Liver In Control Research Articles

Lead-induced hepatotoxicity and evaluation of certain anti-stress adaptogens in poultry

A total of 225 day-old sexed male broiler chicks (Vencobb strain) were divided randomly into 15 groups consisting of 15 chicks in each group to study the toxicity of lead on hepatocytes. Group 1 was maintained on basal diet, group 2 on polyherbal formulation (PHF; stressroak), group 3 on shilajith, group 4 on amla and group 5 on vit E + Se. Group 6 was maintained on lead for 6 weeks and group 7 on lead for 4 weeks and subsequently on basal diet without lead for the remaining 2 weeks. Groups 8, 9, 10 and 11 were given lead along with PHF, shilajith, amla and vit E + Se, respectively, throughout 6 weeks. Groups 12, 13, 14 and 15 were given lead containing diet for the first 4 weeks and subsequently treated with PHF, shilajith, amla and vit E + Se, respectively, for the remaining 2 weeks. The activity of alanine transaminase (ALT) was significantly (P<0.05) increased in the toxic control groups at the end of 4th week as compared to group 1. However, following treatment, there was a significant (P<0.05) reversal in groups 12–15. The activity of Na+/K+-ATPase, Ca2+ATPase, Mg2+ATPase and CYP450 was significantly (P<0.05) reduced in the liver of toxic control groups 6 and 7 as compared to groups1 through 5, which had the maximum activity of all the groups. Groups 8 through 15 revealed a significant (P<0.05) increase in the activity of these hepatocytic enzymes. The histological sections of the liver in lead toxic control (group 6) showed moderate focal lymphoid aggregates in liver, whereas the lesions were mild to moderate in treated groups and there were no observable lesions in plain control groups. The study revealed protective effect of PHF (stressroak), shilajith, amla and vit E + Se in lead-induced hepatocytic damage.

Vagal control of pancreatic ß-cell proliferation.

The physiological mechanisms that preserve pancreatic β-cell mass (BCM) are not fully understood. Although the regulation of islet function by the autonomic nervous system (ANS) is well established, its potential roles in BCM homeostasis and compensatory growth have not been adequately explored. The parasympathetic vagal branch of the ANS serves to facilitate gastrointestinal function, metabolism, and pancreatic islet regulation of glucose homeostasis, including insulin secretion. Given the functional importance of the vagus nerve and its branches to the liver, gut, and pancreas in control of digestion, motility, feeding behavior, and glucose metabolism, it may also play a role in BCM regulation. We have begun to examine the potential roles of the parasympathetic nervous system in short-term BCM maintenance by performing a selective bilateral celiac branch-vagus nerve transection (CVX) in normal Sprague-Dawley rats. CVX resulted in no detectable effects on basic metabolic parameters or food intake through 1 wk postsurgery. Although there were no differences in BCM or apoptosis in this 1-wk time frame, β-cell proliferation was reduced 50% in the CVX rats, correlating with a marked reduction in activated protein kinase B/Akt. Unexpectedly, acinar proliferation was increased 50% in these rats. These data suggest that the ANS, via the vagus nerve, contributes to the regulation of BCM maintenance at the level of cell proliferation and may also mediate the drive for enhanced growth under physiological conditions when insulin requirements have increased. Furthermore, the disparate effects of CVX on β-cell and acinar cells suggest that the endocrine and exocrine pancreas respond to different neural signals in regard to mass homeostasis.

Effects of garlic extract treatment in normal and streptozotocin diabetic rats infected with Candida albicans.

