Combined effects of a high-fat diet and chronic valproic acid treatment on hepatic steatosis and hepatotoxicity in rats

Aim： To investigate the potential interactive effects of a high-fat diet （HFD） and valproic acid （VPA） on hepatic steatosis and hepatotoxicity in rats. Methods： Male SD rats were orally administered VPA （100 or 500 mg.kgl.d1） combined with HFD or a standard diet for 8 weeks. Blood and liver samples were analyzed to determine lipid levels and hepatic function biomarkers using commercial kit assays. Low- molecular-weight compounds in serum, urine and bile samples were analyzed using a metabonomic approach based on GC/TOF-MS. Results： HFD alone induced extensive hepatocyte steatosis and edema in rats, while VPA alone did not cause significant liver lesions. VPA significantly aggravated HFD-induced accumulation of liver lipids, and caused additional spotty or piecemeal necrosis, accompanied by moderate infiltration of inflammatory cells in the liver. Metabonomic analysis of serum, urine and bile samples revealed that HFD significantly increased the levells of amino acids, free fatty acids （FFAs） and 3-hydroxy-butanoic acid, whereas VPA markedly decreased the levels of amino acids, FFAs and the intermediate products of the tricarboxylic acid cycle （TCA） compared with the control group. HFD aggravated VPA-induced inhibition on lipid and amino acid metabolism. Conclusion： HFD magnifies VPA-induced impairment of mitochondria113-oxidation of FFAs and TCA, thereby increases hepatic steatosis and hepatotoxicity. The results suggest the patients receiving VPA treatment should be advised to avoid eating HFD.     

Metabolomic analysis of simvastatin and fenofibrate intervention in high-lipid diet-induced hyperlipidemia rats

Aim:

To investigate the metabolite changes caused by simvastatin or fenofibrate intervention in diet-induced hyperlipidemia rats using a GC-MS-based metabolomic profiling approach.

Methods:

SD rats were fed with high-lipid diet for 4 weeks to induce hyperlipidemia, then the rats were fed with normal diet, and orally administered with simvastatin (10 mg·kg⁻¹·d⁻¹) or fenofibrate (150 mg·kg⁻¹·d⁻¹) for 2 weeks. Blood samples were collected once a week, and potential biomarkers were examined using commercial assay kits and a metabolomic approach. The metabolomics data were analyzed using a multivariate statistical technique and a principal component analysis (PCA).

Results:

Oral administration of simvastatin or fenofibrate significantly decreased the plasma levels of total cholesterol (TC) and low-density lipoprotein (LDL) cholesterol and increased the plasma level of high-density lipoprotein (HDL) cholesterol in the hyperlipidemia rats. Plasma samples were scattered in the PCA scores plots in response to the diet and to the drugs administered. The main metabolites changed in the hyperlipidemia rats were cholesterol, creatinine, linoleic acid, β-hydroxybutyric acid, tyrosine, isoleucine and ornithine. The plasma level of creatinine was significantly lower in the simvastatin-treated rats than in the fenofibrate-treated rats. The plasma tyrosine concentration was declined following intake of high-lipid diet, which was reversed by fenobrate, but not by simvastatin.

Conclusion:

A series of potential biomarkers including tyrosine, creatinine, linoleic acid, β-hydroxybutyric acid and ornithine have been identified by metabolomic profiling, which may be used to identify the metabolic changes during hyperlipidemia progression.     

Application of GC/MS-based metabonomic profiling in studying the lipid-regulating effects of Ginkgo biloba extract on diet-induced hyperlipidemia in rats

Aim:

To evaluate the lipid-regulating effects of extract from Ginkgo biloba leaves (EGB) using pharmacological methods and metabonomic profiling in a rat model of diet-induced hyperlipidemia.

Methods:

EGB was orally administered at a dose level of 40 mg/kg in both the EGB-prevention and -treatment groups. All rat samples obtained were examined for known and potential biomarkers and enzyme activity using commercial assay kits and GC/MS-based metabonomic profiling coupled with principal component analysis (PCA).

