Joanna Kwiatkowska

Effects of morin-5′-sulfonic acid sodium salt (NaMSA) on cyclophosphamide-induced changes in oxido-redox state in rat liver and kidney

Cyclophosphamide (CPX) is an anticancer drug with immunosuppressive properties. Its adverse effects are partly connected to the induction of oxidative stress. Some studies indicate that water-soluble derivative of morin—morin-5′-sulfonic acid sodium salt (NaMSA) exhibits strong antioxidant activity. The aim of present study was to evaluate the effect of NaMSA on CPX-induced changes in oxido-redox state in rat. Experiment was carried out on Wistar rats divided in three experimental groups (N = 12) receiving: 0.9% saline, CPX (15 mg/kg) or CPX (15 mg/kg) + NaMSA (100 mg/kg), respectively, and were given intragastrically for 10 days. Malondialdehyde (MDA) and glutathione (GSH) concentrations and superoxide dismutase (SOD) activity were determined in liver and kidneys. Catalase (CAT) activity was assessed only in liver. Treatment with CPX resulted in significant decrease in MDA level in both tissues, which was completely reversed by NaMSA treatment only in liver. In comparison to the control group significant decrease in SOD activity were observed in both tissues of CPX receiving group. In kidneys this parameter was fully restored by NaMSA administration. CPX evoked significant decrease in GSH concentration in kidneys, which was completely reversed by NaMSA treatment. No significant changes were seen in GSH levels and CAT activity between all groups in liver. Results of our study suggest that CPX may exert significant impact on oxido-redox state in both organs. NaMSA fully reversed the CPX-induced changes, especially MDA level in liver, SOD activity and GSH concentration in kidneys and it may be done by enhancement of activity/concentration of endogenous antioxidants.

Age-related changes in ADMA–DDAH–NO pathway in rat liver subjected to partial ischemia followed by global reperfusion

BACKGROUND Liver function is affected during ischemia/reperfusion (IR). We evaluated the effect of the aging process on selected parameters determining the NO level in rat liver subjected to IR. METHODS The animals were divided into the C-2 and the IR-2 group of young rats (2-4 months old) and the C-12 and the IR-12 group of older rats (12-14 months old). Livers belonging to the IR-2 and the IR-12 group were subjected to partial ischemia (60 min) and reperfusion (4 h). Blood samples were obtained after surgeries to estimate the activity of aminotransferases, as well as just before ischemia and during reperfusion (15, 120, and 240 min) to estimate concentration of arginine (Arg) and its derivatives: asymmetric and symmetric dimethylarginine (ADMA, SDMA). After IR, dimethylarginine dimethylaminohydrolase (DDAH) activity and protein concentration of inducible nitric oxide synthase (iNOS) were measured in liver homogenates. RESULTS In the IR-2 group ADMA level increased the most between 15 and 120 min of reperfusion and was the highest of all the groups (0.72±0.2 μmol/l). In the IR-12 group ADMA level decreased significantly and was lower compared to all the other groups at 15 min (0.42±0.2 μmol/l) and to IR-2 at 120 (0.52±0.1 μmol/l) and 240 min (0.38±0.1 μmol/l) of reperfusion. Only the IR-2 group SDMA level increased significantly between 15 (0.75±0.9 μmol/l) and 240 min (1.0±1.2 μmol/l) of reperfusion. At the beginning of the surgery the Arg level was significantly higher in young rats (C-2: 102.1±35.7 μmol/l; IR-2: 114.63±28.9 μmol/l) than in older ones (C-12: 41.88±44.7 μmol/l; IR-12: 28.64±30.6 μmol/l). In the C-2 group the Arg level (77.41±37.5 μmol/l) and Arg/ADMA (A/A) ratio (138.03±62.8 μmol/l) were significantly higher compared to the ischemic groups at 15 min and to all the other groups at 120 (Arg: 47.17±31.7 μmol/l; A/A: 88.28±66.2 μmol/l) and 240 min (Arg: 43.87±21.9 μmol/l; A/A: 118.02±106.3 μmol/l). In the IR-2 group Arg level (11.4±12.0 μmol/l) and A/A ratio (16.11±16.2 μmol/l) decreased significantly at 15 min and during the next phase of reperfusion the levels of those parameters were low, comparably to those in IR-12. As a result of IR, a decrease in DDAH activity and an increase in iNOS protein concentration were observed only in the young rats. CONCLUSIONS We found that in the non-ischemic groups the Arg level may be affected by the aging process. Under IR conditions, important changes in DDAH-ADMA-NO pathway were observed only in young livers.