The anti-candidial effect of garlic extract (Allium sativum L.) was investigated in normal and streptozotocin-induced diabetic rats. Diabetes was induced after a single intraperitoneal injection of streptozotocin (60 mg/kg). Rats were divided into six groups with fifteen rats in each group: (1) Normal control rats (2) Control rats + C. albicans (3) Control rats + garlic extract + C. albicans (4) Diabetic control rats (5) Diabetic rats + C. albicans (6) Diabetic rats + garlic extract + C. albicans. The concerned groups were inoculated with C.albicans on the 15 th day. At the end of one month experiment, fasted rats were killed by cervical decapitation. Blood was collected for estimation of glucose and C. albicans concentrations were estimated in liver and kidneys homogenates. A significant increase was observed in serum glucose levels in diabetic rats. A loss of bodyweight, polydipsia and polyphagia were observed in diabetic rats. Administration of alcoholic extract of garlic (0.25 g/kg body weight) reduced the hyperglycemia, polydipsia, polyphagia and associated weight loss of streptozotocin-treated rats. Administration of garlic extract significantly reduced C. albicans concentrations in liver and kidneys homogenates in infected control and diabetic rats. It is concluded that garlic extract improves candidia infection in diabetic rats.

Systemic spreading of intraperitoneal Staphylococcus aureus is increased in experimental liver cirrhosis but unaltered by splanchnic sympathectomy

In liver cirrhosis, nosocomial spontaneous bacterial peritonitis (SBP) is associated with poor prognosis and most frequently caused by gram-positive bacteria. We previously reported that the well-known hyperactivity of the sympathetic nervous system (SNS) in advanced cirrhosis contributes to the translocation of E. coli from the peritoneum to mesenteric lymph nodes and extraintestinal sites. However, the role of splanchnic SNS-activity for spreading of gram-positive challanges in cirrhosis remains unclear. Methods: Staphylococcus aureus (S. aureus 106 CFU/ml) was given i.p. (3ml) and 6 hours later mesenteric lymphnodes (MLN), liver, spleen, lung and peripheral blood were harvested sterile from ascitic cirrhotic rats (LC) and healthy controls (Con) with and without splanchnic sympathectomy (±SE) being achieved by anti-dopamine-ß-hydroxylase-saporin treatment i.p. Bacterial tissue burden was determined by standard microbiological culture techniques. Results: After S. aureus challenge LC rats presented with marked increases in incidence of S. aureus translocation to MLN and blood as compared to control rats (Table 1). Intraperitoneal application of S.aureus induced endogenous translocation of gram-negative bacteria to MLN, liver, spleen and lung in LC but not in healthy rats (Fig. 1). SE had neither impact on incidence nor severity of translocation of Staph.aureus to MLN, liver, spleen, lung or blood in either control or LC rats. However, SE tended to reduce translocation of endogenous gram-negative bacteria from the gut to liver, spleen and lung (Fig.1). Conclusions: In cirrhosis, i.p. application of S. aureus is associated with enhanced systemic spreading and induction of endogenous gram-negative bacterial translocation as compared to controls. Splanchnic sympathetic hyperactivity in cirrhosis seems not to contribute to the translocation of Staph.aureus but enhances gram-negative translocation.

Calpain 10 is required for cell viability and is decreased in the aging kidney

Aging is associated with abnormalities in kidney function, but the exact mechanisms are unknown. We examined calpains 1, 2, and 10 protein levels in kidneys from rats, mice, and humans of various ages and determined whether calpain 10 is required for cell viability. Calpain 10 protein expression decreased in the kidney, but not in the liver, of aging Fischer 344 rats, and this decrease was attenuated with caloric restriction. There was no change in calpains 1 or 2 levels in the kidney or liver in control and caloric-restricted aging rats. Aging mice also exhibited decreased calpain 10 protein levels. Calpain 10 protein and mRNA levels decreased linearly in human kidney samples with age in the absence of changes in calpains 1 or 2. Our laboratory previously found calpain 10 to be expressed in both the cytosol and mitochondria of rabbit renal proximal tubular cells (RPTC). Adenoviral-delivered shRNA to rabbit RPTC decreased mitochondrial calpain 10 expression below detectable levels by 3 days while cytosolic calpain 10 levels remained unchanged at 3 days and decreased to approximately 20% of control by 5 days. Knockdown of mitochondrial calpain 10 resulted in nuclear condensation and cleaved procaspase 3, markers of apoptosis. In summary, mitochondrial calpain 10 is required for cell viability and calpain 10 levels specifically decrease in aging rat, mice, and human kidney tissues when renal function decreases, suggesting that calpain 10 is required for renal function and is a biomarker of the aging kidney.