Results:

The data obtained from the assay kits indicated that EGB reduced total cholesterol and low density lipoprotein cholesterol levels and increased high density lipoprotein cholesterol levels in rat plasma obtained from both the EGB-prevention and –treatment groups compared with those of the diet-induced hyperlipidemia group. EGB also increased the activities of lipoprotein lipase and hepatic lipase and excretion of fecal bile acid in rats from the EGB-prevention and–treatment groups. Using GC/MS-based metabonomic analysis, more than 40 endogenous metabolites were identified in rat plasma. PCA of rat plasma samples obtained using GC/MS produced a distinctive separation of the four treatment groups and sampling points within each group. Metabolic changes during hyperlipidemia formation and improvement resulting from EGB treatment were definitively monitored with PCA score plots. Furthermore, elevated levels of sorbitol, tyrosine, glutamine and glucose, and decreased levels of citric acid, galactose, palmitic acid, arachidonic acid, acetic acid, cholesterol, butyrate, creatinine, linoleate, ornithine and proline, were observed in the plasma of rats treated with EGB.

Conclusion:

EGB exerts multi-directional lipid-lowering effects on the rat metabonome, including limitation of the absorption of cholesterol, inactivation of HMGCoA and favorable regulation of profiles of essential polyunsaturated fatty acid (EFA). Further experiments are warranted to explore the mechanisms of action underlying the lipid-regulating effects of EGB against hyperlipidemia.     

Cordyceps sinensis protects against liver and heart injuries in a rat model of chronic kidney disease： a metabolomic analysis

Aim： To test the hypothesis that the traditional Chinese medicine Cordyceps sinensis could improve the metabolic function of extrarenal organs to achieve its anti-chronic kidney disease （CKD） effects. Methods： Male SD rats were divided into CKD rats （with 5/6-nephrectomy）, CKD rats treated with Cordyceps sinensis （4 mg.kg1.d-1, pc）, and sham-operated rats. After an 8-week treatment, metabolites were extracted from the hearts and livers of the rats, and then subjected to 1H-NMR-based metabolomic analysis. Results： Oxidative stress, energy metabolism, amino acid and protein metabolism and choline metabolism were considered as links between CKD and extrarenal organ dysfunction. Within the experimental period of 8 weeks, the metabolic disorders in the liver were more pronounced than in the heart, suggesting that CKD-related extrarenal organ dysfunctions occurred sequentially rather than simultaneously. Oral administration of Cordyceps sinensis exerted statistically significant rescue effects on the liver and heart by reversely regulating levels of those metabolites that are typically perturbed in CKD. Conclusion： Oral administration of Cordyceps sinensis significantly attenuates the liver and heart injuries in CKD rats. The 1H NMR- based metabolomic approach has provided a systematic view for understanding of CKD and the drug treatment, which can also be used to elucidate the mechanisms of action of other traditional Chinese medicines.     

The antidepressant bupropion exerts alleviating properties in an ovariectomized osteoporotic rat model

Aim:

Depression is a risk factor for impaired bone mass and micro-architecture, but several antidepressants were found to increase the incidence of osteoporotic fractures. In the present study we used ovariectomized (OVX) rats as a model of osteoporosis to investigate the effects of the antidepressant bupropion on the femoral bones.

Methods:

OVX animals were treated with bupropion (30, 60 mg·kg⁻¹·d⁻¹) for six weeks. Bone turnover biomarkers (urinary DPD/Cr ratio, serum BALP, OC, TRAcP 5b, CTX and sRANKL levels) and inflammatory cytokines (TNF-α, IL-1β and IL-6) were determined using ELISA. Inductively coupled plasma mass spectroscopy (ICP-MS) was used to determine the femoral bone mineral concentrations. The cortical and trabecular morphometric parameters of femoral bones were determined using micro-CT scan and histopathology.

Results:

In OVX rats, the levels of bone turnover biomarkers and inflammatory cytokines were significantly elevated and femoral bone Ca²⁺ and PO₄³⁻ concentrations were significantly reduced. Moreover, cortical and trabecular morphometric parameters and histopathology of femoral bones were severely altered by ovariectomy. Bupropion dose-dependently inhibited the increases in bone turnover biomarkers and inflammatory cytokines. OVX rats treated with the high dose of bupropion showed normal mineral concentrations in femoral bones. The altered morphometric parameters and histopathology of femoral bones were markedly attenuated by the treatment.

Conclusion:

Bupropion exerts osteo-protective action in OVX rats through suppressing osteoclastogenesis-inducing factors and inflammation, which stabilize the osteoclasts and decrease bone matrix degradation or resorption.     

