RESUMO
PURPOSE: Bladder dysfunction associated with type 2 diabetes mellitus (T2DM) includes urine storage and voiding disorders. We examined pathological conditions of the bladder wall in a rat T2DM model and evaluated the effects of the phosphodiesterase-5 (PDE-5) inhibitor tadalafil. MATERIALS AND METHODS: Male Otsuka Long-Evans Tokushima Fatty (OLETF) rats and Long-Evans Tokushima Otsuka (LETO) rats were used as the T2DM and control groups, respectively. Tadalafil was orally administered for 12 weeks. Micturition behavior was monitored using metabolic cages, and bladder function was evaluated by cystometry. Bladder blood flow was evaluated by laser speckle imaging, and an organ bath bladder distention test was used to measure adenosine triphosphate (ATP) release from the bladder urothelium. The expression levels of vesicular nucleotide transporter (VNUT), hypoxia markers, pro-inflammatory cytokines and growth factors in the bladder wall were measured using real-time polymerase chain reaction and enzyme-linked immunosorbent assay. Bladder wall contractions in response to KCl and carbachol were monitored using bladder-strip tests. RESULTS: With aging, OLETF rats had higher micturition frequency and greater urine volume than LETO rats. Although bladder capacity was not significantly different, non-voiding bladder contraction occurred more frequently in OLETF rats than in LETO rats. Bladder blood flow was decreased and ATP release was increased with higher VNUT expression in OLETF rats than in LETO rats. These effects were suppressed by tadalafil administration, with accompanying decreased HIF-1α, 8-OHdG, IL-6, TNF-α, IGF-1, and bFGF expression. The impaired contractile responses of bladder strips to KCl and carbachol in OLETF rats with aging were restored by tadalafil administration. CONCLUSIONS: The T2DM rats had polyuria, increased ATP release induced by decreased bladder blood flow and impaired contractile function. PDE5 inhibition improved these changes and may prevent T2DM-associated urinary frequency and bladder storage and voiding dysfunctions.
Assuntos
Diabetes Mellitus Tipo 2 , Inibidores da Fosfodiesterase 5 , Poliúria , Tadalafila , Bexiga Urinária , Animais , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/tratamento farmacológico , Masculino , Ratos , Inibidores da Fosfodiesterase 5/farmacologia , Tadalafila/farmacologia , Tadalafila/uso terapêutico , Bexiga Urinária/efeitos dos fármacos , Bexiga Urinária/metabolismo , Bexiga Urinária/patologia , Bexiga Urinária/fisiopatologia , Poliúria/tratamento farmacológico , Ratos Endogâmicos OLETF , Micção/efeitos dos fármacos , Diabetes Mellitus Experimental/complicações , Diabetes Mellitus Experimental/tratamento farmacológico , Contração Muscular/efeitos dos fármacos , Trifosfato de Adenosina/metabolismoRESUMO
Obesity is a major global health concern. Studies suggest that the gut microflora may play a role in protecting against obesity. Probiotics, including lactic acid bacteria and Bifidobacterium, have garnered attention for their potential in obesity prevention. However, the effects of Bifidobacterium-fermented products on obesity have not been thoroughly elucidated. Bifidobacterium, which exists in the gut of animals, is known to enhance lipid metabolism. During fermentation, it produces acetic acid, which has been reported to improve glucose tolerance and insulin resistance, and exhibit anti-obesity and anti-diabetic effects. Functional foods have been very popular around the world, and fermented milk is a good candidate for enrichment with probiotics. In this study, we aim to evaluate the beneficial effects of milks fermented with Bifidobacterium strains on energy metabolism and obesity prevention. Three Bifidobacterium strains (Bif-15, Bif-30, and Bif-39), isolated from newborn human feces, were assessed for their acetic acid production and viability in milk. These strains were used to ferment milk. Otsuka-Long-Evans Tokushima Fatty (OLETF) rats administered Bif-15-fermented milk showed significantly lower weight gain compared to those in the water group. The phosphorylation of AMPK was increased and the expression of lipogenic genes was suppressed in the liver of rats given Bif-15-fermented milk. Additionally, gene expression related to respiratory metabolism was significantly increased in the soleus muscle of rats given Bif-15-fermented milk. These findings suggest that milk fermented with the Bifidobacterium strain Bif-15 can improve lipid metabolism and suppress obesity.