Partial blockage of hepatocyte maturation in hepatoma-derived growth factor transgenic mice

To investigate the role of hepatoma-derived growth factor (HDGF) in liver development, especially in the hepatocyte differentiation. We generated transgenic mice which overexpressed HDGF in hepatocytes under the transcriptional control of mouse albumin promoter/enhancer. To examine the effects of HDGF overexpression on hepatocyte differentiation, we investigated the expression patterns of the differentiation marker genes. The HDGF transgenic mice developed normally and showed no apparent abnormality in the liver. However, the gene expression patterns of the liver in adult transgenic mice were similar to those of the neonatal liver in control mice. These findings suggest that HDGF-overexpression partially suppresses hepatocyte maturation.

The effect of fasting on the glycogen metabolism in heat-acclimated rats

We investigated the influence of successive fasting for 24,48,72, and 96 h on some key enzymes and substrates of liver, kidney, and muscle in control and heat-acclimated (30days at 35 ? 1?C)rats. Short-term fasting (for 24 and 48 h)resulted in decrease of liver glycogen content, blood glucose level, and concentration of glucose-6-phosphate, as well as increase of glucose-6-phosphatase activity, regardless of the previous temperature of acclimation. During a period of prolonged fasting (for 72 and 96 h),there was a rebound of liver glycogen content only in animals kept at room temperature. Fasting induced increase of renal glycogen content in animals kept at room temperature and increase of renal glucose-6-phosphatase activity in both experimental groups. As for muscle metabolism, endogenous nutrition resulted in decrease of muscle glycogen content in heat-acclimated animals. Activity of muscle glycogen phosphorylase (a+b)was decreased in the control and increased in heat-acclimated animals. The obtained results indicate that the examined carbohydrate-related parameters show time-dependent changes during 4 days of fasting. Twenty-four- and 48-h fasting intensifies glycogenolytic processes, while 72- and 96-h fasting intensifies gluconeogenic processes, doing so to a lesser extent in heat-acclimated animals. The changes caused by the fasting were modified by acclimation to moderate heat, primarily in the liver and to a lesser extent in the kidney and muscle.

High Circulating Leptin Receptors with Normal Leptin Sensitivity in Liver-specific Insulin Receptor Knock-out (LIRKO) Mice

Liver-specific insulin receptor knock-out (LIRKO) mice display hyperinsulinemia, abnormal glucose metabolism, and progressive liver dysfunction. In addition, circulating leptin levels appear to be increased more than 10-fold. However, food intake, body weight, and adipose mass are not significantly altered in LIRKO mice compared with wild-type littermates. Using a ligand immunofunctional assay, we found that the apparent increase in circulating leptin in LIRKO mice is because of an 80-fold increased serum level of soluble leptin receptor. Gene expression analysis by microarray and real time PCR reveals the liver as the source of soluble leptin receptor in LIRKO mice, with an increase in expression of the short (Ob-Ra), long (Ob-Rb), and soluble (Ob-Re) forms of the leptin receptor. Direct control of leptin receptor expression by insulin could also be demonstrated in isolated hepatocytes from normal mice. Despite the markedly increased levels of leptin receptor in their circulation, LIRKO mice exhibit normal or even enhanced leptin sensitivity, as assessed by their physiological and molecular responses to exogenous leptin administration and their lower base-line hypothalamic levels of SOCS3 mRNA. Thus, insulin signaling in the liver plays an important role in control of leptin receptor expression and shedding. In the LIRKO mouse, this is lost, leading to markedly increased leptin receptors into the circulation. These high levels of circulating leptin receptor bind leptin and likely alter its clearance, but do not inhibit leptin action and may actually potentiate leptin action. In this manner, insulin signaling in liver plays an important role in leptin homeostasis and fine modulation of leptin action.