Chronic mTOR inhibition by rapamycin induces muscle insulin resistance despite weight loss in rats

BACKGROUND AND PURPOSE

mTOR inhibitors are currently used as immunosuppressants in transplanted patients and as promising anti-cancer agents. However, new-onset diabetes is a frequent complication occurring in patients treated with mTOR inhibitors such as rapamycin (Sirolimus). Here, we investigated the mechanisms associated with the diabetogenic effects of chronic Sirolimus administration in rats and in in vitro cell cultures.

EXPERIMENTAL APPROACH

Sirolimus was administered to rats fed either a standard or high-fat diet for 21 days. Metabolic parameters were measured in vivo and in ex vivo tissues. Insulin sensitivity was assessed by glucose tolerance tests and euglycaemic hyperinsulinaemic clamps. Rapamycin effects on glucose metabolism and insulin signalling were further evaluated in cultured myotubes.

KEY RESULTS

Sirolimus induced a decrease in food intake and concomitant weight loss. It also induced specific fat mass loss that was independent of changes in food intake. Despite these beneficial effects, Sirolimus-treated rats were glucose intolerant, hyperinsulinaemic and hyperglycaemic, but not hyperlipidaemic. The euglycaemic hyperinsulinaemic clamp measurements showed skeletal muscle is a major site of Sirolimus-induced insulin resistance. At the molecular level, long-term Sirolimus administration attenuated glucose uptake and metabolism in skeletal muscle by preventing full insulin-induced Akt activation and altering the expression and translocation of glucose transporters to the plasma membrane. In rats fed a high-fat diet, these metabolic defects were exacerbated, although Sirolimus-treated animals were protected from diet-induced obesity.

CONCLUSIONS AND IMPLICATIONS

Taken together, our data demonstrate that the diabetogenic effect of chronic rapamycin administration is due to an impaired insulin action on glucose metabolism in skeletal muscles.     

Schizandrin ameliorates ovariectomy-induced memory impairment,potentiates neurotransmission and exhibits antioxidant properties

Background and Purpose

Schizandrin (SCH) has been reported to prevent or reduce learning and memory defects. However, it is not known whether SCH ameliorates cognitive impairments induced by oestrogen deficiency. In the present study, we investigated the effect of SCH on memory in ovariectomized (OVX) and non-OVX rats.

Experimental Approach

A passive avoidance test was used to evaluate the effect of SCH on memory. Field EPSPs were recorded in hippocampal slices using an electrophysiological method. In OVX rats, biochemical parameters in the bilateral hippocampus were measured; these included superoxide dismutase (SOD), malondialdehyde (MDA) and AChE. Also, the number of NADPH-diaphorase (NADPH-d) positive neurons was counted by NADPH-d histochemistry staining technique.

Key Results

Oral SCH improved the memory and facilitated the induction of long-term potentiation in non-OVX and OVX rats; this effect was more obvious in OVX rats. Similarly, SCH perfusion enhanced synaptic transmission in hippocampal slices from both non-OVX and OVX rats. However, SCH perfusion reduced the ratio of paired-pulse facilitation only in OVX but not in non-OVX rats. In addition, SCH decreased AChE activity and MDA level and increased SOD activity and the number of NADPH-d-positive neurons in OVX rats.

Conclusions and Implications

SCH improves memory in OVX rats and its potential mechanisms may include a reduction in the loss of hippocampal NADPH-d positive neurons, an increase of antioxidant properties and a potentiation of synaptic transmission that possibly involves to enhance cholinergic function. Overall, our findings indicate that SCH has potential as a therapeutic strategy for the cognitive dysfunctions associated with the menopause.     

Atorvastatin improves insulin sensitivity in mice with obesity induced by monosodium glutamate

Aim:

To examine the mechanisms underlying the effects of atorvastatin on glucose and lipid metabolism.

Methods:

Mice with insulin resistance and obesity induced by monosodium glutamate (MSG) were used. Atorvastatin (80 mg·kg⁻¹·d⁻¹) or vehicle control treatment was given orally once a day for 30 days. Plasma levels of total cholesterol, triglycerides, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and free fatty acids were monitored. Serum insulin and glucose concentrations were used to calculate the insulin resistance index and insulin sensitivity index using a homeostasis model. Body length, waistline circumference, intraperitoneal adipose tissue mass, and total body mass were measured. Semi-quantitative RT-PCR and Western analysis were used to determine the expression of inflammatory factors and proteins involved in inflammation signaling pathways.