Influence of ezetimibe on ADMA-DDAH-NO pathway in rat liver subjected to partial ischemia followed by global reperfusion

BACKGROUND We evaluated effect of ezetimibe on selected parameters determining NO level in rat liver subjected to ischemia reperfusion (IR). METHODS Rats received ezetimibe (5 mg/kg) (groups E0 and EIR) or saline solution (groups C0 and CIR) intragastrically for 21 days. Then, the livers of CIR and EIR underwent ischemia (60 min) and reperfusion (4 h). Blood samples were obtained before surgery to estimate activities of aminotransferases, and just before ischemia and during reperfusion to estimate asymmetric and symmetric dimethylarginine (ADMA, SDMA) and arginine (Arg) levels. After IR, dimethylarginine dimethylaminohydrolase (DDAH) activity and endothelial nitric oxide synthase (eNOS) protein concentration were measured in liver homogenates. DDAH and protein arginine methyltransferase (PRMT) mRNA were quantified by real-time PCR in liver tissue samples. RESULTS In CIR, the ADMA level was significantly higher compared to all other groups in 30 min and to E0 group in 120 min of reperfusion. In EIR, ADMA was low, compared to non-ischemic groups. At 30 and 120 min of reperfusion, in non-ischemic groups the level of Arg and Arg/ADMA ratio were significantly higher than in ischemic groups and E0 was the group with the highest levels of those parameters of all. In CIR, eNOS protein concentration was significantly lower than in ezetimibe-treated groups. Activity of DDAH was significantly higher in E0 than in non-treated groups. In ischemic groups, DDAH mRNA expression was significantly higher than in non-ischemic ones and PRMT mRNA expression was significantly higher in C0 than in all other groups. CONCLUSIONS Influence of ezetimibe on ADMA/DDAH/NO pathway demonstrated in this work may suggest protective properties of this drug on rat livers injured by IR and, to a lower extent, on livers non-subjected to IR.

The influence of bexarotene, a selective agonist of the retinoid receptor X (RXR), and tazarotene, a selective agonist of the retinoid acid receptor (RAR), on bone metabolism in rats

PURPOSE The purpose of this study was to investigate the influence of selective agonists of the retinoid receptor X (RXR) and the retinoid acid receptor (RAR) on bone metabolism in rats. METHODS Thirty six male Wistar rats were divided into three groups: receiving bexarotene, or tazarotene, or to control group. Serum biochemical markers of bone turnover (osteocalcin - OC, tartrate resistant acid phosphatase 5 - TRACP5b and osteoprotegerin - OPG) and mechanical properties of bones were analyzed. RESULTS There was a significant decrease in the femur index value in groups receiving tazarotene and bexarotene on Day 14 (8% and 20% respectively, p=0.0039). On Day 28, 14 days after discontinuation of tazarotene and bexarotene, the difference in femur indexes was still significant (4% for T1-6 and B1-6, p=0.0270). In the bexarotene group an increase in mean plasma osteocalcin level and mean plasma TRACP5b level was detected. In the tazarotene group the mean osteocalcin level remained unchanged and the mean plasma TRACP5b level decreased. An increased yield stress was detected in groups receiving retinoids comparing to controls after 14 days of tazarotene and bexarotene administration. CONCLUSION Although bexarotene and tazarotene administration caused decrease in the femur index, mechanisms responsible for that effect seem to be different. Our results suggest that bexaroten increases bone turnover. On the contrary, tazaroten seems to have inhibitory effect on bone turnover. A counter influence of selective RAR and RXR agonists on the bone turnover might be the reason for inconsistency in results from published research concerning the influence of retinoids on bone metabolism.