Genes that affect cholesterol synthesis, cholesterol absorption, and chylomicron assembly: The relationship between the liver and intestine in control and streptozotosin diabetic rats

Chylomicrons and very low-density lipoproteins (VLDLs) are abnormal in diabetes. The aim of this study was to compare the expression of Niemann-Pick C1-like1 (NPC1L1), adenosine triphosphate–binding cassette (ABC) proteins G5 and G8, microsomal triglyceride transfer protein (MTP), and 3-hydroxy-3-methylglutaryl coenzyme A (HMGCoA) reductase in the fasting and fed states in nondiabetic Sprague-Dawley rats fed a high-fat/cholesterol diet and to examine the messenger RNA (mRNA) expression of these proteins in the liver and intestine of diabetic and control animals using streptozotosin diabetic cholesterol-fed rats. Chylomicron and VLDL concentrations were significantly lower after a 12-hour fast in fasted compared with fed rats ( P < .02). There was no change with fasting in mRNA expression of any of the genes in the intestine, but MTP level was significantly lower in the liver after the 12-hour fast ( P < .01). There was a positive correlation between intestinal NPC1L1 mRNA and chylomicron cholesterol ( P < .01) and between hepatic NPC1L1 mRNA and VLDL cholesterol ( P < .01). The diabetic rats had significantly higher chylomicron and VLDL cholesterol, triglyceride, and apolipoprotein B-48 and B-100 levels compared with control rats ( P < .0001). They had significantly increased NPC1L1 and MTP mRNA in both liver and intestine ( P < .05 and P < .0005, respectively), and ABCG5 and ABCG8 mRNA were significantly reduced ( P < .05). HMGCoA reductase mRNA was increased in diabetic animals ( P < .01). In conclusion, fasting intestinal gene expression reflects the fed state. In diabetes, intestinal and hepatic gene expression correlates with abnormalities in chylomicron and VLDL cholesterol.

Circadian Variations in the Activities of 6‐Phosphogluconate Dehydrogenase and Glucose‐6‐Phosphate Dehydrogenase in the Liver of Conrol and Streptozotocin‐Induced Diabetic Rats

The aim of this study was to examine: the 24 h variation of 6‐phosphogluconate dehydrogenase and glucose‐6‐phosphate dehydrogenase activities, key enzymes for the maintenance of intracellular NADPH concentration, in rat liver in control and streptozotocin‐induced diabetic animals. Adult male rats were fed ad libitum and synchronized on a 12:12 h light‐dark cycle (lights on 08:00 h). One group of animals was treated with streptozotocin (STZ, 55 mg/kg, intraperitoneal) to induce experimental diabetes. Eight weeks after STZ injection, the animals were sacrificed at six different times of day—1, 5, 9, 13, 17 and 21 Hours After Lights On (HALO)—and livers were obtained. Enzyme activities were determined spectrophotometrically in triplicate in liver homogenates and expressed as units per mg protein. 6‐phosphogluconate dehydrogenase activity was measured by substituting 6‐phosphogluconate as substrate. Glucose‐6‐phosphate dehydrogenase activity was determined by monitoring NADPH production. Treatment, circadian time, and interaction between treatment and circadian time factors were tested by either one or two way analysis of variance (ANOVA). Two‐way ANOVA revealed that 6‐phosphogluconate dehydrogenase activity significantly depended on both the treatment and time of sacrifice. 6‐phosphogluconate dehydrogenase activity was higher in control than diabetic animals; whereas, glucose‐6‐phosphate dehydrogenase activity did not vary over the 24 h in animals made diabetic by STZ treatment. Circadian variation in the activity of 6‐phosphogluconate dehydrogenase was also detected in both the control and STZ treatment groups (one‐way ANOVA). Time‐dependent variation in glucose‐6‐phosphate dehydrogenase activity during the 24 h was detected in control but not in diabetic rats. No significant interaction was detected between STZ‐treatment and time of sacrifice for both hepatic enzyme activities. These results suggest that the activities of NADPH‐generating enzymes exhibit 24 h variation, which is not influenced by diabetes.