Results:

Atorvastatin improved insulin sensitivity, ameliorated glucose tolerance, and decreased plasma levels of total cholesterol, triglycerides, LDL-C, HDL-C and free fatty acids. Semi-quantitative RT-PCR and Western analysis revealed increased expression of interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α) in serum and adipose tissue in MSG obese mice. Atorvastatin treatment decreased expression of IL-6, TNF-α, nuclear factor κB (NF-κB) and I-kappa-B (IκB) kinase-β, but increased the expression of IκB, in adipose tissue.

Conclusion:

Atorvastatin is a potential candidate for the prevention and therapy of diseases associated with insulin resistance such as type 2 diabetes mellitus and cardiovascular disease. One possible mechanism underlying the effects of atorvastatin on glucose and lipid metabolism may be to ameliorate a state of chronic inflammation.     

PPARδ agonists have opposing effects on insulin resistance in high fat-fed rats and mice due to different metabolic responses in muscle

BACKGROUND AND PURPOSE

The peroxisome proliferator-activated receptor (PPAR)δ has been considered a therapeutic target for diabetes and obesity through enhancement of fatty acid oxidation. The present study aimed to characterize the effects of PPARδ agonists during insulin resistance of the whole body, muscle and liver.

EXPERIMENTAL APPROACH

Wistar rats and C57BL/J6 mice were fed a high fat diet (HF) and then treated with PPARδ agonists NNC61-5920 and GW501516. The effects on insulin resistance were evaluated by hyperinsulinaemic clamp or glucose tolerance tests combined with glucose tracers.

KEY RESULTS

In HF rats, 3 weeks of treatment with NNC61-5920 reduced the glucose infusion rate (by 14%, P < 0.05) and glucose disposal into muscle (by 20–30%, P < 0.01) during hyperinsulinaemic clamp. Despite increased mRNA expression of carnitine palmitoyltransferase-1, pyruvate dehydrogenase kinase 4 and uncoupling protein 3 in muscle, plasma and muscle triglyceride levels were raised (P < 0.01). Similar metabolic effects were observed after extended treatment with NNC61-5920 and GW501516 to 6 weeks. However, HF mice treated with NNC61-5920 improved their plasma lipid profile, glucose tolerance and insulin action in muscle. In both HF rats and mice, NNC61-5920 treatment attenuated hepatic insulin resistance and decreased expression of stearoyl-CoA desaturase 1, fatty acid translocase protein CD36 and lipoprotein lipase in liver.

CONCLUSIONS AND IMPLICATIONS

PPARδ agonists exacerbated insulin resistance in HF rats in contrast to their beneficial effects on metabolic syndrome in HF mice. These opposing metabolic consequences result from their different effects on lipid metabolism and insulin sensitivity in skeletal muscle of these two species.     

Danthron activates AMP-activated protein kinase and regulates lipid and glucose metabolism in vitro

Aim:

To discover the active compound on AMP-activated protein kinase (AMPK) activation and investigate the effects of the active compound 1,8-dihydroxyanthraquinone (danthron) from the traditional Chinese medicine rhubarb on AMPK-mediated lipid and glucose metabolism in vitro.

Methods:

HepG2 and C2C12 cells were used. Cell viability was determined using MTT assay. Real-time PCR was performed to measure the gene expression. Western blotting assay was applied to investigate the protein phosphorylation level. Enzymatic assay kits were used to detect the total cholesterol (TC), triglyceride (TG) and glucose contents.

Results:

Danthron (0.1, 1, and 10 μmol/L) dose-dependently promoted the phosphorylation of AMPK and acetyl-CoA carboxylase (ACC) in both HepG2 and C2C12 cells. Meanwhile, danthron treatment significantly reduced the lipid synthesis related sterol regulatory element-binding protein 1c (SREBP1c) and fatty acid synthetase (FAS) gene expressions, and the TC and TG levels. In addition, danthron treatment efficiently increased glucose consumption. The actions of danthron on lipid and glucose metabolism were abolished or reversed by co-treatment with the AMPK inhibitor compound C.

Conclusion:

Danthron effectively reduces intracellular lipid contents and enhanced glucose consumption in vitro via activation of AMPK signaling pathway.     