The Negative Impact of Selective Activation of Retinoic Acid Receptors on Bone Metabolism and Bone Mechanical Properties in Rats.

BACKGROUND Drug-induced osteoporosis is a significant health problem, as many drugs have deleterious effects on bone metabolism. Data from several studies concerning the influence of retinol on bone homeostasis are inconsistent. OBJECTIVES The purpose of this study was to investigate the influence of tazarotene, a selective agonist of the retinoic acid receptor (RAR), on bone metabolism and bone mechanical properties in rats. MATERIAL AND METHODS Sixteen male Wistar rats were assigned either to the group receiving tazarotene or to the control group. Serum biochemical markers of bone turnover (osteocalcin: OC, tartrate resistant acid phosphatase 5: TRACP5b, and osteoprotegerin: OPG) and the mechanical properties of bones were analyzed. RESULTS The mean Youngs modulus was 24% higher (p < 0.05) in the control group than in the group receiving tazarotene. The stiffness of femur bones was 25% lower (p < 0.05) in rats receiving tazarotene. Flexural yield stress was slightly (2%) decreased in the tazarotene group, but the difference was not statistically significant. In the tazarotene group significantly lower serum concentration of bone turnover markers were obeserved (TRACP5b: 0.86 ± 0.30 ng/mL vs. 2.17 ± 0.67 ng/mL, OC: 7.77 ± 2.28 ng/mL vs. 13.04 ± 3.54 ng/mL and OPG: 0.09 ± 0.04 ng/mL vs. 0.27 ± 0.10) than in the control group. CONCLUSIONS Tazarotene worsened bone mechanical properties and inhibited bone turnover in rats. These results suggest that tazarotene has a negative impact on bone metabolism and that it exerts osteoporotic activity.

Effects of long-term administration of pantoprazole on bone mineral density in young male rats

BACKGROUND Epidemiological studies suggest that long-term administration of proton pump inhibitors (PPIs) may decrease bone mineral density (BMD) and increase the risk of osteoporotic fractures. The aim of the study was to assess the influence of pantoprazole on bone metabolism in growing rats. METHODS The experiment was carried out on twenty-four young male Wistar rats divided into two groups receiving either pantoprazole at the dose of 3mg/kg or vehicle for 12 weeks. Femoral bone mineral density (BMD) and bone histomorphometry were assessed. Serum total calcium, inorganic phosphate and markers of bone turnover were measured. RESULTS In pantoprazole-treated rats a decreased BMD was detected (0.2618±0.0133g/cm(2)vs. 0.2715±0.0073g/cm(2), p<0.05). Bone histomorphometry revealed a decrease in growth plate thickness (G.Pl.RTh.) (161.0±27.8μm vs. 195.0±20.8, p<0.05) in pantoprazole-treated animals. Serum total calcium level and osteocalcin concentrations were decreased in the pantoprazole-treated group (9.62±0.55mg/dl vs. 10.15±0.38mg/dl, p<0.05 and 242.7±44.4pg/ml vs. 342.5±123.3pg/ml, p<0.05, respectively). CONCLUSION We observed that PPIs might have a negative impact on bone formation in growing rats mainly due to their inhibitory effects on the gastric proton pump, with probable deterioration of calcium absorption and decrease in growth plate thickness.