Role of the liver in the control of glucose-lipid utilization and body weight.

This review depicts recent developments concerning the role of the liver in control of carbohydrate and lipid utilization from ingestion to storage; it covers the liver's influence on food intake, post-absorptive nutrient metabolism and body weight. The mechanisms involved have implications for the pathogenesis of obesity and type II diabetes. Recent studies have identified some of the molecular and biochemical mechanisms which control whole body and hepatic carbohydrate and lipid metabolism, thus providing the basis of the liver's role in the control of food intake, metabolism, and body weight. Fatty acids are known to effect gene transcription in various ways. Advances in our understanding of the control of glucose and lipid utilization by the liver include (1). a better functional characterization of some newly discovered transcription factors, (2). new discoveries concerning the physiological and pathophysiological role of hepatic glucokinase and of the glycogen-targeting subunits of protein phosphatase-1, and (3). the demonstration of substantial overlap in the molecular control mechanisms of glucose-lipid utilization. Also, impaired insulin signaling due to a certain gene (Foxo1) has emerged as a possible unifying mechanism for various common metabolic abnormalities of type II diabetes. Finally, recent findings confirm and extend previous knowledge about the important role of hepatic nerves in the control of liver and whole body glucose-lipid utilization. The identification of new molecular and neural mechanisms of the hepatic control of glucose-lipid utilization and body weight provides a focus for future studies and may eventually help to develop new treatments for obesity and type II diabetes.

Diabetes mellitus induces decreased plasma fibrinolytic activity and increased tissue synthesis of plasminogen activator inhibitor-1 (PAI-1) in the rat

In diabetes, plasma fibrinolytic activity is decreased while plasma plasminogen activator inhibitor-1 (PAI-1) is increased. Both liver and adipose tissue can synthesize and release PAI-1, but PAI-1 synthesis in these tissues has not been investigated in diabetes. Furthermore, little is known about PAI-1 localization in arterial wall cells of diabetic animals. The aim of this study was to determine the effect of chronic hyperglycemia on plasma fibrinolysis and plasma PAI-1 levels and on liver, adipose tissue and arterial wall PAI-1 content in the rat.We compared plasma fibrinolytic activity (lysis of fibrin plates) and plasma PAI-1 activity (chromogenic assay) in 10 Sprague Dowley 90% pancreatectomized rats (a model of diabetes characterized by normal fasting insulin and the absence of obesity, therefore closely resembling lean type 2 diabetes) and in 15 sham-operated rats. Furthermore, we measured PAI-1-related fluorescence, by immunofluorescent staining and Laser Scanning Confocal Microscopy, in liver, adipose tissue and aortic wall in diabetic and control animals.In the diabetic animals plasma fibrinolytic activity was reduced (lysis areas = 163 ± 23 vs 308 ± 21 mm2, P< 0.001), while plasma PAI-1 activity was increased (4.61 ± 2.01 AU vs 0.70 ± 0.59 AU, P< 0.02). PAI-1 related fluorescence was increased in the liver (754 ± 25 vs 299 ± 14 AFU, P< 0.0001), in the adipose tissue (721 ± 32 vs 248 ± 14 AFU, P< 0.001) and in the aorta wall (339 ± 18 vs 274 ± 9 AFU,P < 0.005) of the diabetic animals.These data provide evidence that in diabetes mellitus hyperglycemia is associated with increased PAI-1 content in the liver, adipose tissue and in the arterial wall. This suggests that in diabetes the liver and adipose tissue can be important sources for increased plasma PAI-1 and local fibrinolysis can be affected by increased PAI-1 levels in the arterial wall.

