Telmisartan: An angiotensin receptor blocker regulates osteoclastogenesis via inhibition of the ERK triggering in osteoporotic male rats.

Great attention was recently given to the importance of RAS in controlling inflammatory bone diseases, following the discovery of its local existence in skeletal tissues. Local RAS was found to be expressed on osteoblastic and osteoclastic cells and to exert its action via angiotensin II (AngII) receptors, including angiotensin II type 1 receptor (AT1 R) and angiotensin II type 2 receptors. Telmisartan (TLM), an AT1 R blocker (ARBs), was investigated in the present study for its therapeutic effect on bone health in osteoporotic rats. d-Galactose, a reducing sugar at a dose of 200 mg/kg/day/i.p., was used to induce osteoporosis in male rats. TLM, at a dose of 5 mg/kg/day, was orally introduced in the osteoporotic rats for four consecutive weeks. Tibia and femur bone densitometry was estimated, bone formation and bone resorption biomarkers serum levels were measured, mineral content in blood was also valued, and finally the extracellular regulated kinase (ERK) expression in bone was determined. TLM considerably improved the deleterious effect of d-galactose on bone mineral density. It blunted serum bone-specific alkaline phosphatase and osteocalcin while elevating serum osteoprotegrin (OPG). On the other hand, TLM turned off the pronounced elevation in serum receptor activator of nuclear factor-κß ligand (RANKL), tartrate-resistant acid phosphatase, and cathepsin K. Furthermore, it significantly hindered the bone expression of ERK which hampered osteoclastogenesis. AT1 R inhibition abolished the rise in serum calcium and phosphorus and normalized serum superoxide dismutase and catalase. These TLM protective effects in d-galactose-treated rats were confirmed by the histopathological examination. The results all together denote the potential therapeutic value of ARBs therapy in osteoporosis.

Chloroquine ameliorates bone loss induced by d-galactose in male rats via inhibition of ERK associated osteoclastogenesis and antioxidant effect.

Chloroquine (CQ); a lysosomotropic agent used for decade ago as anti-malarial, was tested against aging induced osteoporosis. Osteoporosis in male rats was induced using d-galactose (D-gal) as a reducing sugar at a dose of 200 mg/kg/day; i.p. Osteoporotic rats were orally treated with CQ (10 mg/kg/day) for four successive weeks. Bone densitometry of tibia and femur were evaluated. Bone formation biomarkers; osteoprotegrin (OPG), bone specific alkaline phosphatse (BALP), and osteocalcin (OCN), and bone resorption biomarker; receptor activator of nuclear factor kappa-B ligand (RANKL), cathepsin-k (CTSK), tartrate-resistant acid phosphatase (TRAP) were estimated. Moreover, the expression of extracellular regulated kinase (ERK) in bone was determined. CQ ameliorated the bone detrimental changes induced by d-galactose. It enhanced bone health as revealed by measurement of bone densitometry, halted the activation of receptor activator of nuclear factor kappa-B ligand (RANKL) and reduced bone manifestation of ERK. Furthermore, CQ treatment abated serum cathepsin-k (CTSK) and serum tartrate-resistant acid phosphatase (TRAP) thus inhibited osteoclastogenesis and consequently restored the RANKL/OPG ratio. CQ demonstrated an antioxidant effect in bone where it increased both Catalase (CAT) and Superoxide dismutase (SOD). These CQ preserving effect in rats treated with d-galactose were confirmed by the histopathological examination. The present study points to the potential therapeutic effect of CQ as anti-osteoporotic agent possibly through its antioxidant effects and suppression of ERK associated osteoclastogenesis.

Role of nitric oxide and KATP channel in the protective effect mediated by nicorandil in bile duct ligation-induced liver fibrosis in rats.

