Hepatic Mitochondria Research Articles

Longitudinal effects of hepatitis C virus treatment on hepatic mitochondrial dysfunction assessed by 13C‐methionine breath test

Hepatitis C virus (HCV) infection is characterized by remarkable levels of oxidative stress induced by virus interactions with hepatic mitochondria. To examine hepatic mitochondrial function in HCV-infected patients assessed by a non-invasive (13)C-methionine breath test (MeBT) and to explore longitudinal effects of antiviral treatment. Twenty-one patients with chronic hepatitis C undergoing antiviral treatment with pegIFNalpha and ribavirin and 20 healthy controls were studied. MeBT was performed at baseline, week 12, end-of-treatment and after 24 weeks of follow-up in all patients with early virological response (n = 15). Twelve patients achieved sustained virological response (SVR); three patients relapsed for HCV-RNA replication. Cumulative percentage 13C-exhalation (cPDR(1.5h)) was significantly decreased in HCV-infected individuals compared to controls irrespective of genotype and fibrosis stage (P < 0.001). Antiviral treatment induced a further decay in cPDR(1.5h) (P < 0.01). After treatment cessation, 13C-exhalation returned at least to baseline values in all patients. SVR was even associated with a mean cPDR(1.5h) increase of 70% compared to baseline. Hepatitis C virus infection and antiviral treatment synergistically impair hepatic mitochondrial function, which may return to normal after sustained virus elimination. MeBT may be a valuable diagnostic instrument for monitoring hepatic mitochondrial function in particular in patients with mitochondrial comorbidities.

Gravinol Ameliorates High-Fructose-Induced Metabolic Syndrome through Regulation of Lipid Metabolism and Proinflammatory State in Rats

Using a rat model with fructose-induced metabolic syndrome, the effect of gravinol was investigated. Male Wistar rats were fed a 65% fructose diet and administered 10 or 20 mg of gravinol/kg of body weight/day for 2 weeks. High-level fructose feeding led to hyperglycemia, hyperlipidemia, hypertri-glyceridemia, and hypertension. On the other hand, the administration of gravinol significantly lowered serum glucose and total cholesterol levels. The tail arterial blood pressure was significantly elevated with the high-fructose diet. However, rats given gravinol showed a lower blood pressure as compared with fructose-fed control rats. In addition, the triglyceride (TG) levels in serum and lipoprotein fraction were dose-dependently reduced in rats fed gravinol. The decreases of hepatic TG and total cholesterol by gravinol were responsible for the down-regulation of hepatic sterol regulatory element binding protein (SREBP)-1. However, gravinol did not affect the protein levels of hepatic peroxisome proliferator-activated receptor-alpha and SREBP-2. Moreover, gravinol administration in the fructose-fed rats markedly reduced the glycosylated protein and thiobarbituric acid-reactive substance levels in the serum and hepatic mitochondria, and it inhibited the increase of the cyclooxygenase-2 protein level as a result of the down-regulation of nuclear factor kappa B (NF-kappaB). Furthermore, the decrease of anti-apoptotic bcl-2 protein levels and the increase of pro-apoptotic bax protein levels by the high-fructose diet were reversed by gravinol. These findings suggest that fructose-induced metabolic syndrome is attenuated by gravinol administration, which is associated with the reduction of serum lipids and protection against the proinflammatory state induced by oxidative stress.

Antioxidant activities of protein-enriched fraction from the larvae of housefly, Musca domestica

The protein-enriched fraction (PEF) was isolated and purified from the larvae of housefly, Musca domestica. This study was designed to investigate amino acid compositions, antioxidative effects and protective effects of PEF on red blood cell (RBC) hemolysis, lipid peroxidation. The effects of PEF treatment were studied on aged mice liver lipid peroxidation and antioxidant enzyme activities, which included superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). Results: PEF not only inhibited H2O2 stimulated oxidative hemolysis of erythrocytes of mice, but also depressed malondialdehyde (MDA) production in mice liver homogenate by auto-oxidation and hepatic mitochondria expanded induced by Fe2+-ascorbic acid system. Compared to control group, treatments of PEF significantly increases SOD and GSH-Px activity of serum and liver homogenate in aged mice. MDA level of serum and liver homogenate decreased significantly in aged mice. In conclusion, this study demonstrates that PEF possesses antioxidative activity and might be a valuable source of natural antioxidative agents.