Effect of long-term administration of ranitidine, a histamine H2 receptor antagonist, on bone metabolism in young growing rats

BACKGROUND Histamine regulates function of osteoclasts and osteoblasts, however data regarding the influence of histamine H2 receptors antagonists on bone tissue are ambiguous. Factors that influence growing skeleton may have an important impact on the peak bone mass and future risk of fractures. The aim of our study was the assessment of influence of ranitidine, on growing bones. METHODS The experiment was carried out on young male Wistar rats divided into two groups receiving either ranitidine (10mg/kg ip) or vehicle. RESULTS A significant decrease in femoral BMD in ranitidine-treated rats (R) compared to vehicle-treated ones (C) was detected (0.262±0.009g/cm2vs. 0.271 ±0.007g/cm2, p<0.05). In group R we observed elevated serum C-terminated telopeptide of type I collagen (CTX) level with concomitantly lowered serum osteocalcin (OC) concentration comparing to control group (151.2±27.2pg/ml vs. 101.5±55.6, p<0.05 and 229.1±50.0pg/ml vs. 292.0±52.9, p<0.05, respectively). Serum concentration of inorganic phosphorus was lower in group R than in group C (134±13mmol/L vs. 157±28mmol/L, p<0.05). CONCLUSIONS Long-term administration of ranitidine increases bone resorption and decreases bone formation in growing rats leading to decrease in BMD.BACKGROUND Histamine regulates function of osteoclasts and osteoblasts, however data regarding the influence of histamine H2 receptors antagonists on bone tissue are ambiguous. Factors that influence growing skeleton may have an important impact on the peak bone mass and future risk of fractures. The aim of our study was the assessment of influence of ranitidine, on growing bones. METHODS The experiment was carried out on young male Wistar rats divided into two groups receiving either ranitidine (10 mg/kg ip) or vehicle. RESULTS A significant decrease in femoral BMD in ranitidine-treated rats (R) compared to vehicle-treated ones (C) was detected (0.262 ± 0.009 g/cm2vs. 0.271 ±0.007 g/cm2, p < 0.05). In group R we observed elevated serum C-terminated telopeptide of type I collagen (CTX) level with concomitantly lowered serum osteocalcin (OC) concentration comparing to control group (151.2 ± 27.2 pg/ml vs. 101.5 ± 55.6, p < 0.05 and 229.1 ± 50.0 pg/ml vs. 292.0 ± 52.9, p < 0.05, respectively). Serum concentration of inorganic phosphorus was lower in group R than in group C (134 ± 13 mmol/L vs. 157 ± 28 mmol/L, p < 0.05). CONCLUSIONS Long-term administration of ranitidine increases bone resorption and decreases bone formation in growing rats leading to decrease in BMD.

Carvedilol Inhibits Matrix Metalloproteinase-2 Activation in Experimental Autoimmune Myocarditis: Possibilities of Cardioprotective Application

Aims: Acute myocarditis is a potentially lethal inflammatory heart disease that frequently precedes the development of dilated cardiomyopathy and subsequent heart failure. At present, there is no effective standardized therapy for acute myocarditis, besides the optimal care of heart failure and arrhythmias in accordance with evidence-based guidelines and specific etiology-driven therapy for infectious myocarditis. Carvedilol has been shown to be cardioprotective by reducing cardiac pro-inflammatory cytokines present in oxidative stress in certain heart diseases. However, effects of carvedilol administration in acute myocarditis with its impact on matrix metalloproteinases’ (MMPs) activation have not been elucidated. Methods and Results: Carvedilol in 3 doses (2, 10, and 30 mg/kg) was given daily to 3 study groups of rats (n = 8) with experimental autoimmune myocarditis by gastric gavage for 3 weeks. In comparison to untreated rats (n = 8) with induced myocarditis, carvedilol significantly prevented the left ventricle enlargement and/or systolic dysfunction depending on the dose in study groups. Performed zymography showed enhanced MMP-2 activity in untreated rats, while carvedilol administration reduced alterations. This was accompanied by prevention of troponin I release and myofilaments degradation in cardiac muscle tissue. Additionally, severe inflammatory cell infiltration was detected in the nontreated group. Carvedilol in all doses tested, had no impact on severity of inflammation. The severity of inflammation did not differ between study groups and in relation to the untreated group. Conclusions: The protective effects of carvedilol on heart function observed in the acute phase of experimental autoimmune myocarditis seem to be associated with its ability to decrease MMP-2 activity and subsequently prevent degradation of myofilaments and release of troponin I while not related to suppression of inflammation.