Liver fibrosis is one of the most serious conditions affecting patients worldwide. In the present study, the role of nitric oxide and KATP channel was investigated for the first time in the possible protection mediated by nicorandil in bile duct ligation-induced liver fibrosis in rats. Nicorandil (3 mg/kg/day) was given orally 24 h after bile duct ligation for 14 days till the end of the experiment. Nicorandil group showed marked improvement in liver function tests, hepatic oxidative stress and inflammatory markers as well as inducible and endothelial nitric oxide synthase protein expressions. Furthermore, nicorandil administration led to significant decrement of phosphorylated protein kinase C, fibrosis and hepatic stellate cells activation as indicated by decreased alpha smooth muscle actin expression. Oral co-administration of glibenclamide (5 mg/kg/day) (a KATP channel blocker) with nicorandil mostly showed similar improvement though not reaching to that of nicorandil group. However, co-adminstration of L-NAME (15 mg/kg/day) (an inhibitor of nitric oxide synthase) completely abolished the protective effects of nicorandil and produced more or less similar results to that of untreated bile duct ligated group. In conclusion, nicorandil is an effective therapy against the development of bile duct ligation-induced liver fibrosis in rats where nitric oxide plays a more prominent role in the protective effect of nicorandil than KATP channel opening.

The Ying and Yang of Adenosine A1 and A2A Receptors on ERK1/2 Activation in a Rat Model of Global Cerebral Ischemia Reperfusion Injury.

Adenosine impacts cerebral ischemia reperfusion (IR) through the inhibitory A1 and the excitatory A2 receptors. The present study aimed at investigating the contrasting role of pERK1/2 in mediating adenosine A1R (protective) versus A2AR (deleterious) effects in IR. Male Wistar rats subjected to bilateral carotid occlusion (45 min) followed by reperfusion (24 h) exhibited increased pERK1/2 activity, downstream from DAG pathway, along with increases in hippocampal glutamate, c-Fos, NF-κB, TNF-α, iNOS, TBARS, cytochrome c, caspase-3, BDNF, Nrf2, and IL-10 contents. Further, hippocampal microglial reactivity, glial TNF-α, and BDNF expression were observed. Although unilateral intrahippocampal injection of either the A1R agonist CHA or the A2AR agonist CGS21680 increased pERK1/2, only CHA mitigated histopathological and behavioral deficits along with reducing glutamate, microglial activation, c-Fos, TNF-α, iNOS, TBARS, cytochrome c and caspase-3 and elevating Nrf2 and IL-10 levels in IR rats. These results yield insight into the double-faceted nature of pERK1/2 in mediating protective and deleterious effects of A1R and A2AR signaling, respectively, against IR injury.

17ß-Estradiol augments antidepressant efficacy of escitalopram in ovariectomized rats: Neuroprotective and serotonin reuptake transporter modulatory effects.

The prevalence or recurrence of depression is seriously increased in women during the transition to and after menopause. The chronic hypo-estrogenic state of menopause may reduce the response to antidepressants; however the influence of estrogen therapy on their efficacy is still controversial. This study aimed at investigating the effects of combining escitalopram with 17ß-estradiol on depression and cognitive impairment induced by ovariectomy, an experimental model of human menopause. Young adult female Wistar rats were subjected to either sham operation or ovariectomy. Ovariectomized animals were treated chronically with escitalopram (10mg/kg/day, i.p) alone or with four doses of 17ß-estradiol (40µg/kg, s.c) given prior to the behavioral tests. Co-administration of 17ß-estradiol improved escitalopram-induced antidepressant effect in forced swimming test verified as more prominent decrease in the immobility time without opposing its memory enhancing effect in Morris water maze. 17ß-estradiol augmented the modulatory effects of escitalopram on the hippocampal levels of brain-derived neurotrophic factor and serotonin reuptake transporter as well as tumor necrosis factor-alpha without altering its effects on the gene expressions of serotonin receptor 1A, estrogen receptors alpha and beta, or acetylcholinestearase content. This combined therapy afforded synergistic protective effects on the brain histopathological architecture, particularly, the hippocampus. The antidepressant effect of 17ß-estradiol was abolished by pretreatment with estrogen receptor antagonist, tamoxifen (10mg/kg, p.o). In conclusion, 17ß-estradiol-induced antidepressant effect was confined to intracellular estrogen receptors activation. Moreover, 17ß-estradiol enhanced escitalopram's efficiency in ameliorating menopausal-like depression, via exerting synergistic neuroprotective and serotonin reuptake transporter modulatory effects, without impeding escitalopram-mediated cognitive improvement.

