Mohamed M. Sayed-Ahmed

Progression of Cisplatin-Induced Nephrotoxicity in a Carnitine-Depleted Rat Model

Background: This study has been initiated to investigate whether endogenous carnitine depletion and/or carnitine deficiency is an additional risk factor and/or a mechanism in cisplatin-induced nephrotoxicity and to gain insights into the possibility of a mechanism-based protection by L-carnitine against this toxicity. Methods: 60 male Sprague-Dawley rats were divided into six groups of 10 animals each and received one of the following treatments: The first three groups were injected intraperitoneally with normal saline, L-carnitine (500 mg/kg), and D-carnitine (750 mg/kg), respectively, for 10 successive days. The 4th, 5th, and 6th groups were injected intraperitoneally with the same doses of normal saline, L-carnitine and D-carnitine, respectively, for 5 successive days before and after a single dose of cisplatin (7 mg/kg). Six days after cisplatin treatment, the animals were sacrificed, and serum as well as kidneys were isolated and analyzed. Results: A single dose of cisplatin resulted in a significant increase in blood urea nitrogen (BUN), serum creatinine, malondialdehyde (MDA) and nitric oxide (NO) and a significant decrease in total carnitine, reduced glutathione (GSH) and adenosine triphosphate (ATP) content in kidney tissues. Interestingly, L-carnitine supplementation attenuated cisplatin-induced nephrotoxicity manifested by normalizing the increase of serum creatinine, BUN, MDA and NO and the decrease in total carnitine, GSH and ATP content in kidney tissues. In the carnitine-depleted rat model, cisplatin induced a progressive increase in serum creatinine and BUN as well as a progressive reduction in total carnitine and ATP content in kidney tissue. Histopathological examination of kidney tissues confirmed the biochemical data, i.e. L-carnitine supplementation protected against cisplatin-induced kidney damage, whereas D-carnitine aggravated cisplatin-induced renal injury. Conclusion: Data from this study suggest that: (1) oxidative stress plays an important role in cisplatin-induced kidney damage; (2) carnitine deficiency should be viewed as an additional risk factor and/or a mechanism in cisplatin-induced renal dysfunction, and (3) L-carnitine supplementation attenuates cisplatin-induced renal dysfunction.

Protective role of carnitine esters against alcohol-induced gastric lesions in rats.

We have investigated in the current study the possible protective effects of two carnitine esters known to have powerful anti-oxidant potential namely, propionyl L-carnitine (PLC) and acetyl L-carnitine (AC) against alcohol-induced gastric lesions in rats. Both drugs were administered as a single oral dose of 200 mg kg(-1) body weight 1h before alcohol intake. Both carnitine esters could protect the gastric mucosa against the injurious effect of absolute alcohol and promote ulcer healing as evidenced from the ulcer index (UI) values. Propionyl L-carnitine prevented alcohol-induced increase in thiobarbituric acid-reactive substances (TBARS), an index of lipid peroxidation. The propionyl carnitine ester also increased the gastric content of reduced glutathione (GSH), besides it increased the enzymatic activities of gastric superoxide dismutase (SOD) and glutathione-S-transferase (GST). Likewise, AC did protect against the ulcerating effect of alcohol and mitigate most of the biochemical adverse effects induced by alcohol in gastric mucosa, but to a lesser extent than PLC. Neither PLC nor AC did affect catalase activity in gastric tissue. Based on these observations, one could conclude that carnitine esters, particularly PLC could partly protect gastric mucosa from alcohol-induced acute mucosal injury, and these gastroprotective effects might be probably induced, at least partly, through anti-oxidant mechanisms.

New aspects in probucol cardioprotection against doxorubicin-induced cardiotoxicity

PurposeDoxorubicin (DOX) is a broad-spectrum anticancer drug with dose-dependent cardiotoxicity. Probucol has been reported to completely prevent DOX-induced cardiomyopathy. The aim of the present study was to determine the possible effect of probucol pretreatment on the pharmacokinetics of DOX and its role in cardioprotection as well as the possible contribution of the lipid-lowering effect of probucol on the disposition of DOX in cardiac tissue.MethodsTwo groups of male albino rats were given either probucol (10xa0mg/kg, i.p.) or corn oil daily for 12xa0days followed by a single dose of DOX (15xa0mg/kg, i.p.). The concentration-time profile of DOX in plasma and its concentration in different tissues, and plasma and myocardial lipids were determined.ResultsA rapid and significant increase in plasma DOX clearance was observed in rats pretreated with probucol. Probucol induced a significant increase in DOX concentration in both liver and kidney tissues and a significant decrease in DOX concentration in the spleen. However, heart and lung DOX concentrations were not affected. Also, probucol pretreatment resulted in a significant reduction in cardiotoxicity indices including peak serum creatine kinase (CK) concentration and the area under the CK concentration-time curve. Moreover, probucol pretreatment not only counteracted significantly the decrease in the ATP/ADP ratio induced by DOX, but also induced a significant increase as compared with the control group. In addition, probucol significantly reduced plasma total cholesterol and low-density lipoprotein, but it did not induce any significant changes in myocardial lipids.ConclusionsThe present study demonstrated, for the first time, that probucol pretreatment alters the pharmacokinetics of DOX. Besides its antioxidant properties, the cardioprotective effect of probucol may be related to its enhancing action on the ATP/ADP ratio.

