The induction of oxidative stress precedes liver injury during experimental obstructive jaundice (OJ). In this sense, different evidences suggest that melatonin (MEL), as antioxidant, may be useful in the protection against apoptosis and necrosis during experimental cholestasis. In addition, we will also assess if MEL-dependent protection is related to a recovery of antioxidant status disturbances induced by OJ. Cholestasis was achieved by double ligature and sectioning of the principal bile duct. MEL was injected intraperitoneally (500 microg/kg/day). Lipid peroxidation was evaluated by the measurement of malondialdehyde (MDA) content in liver. Different parameters related to antioxidant status, such as reduced glutathione (GSH), glutathione peroxidase (GPx), catalase and superoxide dismutase (SOD) were determined in liver. Liver injury was assessed by alanine amino-transferase (ALT) in serum, histological examination, DNA fragmentation and TUNEL assay. The activation of perisinusoidal stellate cells was evaluated by immunohistochemical measurement of alpha-smooth muscle actin in liver sections. The induction of OJ increased all the parameters related to apoptosis and necrosis in liver. The induction of liver injury was associated with stellate cell activation, as well as an increase in MDA (p < 0.0001) and a reduction in GSH, GPx, catalase and SOD content (p < 0.0001) in liver. MEL reduced hepatic apoptosis and necrosis (p < 0.004) with a significant improvement in all oxidative stress markers. In conclusion, our results showed that MEL recovered the antioxidant status and reduced apoptosis and necrosis induced by experimental cholestasis.

No abstract

This study was designed to evaluate the effect of melatonin on cholestatic oxidative stress under constant light exposure. Cholestasis was induced by double ligature and section of the extra-hepatic bile duct. Melatonin was injected i.p.(1000 microg kg(-1) day(-1)). Malondialdehyde, reduced glutathione, catalase, superoxide dismutase, glutathione reductase, peroxidase and transferase were determined in liver. After bile-duct obstruction and under constant light exposure, an increase in malondialdehyde (p < 0.05) and a slight decrease in reduced glutathione were seen. Enzyme activity, with the exception of glutathione reductase, had significantly diminished. After melatonin administration, malondialdehyde fell (p < 0.001), whereas there was an increase in reduced glutathione (p < 0.0001) compared with untreated controls. Constant light exposure was associated with an increase in hepatic oxidative stress. Treatment with melatonin decreased lipid peroxide synthesis, and permitted a recovery of both reduced glutathione and scavenger enzyme activity.

Postoperative renal dysfunction in obstructive jaundice (OJ) patients has been associated with hypovolemia and depletion of the extracellular water compartment (ECW). The aim of the study was to evaluate the preoperative status of body compartments in OJ patients measured by two methods. In a prospective study 39 OJ patients (11 benign and 28 malignant obstructions) were investigated, with 15 healthy subjects used as a control group (CG). Bioelectrical impedance analysis (BIA) determinations and values derived from anthropometric measurements were used to assess body compartment status. The coefficient of variation of BIA was below 4% in both OJ and CG subjects. No differences were found in intracellular water. However total body water (TBW) and ECW were reduced in OJ patients (50.5 +/- 4.6 vs. 56 +/- 8% body weight, p = 0.05; and 21 +/- 4.5 vs. 23.8 +/- 2.5% body weight, p < 0.05, respectively). There were no differences between benign and malignant obstructions. Seventy four percent of OJ patients had an ECW volume below the mean +/- 2 SD in the CG subjects. Anthropometric and BIA determinations correlated closely for TBW measurements in both CG (r = 0.92, p < 0.001) and OJ patients (r = 0.91, p < 0.001). Bland-Altman analysis also showed that for TBW the BIA was in agreement with anthropometry. In the present study, BIA offered a good correlation with anthropometric determinations and was a reliable method for body fluid disturbances assessment in jaundiced patients.

Renal dysfunction in patients with obstructive jaundice was associated with the degree of biliary obstruction, age of the patient and reduced urinary sodium excretion. These alterations were closely related to derangements in sodium- and water-regulating hormones.