The Combination of α-Tocopheryl Succinate and Sodium Selenite on Breast Cancer: A Merit or a Demerit?

α-Tocopheryl succinate (α-TOS), a mitochondria-targeting agent, induces apoptosis in malignant cells in vitro and in vivo. Selenite is a nutritional supplement that has been shown to stimulate apoptosis in cancer cells. This study was designed to investigate the cytotoxic effect of combined treatment of α-TOS and sodium selenite (SSe) in vitro and in vivo and to explore their effect on apoptosis and autophagy in breast cancer. The type of interaction between α-TOS and SSe was evaluated and levels of oxidative stress and apoptotic and autophagic markers were determined. SSe alone showed varying degrees of cytotoxicity on all the tested cell lines. Its combination with α-TOS was antagonistic in vitro in MCF7 and in vivo in mice bearing Ehrlich tumor compared to α-TOS-treated one. Combination of TOS with 2 µM of SSe increased the level of glutathione without changes in antiapoptotic markers Bcl-2 and Mcl-1 at 16 and 48 hrs. SSe decreased caspase 3 activity and protein level of caspases 7 and 9, while it increased autophagic markers beclin-1 and LC3B protein levels of MCF7 cells treated with α-TOS. In conclusion, SSe antagonizes α-TOS-induced apoptosis via inhibition of oxidative stress and promoting prosurvival machinery of autophagy.

Mechanisms Involved in the Anti-inflammatory and Vascular Effects of Iberis amara Extract.

The anti-inflammatory potential and vasoprotective effects of an Iberis amara extract in a rat model of arthritis were investigated. I. amara, or bitter candytuft, has long been known for its anti-inflammatory properties on account of its active constituents, including cucurbitacins, kaempferol, and sinapic acid. The present study was intended to explore more in depth its anti-inflammatory activity in both acute (carrageenan rat paw edema) and chronic (adjuvant-induced arthritis) models of inflammation. An extract of I. amara dose-dependently reduced the extent of edema in both models. In the chronic model, this was associated with a reduction in the inflammation mediators tumor necrosis factor-α, interleukin-1ß, and prostaglandin E2 and in the antioxidant biomarkers malondialdehyde and total nitrate/nitrite. Because arthritis was reported both clinically and experimentally to contribute towards different vascular complications, it was of interest to study ex vivo the sensitivity of aortic rings in our experimental setup towards norepinephrine, acetylcholine, and sodium nitroprusside. The aortic rings from arthritic rats showed no change in sensitivity to norepinephrine, but showed a reduced sensitivity to sodium nitroprusside and acetylcholine. To show whether the treatment of the arthritis would restore endothelial function, I. amara extract was shown to markedly reduce the reactivity to norepinephrine, but not to appreciably affect the reactivity towards sodium nitroprusside and it had a tendency towards normalizing reactivity to acetylcholine. Taken collectively, the findings imply an improvement in endothelial function and lend support to the use of the extract in rheumatic inflammatory conditions to help safeguard the integrity of the endothelium and reduce the risk of vascular complications.

Role of oxidative stress, inflammation, nitric oxide and transforming growth factor-beta in the protective effect of diosgenin in monocrotaline-induced pulmonary hypertension in rats.