Assuntos
Bifidobacterium , Metabolismo dos Lipídeos , Lipogênese , Obesidade , Animais , Obesidade/metabolismo , Obesidade/microbiologia , Bifidobacterium/metabolismo , Ratos , Humanos , Masculino , Probióticos , Músculo Esquelético/metabolismo , Produtos Fermentados do Leite/microbiologia , Leite/metabolismo , Leite/microbiologia , Fermentação , Ratos Endogâmicos OLETF , Fígado/metabolismo , Metabolismo EnergéticoRESUMO
Chronic inflammation in adipose tissue is thought to contribute to insulin resistance, which involves the gut microbiota. Our previous studies have demonstrated that ingestion of 1-kestose can alter the gut microbiota composition, increase cecal butyrate levels, and improve insulin resistance in Otsuka Long-Evans Tokushima Fatty (OLETF) rats. Additionally, we found that 1-kestose supplementation ameliorated insulin resistance in obese rat models fed a high-fat diet (HFD), although the effects of 1-kestose on the abundance of inflammation-related gene in adipose tissue and gut microbiota composition in these rats were not explored. This study aimed to investigate the impact of 1-kestose on these parameters in HFD-fed rats, compared to OLETF rats. Male Sprague-Dawley rats were divided into two dietary groups, control or HFD, for 19 wk. Each group was further subdivided to receive either tap water or tap water supplemented with 2% (w/v) 1-kestose throughout the study. We evaluated gene expression in adipose tissue, as well as short-chain fatty acids (SCFAs) levels and microbial composition in the cecum contents. 1-Kestose intake restored the increased relative abundance of tumor necrosis factor (Tnf) mRNA in adipose tissue and the reduced level of butyrate in the cecum contents of HFD-fed rats to those observed in control diet-fed rats. Additionally, 1-kestose consumption changed the composition of the gut microbiota, increasing Butyricicoccus spp., decreasing UGC-005 and Streptococcus spp., in the cecum contents of HFD-fed rats. Our findings suggest that 1-kestose supplementation reduces adipose tissue inflammation and increases butyrate levels in the gut of HFD-fed rats, associated with changes in the gut microbiota composition, distinct from those seen in OLETF rats.
Assuntos
Tecido Adiposo , Ceco , Dieta Hiperlipídica , Ácidos Graxos Voláteis , Microbioma Gastrointestinal , Inflamação , RNA Mensageiro , Ratos Sprague-Dawley , Animais , Microbioma Gastrointestinal/efeitos dos fármacos , Masculino , Tecido Adiposo/metabolismo , Tecido Adiposo/efeitos dos fármacos , Inflamação/metabolismo , RNA Mensageiro/metabolismo , Ratos , Ácidos Graxos Voláteis/metabolismo , Ceco/microbiologia , Ceco/metabolismo , Resistência à Insulina , Ratos Endogâmicos OLETF , Obesidade/metabolismo , Obesidade/microbiologia , Suplementos Nutricionais , Butiratos/metabolismoRESUMO
This study examined the effects of exercise and detraining at a young age on fat accumulation in various organs. Four-week-old male Otsuka Long-Evans Tokushima Fatty (OLETF) rats were assigned to either the non-exercise sedentary (OLETF Sed) or exercise groups. The exercise group was subdivided into two groups: exercise between 4 and 12 weeks of age (OLETF Ex) and exercise between 4 and 6 weeks of age followed by non-exercise between 6 and 12 weeks of age (OLETF DT). Body weight was significantly lower in the OLETF Ex group than in the OLETF Sed group at 12 weeks of age. Fat accumulation in the epididymal white adipose tissue, liver, and brown adipose tissue was suppressed in the OLETF Ex group. During the exercise period, body weight and food intake in the OLETF DT group were significantly lower than those in the OLETF Sed group. However, food intake was significantly higher in the OLETF DT group than in the OLETF Sed group after exercise cessation, resulting in extreme obesity with fatty liver and brown adipose tissue whitening. Detraining after early-onset exercise promotes hyperphagia, causing extreme obesity. Overeating should be avoided during detraining periods in cases of exercise cessation at a young age.
Assuntos
Tecido Adiposo Marrom , Fígado Gorduroso , Hiperfagia , Obesidade , Condicionamento Físico Animal , Ratos Endogâmicos OLETF , Animais , Masculino , Tecido Adiposo Marrom/metabolismo , Hiperfagia/fisiopatologia , Hiperfagia/metabolismo , Ratos , Fígado Gorduroso/metabolismo , Fígado Gorduroso/etiologia , Obesidade/metabolismo , Obesidade/fisiopatologia , Obesidade/etiologia , Ingestão de Alimentos , Fígado/metabolismo , Peso CorporalRESUMO
During insulin resistance, the heart undergoes a metabolic shift in which fatty acids (FA) account for roughly about 99% of the ATP production. This metabolic shift is indicative of impaired glucose metabolism. A shift in FA metabolism with impaired glucose tolerance can increase reactive oxygen species (ROS), lipotoxicity, and mitochondrial dysfunction, ultimately leading to cardiomyopathy. Thyroid hormones (TH) may improve the glucose intolerance by increasing glucose reabsorption and metabolism in peripheral tissues, but little is known on its effects on cardiac tissue during insulin resistance. In the present study, insulin resistant Otsuka Long Evans Tokushima Fatty (OLETF) rats were used to assess the effects of exogenous thyroxine (T4) on glucose metabolism in cardiac tissue. Rats were assigned to four groups: (1) lean, Long Evans Tokushima Otsuka (LETO; n=6), (2) LETO + T4 (8 µg/100 g BM/d × 5 wks; n = 7), (3) untreated OLETF (n = 6), and (4) OLETF + T4 (8 µg/100 g BM/d × 5 wks; n = 7). T4 increased GLUT4 gene expression by 85% in OLETF and increased GLUT4 protein translocation to the membrane by 294%. Additionally, T4 increased p-AS160 by 285%, phosphofructokinase-1 (PFK-1) mRNA, the rate limiting step in glycolysis, by 98% and hexokinase II by 64% in OLETF. T4 decreased both CPT2 mRNA and protein expression in OLETF. The results suggest that exogenous T4 has the potential to increase glucose uptake and metabolism while simultaneously reducing fatty acid transport in the heart of insulin resistant rats. Thus, L-thyroxine may have therapeutic value to help correct the impaired substrate metabolism associated with diabetic cardiomyopathy.
