F. Berté

Exogenous melatonin enhances bile flow and ATP levels after cold storage and reperfusion in rat liver: Implications for liver transplantation

Abstract:   Although the use of melatonin in the transplantation field has been suggested, it has not been previously tested in a liver cold‐storage model. We used a rat liver model to study (a) the dose‐dependent effect of melatonin on bile production, and (b) the potential of melatonin to improve liver function after cold‐storage. Male Wistar rats were perfused with Krebs–Henseleit bicarbonate buffer (KHB) at 37°C without or with 25, 50, 100 and 200 μm melatonin. Each dose of melatonin stimulated bile production. For cold‐storage studies, livers were flushed with either University of Wisconsin (UW) or Celsior solution and stored for 20 hr at 4°C. Reperfusion (120 min) was performed with KHB at 37°C. In subsequent studies, 100 μm melatonin were added to the perfusate during the reperfusion period. ATP and melatonin levels in the tissue were measured. Bile analysis was performed by measuring melatonin, bilirubin and gamma‐glutamyl transpeptidase (γ‐GT) levels in the fluid. A dose‐dependent increase in bile secretion, associated with an enhanced melatonin and bilirubin levels in the bile were observed. Also, tissue levels of melatonin increased in a dose‐dependent manner. When melatonin was added during the reperfusion period, bile production and bile bilirubin levels increased both with UW and Celsior solutions. The analysis of γ‐GT in the bile showed an increase in the Celsior‐preserved liver and the addition of melatonin to the perfusate reduced this effect. Tissue ATP levels were higher when melatonin was added to the perfusion medium. Higher levels of melatonin in bile than in tissue were found. In conclusion, we demonstrate that melatonin improves significantly the restoration of liver function after cold‐storage and reperfusion.

On the role of mitochondria in cell injury caused by vanadate-induced Ca2+ overload

Incubation of isolated rat hepatocytes with vanadate (0.25, 0.5 and 1 mM) resulted in progressive accumulation of Ca2+ in the intracellular compartments. Vanadate- induced Ca2+ accumulation was related to inhibition of the plasma membrane Ca2+-extruding system, but did not involve either enhanced plasma membrane permeability to Ca2+ or the enhanced operation of a putative Na+/Ca2+ exchanger. After an initial rise in the cytosolic free Ca2+ concentration, as revealed by phosphorylase activation, Ca2+ was sequestered predominantly by the mitochondria with little contribution from the endoplasmic reticulum. As the amount of Ca2+ in the mitochondria increased, a progressive decrease in mitochondrial membrane potential occurred, together with an impairment of the ability of these organelles to further sequester Ca2+. Associated with this, there was a decrease in intracellular ATP level, formation of surface blebs and cytotoxicity. Addition of an uncoupler to vanadate-treated hepatocytes dramatically accelerated the appearance of plasma membrane blebs and toxicity. Our results demonstrate that under conditions in which the plasma membrane Ca2+ pump is inhibited, mitochondria play an important role in protecting hepatocytes against damage induced by Ca2+ overload.

Haloperidol-induced changes in glutathione and energy metabolism: effect of nicergoline.

The aim of this study was to evaluate the possible effects of nicergoline, a semisynthetic ergot derivative, on the biochemical changes observed during chronic treatment with haloperidol in male Sprague-Dawley rats. Chronic treatment with haloperidol induced a significant decrease in the cellular glutathione (GSH) content in selected areas of the brain (cerebellum, striatum and cortex) and in the liver. Prolonged nicergoline administration was able to antagonize the haloperidol-induced GSH decrease, maintaining the GSH concentration at levels comparable to those observed in the control group. Analysis of the energy charge revealed changes similar to those observed for GSH: haloperidol induced a significant decrease in ATP and energy charge that was completely reversed by repeated nicergoline administration. In conclusion, chronic treatment with the classical antipsychotic haloperidol induces profound biochemical changes in the brain and in the liver. Nicergoline treatment is able to counteract the haloperidol-induced decrease in GSH levels and energy charge, suggesting a potential role of the drug in the treatment of neuroleptic-induced side effects.

1,2-Dichloropropane (DCP) toxicity is correlated with DCP-induced glutathione (GSH) depletion and is modulated by factors affecting intracellular GSH.