Pulmonary hypertension is a progressive disease of various origins that is associated with right ventricular dysfunction. In the present study, the protective effect of diosgenin was investigated in monocrotaline-induced pulmonary hypertension in rats. Pulmonary hypertension was induced by a single subcutaneous injection of monocrotaline (60 mg/kg). Diosgenin (100 mg/kg) was given by oral administration once daily for 3 weeks. At the end of the experiment, mean arterial blood pressure, electrocardiography and echocardiography were recorded. Rats were then sacrificed and serum was separated for determination of total nitrate/nitrite level. Right ventricles and lungs were isolated for estimation of oxidative stress markers, tumor necrosis factor-alpha, total nitrate/nitrite and transforming growth factor-beta contents. Myeloperoxidase and caspase-3 activities in addition to endothelial and inducible nitric oxide synthase protein expression were also determined. Moreover, histological analysis of pulmonary arteries and cardiomyocyte cross-sectional area was performed. Diosgenin treatment provided a significant improvement toward preserving hemodynamic changes and alleviating oxidative stress, inflammatory and apoptotic markers induced by monocrotaline in rats. Furthermore, diosgenin therapy prevented monocrotaline-induced changes in nitric oxide production, endothelial and inducible nitric oxide synthase protein expression as well as histological analysis. These findings support the beneficial effect of diosgenin in pulmonary hypertension induced by monocrotaline in rats.

Naringenin adds to the protective effect of L-arginine in monocrotaline-induced pulmonary hypertension in rats: favorable modulation of oxidative stress, inflammation and nitric oxide.

The present study was directed to investigate the possible modulatory effect of naringenin when co-administered with L-arginine in monocrotaline-induced pulmonary hypertension in rats. Pulmonary hypertension was induced by a single subcutaneous injection of monocrotaline (60 mg/kg). L-arginine (500 mg/kg) and naringenin (50 mg/kg) were orally administered daily, alone and in combination, for 3 weeks. Mean arterial blood pressure, electrocardiography and echocardiography were then recorded and rats were sacrificed and serum was separated for determination of total nitrate/nitrite level. Right ventricles and lungs were isolated for estimation of oxidative stress markers, tumor necrosis factor-alpha, total nitrate/nitrite and transforming growth factor-beta. Myeloperoxidase and caspase-3 activities in addition to endothelial and inducible nitric oxide synthase protein expression were also determined. Moreover, histological analysis of pulmonary arteries and cardiomyocyte cross-sectional area was performed. Combined therapy provided a significant improvement in L-arginine protective effect toward preserving hemodynamic changes and alleviating oxidative stress, inflammatory and apoptotic markers induced by monocrotaline treatment. Furthermore, combined therapy prevented monocrotaline-induced changes in endothelial and inducible nitric oxide synthase protein expression as well as histological analysis compared with either treatment alone. In conclusion, naringenin significantly adds to the protective effect of L-arginine in pulmonary hypertension induced by monocrotaline in rats.

Red yeast rice and coenzyme Q10 as safe alternatives to surmount atorvastatin-induced myopathy in hyperlipidemic rats.

Statins are the first line treatment for the management of hyperlipidemia. However, the primary adverse effect limiting their use is myopathy. This study examines the efficacy and safety of red yeast rice (RYR), a source of natural statins, as compared with atorvastatin, which is the most widely used synthetic statin. Statin interference with the endogenous synthesis of coenzyme Q10 (CoQ10) prompted the hypothesis that its deficiency may be implicated in the pathogenesis of statin-associated myopathy. Hence, the effects of combination of CoQ10 with either statin have been evaluated. Rats were rendered hyperlipidemic through feeding them a high-fat diet for 90 days, during the last 30 days of the diet they were treated daily with either atorvastatin, RYR, CoQ10, or combined regimens. Lipid profile, liver function tests, and creatine kinase were monitored after 15 and 30 days of drug treatments. Heart contents of CoQ9 and CoQ10 were assessed and histopathological examination of the liver and aortic wall was performed. RYR and CoQ10 had the advantage over atorvastatin in that they lower cholesterol without elevating creatine kinase, a hallmark of myopathy. RYR maintained normal levels of heart ubiquinones, which are essential components for energy production in muscles. In conclusion, RYR and CoQ10 may offer alternatives to overcome atorvastatin-associated myopathy.

Potential protective effect of honey against paracetamol-induced hepatotoxicity.