Assuntos
Transportador de Glucose Tipo 4 , Resistência à Insulina , Miocárdio , Tiroxina , Animais , Masculino , Ratos , Ácidos Graxos/metabolismo , Glucose/metabolismo , Transportador de Glucose Tipo 4/metabolismo , Transportador de Glucose Tipo 4/genética , Miocárdio/metabolismo , Transporte Proteico/efeitos dos fármacos , Ratos Endogâmicos OLETF , Tiroxina/administração & dosagemRESUMO
Patients with diabetes exhibit altered taste sensitivity, but its details have not been clarified yet. Here, we examined alteration of sweet taste sensitivity with development of glucose intolerance in Otsuka Long-Evans Tokushima Fatty (OLETF) rats as a model of non-insulin-dependent diabetes mellitus. Compared to the cases of Long Evans Tokushima Otsuka (LETO) rats as a control, glucose tolerance of OLETF rats decreased with aging, resulting in development of diabetes at 36-weeks-old. In brief-access tests with a mixture of sucrose and quinine hydrochloride, OLETF rats at 25 or more-weeks-old seemed to exhibit lower sweet taste sensitivity than age-matched LETO ones, but the lick ratios of LETO, but not OLETF, rats for the mixture and quinine hydrochloride solutions decreased and increased, respectively, aging-dependently. Expression of sweet taste receptors, T1R2 and T1R3, in circumvallate papillae (CP) was almost the same in LETO and OLETF rats at 10- and 40-weeks-old, while expression levels of a bitter taste receptor, T2R16, were greater in 40-weeks-old rats than in 10-weeks-old ones in both strains. There was no apparent morphological alteration in taste buds in CP between 10- and 40-weeks-old LETO and OLETF rats. Metagenomic analysis of gut microbiota revealed strain- and aging-dependent alteration of mucus layer-regulatory microbiota. Collectively, we concluded that the apparent higher sweet taste sensitivity in 25 or more-weeks-old OLETF rats than in age-matched LETO rats was due to the aging-dependent increase of bitter taste sensitivity in LETO rats with alteration of the gut microbiota.
Assuntos
Diabetes Mellitus Tipo 2 , Intolerância à Glucose , Humanos , Ratos , Animais , Ratos Endogâmicos OLETF , Paladar , Peso Corporal , Disgeusia , Quinina/farmacologia , Teste de Tolerância a Glucose , Diabetes Mellitus Tipo 2/metabolismo , Ratos Long-Evans , Glicemia/análiseRESUMO
In this study, we investigated the effects of a porcine liver protein hydrolysate (PLH) diet on lipid metabolism in Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a model of type II diabetes. OLETF rats (20-wk-old males) were pair-fed with either a PLH diet containing 20% PLH or a casein diet for 14 wk. Dietary PLH significantly lowered serum cholesterol and phospholipid concentrations, mainly by decreasing low-density lipoprotein and high-density lipoprotein fractions. Fecal cholesterol was significantly increased in the PLH diet group; however, the total bile acid concentration in the feces was not significantly different between the groups. In addition, the PLH diet significantly decreased serum thiobarbituric acid reactive substance concentrations. These results suggest that dietary PLH exerts hyperlipidemic and antioxidant effects, indicating that it is a novel functional food ingredient.
Assuntos
Diabetes Mellitus Tipo 2 , Carne de Porco , Carne Vermelha , Ratos , Masculino , Animais , Suínos , Ratos Endogâmicos OLETF , Diabetes Mellitus Tipo 2/metabolismo , Antioxidantes/farmacologia , Hidrolisados de Proteína/farmacologia , Hidrolisados de Proteína/metabolismo , Fígado/metabolismo , Colesterol/metabolismoRESUMO
Patients with diabetes mellitus (DM) often experience complications such as peripheral arterial disease (PAD), which is thought to be caused by vascular damage resulting from increased oxidative stress. Dipeptidyl peptidase-4 inhibitors have been reported to reduce oxidative stress, although the exact mechanism remains unclear. This study aimed to investigate the impact of long-term (6 weeks) anagliptin treatment at a dose of 200 mg/kg/d against oxidative stress in the femoral artery of Otsuka Long-Evans Tokushima Fatty (OLETF) rats using a well-established animal model for type 2 DM. Serum toxic advanced glycation end-products concentrations and blood glucose levels after glucose loading were significantly elevated in OLETF rats compared to Long-Evans Tokushima Otsuka (LETO) rats but were significantly suppressed by anagliptin administration. Plasma glucagon-like peptide-1 concentrations after glucose loading were significantly increased in anagliptin-treated rats. Superoxide production and reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity in femoral arteries were significantly increased in OLETF rats compared to LETO rats but were significantly decreased by anagliptin administration. The expressions of NADPH oxidase components (p22phox in the intima region and p22phox and gp91phox in the media region) in the femoral artery were significantly increased in OLETF rats compared to LETO rats but were significantly suppressed by anagliptin administration. Furthermore, the femoral artery showed increased wall thickness in OLETF rats compared to LETO rats, but anagliptin administration reduced the thickening. This study suggests that long-term anagliptin administration can reduce oxidative stress in femoral arteries and improve vascular injury.
