Content In Liver Of Rats Research Articles

Dietary Protein Restriction Decreases Oxidative Protein Damage, Peroxidizability Index, and Mitochondrial Complex I Content in Rat Liver

Caloric restriction (CR) decreases oxidative damage, which contributes to the slowing of aging rate. It is not known if such decreases are due to calories themselves or specific dietary components. In this work, the ingestion of proteins of Wistar rats was decreased by 40% below that of controls. After 7 weeks, the liver of the protein-restricted (PR) animals showed decreases in oxidative protein damage, degree of membrane unsaturation, and mitochondrial complex I content. The results and previous information suggest that the decrease in the rate of aging induced by PR can be due in part to decreases in mitochondrial reactive oxygen species production and DNA and protein oxidative modification, increases in fatty acid components more resistant to oxidative damage, and decreased expression of complex I, analogously to what occurs during CR. Recent studies suggest that those benefits of PR could be caused, in turn, by the lowered methionine intake of that dietary manipulation.

Comparative study of CYP2B induction in the liver of rats and mice by different compounds

Male Wistar rats and C57BL mice were treated by phenobarbital (PB), 2,4,6-triphenyldioxane-1,3 (TPD) and 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP). The CYP2B specific activities (PROD and BROD) were determined in the animal livers. PB administration significantly increased levels of PROD- and BROD-activity in the rat and mouse livers, whereas TPD induced CYP2B activities only in rat liver and TCPOBOP — only in mouse liver. The result of Western-blot analysis showed that PB and TPD increased CYP2B protein content in rat liver, PB and TCPOBOP — in mouse liver. Results of multiplex RT-PCR showed that the increase in CYP2B enzymatic activities reflected at least in part an increased mRNA levels. Thus, our results provide evidence to support the conclusion that the species-dependent differences of CYP2B induction occur because of differences of transcriptional activation of CYP2B genes.

Effects of hypobaric hypoxia on adenine nucleotide pools, adenine nucleotide transporter activity and protein expression in rat liver

To explore the effect of hypobaric hypoxia on mitochondrial energy metabolism in rat liver. Adult male Wistar rats were exposed to a hypobaric chamber simulating 5,000 m high altitude for 23 h every day for 0 (H0), 1 (H1), 5 (H5), 15 (H15) and 30 d (H30) respectively. Rats were sacrificed by decapitation and liver was removed. Liver mitochondria were isolated by differential centrifugation program. The size of adenine nucleotide pool (ATP, ADP, and AMP) in tissue and mitochondria was separated and measured by high performance liquid chromatography (HPLC). The adenine nucleotide transporter (ANT) activity was determined by isotopic technique. The ANT total protein level was determined by Western blot. Compared with H0 group, intra-mitochondrial ATP content decreased in all hypoxia groups. However, the H5 group reached the lowest point (70.6%) (P<0.01) when compared to the control group. Intra-mitochondrial ADP and AMP level showed similar change in all hypoxia groups and were significantly lower than that in H0 group. In addition, extra-mitochondrial ATP and ADP content decreased significantly in all hypoxia groups. Furthermore, extra-mitochondrial AMP in groups H5, H15 and H30 was significantly lower than that in H0 group, whereas H1 group had no marked change compared to the control situation. The activity of ANT in hypoxia groups decreased significantly, which was the lowest in H5 group (55.7%) (P<0.01) when compared to H0 group. ANT activity in H30 group was higher than in H15 group, but still lower than that in H0 group. ANT protein level in H5, H15, H30 groups, compared with H0 group decreased significantly, which in H5 group was the lowest, being 27.1% of that in H0 group (P<0.01). ANT protein level in H30 group was higher than in H15 group, but still lower than in H0 group. Hypobaric hypoxia decreases the mitochondrial ATP content in rat liver, while mitochondrial ATP level recovers during long-term hypoxia exposure. The lower level of extra-mitochondrial ATP may be related to the decrease of ANT activity during hypoxia exposure.