BACKGROUND: Paracetamol overdose causes severe hepatotoxicity that leads to liver failure in both humans and experimental animals. The present study investigates the protective effect of honey against paracetamol-induced hepatotoxicity in Wistar albino rats. We have used silymarin as a standard reference hepatoprotective drug. METHODS: Hepatoprotective activity was assessed by measuring biochemical parameters such as the liver function enzymes, serum alanine aminotransferase (ALT) and serum aspartate aminotransferase (AST). Equally, comparative effects of honey on oxidative stress biomarkers such as malondialdyhyde (MDA), reduced glutathione (GSH) and glutathione peroxidase (GPx) were also evaluated in the rat liver homogenates.  We estimated the effect of honey on serum levels and hepatic content of interleukin-1beta (IL-1ß) because the initial event in paracetamol-induced hepatotoxicity has been shown to be a toxic-metabolic injury that leads to hepatocyte death, activation of the innate immune response and upregulation of inflammatory cytokines. RESULTS: Paracetamol caused marked liver damage as noted by significant increased activities of serum AST and ALT as well as the level of Il-1ß. Paracetamol also resulted in a significant decrease in liver GSH content and GPx activity which paralleled an increase in Il-1ß and MDA levels. Pretreatment with honey and silymarin prior to the administration of paracetamol significantly prevented the increase in the serum levels of hepatic enzyme markers, and reduced both oxidative stress and inflammatory cytokines. Histopathological evaluation of the livers also revealed that honey reduced the incidence of paracetamol-induced liver lesions. CONCLUSION: Honey can be used as an effective hepatoprotective agent against paracetamol-induced liver damage.

Cardioprotective effects of ozone oxidative preconditioning in an in vivo model of ischemia/reperfusion injury in rats.

BACKGROUND: Several studies have demonstrated the beneficial effects of ozone oxidative preconditioning in several pathologies characterized by cellular oxidative and inflammatory burden. The present study was designed to investigate the cardioprotective effects of oxidative preconditioning in ischemia/reperfusion (I/R) injury. METHODS: Rats were randomly assigned into five groups. Groups 1 and 2 were normal and I/R groups, respectively. Two of the other groups received two different doses of ozone therapies by rectal insufflations. The last group received vehicle (oxygen). Rats were subjected to myocardial I/R (40 min/10 min). Heart rate and ventricular arrhythmias were recorded during I/R progress. At the end of reperfusion, plasma creatine kinase-MB (CK-MB) activity and total nitrate/nitrite (NO(x)) were determined. In addition, lactate, adenine nucleotides, thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH) and myeloperoxidase (MPO) activity were estimated in the heart left ventricle. Histological examination was also performed to visualize the protective cellular effects. RESULTS: Both doses of ozone therapy were equally protective in reducing CK-MB release. However, the higher dose was more effective in reducing oxidative stress, lactate accumulation, elevated MPO activity and plasma NO(x) as well as preserving myocardial adenine nucleotides. Histological examination also revealed better improvement with a higher dose of ozone therapy compared to the I/R group. CONCLUSION: Ozone therapy can afford significant cardioprotection against biochemical and histological changes associated with I/R injury.

Comparative study of the cardioprotective effects of local and remote preconditioning in ischemia/reperfusion injury.