Long-term baicalin administration ameliorates metabolic disorders and hepatic steatosis in rats given a high-fat diet

Aim:

Baicalin, one of the major flavonoids in Scutellaria baicalensis, possesses antioxidant and anti-inflammatory properties. However, the effects of baicalin on metabolic disorders and hepatic steatosis have not been investigated.

Methods:

Body weight was examined in high-fat diet (HFD)-fed rats with or without baicalin treatment. At the end of the experiment, serum biochemical parameters, liver histology and lipid profile were analyzed to assess whether the animals were suffering from metabolic disorders or hepatic steatosis. In the liver, the phosphorylation of AMP activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) and the gene expression of some enzymes involved in lipogenesis were examined. The effects of baicalin on the phosphorylation of AMPK and lipid accumulation induced by high glucose in human hepatoma HepG2 cells were also examined.

Results:

Baicalin (80 mg/kg) administered ip for 16 weeks suppressed body weight gain in HFD-fed rats. Weight reduction was accompanied by the reduction of visceral fat mass. Baicalin significantly decreased the elevated serum cholesterol, free fatty acid and insulin concentrations caused by the HFD. Baicalin also suppressed systemic inflammation by reducing the serum level of tumor necrosis factor α. Baicalin reduced hepatic lipid accumulation, enhanced the phosphorylation of AMPK and ACC and down-regulated genes involved in lipogenesis, including fatty acid synthase and its upstream regulator SREBP-1c. In HepG2 cells, baicalin (5 and 10 μmol/L) increased the phosphorylation of AMPK and decreased lipid accumulation following the addition of high glucose.

Conclusion:

Our study suggests that baicalin might have beneficial effects on the development of hepatic steatosis and obesity-related disorders by targeting the hepatic AMPK.     

High cholesterol diet increases osteoporosis risk via inhibiting bone formation in rats

Aim:

To investigate the effects of high cholesterol diet on the development of osteoporosis and the underlying mechanisms in rats.

Methods:

Female Sprague-Dawley rats were randomly separated into 3 groups: (1) the high cholesterol fed rats were fed a high cholesterol diet containing 77% normal diet food, 3% cholesterol and 20% lard for 3 months; (2) ovariectomised (OVX) rats were bilaterally ovariectomised and fed a standard diet; and (3) the control rats were fed the standard diet. Bone mineral density (BMD) of the rats was measured using dual-energy X-ray absorptiometry. Serum levels of oestradiol (E2), osteocalcin (BGP) and carboxy-terminal collagen crosslinks (CTX) were measured using ELISA. Gene expression profile was determined with microarray. Mouse osteoblast cells (MC3T3-E1) were used for in vitro study. Proliferation, differentiation and oxidative stress of the osteoblasts were investigated using MTT, qRT-PCR and biochemical methods.

Results:

In high cholesterol fed rats, the femur BMD and serum BGP level were significantly reduced, while the CTX level was significantly increased. DNA microarray analysis showed that 2290 genes were down-regulated and 992 genes were up-regulated in this group of rats. Of these genes, 1626 were also down-regulated and 1466 were up-regulated in OVX rats. In total, 370 genes were up-regulated in both groups, and 976 genes were down-regulated. Some of the down-regulated genes were found to code for proteins involved in the transforming growth factor beta (TGF-β)/bone morphogenic protein (BMP) and Wnt signaling pathways. The up-regulated genes were found to code for IL-6 and Ager with bone-resorption functions. Treatment of MC3T3-E1 cells with cholesterol (12.5-50 μg/mL) inhibited the cell proliferation and differentiation in vitro in a concentration-dependent manner. The treatment also concentration-dependently reduced the expression of BMP2 and Cbfa1, and increased the oxidative injury in MC3T3-E1 cells.

Conclusion:

The results suggest a close correlation between hypercholesterolaemia and osteoporosis. High cholesterol diet increases the risk of osteoporosis, possible via inhibiting the differentiation and proliferation of osteoblasts.     

Differential regulations of blood pressure and perturbed metabolism by total ginsenosides and conventional antihypertensive agents in spontaneously hypertensive rats

Aim:

To investigate the regulatory effects of total ginsenosides and the conventional antihypertensive agents (captopril, amlodipine, terazosin and hydrochlorothiazide) on the blood pressure and perturbed metabolism in spontaneously hypertensive rats (SHRs) and to analyze the cause-effect relationships between high blood pressure and the metabolic disorders of hypertension.