Hepatoprotective effect of the natural fruit juice from Aronia melanocarpa on carbon tetrachloride-induced acute liver damage in rats

The fruits of Aronia melanocarpa are rich in anthocyanins — plant pigments with anti-inflammatory and anti-oxidant activity. We studied the effect of the natural fruit juice from A. melanocarpa (NFJAM) on carbon tetrachloride (CCl 4)-induced acute liver damage in rats. Histopathological changes such as necrosis, fatty change, ballooning degeneration and inflammatory infiltration of lymphocytes around the central veins occurred in rats following acute exposure to CCl 4 (0.2 ml kg −1, 2 days). The administration of CCl 4 increased plasma aspartate transaminase (AST) and alanine transaminase (ALT) activities, induced lipid peroxidation (as measured by malondialdehyde (MDA) content in rat liver and plasma) and caused a depletion of liver reduced glutathione (GSH). NFJAM (5, 10 and 20 ml kg −1, 4 days) dose-dependently reduced the necrotic changes in rat liver and inhibited the increase of plasma AST and ALT activities, induced by CCl 4 (0.2 ml kg −1, 3rd and 4th days). NFJAM also prevented the CCl 4-induced elevation of MDA formation and depletion of GSH content in rat liver.

Effects of dimephosphone, xydiphone, and ionol on the content and activities of rat liver cytochromes P-450 during long-term treatment with phenobarbital

Effects of dimephosphone, xydiphone, and ionol administered in parallel with phenobarbital on the content of cytochromes P-450 in rat liver and on the rate of C-hydroxylation of diazepam, haloperidol, and prednisolone by rat liver microsomal enzymes were studied in vitro. Dimephosphone, xydiphone, and ionol exhibited similar inductive effects on C-hydroxylation reactions in the CYP P-450 system during treatment with phenobarbital. Xydiphone and ionol in a dose of 1 mmol/kg canceled phenobarbital-induced increase in P-450 cytochrome content in rat liver. Sex-dependent cytochromes P-450 are involved in the prednisolone and haloperidol C-hydroxylation reactions in rats.

Healing and preventive effects of low-esterified pectin on liver injury induced by carbon tetrachloride in rats

The purpose of this study was to investigate the pharmacological effects of low-esterified pectin on carbon tetrachloride <TEX>$(CCL_4)-induced$</TEX> hepatotoxicity in rats. The study included two experiments. In the first experiment the animals were given daily <TEX>$CCL_4$</TEX> through gavage for 7 days and then 10, 50, or 250 mg/kg b.w. of pectin for 21 days. At the end of experiment rats were killed within 24 hours. The increased bilirubin level, enhanced alanine aminotransferase and aspartate aminotransferase activity in plasma induced by <TEX>$CCL_4$</TEX> were partly normalized by pectin administration in a dose-dependent manner. The pectin treatment also resulted in significant recovery of <TEX>$CCL_4-induced$</TEX> decrease of the liver glycogen content. In addition, pectin significantly improved <TEX>$CCL_4-induced$</TEX> alterations of pro-oxidant and antioxidant biochemical parameters in liver and plasma compared to those of rats administered <TEX>$CCL_4$</TEX>. In the second experiment the animals were given daily 10, 50 or 250 mg/ kg b.w. of pectin for 21 days before a 7-day administration of <TEX>$CCL_4$</TEX>. Rats were killed 24 hours after the end of experiment. Pretreatment with pectin before <TEX>$CCL_4$</TEX> administration resulted in significantly inhibited increase of the blood enzymatic activities of alanine and aspartate aminotransferases and bilirubin level in a dose-dependent manner. Also, preliminary administration of pectin prevented elevation of malondialdehyde and conjugated diene levels in liver and plasma as well as a reduction of glutathione content in liver of rats given <TEX>$CCL_4$</TEX>. These results suggest that low-esterified pectin exert healing and preventive effects on <TEX>$CCL_4-induced$</TEX> hepatotoxicity in rats.

Regulation by carbohydrate and clofibric acid of palmitoyl-CoA chain elongation in the liver of rats.

