Addition of human recombinant tumor necrosis factor-α (hrTNF) to confluent 3T3-L1 preadipocytes in the presence of differentiation inducers depressed both cellular differentiation into adipocytes and gene expression of hormone-sensitive lipase (HSL) without diminishing cellular viability. When hrTNF was added to 3T3-L1 cells that had differentiated into adipocytes, the cellular level of HSL mRNA was dose dependently reduced over the period of 3-12h with a concomitant reduction in HSL activity. The reducing effect of hrTNF on the HSL mRNA level was reversible. Cycloheximide (0.1mg/ml) suppressed the reducing effect of hrTNF, indicating that de novo protein synthesis is required for the hrTNF action. Actinomycin D (1μg/ml) gradually reduced the HSL mRNA level in the adipocytes over 12h without affecting the ratio of HSL mRNA to β-actin mRNA. The HSL mRNA level in primary cultures of Leydig cells was not affected by 1nM hrTNF. In addition, interleukin-1β(100nM) did not inhibit HSL gene expression when it was added to 3T3-L1 cells, regardless of their differentiation stage.
Oral administration of methacrylonitrile to male Wistar rats at a dose of 40mg/kg body weight/day (LD50, 200mg/kg body weight/day) for 2 weeks caused an increase in blood glucose levels with a depletion of liver glycogen. An increased rate of glycolysis and enhanced glycogenolysis and gluconeogenesis, along with the activation of the hexose monophosphate pathway shunt, were observed, indicating a significant disturbance in the carbohydrate metabolism.
systemic endotoxemia and its relation to the fibrotic process were studied in two forms of hepatic disorders in experimental animals. The first was bilharzial liver disease, and the second was CCl4-induced cirrhosis. Endotoxin results were correlated with total hepatic collagen and tissue fibronectin, which are two indices of the fibrotic process. In schistosome-infested hamsters, early significant progressive elevation of plasma endotoxin was detected 6 weeks post-infestation and was correlated with significantly elevated total hepatic collagen and tissue fibronectin. In rats with CCl4-induced cirrhosis, significant rise in plasma endotoxin, total hepatic collagen, and tissue fibronectin was observed at the 10th week after injections. We noticed that removal of intestinal endotoxins by neomycin administration, induction of endotoxin tolerance, or enhancement of macrophage functions by interferon (IFN) injections resulted in significant lower levels of systemic endotoxemia and fibrogenesis in both rats and hamsters.
Blood glucose levels of rats with alloxan-induced diabetes dropped from hyperglycemic levels to hypoglycemic ones after treatment with bis-salicylidine ethylenediiminato oxovanadium (IV) complex for a period of 30 days. However, the diabetic condition reappeared after withdrawal of the vanadyl complex. Assay of carbohydrate-metabolizing enzymes clearly indicated that the vanadyl complex activates the glycolysis, glycogenesis and depresses the glycogenolysis and gluconeogenesis in diabetic rats, suggesting its insulin-like nature. The optimum dose of bissalicylidine ethylenediiminato oxovanadium (IV) complex to produce the normoglycemic level in the diabetic rats was 7.5mg of vanadium/kg body wt/day.
We studied the effects of an enterally administered diet containing medium-chain triglycerides (MCT) on protein metabolism in septic Wistar rats and compared them with those of a long-chain triglycerides (LCT). The sepsis was induced by cecal ligation and puncture. The rats were divided into two groups. One group was fed a diet containing a MCT and LCT mixture (MCT/LCT), and the other was fed one containing LCT, as 10% of total energy. The diets also contained protein, dextrin, vitamins, and electrolytes. The experimental diets were via an intraduodenal catheter for 6 days. The MCT/LCT group showed a higher nitrogen balance after 3 days of the feeding and a higher liver protein content compared with the LCT group on the last day. Furthermore, the concentrations of serum total protein and albumin in the MCT/LCT group were higher than those in the LCT group. These results indicate that the enteral diet containing MCT combined with LCT may be advantageous to protein metabolism in septic rats over the diet with LCT alone.
Alteration of liver function is an inevitable phenomenon in hepatic fibrosis. Since many enzymes are useful in diagnosing liver diseases, the alteration of the lactate dehydrogenase (LDH) isoenzyme pattern was studied in experimentally induced liver fibrosis. The liver injury was induced by intraperitoneal injections of dimethylnitrosamine (DMN) into adult male albino rats belonging to the Wistar strain. The injections were given on the first 3 consecutive days of each week over a period of 3 weeks. The degree of hepatic fibrosis was assessed by histopathological examination as well as by monitoring the collagen content of the liver tissue. The LDH isoenzymes in serum and liver were separated by polyacrylamide gel electrophoresis. The percentage distribution of the isoenzymes was determined, and the M/H ratio was calculated. The total LDH activity was also studied in the liver and serum samples. The results demonstrated many pathological changes including centrilobular necrosis and fibrosis after DMN treatment. The collagen content was increased to about 4 times normal by the 21st day of DMN administration. The total LDH activity was significantly increased in the serum on the 14th and 21st days. But in the liver tissue, a significant increase was noticed only on the 7th day. The LDH isoenzyme patterns indicated a sharp increase in the activities of LDH4 and LDH5 in the serum on the 14th and 21st days of DMN treatment. A remarkable increase was noticed in the M/H ratio on the 14th and 21st days in the serum and on all the days in the liver tissue. Increased serum LDH activity suggests deterioration of liver functions during hepatic fibrosis. The present study demonstrated that serum LDH isoenzyme assay is a useful tool in the diagnosis of hepatic fibrosis along with other biochemical tests.
To investigate the effect of primary biotin deficiency on growth and the skin, germ-free and conventional mice were given a purified biotin-deficient diet without egg white for 57 days. The body weight was significantly reduced in germ-free mice fed the biotin-deficient diet, whereas no reduction was seen in the conventional mice. Biotin levels decreased significantly in tissues of conventional and germ-free mice fed a biotin-deficient diet except in the heart of the conventional mice. Pyruvate carboxylase activity also decreased significantly in the liver, kidneys, and skin of conventional and germ-free mice fed a biotin-deficient diet, and the activity in the tissues of germ-free mice was lower than that in the conventional mice. Most germ-free mice fed the biotin-deficient diet exhibited severe alopecia, whereas conventional mice on the same diet did not. The histological changes in the alopecic skin were degeneration of the medulla of hair and the cortex of hair in germ-free mice fed the deficient diet. These degenerative changes in the skin of germ-free mice fed the biotin-deficient diet induced downgrowth of the hair root.