Acute 1,2-dichloropropane (DCP) poisoning in humans is relatively frequent in Italy, where DCP is widely diffused as a constituent of commercial solvents and dry cleaners. In this study we have investigated the effects of DCP on intracellular glutathione (GSH) content in main target tissues of male Wistar rats, i.e. liver, kidney and blood, in order to establish if a correlation between DCP-induced GSH depletion and tissue damage exists. Administration of DCP (2 ml/kg body weight orally) caused a dramatic loss of tissue GSH occurring 24 h after DCP intoxication, followed by a slow restoration approaching physiological levels after 96 h. GSH depletion was associated with a marked increase in serum GOT, GPT, 5′-nucleotidase, gamma-glutamyl transpeptidase, alkaline phosphatase, urea and creatinine, and a significant degree of hemolysis. When animals were pretreated with a GSH depleting agent, buthionine-sulfoximine (BSO) (0.5 g/kg body weight) i. p. 4 h before DCP intoxation, an increase of overall mortality was found, significantly different from the group of animals treated with DCP alone. On the contrary, the administration of a GSH precursor, N-acetylcysteine (NAC) i. p. (250 mg/kg body weight) 2 and 16 h after DCCP intoxication prevented the dramatic loss of cellular GSH and reduced the extent of injury in target tissues, as demonstrated by laboratory indices. Furthermore, statistical analysis of the data revealed a correlation between: (1) depletion of liver GSH and increase in serum GOT, GPT, 5′-nucleotidase, (2) depletion of kidney GSH and increase in serum urea and creatinine and (3) depletion of blood GSH and the occurence of hemolysis. Our findings demonstrate that GSH plays a critical role in modulating the toxicity of DCP. They also highlight the protective role of NAC and suggest that this glutathione precursor could rationally be employed in DCP poisoning in humans.

Effects of thallium on primary cultures of testicular cells

The objective of this in vitro study was to examine the response of mixed cultures of Sertoli and germ cells to treatment with thallium (Tl) at the range of concentrations that, in previous studies, was shown in vivo to affect reproduction. Cultures were prepared from the testis of Sprague-Dawley rats. Cultures containing approximately 3.75 x 10(6) cells/ml were treated with Tl concentrations corresponding to 35, 7, and 1.4 micrograms Tl/g testis, estimated from protein content of cultures. Observations at 24, 48, and 72 h after treatment showed a significant release of germ cells into the culture medium that was both concentration and time dependent. Cultures treated with 35 micrograms Tl/g testis showed a threefold increase in germ-cell detachment compared with controls after only 24 h of exposure. As the treatment time increased to 48 h of exposure, even cultures exposed at the lowest Tl concentration (1.4 micrograms Tl/g testis) showed significant loss of germ cells. After 48 h, cultures exposed to 7 micrograms Tl/g testis exhibited a 2.5-fold increase in germ-cell detachment, and those exposed to 35 micrograms Tl/g testis exhibited a 10-fold increase over controls. Morphological investigations of cell cultures showed evident loss of germ cells with significant reduction in prepachytene and pachytene spermatocytes and changes in the shape of Sertoli cells. These results are in agreement with in vivo studies, in which thallium treatment at comparable exposure levels manifested its earliest toxic testicular effects in Sertoli and germ cells. They also demonstrate the usefulness of this in vitro culture technique to assess toxic testicular damage rapidly.

Bone remodelling in osteoarthrosic subjects undergoing a physical exercise program.

BACKGROUND The connection between osteoarthritis (OA) and osteoporosis (OP) has attracted considerable attention but reports about bone mass density (BMD) in OA are often contradictory. Some data indicate that BMD is higher in OA patients than in healthy subjects, whereas other studies showed no differences. It has been observed that mud pack treatment (MPT) induces a decrease in cytokines with bone-resorbing effects. The aim of this study is to evaluate the response of bone and connective tissue to physical exercise and thermal treatment. METHODS Forty osteoarthrosic patients were divided in group A (physical exercise and MPT), and group B (physical exercise alone). Blood and urine samples were collected before and after the treatments to assay blood metabolic markers and urinary hydroxyproline. RESULTS In group A, some parameters show statistically significant differences before and after mud pack treatment (MPT). In group B, all parameters present no statistical significant changes before and after the physical exercise program. CONCLUSIONS Few studies established the importance of exercise to maintain normal cartilage and bone metabolism. In group A of the present study, an influence on all the parameters of bone metabolism is evident. It is possible that physical exercise only if combined with MPT stimulates physiologic bone metabolism and favors skeletal health.