Methods:

SHRs were administrated with total ginsenosides or the antihypertensive agents for eight weeks. Systolic blood pressure (SP) was measured every week and low-molecular-weight compounds in blood plasma were quantitatively analyzed using a nontargeted high-throughput metabolomic tool: gas chromatography/time of flight mass spectrometry (GC/TOFMS) . The metabolic patterns were evaluated using principal components analysis and potential markers of hypertension were identified.

Results:

Total ginsenosides and the antihypertensive agents differentially regulated SP and the metabolic pattern in SHRs. Total ginsenosides caused a progressive and prolonged reduction of SP and markedly normalized the perturbed metabolism with 14 of 27 (51.8%) markers of hypertension which were regulated toward normal. Total ginsenosides also reduced free fatty acids'' level toward normal levels. In contrast, captopril, amlodipine and terazosin efficiently depressed SP, but had little effect on metabolic perturbation with only 8 (29.6%), 4 (14.8%), and 4 (14.8%) markers, respectively, which were regulated.

Conclusion:

The metabolic changes persisted when the blood pressure was lowered by the conventional antihypertensive agents, suggesting that hypertension may not be the cause of the metabolic perturbation in SHRs.     

Pharmacological inhibition of diacylglycerol acyltransferase 1 reduces body weight gain, hyperlipidemia, and hepatic steatosis in db/db mice

Aim:

To test whether pharmacological inhibition of Diacylglycerol acyltransferase 1 (DGAT1) by a small-molecule inhibitor H128 can improve metabolism disorders in leptin receptor-deficient db/db mice.

Methods:

To investigate the effect of H128 on intestinal fat absorption,db/db mice were acutely given a bolus of corn oil by gavage. The mice were further orally administered H128 (3 and 10 mg/kg) for 5 weeks. Blood glucose, lipids, insulin, ALT, and AST as well as hepatic triglycerides were measured. The insulin tolerance test was performed to evaluate insulin sensitivity. The expression of genes involved in fatty acid oxidation was detected by RT-PCR.

Results:

Oral administration of H128 (10 mg/kg) acutely inhibited intestinal fat absorption following a lipid challenge in db/db mice. Chronic treatment with H128 significantly inhibited body weight gain, decreased food intake, and induced a pronounced reduction of serum triglycerides. In addition, H128 treatment markedly ameliorated hepatic steatosis, characterized by decreased liver weight, lipid droplets, and triglyceride content as well as serum ALT and AST levels. Furthermore, H128 treatment increased the expression of the CPT1 and PPARα genes in liver, suggesting that H128 enhanced fatty acid oxidation in db/db mice. However, neither blood glucose nor insulin tolerance was affected by H128 treatment throughout the 5-week experimental period.

Conclusion:

DGAT1 may be an effective therapeutic target for the treatment of obesity, hyperlipidemia and hepatic steatosis.     

Effect of ethanolic extract of Lepidium meyenii Walp on serum hormone levels in ovariectomized rats

Objective:

To evaluate the effect of long-term ethanol extract of Lepidium meyenii (Maca) on serum hormone levels in ovariectomized (OVX) rats and compare them with the effect of diethylstilbestrol.

Materials and Methods:

Fifty female Sprague-Dawley rats were ovariectomized or sham operated. Both sham and OVX control groups (n = 10, respectively) received the vehicle. The remaining OVX rats were oral administrated with ethanol extract of Maca (0.096, or 0.24g/kg; n = 10, respectively) and diethylstilbestrol (0.05 mg/kg; n = 10). The treatment continued for 28 weeks. At week 12 and week 28, the blood of rats was collected and serum hormone levels, including estradiol (E2), testosterone (T) and follicle-stimulating hormone (FSH) were measured by radioimmunoassay.

Results:

At week 12, the levels of serum E2 were slightly higher in Maca groups than that in OVX group; T levels were significantly decreased; and FSH levels were advanced slightly in Maca groups than that in sham group. After 28 weeks administration, serum E2 levels in Maca-treated animals did not differ significantly from sham control, the low dose of Maca increased serum E2 levels, and Maca prevented increase in serum FSH levels compared with OVX group.