Assuntos
Diabetes Mellitus Experimental , Diabetes Mellitus Tipo 2 , Pirimidinas , Lesões do Sistema Vascular , Humanos , Ratos , Animais , Artéria Femoral , Lesões do Sistema Vascular/tratamento farmacológico , Ratos Endogâmicos OLETF , Ratos Long-Evans , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/tratamento farmacológico , GlucoseRESUMO
Cannabidiol (CBD) use has grown exponentially more popular in the last two decades, particularly among older adults (>55 yr), though very little is known about the effects of CBD use during age-associated metabolic dysfunction. In addition, synthetic analogues of CBD have generated great interest because they can offer a chemically pure product, which is free of plant-associated contaminants. To assess the effects of a synthetic analogue of CBD (H4CBD) on advanced metabolic dysfunction, a cohort of 41-wk-old Otsuka Long-Evans Tokushima Fatty (OLETF) rats were administered 200 mg H4CBD/kg by oral gavage for 4 wk. Animals were fed ad libitum and monitored alongside vehicle-treated OLETF and Long-Evans Tokushima Otsuka (LETO) rats, the lean-strain controls. An oral glucose-tolerance test (oGTT) was performed after 4 wk of treatment. When compared with vehicle-treated, OLETF rats, H4CBD decreased body mass (BM) by 15%, which was attributed to a significant loss in abdominal fat. H4CBD reduced glucose response (AUCglucose) by 29% (P < 0.001) and insulin resistance index (IRI) by 25% (P < 0.05) compared with OLETF rats. However, H4CBD did not statically reduce fasting blood glucose or plasma insulin, despite compensatory increases in skeletal muscle native insulin receptor (IR) protein expression (54%; P < 0.05). H4CBD reduced circulating adiponectin (40%; P < 0.05) and leptin (47%; P < 0.05) and increased ghrelin (75%; P < 0.01) compared with OLETF. Taken together, a chronic, high dose of H4CBD may improve glucose response, independent of static changes in insulin signaling, and these effects are likely a benefit of the profound loss of visceral adiposity.NEW & NOTEWORTHY Cannabis product use has grown in the last two decades despite the lack of research on Cannabidiol (CBD)-mediated effects on metabolism. Here, we provide seminal data on CBD effects during age-associated metabolic dysfunction. We gave 41-wk-old OLETF rats 200 mg H4CBD/kg by mouth for 4 wk and noted a high dose of H4CBD may improve glucose response, independent of static changes in insulin signaling, and these effects are likely a benefit of loss of visceral adiposity.
Assuntos
Canabidiol , Diabetes Mellitus Tipo 2 , Síndrome Metabólica , Humanos , Ratos , Animais , Idoso , Ratos Endogâmicos OLETF , Síndrome Metabólica/tratamento farmacológico , Insulina , Glucose , Canabidiol/farmacologia , Ratos Long-Evans , Diabetes Mellitus Tipo 2/metabolismo , Glicemia/metabolismoRESUMO
Alterations in dopamine neurotransmission are associated with obesity and food preferences. Otsuka Long-Evans Tokushima Fatty (OLETF) rats that lack functional cholecystokinin receptor type-1 (CCK-1R), due to a natural mutation, exhibit impaired satiation, are hyperphagic, and become obese. In addition, compared to lean control Long-Evans Tokushima (LETO) rats, OLETF rats have pronounced avidity for over-consuming palatable sweet solutions, have greater dopamine release to psychostimulants, reduced dopamine 2 receptor (D2R) binding, and exhibit increased sensitivity to sucrose reward. This supports altered dopamine function in this strain and its general preference for palatable solutions such as sucrose. In this study, we examined the relationship between OLETF's hyperphagic behavior and striatal dopamine signaling by investigating basal and amphetamine stimulated motor activity in prediabetic OLETF rats before and after access to sucrose solution (0.3 M) compared to non-mutant control LETO rats, as well as availability of dopamine transporter (DAT) using autoradiography. In the sucrose tests, one group of OLETF rats received ad libitum access to sucrose while the other group received an amount of sucrose equal to that consumed by the LETO. OLETFs with ad libitum access consumed significantly more sucrose than LETOs. Sucrose exerted a biphasic effect on basal activity in both strains, i.e., reduced activity for 1 week followed by increased activity in weeks 2 and 3. Basal locomotor activity was reduced (-17%) in OLETFs prior to sucrose, compared to LETOs. Withdrawal of sucrose resulted in increased locomotor activity in both strains. The magnitude of this effect was greater in OLETFs and the activity was increased in restricted compared to ad-libitum-access OLETFs. Sucrose access augmented AMPH-responses in both strains with a greater sensitization to AMPH during week 1, an effect that was a function of the amount of sucrose consumed. One week of sucrose withdrawal sensitized AMPH-induced ambulatory activity in both strains. In OLETF with restricted access to sucrose, withdrawal resulted in no further sensitization to AMPH. DAT availability in the nucleus accumbens shell was significantly reduced in OLETF compared with aged-matched LETO. Together, these findings show that OLETF rats have reduced basal DA transmission and a heightened response to natural and pharmacological stimulation.