Regulation of palmitoyl-CoA chain elongation (PCE) and its contribution to oleic acid formation were investigated in rat liver in comparison with stearoyl-CoA desaturase (SCD). Hepatic PCE activity was induced by the administration of 20% wt/vol glucose or fructose in the drinking water of normal rats. In streptozotocin-induced diabetic rats, the activities of both PCE and SCD were suppressed, and fructose, but not glucose, feeding caused an increase in the activities of both enzymes. Treatment of normal rats with clofibric acid in combination with carbohydrate further increased PCE, but not SCD, activity. FA analysis of hepatic lipids revealed that the proportion of oleic acid (18:1 n-9) increased upon administration of carbohydrate or clofibric acid. The treatment of rats with clofibric acid in combination with carbohydrate greatly increased the proportion of 18:1 n-9. A significant correlation was observed between PCE activity and the hepatic proportion of 18:1 n-9 (r2 = 0.874, P < 0.01), whereas the relationship between SCD activity and the proportion of 18:1 n-9 was not significant (r2 = 0.552, P > 0.05). Taken together, these results suggest that carbohydrate induces PCE as well as SCD activity to increase the hepatic 18:1 content in rat liver, and the increased PCE activity seems to be responsible for the further increase in 18:1 n-9 when carbohydrate is administered in combination with clofibric acid.

Pro-oxidant effect of dehydroepiandrosterone in rats is mediated by PPAR activation

DHEA-treatment exerts a dual effect, prooxidant or antioxidant, depending on the dosage and, therefore, on the tissue concentration reached. In agreement with previous studies showing a prooxidant effect of DHEA, here we show that pharmacological doses of DHEA produce increased H 2O 2 levels and a marked reduction of GSH content in rat liver. DHEA, also increases both catalase (by 30%) and cytochrome-C-reductase (by 30%) activities in the liver cytosol. The effectiveness of the state of increased oxidative stress is also documented by changes in fatty acid pattern of the microsomal membranes. Moreover, DHEA, at high doses, enhances β-oxidation, as demonstrated by an increase of acyl-CoA-oxidase activity and of cytochrome P450 4A content, confirming that it acts as a PPARs inducer. Both PPARs induction and proxidant effects completely disappear when DHEA is administered at lower doses. Seven days treatment (4 or 10 mg) is unable to affect either levels of proxidant species and of antioxidant molecules, or cytochrome P450 4A content and β-oxidation. Prolonged DHEA treatment (4 mg/day) for three weeks not only is unable to affect PPARs activation and β-oxidation, but it also exerts a protective effect against ADP/Fe 2+ induced lipid peroxidation. This latter result confirms the antioxidant effects of DHEA at low doses, as already previously documented.

Effect of in vivo administered hexachlorobenzene on epidermal growth factor receptor levels, protein tyrosine kinase activity, and phosphotyrosine content in rat liver

In the present study, the effects of hexachlorobenzene (HCB) on epidermal growth factor receptor (EGFR) content of liver microsomes and plasma membrane, and on EGFR-tyrosine kinase activity in the microsomal fraction were investigated. In addition, we studied the parameters of the tyrosine kinase signalling pathway such as protein tyrosine kinase (PTK) activity and phosphotyrosine content in microsomal and cytosolic protein. To determine whether the observed alterations were correlated with a manifestation of overt toxicity, a single very low dose of HCB (1 mg/kg body wt) and two much higher doses (100 and 1000 mg/kg body wt), the highest being toxicologically significant in that it reduced serum thyroxine (T 4) and inhibited uroporphyrinogen decarboxylase (URO-D) (EC 4.1.1.37) activity, were tested. Our results demonstrated that liver microsomes of rats treated with HCB had higher levels of EGFR than untreated rats; treated rats also had less EGFR present in hepatocyte plasma membrane fractions than did untreated rats. HCB altered the phosphotyrosine content and protein phosphorylation of some microsomal and cytosolic proteins in a biphasic dose–response relationship. At the low dose, phosphorylation and phosphotyrosine content of several microsomal proteins were increased; however, these effects were diminished or reversed at the higher doses. Our results suggest that chronic HCB treatment produces a down-regulation of the EGFR and a dose-dependent increase in EGFR-tyrosine kinase activity in the microsomal fraction. This effect may contribute to the alteration of membrane and cytosolic protein tyrosine phosphorylation. The level of sensitivity encountered in our studies is extraordinary, occurring at 1/10 to 1/1000 the doses of HCB known to cause other toxicological lesions.

Contrasting effects of fish oil and safflower oil on hepatic peroxisomal and tissue lipid content.