Conclusions:

Long-term Maca supply modulates endocrine hormone balance in OVX rats, especially it decreases enhanced FSH levels. It is proposed that Maca may become a potential choice for postmenopausal women.KEY WORDS: Lepidium meyenii, maca, ovariectomized rats, serum hormone     

Genistein aglycone improves skin repair in an incisional model of wound healing: a comparison with raloxifene and oestradiol in ovariectomized rats

Background and purpose:

Oestrogen loss at menopause is frequently related to poor wound healing. Genistein has been tested in anti-ageing cosmetic preparations with interesting results on skin health. Here, we investigated the effects of the genistein aglycones, given systemically, in an incisional model of wound healing, compared to systemic oestradiol and raloxifene.

Experimental approach:

Six months after ovariectomy (OVX), rats were randomly assigned to groups of 12 animals each and treated daily with genistein aglycone (1 and 10 mg·kg⁻¹ s.c.), raloxifene hydrochloride (0.05 and 0.5 mg·kg⁻¹ s.c.) or 17-α-ethinyl oestradiol (0.003 and 0.03 mg·kg⁻¹ s.c.) for 12 weeks. Untreated OVX and sham OVX rats were used as controls. Then, 14 or 7 days before the end of the experiment, an incisional wound healing procedure was performed and skin specimens were collected to evaluate molecular, histological and functional measurements.

Key results:

Seven and fourteen days after wounding, samples from OVX rats showed a decrease in transforming growth factor-β1, tissue transglutaminase 2 and vascular endothelial growth factor compared to samples from sham OVX rats. Oestradiol, raloxifene and genistein all significantly modified this decrease, but the lowest genistein dose exerted a greater effect than the other treatments. Moreover, the lowest dose of genistein was the most effective in improving skin healing and wound tensile strength.

Conclusions and implications:

Genistein aglycone might be an alternative therapy for the management of skin wound healing.     

Genistein aglycone, a soy-derived isoflavone, improves skin changes induced by ovariectomy in rats

BACKGROUND AND PURPOSE

Ovariectomy accelerates age-related skin changes as adequate oestrogen levels are required to control structural integrity and functional capacity of skin. Genistein, a soy-derived isoflavone, has been tested in anti-ageing cosmetic preparations with interesting results on skin elasticity, photoaging and skin cancer prevention. We investigated the effects of genistein aglycone and compared them with systemic raloxifene hydrochloride and 17-α-ethinyloestradiol on skin changes in aged, ovariectomized (OVX) rats.

EXPERIMENTAL APPROACH

Six months after ovariectomy, rats were randomly allocated to different groups and treated, daily, with genistein aglycone (1 and 10 mg·kg⁻¹ s.c.), raloxifene hydrochloride (0.05 and 0.5 mg·kg⁻¹ s.c.) or 17-α-ethinyloestradiol (0.003 and 0.03 mg·kg⁻¹ s.c.) for 12 weeks. Controls were untreated OVX and sham OVX rats. At the end of the treatment period, a skin biopsy was carried out and skin samples were assessed for molecular, histological and functional changes.

KEY RESULTS

Skin samples of untreated OVX rats showed a decrease in TGF-β1, VEGF, MMP-2, MMP-9, tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 compared with sham OVX rats. All the treatments significantly restored this depressed molecular profile revealed in OVX rats. Genistein aglycone, 1 mg·kg⁻¹, also significantly increased the thickness of collagen and breaking strength of skin in the OVX rats.

CONCLUSIONS AND IMPLICATIONS

Relatively long-term, systemic treatment with genistein aglycone shows comparable efficacy to oestrogen in reversing some molecular, histological and functional changes of the skin associated with ovariectomy in aged rats. This suggests that genistein aglycone might be an effective alternative therapy for the management of age-related skin changes in postmenopausal women.     

Impact of chronic low to moderate alcohol consumption on blood lipid and heart energy profile in acetaldehyde dehydrogenase 2-deficient mice

Aim:

To investigate the roles of acetaldehyde dehydrogenase 2 (ALDH2), the key enzyme of ethanol metabolism, in chronic low to moderate alcohol consumption-induced heart protective effects in mice.

Methods:

Twenty-one male wild-type (WT) or ALDH2-knockout (KO) mice were used in this study. In each genotype, 14 animals received alcohol (2.5%, 5% and 10% in week 1–3, respectively, and 18% in week 4–7), and 7 received water for 7 weeks. After the treatments, survival rate and general characteristics of the animals were evaluated. Serum ethanol and acetaldehyde levels and blood lipids were measured. Metabolomics was used to characterize the heart and serum metabolism profiles.