Obesity is associated with tissue-specific activation of renal angiotensin-converting enzyme in vivo: evidence for a regulatory role of endothelin.

In the C57BL/6J mice model, we investigated whether obesity affects the function or expression of components of the tissue renin-angiotensin system and whether endothelin (ET)-1 contributes to these changes. ACE activity (nmol. L His-Leu. mg protein(-1)) was measured in lung, kidney, and liver in control (receiving standard chow) and obese animals treated for 30 weeks with a high-fat, low cholesterol diet alone or in combination with LU135252, an orally active ET(A) receptor antagonist. ACE mRNA expression was measured in the kidney, and the effects of LU135252 on purified human ACE were determined. Aortic and renal tissue ET-1 protein content was measured, and the vascular contractility to angiotensin II was assessed. Obesity was associated with a tissue-specific increase in ACE activity in the kidney (55+/-4 versus 33+/-3 nmol/L) but not in the lung (34+/-2 versus 32+/-2 nmol/L). Long-term LU135252 treatment completely prevented this activation (13.3+/-0.3 versus 55+/-4 nmol/L, P<0.05) independent of ACE mRNA expression, body weight, or renal ET-1 protein but did not affect pulmonary or hepatic ACE activity. Obesity potentiated contractions in response to angiotensin II in the aorta (from 6+/-2% to 33+/-5% KCl) but not in the carotid artery (4+/-1% to 3.6+/-1% KCl), an effect that was completely prevented with LU135252 treatment (6+/-0.4% versus 33+/-5% KCl). No effect of LU135252 on purified ACE was observed. Thus, obesity is associated with the activation of renal ACE in vivo independent of its mRNA expression and enhanced vascular contractility to angiotensin II. These effects are regulated by ET in an organ-specific manner, providing novel mechanisms by which ET antagonists may exert organ protection.

The effect of adaptation to cold and re-adaptation to room temperature on the level of glutathione in rat tissues

1. Glutathione (GSH) was assayed in plasma, liver and IBAT in control (22±1°C) and cold adapted rats (45 days in 5±1°C), and in rats cold adapted and brought back to room temperature after 1, 3, 7 and 15 days. 2. Adaptation to the cold led to reduced GSH in the liver and plasma while the level in intrascapular brown adipose tissue (IBAT) was increased in comparison to controls. 3. On the first day of re-adaptation, plasma GSH was similar to the control level, as were hepatic levels on the first and fifteenth day, but GSH in IBAT remained higher even after fifteen days.

Role of the liver in long-term control of drinking behavior, Na+ balance, and arterial pressure in Dahl rats.

The role of postabsorptive mechanisms in long-term control of drinking behavior, Na+ balance, and arterial pressure was examined in Dahl salt-sensitive (DS) and salt-resistant (DR) rats. NaCl (0.15 M) was infused (0.5 ml/h) into either the inferior vena cava (IVC) or the portal vein (PV) for 7 days, and then 1.5 M NaCl was infused for 10 days. During 1.5 M infusion, the IVC group retained more Na+ than the PV group. Furthermore, in DS rats, mean arterial pressure was higher in the IVC group than in the PV group. Regardless of the strain and infusion route, 1.5 M infusion had no effect on volume of daily saline consumption. However, when the data for light and dark periods were analyzed separately, dark period saline consumption in the PV group was decreased by 1.5 M infusion but was not changed in the IVC group. These results indicate that, in Dahl rats, the postabsorptive mechanism plays a significant role in controlling long-term saline drinking behavior and Na+ balance and has a significant role in controlling arterial pressure in DS, but not DR, rats.

Influence of nitric oxide synthase and kinin antagonists on metabolic parameters in chronic streptozotocin-induced diabetes mellitus.

