antiulcer activity. Using ethanol-induced and pyloric ligation-induced gastric ulcer models, we investigated the gastroprotective effect of cilostazol (5 or 10 mg/kg, p.o.) in comparison with the standard antiulcer ranitidine (50 mg/kg, p.o.) in rats. Gastric mucosa was examined macroscopically, histologically, and biochemically for ulcer severity, markers of oxidative stress, proinflammatory cytokines, apoptotic, and cytoprotective mediators. Gastric acidic output, peptic activity, and mucin content were measured in gastric fluids. Pretreatment with cilostazol reduced ulcer number and severity, ameliorated redox status (reduced glutathione and malonaldehyde content), and decreased levels of IL-1ß, IL-6, and TNF-훼 in gastric mucosa, in parallel with increases in mucosal defensive factors nitric oxide (NO), prostaglandin E2 (PGE2), and heat-shock protein 70 (HSP70) promoting mucus secretion, tissue perfusion, and regeneration. Histological examination confirmed the beneficial effects of cilostazol in terms of reducing focal necrosis and infiltration of inflammatory cells, as well as increasing mucopolysaccharide content. These beneficial effects are likely secondary to an increase in cAMP and decrease in apoptosis regulator Bcl-2-associated X protein (BAX). Cilostazol, in a dose-dependent effect, exhibited vasodilatory, anti-inflammatory, and antiapoptotic actions in the gastric mucosa resulting in significant antiulcer activity comparable with the standard drug, ranitidine, but devoid of antisecretory activity. Therefore, its use should be dose and ulcer-inducer dependent.

Programming of Vascular Dysfunction in the Intrauterine Milieu of Diabetic Pregnancies.

With the rising global tide of obesity, gestational diabetes mellitus (GDM) burgeoned into one of the most common antenatal disorders worldwide. Macrosomic babies born to diabetic mothers are more likely to develop risk factors for cardiovascular disease (CVD) before they reach adulthood. Rodent studies in offspring born to hyperglycemic pregnancies show vascular dysfunction characterized by impaired nitric oxide (NO)-mediated vasodilation and increased production of contractile prostanoids by cyclooxygenase 2 (COX-2). Vascular dysfunction is a key pathogenic event in the progression of diabetes-related vascular disease, primarily attributable to glucotoxicity. Therefore, glucose-induced vascular injury may stem directly from the hyperglycemic intrauterine environment of GDM pregnancy, as evinced by studies showing endothelial activation and inflammation at birth or in childhood in offspring born to GDM mothers. This review discusses potential mechanisms by which intrauterine hyperglycemia programs dysfunction in the developing vasculature.

Sulfaphenazole treatment restores endothelium-dependent vasodilation in diabetic mice.

Vascular dysfunction is linked with increased free radical generation and is a major contributor to the high mortality rates observed in diabetes. Several probable sources of free radical generation have been suggested in diabetes, including cytochrome P450 (CYP) monooxygenase-dependent pathways. CYP-mediated superoxide production reduces nitric oxide (NO) bioavailability. In this study, we focus on the contribution of monooxygenase enzyme-generated reactive oxygen species in vascular dysfunction in an experimental model of diabetes mellitus type II. Diabetic male mice (db/db strain) and their age-matched controls received daily intraperitoneal injections of either the CYP 2C inhibitor sulfaphenazole (5.13 mg/kg) or saline (vehicle control) for 8 weeks. Although sulfaphenazole did not change endothelium-dependent vasodilation in control mice, it restored endothelium-mediated relaxation in db/db mice. We report for the first time that CYP 2C inhibition reduces oxidative stress (measured as plasma levels of 8-isoprostane), increases NO bioavailability (measured as NO(2)(-)) and restores endothelial function in db/db mice without affecting plasma glucose levels. Based on our findings, we speculate that inhibition of free radical generating CYP 450 monooxygenase enzymes restores endothelium-dependent vasodilation to acetylcholine. In addition, it reduces oxidative stress and increases NO bioavailability.

Increased vascular contractility in isolated vessels from cigarette smoking rats is mediated by basal endothelin release.

The effect of chronic cigarette smoking on endothelin modulation of vascular contraction, and CYP enzyme levels was studied in 20 male Sprague-Dawley rats. The animals were divided equally into smoking and non-smoking groups. The smoking group was exposed to 6 research cigarettes per rat per day 5 days a week for 16 weeks. The control group was sham smoked. Functional contractile studies were performed in aortas and carotid arteries to determine the regulation of vascular tone by basal release of endothelin. Liver samples were analyzed for CYP1A1 and CYP1A2 gene expression by RT-PCR. Plasma samples were assessed for endothelin-1 (ET-1) level by enzyme immuno assay (EIA). Treatment of aortas and carotid arteries with bosentan, the dual endothelin receptor antagonist, caused a significant reduction in constrictor responses of smoking rats, indicating, increase greater regulation of tone by endothelin in smoker rats compared to controls. There was a greater expression of the cytochrome P450-liver enzymes (CYP1A1 and CYP1A2) in smoker rats. Body weight gain was also significantly decreased in smoker rats. We conclude that increased endothelin release in smoker rats significantly contributes to increased arterial tone and so contribute to the cardiovascular pathophysiology associated with cigarette smoking, such as increased vascular muscularization, increased contraction, decreased dilation and possibly vasospasm.