Assuntos
Dopamina , Receptores da Colecistocinina , Animais , Ratos , Proteínas da Membrana Plasmática de Transporte de Dopamina/genética , Obesidade/metabolismo , Ratos Endogâmicos OLETF , Ratos Long-Evans , Receptores da Colecistocinina/metabolismo , Sacarose/farmacologiaRESUMO
Background and Objectives: Patients with diabetes are more susceptible to upper respiratory tract infections (URTIs) because they are easily infected. Salivary IgA (sali-IgA) levels play a major role in transmitting URTIs. Sali-IgA levels are determined by salivary gland IgA production and polymeric immunoglobulin receptor (poly-IgR) expression. However, it is unknown whether salivary gland IgA production and poly-IgR expression are decreased in patients with diabetes. While exercise is reported to increase or decrease the sali-IgA levels, it is unclear how exercise affects the salivary glands of patients with diabetes. This study aimed to determine the effects of diabetes and voluntary exercise on IgA production and poly-IgR expression in the salivary glands of diabetic rats. Materials and Methods: Ten spontaneously diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats (eight-week-old) were divided into two groups of five rats each: a non-exercise group (OLETF-C) and a voluntary wheel-running group (OLETF-E). Five Long-Evans Tokushima Otsuka (LETO) rats without diabetes were bred under the same conditions as the OLETF-C. Sixteen weeks after the study began, the submandibular glands (SGs) were collected and analyzed for IgA and poly-IgR expression levels. Results: IgA concentrations and poly-IgR expression levels in SGs were lower in OLETF-C and OLETF-E than in LETO (p < 0.05). These values did not differ between the OLETF-C and OLETF-E. Conclusions: Diabetes decreases IgA production and poly-IgR expression in the salivary glands of rats. Moreover, voluntary exercise increases sali-IgA levels but does not increase IgA production and poly-IgR expression in the salivary glands of diabetic rats. Increasing IgA production and poly-IgR expression in the salivary glands, which is reduced in diabetes, might require slightly higher-intensity exercise than voluntary exercise under the supervision of a doctor.
Assuntos
Diabetes Mellitus Experimental , Diabetes Mellitus Tipo 2 , Receptores de Imunoglobulina Polimérica , Ratos , Animais , Glândula Submandibular/metabolismo , Ratos Long-Evans , Ratos Endogâmicos OLETF , Imunoglobulina ARESUMO
AIMS/INTRODUCTION: We previously showed that upregulation of myocardial adenosine monophosphate deaminase (AMPD) is associated with pressure overload-induced diastolic dysfunction in type 2 diabetes hearts. Here, we examined involvement of AMPD localized in the endoplasmic reticulum-mitochondria interface in mitochondrial Ca2+ overload and its pathological significance. MATERIALS AND METHODS: We used type 2 diabetes Otsuka Long-Evans Tokushima Fatty rats (OLETF) and non-diabetes Long-Evans Tokushima Otsuka Fatty rats (LETO) as well as AMPD3-overexpressing H9c2 cells and human embryonic kidney 293 cells. RESULTS: OLETF, but not LETO, showed diastolic dysfunction under the condition of phenylephrine-induced pressure overload. The levels of 90-kDa AMPD3 in outer mitochondrial membranes/endoplasmic reticulum and mitochondria-associated endoplasmic reticulum membrane (MAM) fractions were significantly higher in OLETF than in LETO. The area of the MAM quantified by electron microscopic analysis was 57% larger, mitochondrial Ca2+ level under the condition of pressure overload was 47% higher and Ca2+ retention capacity in MAM-containing crude mitochondria isolated before the pressure overloading was 21% lower in OLETF than in LETO (all P-values <0.05). Transfection of FLAG-AMPD3 in cells resulted in significant enlargement of the MAM area, and impairment in pyruvate/malate-driven adenosine triphosphate-stimulated and uncoupler-stimulated mitochondrial respiration compared with those in control cells. CONCLUSIONS: The findings suggest that 90-kDa AMPD3 localized in the endoplasmic reticulum-mitochondria interface promotes formation of the MAM, inducing mitochondrial Ca2+ overload and dysfunction in type 2 diabetes hearts.