In vivo administration of HOE 140 (a new bradykinin receptor antagonist) and L-NAME (nitric oxide synthase inhibitor) was performed in chronic streptozotocin-diabetic rats. Basal increases (in umol.g dw-1) in liver (45.0 +/- 3.4.1) and uterine (40.0 +/- 2.95) triglyceride levels in diabetic animals vs control (liver: 34.0 +/- 3.87; uterus: 30.2 +/- 4.01) were partially prevented by L-NAME (p < 0.01), HOE 140 (p < 0.01) and L-NAME + HOE 140 (p < 0.01). High glycogen levels (in mg.g dw-1) observed in diabetic uterine tissue (3.07 +/- 0.90), and decreased glycogen content detected in diabetic liver (11.64 +/- 1.50) vs. control (uterus: 1.59 +/- 0.15, liver: 17.25 +/- 0.87) were unaffected. Uterine 14CO2 production from 14C-U-Glucose (in uCi.mg dw), which is lower in diabetic (35.0 +/- 5.12) than in control (50.12 +/- 4.54) tissues, was improved by HOE 140 (p < 0.05) and L-NAME+HOE 140 (p < 0.05), while hepatic glucose oxidation was not increased by the drugs. Glycemia levels were decreased in diabetic rats injected with L-NAME and L-NAME plus HOE 140. Pancreatic 6-Keto-prostaglandin F1 alpha to Thromboxane B2 ratio was lower in diabetic animals than in controls, and L-NAME and/or HOE 140 treatment prevented the decrement. These findings suggest that vasoactive compounds might prevent streptozotocin-induced damage in pancreatic tissue from chronic diabetic rats.

Influence of Nitric Oxide Synthase and Kinin Antagonists on Metabolic Parameters in Chronic Streptozotocin-Induced Diabetes Mellitus

In vivo administration of HOE 140 (a new bradykinin receptor antagonist) and L-NAME (Nitric oxide synthase inhibitor) was performed in chronic streptozotocin-diabetic rats. Basal increases (in umol.g dw −1) in liver (45.0 ± 3.4.1) and uterine (40.0 ± 2.95) triglyceride levels in diabetic animals vs control (liver: 34.0 ± 3.87; uterus: 30.2 ± 4.01) were partially prevented by L-NAME (p < 0.01), HOE 140 (p < 0.01) and L-NAME + HOE 140 (p < 0.01). High glycogen levels (in mg.g dw −1) observed in diabetic uterine tissue (3.07 ± 0.90), and decreased glycogen content detected in diabetic liver (11.64 ± 1.50) vs. control (uterus: 1.59 ± 0.15; liver: 17.25 ± 0.87) were unaffected. Uterine 14CO 2 production from 14C-U-Glucose (in uCi.mg dw), which is lower in diabetic (35.0 ± 5.12) than in control (50.12 ± 4.54) tissues, was improved by HOE 140 (p < 0.05) and L-NAME + HOE 140 (p < 0.05), while hepatic glucose oxidation was not increased by the drugs. Glycemia levels were decreased in diabetic rats injected with L-NAME and L-NAME plus HOE 140. Pancreatic 6-Keto-prostaglandin F 1alpha to Thromboxane B 2 ratio was lower in diabetic animals than in controls, and L-NAME and/or HOE 140 treatment prevented the decrement. These findings suggest that vasoactive compounds might prevent streptozotocin-induced damage in pancreatic tissue from chronic diabetic rats.

Expression of human lecithin:cholesterol acyltransferase in transgenic mice: effects on cholesterol efflux, esterification, and transport