To examine the mechanism by which fish oil protects against fat-induced insulin resistance, we studied the effects of control, fish oil, and safflower oil diets on peroxisomal content, fatty acyl-CoA, diacylglycerol, and ceramide content in rat liver and muscle. We found that, in contrast to control and safflower oil-fed rats, fish oil feeding induced a 150% increase in the abundance of peroxisomal acyl-CoA oxidase and 3-ketoacyl-CoA thiolase in liver but lacked similar effects in muscle. This was paralleled by an almost twofold increase in hepatic peroxisome content (both P < 0.002 vs. control and safflower). These changes in the fish oil-fed rats were associated with a more than twofold lower hepatic triglyceride/diacylglycerol, as well as intramuscular triglyceride/fatty acyl-CoA, content. In conclusion, these data strongly support the hypothesis that n-3 fatty acids protect against fat-induced insulin resistance by serving as peroxisome proliferator-activated receptor-alpha ligands and thereby induce hepatic, but not intramuscular, peroxisome proliferation. In turn, an increased hepatic beta-oxidative capacity results in lower hepatic triglyceride/diacylglycerol and intramyocellular triglyceride/fatty acyl-CoA content.

Glycogen content in rat liver: Importance for CT and MR imaging

Purpose: CT and MR imaging are appropriate modalities for imaging of the liver. Contrast media are used to obtain a greater difference in attenuation and signal intensity, respectively, between normal liver tissue and focal lesions. However, no studies have attempted to determine whether physiological nutritional status of the liver during fasting is of importance for the native signal of normal liver tissue. Material and Methods: Using normal and fasting rats, we performed hepatic CT and MR imaging and glycogen analyses from excised tissue. Results: A significantly higher liver attenuation in normal rats compared to fasting rats was found in CT. In MR images, there was a small but significantly lower liver signal-to-noise ratio in normal rats compared to fasting rats in T1-weighted and proton density-weighted images. Glycogen analyses showed depleted glycogen deposits in fasting rats and a mean glycogen content of 50.1 mg glucose equivalent/g liver tissue in normal rats. Conclusion: In CT, a normal nutritional status increases the native attenuation in normal liver tissue. The changes in attenuation in normal liver tissue correlate well with the additional attenuation of glycogen storage in the hepatocyte. The results indicate that the nutritional status is of less importance in MR imaging.

GLYCOGEN CONTENT IN RAT LIVER. Importance for CT and MR imaging

Purpose: CT and MR imaging are appropriate modalities for imaging of the liver. Contrast media are used to obtain a greater difference in attenuation and signal intensity, respectively, between normal liver tissue and focal lesions. However, no studies have attempted to determine whether physiological nutritional status of the liver during fasting is of importance for the native signal of normal liver tissue. Material and Methods: Using normal and fasting rats, we performed hepatic CT and MR imaging and glycogen analyses from excised tissue. Results: A significantly higher liver attenuation in normal rats compared to fasting rats was found in CT. In MR images, there was a small but significantly lower liver signal-to-noise ratio in normal rats compared to fasting rats in T1-weighted and proton density-weighted images. Glycogen analyses showed depleted glycogen deposits in fasting rats and a mean glycogen content of 50.1 mg glucose equivalent/g liver tissue in normal rats. Conclusion: In CT, a normal nutritional status increases the native attenuation in normal liver tissue. The changes in attenuation in normal liver tissue correlate well with the additional attenuation of glycogen storage in the hepatocyte. The results indicate that the nutritional status is of less importance in MR imaging.

POSSIBLE ROLE OF GLUTATHIONE IN PREVENTION OF ACETAMINOPHEN-INDUCED HEPATOTOXICITY ENHANCED BY FISH OIL IN MALE WISTAR RATS

It has been reported that fish oil protects the rat liver against acetaminophen (APAP) induced toxicity; however, this finding is controversial. The present study was undertaken to investigate the effects of fish oil-enriched diet on APAP-induced liver injury in Wistar rats. Rats were fed a diet supplemented with either 8% fish oil or 8% corn oil, or standard rat feed for 6 wk. After an overnight fast, rats in each group were given either 2 g/kg APAP or saline orally. Our findings showed that APAP increased serum alanine aminotransferase (ALT) and that this rise was potentiated in the presence of dietary fat. Further fish oil ingestion increased the glutathione (GSH) content in rat liver; however, this was not effective in protecting liver from APAP-induced toxicity. Data suggest that GSH may be necessary to detoxify APAP metabolites, which are known to induce hepatotoxicity but are increased by dietary fat.