Assuntos
Diabetes Mellitus Tipo 2 , Ratos , Animais , Humanos , Diabetes Mellitus Tipo 2/patologia , Ratos Endogâmicos OLETF , Ratos Long-Evans , Mitocôndrias/patologia , Retículo Endoplasmático/metabolismo , Retículo Endoplasmático/patologia , Monofosfato de Adenosina/metabolismoRESUMO
Systemic branched-chain amino acid (BCAA) metabolism is dysregulated in cardiometabolic diseases. We previously demonstrated that upregulated AMP deaminase 3 (AMPD3) impairs cardiac energetics in a rat model of obese type 2 diabetes, Otsuka Long-Evans-Tokushima fatty (OLETF). Here, we hypothesized that the cardiac BCAA levels and the activity of branched-chain α-keto acid dehydrogenase (BCKDH), a rate-limiting enzyme in BCAA metabolism, are altered by type 2 diabetes (T2DM), and that upregulated AMPD3 expression is involved in the alteration. Performing proteomic analysis combined with immunoblotting, we discovered that BCKDH localizes not only to mitochondria but also to the endoplasmic reticulum (ER), where it interacts with AMPD3. Knocking down AMPD3 in neonatal rat cardiomyocytes (NRCMs) increased BCKDH activity, suggesting that AMPD3 negatively regulates BCKDH. Compared with control rats (Long-Evans Tokushima Otsuka [LETO] rats), OLETF rats exhibited 49% higher cardiac BCAA levels and 49% lower BCKDH activity. In the cardiac ER of the OLETF rats, BCKDH-E1α subunit expression was downregulated, while AMPD3 expression was upregulated, resulting in an 80% lower AMPD3-E1α interaction compared to LETO rats. Knocking down E1α expression in NRCMs upregulated AMPD3 expression and recapitulated the imbalanced AMPD3-BCKDH expressions observed in OLETF rat hearts. E1α knockdown in NRCMs inhibited glucose oxidation in response to insulin, palmitate oxidation, and lipid droplet biogenesis under oleate loading. Collectively, these data revealed previously unrecognized extramitochondrial localization of BCKDH in the heart and its reciprocal regulation with AMPD3 and imbalanced AMPD3-BCKDH interactions in OLETF. Downregulation of BCKDH in cardiomyocytes induced profound metabolic changes that are observed in OLETF hearts, providing insight into mechanisms contributing to the development of diabetic cardiomyopathy.
Assuntos
3-Metil-2-Oxobutanoato Desidrogenase (Lipoamida) , AMP Desaminase , Diabetes Mellitus Tipo 2 , Animais , Ratos , AMP Desaminase/genética , AMP Desaminase/metabolismo , Glicemia/metabolismo , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/metabolismo , Regulação para Baixo , Proteômica , Ratos Endogâmicos OLETF , Ratos Long-Evans , 3-Metil-2-Oxobutanoato Desidrogenase (Lipoamida)/genéticaRESUMO
Alcohol consumption exacerbates liver abnormalities in animal models, but whether it increases the severity of liver disease in early diabetic or prediabetic rats is unclear. To investigate the molecular mechanisms underlying alcohol-induced liver steatosis or hepatitis, we used a prediabetic animal model. Otsuka Long-Evans Tokushima Fatty (OLETF) and Long-Evans Tokushima Fatty (LETO) rats were pair-fed with an ethanol-containing liquid diet for 6 weeks. Compared with controls, OLETF and LETO rats displayed more pronounced liver steatosis and higher plasma levels of serum glutamic oxaloacetic transaminase (SGOT) and serum glutamate pyruvate transaminase (SPGT), indicating liver injury. Ethanol-fed LETO (Pd-L-E) rats showed mild liver steatosis and no inflammation compared with ethanol-fed OLETF (Pd-O-E) rats. Although precursor and active SREBP-1 levels in the liver of ethanol-fed OLETF rats significantly increased compared with control diet-fed OLETF rats (Pd-O-C), those of Pd-L-E rats did not. Bone morphogenetic protein (BMP) and TGF-ß1 balance in Pd-O-E rats was significantly altered because BMP signaling was upregulated by inducing BMP2, BMP4, BMP7, BMP9, Smad1, and Smad4, whereas TGF-ß1, Smad3, and Erk were downregulated. Activation of TGF-ß/Smad signaling inhibited BMP2 and BMP9 expression and increased epithelial-mesenchymal transition (EMT) marker levels (Hepcidin, Snail, and Twist) in the liver of LETO rats. Livers of ethanol-fed OLETF rats showed increased levels of vimentin, FSP-1, α-SMA, MMP1, MMP13, and collagen III compared with rats of other groups, whereas EMT marker levels did not change. Thus, BMP exerted anti- and/or pro-fibrotic effects in ethanol-fed rats. Therefore, BMP and TGF-ß, two key members of the TGF-ß superfamily, play important but diverse roles in liver steatosis in young LETO and OLETF rats.
Assuntos
Diabetes Mellitus Tipo 2 , Hepatopatia Gordurosa não Alcoólica , Estado Pré-Diabético , Masculino , Ratos , Animais , Ratos Endogâmicos OLETF , Estado Pré-Diabético/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Fator de Crescimento Transformador beta1 , Etanol/toxicidade , Hepatopatia Gordurosa não Alcoólica/etiologia , Fator de Crescimento Transformador beta , Modelos Animais de DoençasRESUMO
The present study tried to clarify if mumefural would prevent hyperglycemia, one of the typical symptoms of type 2 diabetes mellitus (T2DM), since mumefural is an extract from Japanese apricots preventing hyperglycemia. To clarify if mumefural would prevent T2DM pathogenesis, we used Otsuka Long-Evans Tokushima fatty (OLETF) rats, T2DM model. Mumefural diminished hyperglycemia, HOMA-IR and plasma triglyceride concentration in OLETF rats under fasting conditions. In addition, mumefural elevated protein expression of sodium-coupled monocarboxylate transporter 1 (SMCT1) in the distal colon participating in absorption of weak organic acids, which behave as bases but not acids after absorption into the body. Mumefural also increased the interstitial fluid pH around the brain hippocampus lowered in OLETF rats compared with non-T2DM LETO rats used as control for OLETF rats. Amyloid-beta accumulation in the brain decreased in accordance with the pH elevation. On the one hand, mumefural didn't affect plasma concentrations of glucagon, GLP-1, GIP or PYY under fasting conditions. Taken together, these observations indicate that: 1) mumefural would be a useful functional food improving hyperglycemia, insulin resistance and the lowered interstitial fluid pH in T2DM; 2) the interstitial fluid pH would be one of key factors influencing the accumulation of amyloid-beta.