AIMS: Though the cardioprotective effects of local or remote preconditioning have been estimated, it is still unclear which of them is more reliable and provides more cardioprotection. The present investigation was directed to compare, in one study, the cardioprotective effects of different cycles of local or remote preconditioning in ischemia/reperfusion (I/R)-induced electrophysiological, biochemical and histological changes in rats. MAIN METHODS: Rats were randomly assigned into 10 groups. Groups 1 and 2 were normal and I/R groups, respectively. Other groups were subjected to 1, 2, 3, 4 cycles of local or remote preconditioning before myocardial I/R (40 min/10 min). Heart rate and ventricular arrhythmias were recorded during I/R progress. At the end of reperfusion, plasma creatine kinase-MB (CK-MB) activity and total nitrate/nitrite (NO(x)) were determined. In addition, lactate, adenine nucleotides, thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH) and myeloperoxidase (MPO) activity were estimated in the heart left ventricle. Histological examination was also performed to visualize the protective cellular effects of the effective cycle of local or remote preconditioning. KEY FINDINGS: In general, local preconditioning was more effective than remote preconditioning in reducing ventricular arrhythmias, CK-MB release, lactate accumulation and elevated MPO activity as well as preserving adenine nucleotides. Concerning the most effective group in each therapy, 3 cycles of local preconditioning provided more cardioprotection than that of remote preconditioning in the histological examination. SIGNIFICANCE: Despite being invasive, local preconditioning provided more effective cardioprotection than remote preconditioning in ameliorating the overall electrophysiological, biochemical and histological changes.

Pharmacological preconditioning with nicorandil and pioglitazone attenuates myocardial ischemia/reperfusion injury in rats.

The present investigation was designed to study the cardioprotective effects of nicorandil and pioglitazone preconditioning in myocardial ischemia/reperfusion-induced hemodynamic, biochemical and histological changes in rats. Oral doses of nicorandil (3 or 6 mg/kg) and pioglitazone (10 or 20mg/kg) were administered once daily for 5 consecutive days. Rats were then subjected to myocardial ischemia/reperfusion (40 min/10 min). Heart rate and ventricular arrhythmias were recorded during ischemia/reperfusion progress. At the end of reperfusion, plasma creatine kinase-MB activity and total nitrate/nitrite were determined. In addition, lactate, adenine nucleotides, thiobarbituric acid reactive substances, reduced glutathione and myeloperoxidase activity were estimated in the heart left ventricle. Finally, histological examination was performed to visualize the protective cellular effects of different pretreatments. Nicorandil (3 or 6 mg/kg) was effective in attenuating the ischemia/reperfusion-induced ventricular arrhythmias, creatine kinase-MB release, lactate accumulation and oxidative stress. Nicorandil (3 mg/kg) was more effective in improving the energy production and lowering the elevated myeloperoxidase activity. Both doses of pioglitazone (10 or 20 mg/kg) were equally effective in reducing lactate accumulation and completely counteracting the oxidative stress. Pioglitazone (10 mg/kg) was more effective in improving energy production and reducing ventricular arrhythmias, plasma creatine kinase-MB release and total nitrate/nitrite. It seems that selective mitochondrial K(ATP) channel opening by lower doses of nicorandil and pioglitazone in the present study provided more cardioprotection against ventricular arrhythmias and biochemical changes induced by ischemia/reperfusion. Histological examination revealed also better improvement by the lower dose of nicorandil than that of pioglitazone.

Prophylactic effect of aqueous propolis extract against acute experimental hepatotoxicity in vivo.

Propolis has been extensively used in folk medicine for the management of a wide spectrum of disorders. In a previous study, we demonstrated the protective effect of the aqueous propolis extract (APE) against the injurious effects of carbon tetrachloride (CCl4) on hepatocytes in vitro. The present investigation was carried out to show whether the hepatoprotective effect of the extract could also be manifested in vivo. Rats were given APE orally for 14 consecutive days, before being subjected to a single intraperitoneal injection of CCl4. One day after the CCl4 injection, the animals were sacrificed, hepatocytes were isolated and liver homogenates were prepared for the assessment of liver injury. In isolated hepatocytes, APE afforded protection against CCl4-induced injury as manifested by a decrease in the leakage of the cytosolic enzyme lactate dehydrogenase (LDH), decreased generation of lipid peroxide and maintenance of cellular reduced glutathione (GSH) content. In principle, similar findings were observed in liver homogenates. The present findings show that APE has in vivo hepatoprotective potential which could be attributed at least in part to the maintenance of cellular GSH content. The latter effect seems to play an important role in conserving the integrity of biomembranes as it was associated with a decrease in lipid peroxidation and reduced leakage of cytosolic LDH.