Troglitazone-induced hepatic mitochondrial proteome expression dynamics in heterozygous Sod2 +/− mice: Two-stage oxidative injury

The determinants of susceptibility to troglitazone-induced idiosyncratic liver injury have not yet been determined; however, troglitazone has been shown to target mitochondria and induce mitochondria-mediated hepatocellular injury in vitro. The aim of this study was to use a systems approach to analyze the dynamics of mitochondrial changes at the proteome level and more clearly define the mechanisms and time course of troglitazone hepatotoxicity by using a previously characterized mouse model that is highly sensitized to troglitazone hepatotoxicity. Mice heterozygous in mitochondrial superoxide dismutase-2 ( Sod2 +/− ) were injected intraperitoneally with troglitazone (30 mg/kg/day) or vehicle daily for 2 or 4 weeks. Hepatic mitochondria were isolated, purified, and subjected to two-dimensional difference gel electrophoresis (2D-DIGE). We found that among the ~ 1500 resolved hepatic mitochondrial proteins, 70 exhibited significantly altered abundance after troglitazone treatment. MALDI-TOF/TOF MS/MS analysis revealed that early changes (2 weeks) included increased levels of heat shock protein family members (mortalin, HSP7C), Lon protease, and catalase, indicating induction of a mitochondrial stress response. In contrast, after 4 weeks, a number of critical proteins including ATP synthase β-subunit, aconitase-2, and catalase exhibited decreased abundance, and total protein carbonyls were significantly increased, suggesting uncompensated oxidative damage. Aconitase-2 (ACO2) was decreased at both time points, making this protein a potential sensitive and early biomarker for mitochondrial oxidant stress. These results show that, in this murine model of underlying clinically silent mitochondrial stress, superimposed troglitazone induces a two-stage response: an initial adaptive response, followed by a toxic response involving oxidant injury to mitochondrial proteins.

Uncoupling protein‐2 induction in rat hepatocytes after acute carbon tetrachloride liver injury

This study is focused on the role of UCP-2 in hepatic oxidative metabolism following acute CCl(4) administration to rats. UCP-2 mRNA, almost undetectable in the liver of controls, was significantly increased 24 h after CCl(4) administration, peaked at 72 h and then tended to disappear. UCP-2 protein, undetectable in controls, increased 48-72 h after CCl(4) treatment. Experiments with isolated liver cells indicated that in control rats UCP-2 was expressed in non-parenchymal cells and not in hepatocytes, whereas in CCl(4)-treated rats UCP-2 expression was induced in hepatocytes and was not affected in non-parenchymal cells. Addition of CCl(4) to the culture medium of hepatocytes from control rats failed to induce UCP-2 expression. Liver mitochondria from CCl(4)-treated rats showed an increase of H(2)O(2) release at 12-24 h, followed by a rise of TBARS. Vitamin E protected liver from CCl(4) injury and reduced the expression of UCP-2. Treatment with GdCl(3) prior to CCl(4), in order to inhibit Kupffer cells, reduced TBARS and UCP-2 mRNA increase in hepatic mitochondria. Our data indicate that CCl(4) induces the expression of UCP-2 in hepatocytes with a redox-dependent mechanism involving Kupffer cells. A role of UCP-2 in moderating CCl(4)-induced oxidative stress during tissue regeneration after injury is suggested.