Antioxidant properties of MDL and MMDL, two nicergoline metabolites, during chronic administration of haloperidol

We evaluated the effects of 10-alpha-methoxy-9,10-dihydrolysergol (MDL) and 1-methyl-10-alpha-methoxy-9,10-dihydrolysergol (MMDL), two nicergoline metabolites, during chronic treatment with haloperidol in rats. Haloperidol induced a significant decrease in the glutathione (GSH) content in selected areas of the brain and in the liver. Prolonged administration of MDL, MMDL or nicergoline antagonized the haloperidol-induced GSH decrease. Lipid peroxidation in the cortex and striatum was suppressed by MDL, MMDL or nicergoline administration. Our results show that MDL, MMDL and nicergoline have antioxidant activity, preventing not only GSH depletion but also lipid peroxidation. These observations suggest beneficial properties of MDL and MMDL in the treatment of neuroleptic-induced side effects.

Beta-alanine protection against hypoxic liver injury in the rat

Liver hypoxia still represents an important cause of liver injury during shock and liver transplantation. We have investigated the protective effects of beta-alanine against hypoxic injury using isolated perfused rat livers and isolated rat hepatocyte suspensions. Perfusion with hypoxic Krebs-Henseleit buffer increased liver weight and caused a progressive release of lactate dehydrogenase (LDH) in the effluent perfusate. The addition of 5 mmol/l beta-alanine to the perfusion buffer completely prevented both weight increase and LDH leakage. These findings were confirmed by histological examinations showing that beta-alanine blocked the staining by trypan blue of either liver parenchymal and sinusoidal cells. Studies performed in isolated hepatocytes revealed that beta-alanine exerted its protective effects by interfering with Na+ accumulation induced by hypoxia. The addition of gamma-amino-butyric acid, which interfered with beta-alanine uptake by the hepatocytes or of Na+/H+ ionophore monensin, reverted beta-alanine protection in either hepatocyte suspensions or isolated perfused livers. We also observed that liver receiving beta-alanine were also protected against LDH leakage and weight increase caused by the perfusion with an hyposmotic (205 mosm) hypoxic buffer obtained by decreasing NaCl content from 118 to 60 mmol/l. This latter effect was not reverted by blocking K+ efflux from hepatocyte with BaCl(2) (1mmol/l). Altogether these results indicated that beta-alanine protected against hypoxic liver injury by preventing Na+ overload and by increasing liver resistance to osmotic stress consequent to the impairment of ion homeostasis during hypoxia.

Effects of Phenobarbitone on the Distribution, Metabolism and Biliary Excretion of Erythromycin in Rats

The administration of phenobarbitone to the rat (8 mg/100 g BW) once daily for 3 days significantly decreased the serum and tissue levels of erythromycin administered intraperitoneally (5 mg/100 g BW). Furthermore, phenobarbitone stimulated the hepatic microsomal N-demethylation of erythromycin and increased the biliary concentration and the biliary excretion rate of the unmetabolized antibiotic. These effects were accompanied by augmented liver mass and bile flow. The possibility is discussed that erythromycin concentrates in the bile through a specialized hepatic drug transport system, activated by phenobarbitone.

Tissue Distribution of Cephalexin in Pregnant Rabbit and Fetus after Oral and Intramuscular Administration

The tissue distribution of cephalexin, a cephalosporin C derivative, was studied in New Zealand rabbits at 25 days of pregnancy, following oral or i.m. administration. Evidence was obtained that this antibiotic is well absorbed when given orally The placental transfer of cephalexin occurred in both oral and parenteral treatments, however, the drug levels detected in fetal tissues were lower than in the pregnant. Marked differences were observed in the maternal and fetal tissue distribution of the cephalexin between orally- and parenterally-treated rabbits.