Assuntos
Diabetes Mellitus Tipo 2 , Hiperglicemia , Resistência à Insulina , Ratos , Animais , Ratos Endogâmicos OLETF , Glicemia/metabolismo , Insulina , Líquido Extracelular/metabolismo , Encéfalo/metabolismo , Concentração de Íons de HidrogênioRESUMO
SGLT2 inhibitors (SGLT2i) are emerging as a novel therapy for type 2 diabetes due to their effective hypoglycemic and potential cardio- and nephroprotective effects, while caloric restriction (CR) is a common behavioral modification to improve adiposity and insulin resistance. Therefore, both interventions simultaneously may potentially further improve metabolic syndrome by enhancing carbohydrate metabolism. To test this hypothesis, cohorts of 10-week old, male Long Evans Tokushima Otsuka (LETO) and Otsuka Long Evans Tokushima Fatty (OLETF) rats were treated with SGLT2i (10 mg luseoglifozin/kg/day x 4 wks) (OLETF only) and/or 30% CR (2 wks at 12 weeks of age). CR maintained body mass in both strains while SGLT2i alone did not have any effect on body mass. Simultaneous treatments decreased SBP in OLETF vs SGLT2i alone, decreased insulin resistance index (IRI), and increased creatinine clearance vs OLETF ad lib. Conversely, CR decreased albuminuria independent of SGLT2i. In conclusion, SGLT2i treatment by itself did not elicit significant improvements in insulin resistance, kidney function or blood pressure. However, when combined with CR, these changes where more profound than with CR alone without inducing chronic hypoglycemia.
Assuntos
Resistência à Insulina , Inibidores do Transportador 2 de Sódio-Glicose , Animais , Masculino , Ratos , Glicemia/metabolismo , Restrição Calórica , Diabetes Mellitus Tipo 2/metabolismo , Rim/metabolismo , Ratos Endogâmicos OLETF , Transportador 2 de Glucose-Sódio/metabolismo , Inibidores do Transportador 2 de Sódio-Glicose/farmacologiaRESUMO
Metabolic syndrome (MetS) is a rapidly increasing health concern during midlife and is an emerging risk factor for the development of neurodegenerative diseases, such as Alzheimer's disease (AD). While angiotensin receptor blockers (ARB) are widely used for MetS-associated hypertension and kidney disease, its therapeutic potential in the brain during MetS are not well-described. Here, we tested whether treatment with ARB could alleviate the brain pathology and inflammation associated with MetS using the Otsuka Long-Evans Tokushima Fatty (OLETF) rat. Here, we report that chronic ARB treatment with olmesartan (10 mg/kg/day by oral gavage for 6 weeks) partially but significantly ameliorated accumulation of oxidized and ubiquitinated proteins, astrogliosis and transformation to neurotoxic astrocytes in the brain of old OLETF rats, which otherwise exhibit the progression of these pathological hallmarks associated with MetS. Additionally, olmesartan treatment restored claudin-5 and ZO-1, markers of the structural integrity of the blood-brain barrier as well as synaptic protein PSD-95, which were otherwise decreased in old OLETF rats, particularly in the hippocampus, a critical region in cognition, memory and AD. These data demonstrate that the progression of MetS in OLETF rats is associated with deterioration of various aspects of neuronal integrity that may manifest neurodegenerative conditions and that overactivation of angiotensin receptor directly or indirectly contributes to these detriments. Thus, olmesartan treatment may slow or delay the onset of degenerative process in the brain and subsequent neurological disorders associated with MetS.
Assuntos
Diabetes Mellitus Tipo 2 , Síndrome Metabólica , Ratos , Animais , Ratos Endogâmicos OLETF , Antagonistas de Receptores de Angiotensina , Receptores de Angiotensina , Inibidores da Enzima Conversora de Angiotensina , Obesidade/complicações , Obesidade/tratamento farmacológico , Obesidade/metabolismo , Ratos Long-Evans , Síndrome Metabólica/metabolismo , Encéfalo/metabolismo , Glicemia/metabolismoRESUMO
Increased angiotensin II (Ang II) signaling contributes to insulin resistance and liver steatosis. In addition to ameliorating hypertension, angiotensin receptor blockers (ARBs) improve lipid metabolism and hepatic steatosis, which are impaired with metabolic syndrome (MetS). Chronic blockade of the Ang II receptor type 1 (AT1) increases plasma angiotensin 1-7 (Ang 1-7), which mediates mechanisms counterregulatory to AT1 signaling. Elevated plasma Ang 1-7 is associated with decreased plasma triacylglycerol (TAG), cholesterol, glucose, and insulin; however, the benefits of RAS modulation to prevent non-alcoholic fatty liver disease (NAFLD) are not fully investigated. To better address the relationships among chronic ARB treatment, plasma Ang 1-7, and hepatic steatosis, three groups of 10-week-old-rats were studied: (1) untreated lean Long Evans Tokushima Otsuka (LETO), (2) untreated Otsuka Long Evans Tokushima Fatty (OLETF), and (3) OLETF + ARB (ARB; 10 mg olmesartan/kg/d × 6 weeks). Following overnight fasting, rats underwent an acute glucose load to better understand the dynamic metabolic responses during hepatic steatosis and early MetS. Tissues were collected at baseline (pre-load; T0) and 1 and 2 h post-glucose load. AT1 blockade increased plasma Ang 1-7 and decreased liver lipids, which was associated with decreased fatty acid transporter 5 (FATP5) and fatty acid synthase (FASN) expression. AT1 blockade decreased liver glucose and increased glucokinase (GCK) expression. These results demonstrate that during MetS, overactivation of AT1 promotes hepatic lipid deposition that is stimulated by an acute glucose load and lipogenesis genes, suggesting that the chronic hyperglycemia associated with MetS contributes to fatty liver pathologies via an AT1-mediated mechanism.