Differential effects of selegiline on glucose synthesis in rabbit kidney-cortex tubules and hepatocytes: In vitro and in vivo studies

The action of selegiline, a selective and irreversible inhibitor of monoamine oxidase B, commonly applied in the therapy of Parkinson's disease, on glucose formation was investigated in isolated rabbit hepatocytes and kidney-cortex tubules, maintaining the whole body glucose homeostasis via gluconeogenic pathway activity. An intensive hepatic metabolism of selegiline resulted in formation of selegiline- N-oxide, desmethylselegiline, methamphetamine and amphetamine, whereas during slow degradation of the drug in freshly isolated renal tubules selegiline- N-oxide was mainly produced. At 100 μM concentration selegiline markedly diminished glucose synthesis in isolated renal tubules incubated with dihydroxyacetone or alanine + glycerol + octanoate (by about 60 and 30%, respectively), while at 5 μM concentration a similar degree of inhibition was achieved in renal tubules grown in primary culture under the same conditions (about 40 and 60%, respectively). Moreover, desmethylselegiline and selegiline- N-oxide considerably diminished glucose production in renal tubules whereas selegiline and its metabolites did not affect gluconeogenesis in hepatocytes. Contrary to control animals, following selegiline administration to alloxan-diabetic rabbits for 8 days (10 mg kg −1 body wt. daily) the blood glucose and serum creatinine levels were significantly diminished, suggesting a decrease in renal gluconeogenesis and improvement of kidney functions. Since in renal tubules selegiline induced a decline in the intracellular levels of gluconeogenic intermediates and ATP content accompanied by a decrease in oxygen consumption in both kidney-cortex and hepatic mitochondria it seems possible that its inhibitory action on renal gluconeogenesis might result from an impairment of mitochondrial function, while an intensive selegiline metabolism in hepatocytes causes decrease of its concentration and in consequence no inhibition of gluconeogenesis. In view of these observations it is likely that an increased risk of selegiline-induced hypoglycemia might be expected particularly in patients exhibiting an impairment of liver function and following transdermal administration of this drug, i.e. under conditions of increased serum selegiline concentrations.

Hyperammonemia Due to Valproic Acid in the Psychiatric Setting

Hyperammonemia Due to Valproic Acid in the Psychiatric Setting

Hyperammonemia Due to Valproic Acid in the Psychiatric Setting

In 1980 Coulter and Allen (1) reported the first case of hyperammonemia, to our knowledge, with otherwise normal hepatic function tests in a child with epilepsy treated with valproic acid. Since that time, there have been several additional case reports and studies within the neurology literature that have established hyperammonemia with otherwise normal hepatic function as a potential side effect of valproic acid, especially in children and adolescents (2). Settle (3) published the first case of hyperammonemia, to our knowledge, in a psychiatric setting in 1995. Several additional cases have followed it. Unfortunately, to date, to our knowledge, there has only been one prospective study published within the psychiatric literature (4). We present here a patient’s history that illustrates how the symptoms of a psychiatric disorder might make the diagnosis of hyperammonemic encephalopathy difficult.

Long-term fructose intake reduces oxidative defense and alters mitochondrial performance in mice

Mitochondria are involved in the production of reactive oxygen species and subsequently are very susceptible to oxidative stress. Fructose, a reducing monosaccharide, is widely used as a food ingredient and has a high potential to intensify oxidative stress through the Maillard reaction or autooxidation processes. This study presents a new insight into the long-term effects of fructose consumption on the mouse mitochondria. Examination of carbonyl levels, as a marker of protein oxidative modification, in 17-month-old ICR mice introduced to fructose solutions vs water, showed a significant decrease in hepatic carbonyl levels of fructose-treated animals although no changes in brain and skeletal mitochondria. The activity of manganese superoxide dismutase (MnSOD), the main mitochondrial antioxidative enzyme, was significantly decreased in all the tested tissues after fructose consumption. No correlation was found between the expression levels of MnSOD and its specific activity. These findings suggest that a defense mechanism is activated in hepatic mitochondria of fructose-treated mice, excluding MnSOD as an option. Electron microscopy examination indicated changes in mitochondrial morphology caused by prolonged drinking of fructose solutions. These findings support the concern directed at the extensive use of fructose in the food industry.