Modulation of cytochrome P-450-dependent monooxygenases, glutathione and glutathione S-transferase in rat liver by geniposide from gardenia jasminoides

Geniposide is an iridoid glycoside extracted from the fruits of Gardenia jasminoides, which are used as a food colorant and as a traditional Chinese medicine for treatment of hepatic and inflammatory diseases. The effects of geniposide and G. jasminoides fruit crude extract on liver cytochrome P-450 ( P-450)-dependent monooxygenases, glutathione and glutathione S-transferase were investigated using rats treated orally with the iridoid glycoside (0.1 g/kg body weight/day) or the fruit crude extract (2 g/kg/day) for 4 days. The treatments decreased serum urea nitrogen level but increased liver to body weight ratio, total hepatic glutathione content and hepatic cytosolic glutathione S-transferase activity. Treatments with geniposide and G. jasminoides decreased P-450 content, benzo[a]pyrene hydroxylation, 7-ethoxycoumarin O-deethylation, and erythromycin N-demethylation activities in liver microsomes without affecting aniline hydroxylation activity. The natural products had no effect on glutathione content and monooxygenase activities in kidney microsomes. Immunoblotting analyses of liver microsomal proteins using mouse monoclonal antibody 2-13-1 to rat P4503 A 1 2 revealed that geniposide and G. jasminoides crude extract decreased the intensity of a P4503A-immunorelated protein. Protein blots probed with mouse monoclonal antibody 1-12-3 to rat P4501A1 and rabbit polyclonal antibody against human P4502E1 showed that both treatments had little or no effect on P4501A and 2E proteins. The present findings demonstrate that geniposide from G. jasminoides has the ability to inhibit a P4503A monooxygenase and increase glutathione content in rat liver.

Collagen content in rat liver after experimentally induced cholestasis followed by choledochojejunostomy and X-irradiation.

The right part of the median lobe of the liver of female Wistar rats was irradiated, 12.5 or 25 Gy, at a field size of 15 x 20 mm. The central part of the irradiated liver lobe was fixed and used for the estimation of the collagen protein ratio by means of the Sirius Red-Fast Green extraction method, immediately, 8, 16 or 32 weeks after irradiation. No significant increase in collagen content could be demonstrated in this time range, both after irradiation at 12.5 Gy and at 25 Gy. Partial hepatectomy according to Higgins led to rapid regrowth of the remaining liver lobes. The right lobe grew out rapidly to replace the median lobe. Two days after partial hepatectomy the right lobe was irradiated at the same field size. Measurement of the collagen protein ratio in this experiment did not show a significant increase 8, 16 or 32 weeks after irradiation. However, the 25 Gy group did not survive long enough to obtain data at 16 or 32 weeks. The animals in this latter experiment suffered from ascites before dying. Experimentally induced cholestasis was obtained by ligation and partial resection of the common bile duct. After two weeks of cholestasis the bile flow was restored by Roux-en-Y choledochojejunostomy. The effect of irradiation 2 days after repair surgery was studied. Without irradiation the collagen protein ratio is increased. Irradiation of the right part of the median lobe led to a relatively enhanced collagen content in this lobe. Our results indicate that radiation itself does not lead to a significantly enhanced degree of fibrosis in the liver. However when an increase in collagen content was induced by cholestasis, the partial "dilution" of enhanced fibrosis as a result of proliferation of liver parenchyma cells following repair surgery was inhibited by irradiation.

The Circadian Rhythm in Activity of the Periodic Acid Schiff Reaction and of the Mg and Ca Content in Rat Liver in Relation to Age and Season of the Year

The experiments were carried out on male Wistar rats aged 6, 12 and 24 months, over the four seasons of the year. Analysis of the results obtained in all age groups disclosed that changes in activity of the p.a.S (periodic acid Schiff) reaction and in concentrations of Mg and Ca in the liver showed rhythmic oscillations with a period of 12 hours. The maximal p.a.S reaction activity and of Ca and Mg levels were generally found to coincide throughout all seasons and in all age groups. The rhythms of change in these parameters in 12- and 24-month-old rats showed a phase shift as compared to the 6-month-old animals.

Mechanism of hypocholesterolemic effect of oyster mushroom (Pleurotus ostreatus) in rats: reduction of cholesterol absorption and increase of plasma cholesterol removal.