Results:

Chronic alcohol intake decreased the survival rate of KO mice by 50%, and significantly decreased their body weight, but did not affect those of WT mice. Chronic alcohol intake significantly increased the serum ethanol levels in both WT and KO mice, but KO mice had significantly higher serum acetaldehyde levels than WT mice. Chronic alcohol intake significantly increased the serum HDL cholesterol levels in WT mice, and did not change the serum HDL cholesterol levels in KO mice. After chronic alcohol intake, WT and KO mice showed differential heart and serum metabolism profiles, including the 3 main energy substrate types (lipids, glucose and amino acids) and three carboxylic acid cycles.

Conclusion:

Low to moderate alcohol consumption increases HDL cholesterol levels and improves heart energy metabolism profile in WT mice but not in ALDH2-KO mice. Thus, preserved ALDH2 function is essential for the protective effect of low to moderate alcohol on the cardiovascular system.     

Methionine down-regulates TLR4/MyD88/NF-κB signalling in osteoclast precursors to reduce bone loss during osteoporosis

BACKGROUND AND PURPOSE

Studies have demonstrated that a moderate intake of amino acids is associated with development of bone health. Methionine, a sulphur-containing essential amino acid, has been largely implicated for improving cartilage formation, however its physiological significance on bone integrity and functionality have not been elucidated. We investigated whether methionine can prevent osteoporotic bone loss.

EXPERIMENTAL APPROACH

The anti-resorptive effect of methionine, (250 mg kg⁻¹ body wt administered in drinking water for 10 weeks), was evaluated in ovariectomized (OVX) rats by monitoring changes in bone turnover, formation of osteoclasts from blood-derived mononuclear cells and changes in the synthesis of pro-osteoclastogenic cytokines.

KEY RESULTS

Methionine improved bone density and significantly decreased the degree of osteoclast development from blood mononuclear cells in OVX rats, as indicated by decreased production of osteoclast markers tartarate resistant acid phosphatase b (TRAP5b) and MIP-1α. siRNA-mediated knockdown of myeloid differentiation primary response 88 [MyD88], a signalling molecule in the toll-like receptor (TLR) signalling cascade, abolished the synthesis of both TRAP5b and MIP-1α in developing osteoclasts. Methionine supplementation disrupted osteoclast development by inhibiting TLR-4/MyD88/NF-κB pathway.

CONCLUSIONS AND IMPLICATIONS

TLR-4/MyD88/NF-κB signalling pathway is integral for osteoclast development and this is down-regulated in osteoporotic system on methionine treatment. Methionine treatment could be beneficial for the treatment of postmenopausal osteoporosis.     

Decreased exposure of simvastatin and simvastatin acid in a rat model of type 2 diabetes

Aim:

Simvastatin is frequently administered to diabetic patients with hypercholesterolemia. The aim of the study was to investigate the pharmacokinetics of simvastatin and its hydrolysate simvastatin acid in a rat model of type 2 diabetes.

Methods:

Diabetes was induced in 4-week-old rats by a treatment of high-fat diet combined with streptozotocin. After the rats received a single dose of simvastatin (20 mg/kg, po, or 2 mg/kg, iv), the plasma concentrations of simvastatin and simvastatin acid were determined. Simvastatin metabolism and cytochrome P4503A (Cyp3a) activity were assessed in hepatic microsomes, and its uptake was studied in freshly isolated hepatocytes. The expression of Cyp3a1, organic anion transporting polypeptide 2 (Oatp2), multidrug resistance-associated protein 2 (Mrp2) and breast cancer resistance protein (Bcrp) in livers was measured using qRT-PCR.

Results:

After oral or intravenous administration, the plasma concentrations and areas under concentrations of simvastatin and simvastatin acid were markedly decreased in diabetic rats. Both simvastatin metabolism and Cyp3a activity were markedly increased in hepatocytes of diabetic rats, accompanied by increased expression of hepatic Cyp3a1 mRNA. Furthermore, the uptake of simvastatin by hepatocytes of diabetic rats was markedly increased, which was associated with increased expression of the influx transporter Oatp2, and decreased expression of the efflux transporters Mrp2 and Bcrp.

Conclusion:

Diabetes enhances the metabolism of simvastatin and simvastatin acid in rats via up-regulating hepatic Cyp3a activity and expression and increasing hepatic uptake.