Biotransformation and cytotoxicity of a brominated flame retardant, tetrabromobisphenol A, and its analogues in rat hepatocytes

The metabolism and cytotoxic effects of tetrabromobisphenol A (TBBPA), a phenolic flame retardant, and its analogues were studied in freshly isolated rat hepatocytes and isolated hepatic mitochondria, respectively. The exposure of hepatocytes to TBBPA caused not only concentration (0.25–1.0 mM)- and time- (0–3 h) dependent cell death accompanied by the loss of cellular ATP, adenine nucleotide pools, reduced glutathione, and protein thiols, but also the accumulation of oxidized glutathione and malondialdehyde, indicating lipid peroxidation. TBBPA at a weakly toxic level (0.25 mM) was metabolized to monoglucuronide and monosulfate conjugates: the amounts of glucuronide rather than sulfate conjugate predominantly increased, accompanied by a loss of the parent compound, with time. In comparative effects based on cell viability, mitochondrial membrane potential and some toxic parameters, bisphenol A (BPA) was less toxic than TBBPA and tetrachlorobisphenol A (TCBPA), which are not significant differences in these parameters. In mitochondria isolated from rat liver, TBBPA and TCBPA caused an increase in the rate of State 4 oxygen consumption in the presence of succinate, indicating an uncoupling effect and a decrease in the rate of State 3 oxygen consumption in a concentration-dependent manner (5–25 µM). Taken collectively, our results indicate that (i) mitochondria are target organelles for TBBPA, which elicits cytotoxicity through mitochondrial dysfunction related to oxidative phosphorylation at an early stage and subsequently lipid peroxidation at a later stage; and (ii) the toxicity of TBBPA and TCBPA is greater than that of BPA, suggesting the participation of halogen atoms such as bromine and chlorine in the toxicity.

Orotic Acid Excretion and Arginine Metabolism

The urinary excretion of orotic acid, an intermediate in the pyrimidine biosynthetic pathway, is markedly increased in many inborn errors of the urea cycle and in a number of other disorders involving arginine metabolism. Carbamoyl phosphate, which accumulates within hepatic mitochondria in patients with ornithine transcarbamoylase deficiency, can diffuse to the cytosol and enter the pyrimidine pathway, resulting in greatly increased orotic acid production and excretion. This orotic aciduria also occurs in inborn errors of the mitochondrial ornithine/citrulline transporter, arginase, argininosuccinate synthetase, and argininosuccinate lyase. Increased orotic acid excretion is also found in a number of hypoargininemic states, such as lysinuric protein intolerance. However, orotic aciduria should not be used uncritically as an index of arginine deficiency because it is found in patients with arginase deficiency who exhibit hyperargininemia. Increased orotic acid excretion can also arise as a result of impairments of pyrimidine synthesis, whether brought about by a genetic defect (e.g., in UMP synthase) or by drugs that inhibit the terminal part of the pathway (e.g., allopurinol or 6-azauridine). When used appropriately, measurement of urinary orotic acid is a valuable tool for the study of many derangements of arginine metabolism, including arginine depletion, and to assess the efficacy of therapies used to replete this amino acid.