The content of cholesterol in the serum and liver of male Wistar rats fed, for the period of 8 weeks shortly after weaning, a diet containing 0.3% of cholesterol was reduced by 33 and 27% by the addition of 5% of dried oyster mushroom powder. Although the level of serum triacylglycerols was not affected by oyster mushroom, their content in liver of rats on mushroom diet was reduced by 41%. Very-low-density lipoproteins and low-density lipoproteins participated by 55 and 38%, respectively, in the total reduction of serum cholesterol. Cholesterol content in high-density lipoproteins was not significantly affected by oyster mushroom. Cholesterol absorption as determined by dual-isotope plasma ratio method was significantly reduced by 14% with oyster mushroom diet. Similarly, this diet increased by 42% the fractional catabolic rate of cholesterol determined by the analysis of decay curve of [4-14C]cholesterol.

Suppressive effects of polygonati rhizoma on hepatic glucose output, GLUT2 mRNA expression and its protein content in rat liver.

The intraperitoneal administration of the methanol extract of Polygonati Rhizoma (OM) into normal rats caused a significant decrease in the blood glucose level at 4 h after its administration of 800 mg/kg (P < 0.01), but not the serum insulin level. Using the perfused rat liver in vitro, a significant decrease of the hepatic glucose output was observed by the infusion of OM (P < 0.05 at 250 micrograms/ml OM). In addition, the hepatic content of facilitative glucose transporter isoform 2 (GLUT2) mRNA and its protein content in the total membrane fraction from rat liver significantly decreased in the intraperitoneally OM-treated rats when compared to that in the controls (mRNA P < 0.01, protein P < 0.001). On the other hand, OM (500 micrograms/ml) exhibited no apparent stimulatory effect on the insulin secretion from the isolated rat pancreatic islets. These results suggest that the hypoglycemic effect of OM is derived, at least in part, from the decrease in hepatic glucose output, due presumably to the reduction of GLUT2 mRNA expression and its protein content in total membrane of the liver, and that because of its unique therapeutic mechanism, OM could be a new category of therapeutic agent for non-insulin-dependent diabetes mellitus.

Effect of dietary proteins on insulin-like growth factor-1 (IGF-1) messenger ribonucleic acid content in rat liver.

Effects of quantity and quality of dietary proteins on plasma immunoreactive insulin-like growth factor-1 (IGF-1) concentration, and content of IGF-1 mRNA in rat liver were investigated in rats. Plasma immunoreactive IGF-1 concentration in rats given a casein diet was higher than that in rats given a soya-bean-protein or protein-free diet. The IGF-1 mRNA content in liver was estimated by the Northern blot hybridization technique employing 32P-labelled rat IGF-1 complementary DNA (cDNA). At least four molecular species of IGF-1 mRNA of different molecular weight were found in rat liver. The sizes were 0.8-1.2, 2.0, 3.6-4.0 and 7.4 kb. Most of the mRNA species decreased in the livers of rats given a gluten diet (120 g gluten/kg diet) compared with rats given the casein diet. In particular, mRNA of 7.4 kb decreased markedly. When rats were fed on the protein-free diet, mRNA of all species decreased significantly. The estimated IGF-1 mRNA in the livers of rats fed on the gluten or protein-free diet was almost 0.4 of that of the rats given the casein diet. Feeding the soya-bean-protein diet did not result in a marked effect on the hepatic content of mRNA species of IGF-1. The results showed that liver IGF-1 mRNA content is sensitively regulated by quantity and nutritional quality of dietary proteins.

Role of vagus nerve in increased DNA synthesis after hypothalamic ventromedial lesions in rat liver.

We recently reported that ventromedial hypothalamic (VMH) lesions produced an increase in DNA content in rat liver. In the present study, we examined the mechanism of increased hepatic DNA content produced by VMH lesions. Hepatic DNA content began to increase 3 days after VMH lesioning and continued to increase until 7 days after the lesioning. Hepatic DNA synthesis increased and reached maximum 3 days after the lesioning and then decreased to the initial level 7 days after lesioning. The increased DNA content and synthesis after VMH lesioning were completely inhibited by vagotomy (hepatic vagotomy or bilateral subdiaphragmatic vagotomy) and largely inhibited by the administration of atropine but not by administration of anti-insulin antibody. These results suggest that vagus firing produced by VMH lesions stimulates DNA synthesis in rat liver mainly through cholinergic receptor mechanisms.