Assuntos
Diabetes Mellitus Tipo 2 , Fígado Gorduroso , Síndrome Metabólica , Angiotensina I , Antagonistas de Receptores de Angiotensina , Inibidores da Enzima Conversora de Angiotensina , Animais , Expressão Gênica , Glucose , Insulina , Lipogênese , Fígado , Obesidade , Fragmentos de Peptídeos , Ratos , Ratos Endogâmicos OLETF , Receptor Tipo 1 de AngiotensinaRESUMO
The preventive effects of regular exercise on obesity-related health problems are carried over to the non-exercise detraining period, even when physical activity decreases with aging. However, it remains unknown whether regular childhood exercises can be carried over to adulthood. Therefore, this study aimed to investigate the effects of long-term childhood exercise and detraining on lipid accumulation in organs to prevent obesity in adulthood. Four-week-old male Otsuka Long-Evans Tokushima Fatty (OLETF) rats were used as obese animals. OLETF rats were allocated into sedentary and exercise groups: exercise from 4- to 12-week-old and detraining from 12- to 20-week-old. At 12-week-old immediately after the exercise period, regular exercise completely inhibited hyperphagia, obesity, enlarged pancreatic islets, lipid accumulation and lobular inflammation in the liver, hypertrophied adipocytes in the white adipose tissue (WAT), and brown adipose tissue (BAT) whitening in OLETF rats. Additionally, exercise attenuated the decrease in the ratio of muscle wet weight to body weight associated with obesity. Decreased food consumption was maintained during the detraining period, which inhibited obesity and diabetes at 20-week-old after the detraining period. Histologically, childhood exercise inhibited the enlargement of pancreatic islets after the detraining period. In addition, inhibition of lipid accumulation was completely maintained in the WAT and BAT after the detraining period. However, the effectiveness was only partially successful in lipid accumulation and inflammation in the liver. The ratio of muscle wet weight to body weight was maintained after detraining. In conclusion, early long-term regular exercise effectively prevents obesity and diabetes in childhood, and its effectiveness can be tracked later in life. The present study suggests the importance of exercise during childhood and adolescence to inhibit hyperphagia-induced lipid accumulation in metabolic-related organs in adulthood despite exercise cessation.
Assuntos
Hiperfagia , Obesidade , Adulto , Animais , Exercício Físico , Humanos , Inflamação , Lipídeos , Masculino , Obesidade/patologia , Obesidade/prevenção & controle , Ratos , Ratos Endogâmicos OLETFRESUMO
Follistatin-like 1 (FSTL1), which is mainly secreted from skeletal muscle and myocardium, upregulates protein kinase B (Akt) and endothelial nitric oxide synthase (eNOS) phosphorylation in vascular endothelial cells. It is unclear whether skeletal muscle- and myocardium-derived FSTL1 secretion induced by aerobic exercise training is involved in the reduction of arterial stiffness via arterial NO production in obese rats. This study aimed to clarify whether aerobic exercise training-induced FSTL1 secretion in myocardium and skeletal muscle is associated with a reduction in arterial stiffness via arterial Akt-eNOS signaling pathway in obese rats. Sixteen Otsuka Long-Evans Tokushima Fatty (OLETF) obese rats were randomly divided into two groups: sedentary control (OLETF-CON) and eight-week aerobic exercise training (treadmill for 60min at 25m/min, 5days/week, OLETF-AT). Eight Long-Evans Tokushima Otsuka (LETO) rats were used as a healthy sedentary control group. In OLETF-CON, serum FSTL1, arterial Akt and eNOS phosphorylation, and arterial nitrite/nitrate (NOx) levels were significantly lower, and carotid-femoral pulse wave velocity (cfPWV) was significantly greater than those in LETO. These parameters were improved in the OLETF-AT compared to the OLETF-CON. In the OLETF-AT, FSTL1 levels in slow-twitch fiber-rich soleus muscle were significantly greater than those in the OLETF-CON, but not in myocardium, fast-twitch fiber-rich tibialis anterior muscle, and adipose tissue. Serum FSTL1 levels were positively correlated with soleus FSTL1, arterial eNOS phosphorylation, and NOx levels and negatively correlated with cfPWV. Thus, aerobic exercise training-induced FSTL1 secretion in slow-twitch fiber-rich muscles may be associated with a reduction in arterial stiffness via arterial NO production in obese rats.