Human lecithin:cholesterol acyltransferase (LCAT) is a key enzyme in the plasma metabolism of cholesterol and is postulated to participate in a physiologic process called reverse cholesterol transport. We have used transgenic mice expressing the human LCAT transgene to study the effect of increased plasma levels of LCAT in each of the proposed steps involved in the reverse cholesterol transport pathway. High density lipoprotein (HDL) from LCAT transgenic mice was 44% more efficient than control mouse HDL in the efflux of cholesterol from human skin fibroblasts. Esterification of cell-derived cholesterol was also markedly increased in mice expressing the human LCAT transgene. The rate of plasma clearance of HDL cholesteryl ester was virtually the same in both types of animals whereas the HDL cholesteryl ester transport rate was significantly increased in mice expressing the human LCAT transgene (152.3 +/- 16.9 micrograms/h vs. 203.1 +/- 30.9 micrograms/h in control and transgenic mice, respectively). Liver cholesteryl ester uptake was significantly increased in mice expressing human LCAT (58.0 +/- 1.4 micrograms/h/g liver vs. 77.9 +/- 1.7 micrograms/h/g liver in control and transgenic mice, respectively). These studies indicate that LCAT modulates the rate by which cholesterol is effluxed from cell membranes onto HDL, esterified, and transported to the liver.

Effect of arachidonate on lipid metabolism in ethanol-treated rats fed with lard.

Two groups of rats, ethanol-treated and sucrose-administered control rats, were fed diets with different AA content (0, 2 and 3% weight) for 14 days. Ethanol was administered by gavage at a single daily dose of 3 g/kg body weight. The ethanol-treated rats showed significantly higher levels (p < 0.01) of serum ALT activity. The dietary AA supplement lowered the serum ALT activity and liver triglyceride both in control and ethanol-treated rats. Significantly lower levels of 20:4n - 6 and 20:4n - 6/18:2n - 6 ratio and higher levels of 18:1n - 9 in both the serum and liver triglyceride were observed in the ethanol-treated rats. The AA-supplemented diet induced a marked increase of 20:4n - 6 and subsequent significant decrease of 18:2n - 6 both in the liver and serum phospholipid in control and ethanol-treated rats. 18:1n - 9 in the serum and liver triglyceride in both groups was also markedly decreased by AA supplement. No significant difference was observed in the liver 6-keto-PGF(1 alpha) level between the ethanol-treated and control rats. In the ethanol-treated rats, the level of 6-keto-PGF(1 alpha) was elevated in the rats fed the 3% AA-supplemented diet. Though the liver leukotriene B4 levels were increased by ethanol administration in all rats, these levels were not increased by dietary AA.

Protective Effects of .ALPHA.-Tocopherol against Glucose Intolerance and Mitochondrial Damage in Reperfused Rat Liver.

We examined the protective effects of α-tocopherol against glucose intolerance and mitochondrial damage in rat liver after partial in vivo ischemia and reperfusion, while glucose was intravascularly supplemented. Rats were given α-tocopherol or vehicle for three consecutive days before the experiment. Left and median lobes of the liver received 90-min ischemia and 60-min reperfusion. Besides plasma levels of glucose, insulin, and lipid peroxide, we also measured oxidative phosphorylation, cytochrome c oxidase (CCO) activity, and lipid peroxide levels in mitochondria in both ischemic and non-ischemic lobes of the liver in control and α-tocopherol groups before and at the end of ischemia and after reperfusion. Both plasma glucose and insulin levels after reperfusion were lower in the α-tocopherol-treated group than in the control group. Ischemia markedly suppressed both mitochondrial respiration supported by succinate and CCO activity in the ischemic lobes in both groups. Reperfusion recovered mitochondrial function and CCO activity better in the α-tocopherol-treated group than in the control group, whereas the lipid peroxide levels in both plasma and mitochondria were significantly lower in the α-tocopherol-treated group. In non-ischemic lobes, ischemia-reperfusion slightly accelerated both the oxidative phosphorylation rate (OPR) and CCO activity, whereas lipid peroxide levels were unaffected. The results suggest that glucose intolerance during the early phase of reperfusion was not due to lowered plasma insulin level, but might be related to liver damage, as assessed in terms of mitochondrial functions, in the ischemic lobes. α-Tocopherol could protect against mitochondrial damage and glucose intolerance. Oxidative phosphorylation in non-ischemic lobes likely compensated for the decreased mitochondrial activity in the ischemic lobes during ischemia and reperfusion.