Carnitine deficiency aggravates cyclophosphamide-induced cardiotoxicity in rats.

Background: This study examined, for the first time, the involvement of carnitine deficiency in cardiotoxicity, particularly cyclophosphamide (CP)-induced cardiomyopathy, as well as effects of carnitine supplementation with propionyl-L-carnitine (PLC) on cardiotoxicity. Methods: An animal model of carnitine deficiency was developed in rats treated with D-carnitine (DC)-mildronate (MD). Adult male Wistar albino rats were assigned to one of six treatment groups: the first three groups were injected intraperitoneally with normal saline, PLC (250 mg/kg/day), and DC (250 mg/kg/day) combined with MD (200 mg/kg/day), respectively, for 10 successive days. In groups 4–6, the same doses of normal saline, PLC and DC-MD were injected, respectively, during the 5 successive days before and after a single dose of CP (200 mg/kg). On day 6 after CP treatment, 24-hour urine was collected, then animals were sacrificed, and serum as well as hearts were isolated. Results: CP caused a significant increase in serum creatine phosphokinase isoenzyme (CK-MB), lactate dehydrogenase (LDH), urinary carnitine excretion and clearance and intramitochondrial acetyl-CoA/CoA-SH, and a significant decrease in serum free carnitine, total carnitine and adenosine triphosphate (ATP) contents in cardiac tissue. In the carnitine-depleted rats, CP induced dramatic increases in CK-MB and LDH levels, carnitine clearance and intramitochondrial acetyl-CoA/CoA-SH, as well as progressive reduction in total carnitine and ATP in cardiac tissues. Interestingly, PLC supplementation completely reversed the biochemical and histopathological changes induced by CP to the control values. Conclusion: (1) Carnitine deficiency is a risk factor which is involved in CP-related cardiomyopathy; (2) serum and urinary carnitine levels should be monitored and viewed as indices of CP-induced multiple organ toxicity, and (3) carnitine supplementation, using PLC, prevents the development of CP-induced cardiotoxicity.

Methylation of SFRPs and APC genes in ovarian cancer infected with high risk human papillomavirus.

BACKGROUNDnSecreted frizzled-related protein (SFRP) genes, new tumor suppressor genes, are negative regulators of the Wnt pathway whose alteration is associated with various tumors. In ovarian cancer, SFRPs genes promoter methylation can lead to gene inactivation. This study investigated mechanisms of SFRP and adenomatous polyposis coli (APC) genes silencing in ovarian cancer infected with high risk human papillomavirus.nnnMATERIALS AND METHODSnDNA was extracted from 200 formalin-fixed paraffin-embedded ovarian cancer and their normal adjacent tissues (NAT) and DNA methylation was detected by methylation specific PCR (MSP). High risk human papillomavirus (HPV) was detected by nested PCR with consensus primers to amplify a broad spectrum of HPV genotypes.nnnRESULTSnThe percentages of SFRP and APC genes with methylation were significantly higher in ovarian cancer tissues infected with high risk HPV compared to NAT. The methylated studied genes were associated with suppression in their gene expression.nnnCONCLUSIONnThis finding highlights the possible role of the high risk HPV virus in ovarian carcinogenesis or in facilitating cancer progression by suppression of SFRP and APC genes via DNA methylation.

Inhibition of Gene Expression of Organic Cation/Carnitine Transporter and Antioxidant Enzymes in Oxazaphosphorines-Induced Acute Cardiomyopathic Rat Models

It is well documented that high therapeutic doses of oxazaphosphorines, cyclophosphamide (CP) and ifosfamide (IFO), are associated with cardiomyopathy. This study investigated whether oxazaphosphorines alter the expression of organic cation/carnitine transporter (OCTN2) and antioxidant genes and if so, whether these alterations contribute to CP and IFO-induced cardiotoxicity. Adult male Wistar albino rats were assigned to one of six treatment groups namely, control, L carnitine, CP, IFO, CP plus L carnitine and IFO plus L carnitine. In cardiac and kidney tissues, CP and IFO significantly decreased mRNA and protein expression of OCTN2. Oxazaphosphorines significantly increased serum acyl-carnitine/free carnitine ratio and urinary carnitine excretion and significantly decreased total carnitine in cardiac tissues. Interestingly, carnitine supplementation completely reversed the biochemical and gene expression changes-induced by oxazaphosphorines to the control values, except OCTN2 expression remained inhibited by IFO. Data from this study suggest that: (1) Oxazaphosphorines decreased myocardial carnitine content following the inhibition of OCTN2 mRNA and protein expression in cardiac tissues. (2) Oxazaphosphorine therapy increased urinary loss of carnitine secondary to the inhibition of OCTN2 mRNA and protein expression in proximal tubules of the kidney. (3) Carnitine supplementation attenuates CP but not IFO-induced inhibition of OCTN2 mRNA and protein expression in heart and kidney tissues.