Apoptotic markers in the mitochondria, cytosol, and nuclei of brain cells during ammonia toxicity

The effects of toxic doses of ammonia on the induction of pro-apoptotic markers in rat brain cells were studied. It was found that neither induction of caspase-9 and caspase-3, nor changes in the membrane potential in nonsynaptic brain mitochondria, release of cytochrome c from mitochondria to cytosol, or apoptosis-inducing signals in the cell nuclei, were responsible for the ammonia toxicity in vivo. Thus, no evidence was found for any functional significance of mitochondria in cell death associated with acute hyperammonemia. The resistance of cell nuclei to ammonia-induced apoptosis could be caused either by a disordered translocation of the p53 protein from the cytosol into the nucleus or by translocation of its inactive form. The nonsynaptic brain mitochondria were also shown to be more resistant to the formation of nonspecific permeability pores and to Ca2+-induced swelling than cardiac and hepatic mitochondria and, as well, supported their membrane potential even under conditions of ammonia-stimulated production of active oxygen metabolites, excessive accumulation of Ca2+, oxidative stress, and impaired energy metabolism.

The Increase in Hepatic Uncoupling by Fenofibrate Contributes to a Decrease in Adipose Tissue in Obese Rats

Fenofibrate is a drug that has been suggested to inhibit weight gain by increasing the catabolism of fatty acid in the hepatic mitochondria. We hypothesized that fenofibrate induces an increase in energy expenditure in the hepatic mitochondria, which results in the reduction of adipose tissue. In this study we measured hepatic uncoupling protein (UCP)-2, -3, core temperatures and abdominal fat composition with MRI in Otsuka Long-Evans Tokushima Fatty rats. The fenofibrate group (n=7) was fed fenofibrate (320 mg/kg) mixed chow. The control group (n=7) was fed chow only. The body weight (531.6±7.6 g) of the fenofibrate group was significantly lower than that (744.3±14.9 g) of the control group (p<0.005). The areas of visceral and subcutaneous fat in the fenofibrate group (11.0±0.9 cm2, 4.2±0.3 cm2) were significantly less than those in the control group (21.0±0.7 cm2, 7.4±0.4 cm2) (p=0.046, respectively). The esophageal and rectal temperatures of the fenofibrate group (37.7±0.1℃, 33.1±0.2℃) were significantly higher than those of the control group (37.3±0.1℃, 32.2±0.1℃) (p=0.025, p=0.005). There was de novo expression of UCP-3 in the liver of the fenofibrate group. These data suggest that increased energy dissipation, via hepatic UCP-3 by fenofibrate, contribute to decreased weight gain in obese rats.

Subcutaneous vitamin E ameliorates liver injury in an in vivo model of steatocholestasis†‡

Several genetic metabolic liver diseases share the pathological features of combined steatosis and cholestasis, or steatocholestasis. The aims of this study were to develop and characterize an in vivo model for steatocholestasis and to evaluate the effects of an antioxidant treatment on liver injury, oxidative stress, and mitochondrial perturbations in this model. Obese and lean Zucker rats received intravenous (IV) injections of glycochenodeoxycholic acid (GCDC) and were killed 4 hours later. Liver enzymes were measured; the liver histology was assessed, and hepatic mitochondria were analyzed for mitochondrial lipid peroxidation. In separate experiments, rats received daily injections of subcutaneous (SQ) vitamin E before GCDC infusion. Bile acid-induced injury (serum AST and ALT and liver histology) was more severe in the obese rats than in the lean rats, characterized predominantly by extensive cell necrosis with minimal evidence of apoptosis. SQ vitamin E provided significant protection against IV GCDC-induced hepatic injury, in vitro GCDC-induced permeability transition, and cytochrome C and apoptosis-inducing factor release from isolated mitochondria. Steatosis sensitizes the liver to bile acid-induced necrotic hepatocyte injury, which is responsive to vitamin E therapy.

Effect of Tacrolimus on the Production of Oxygen Free Radicals in Hepatic Mitochondria

Objectives Cyclosporine (CsA) causes side effects that occur mainly in the kidney but also in the liver. Several reports have strongly suggested that the production of oxygen free radicals (OFRs) is a common mechanism of CsA toxicity. However, tacrolimus is believed to suppress the production of OFRs. Methods We obtained the mitochondrial fraction with 96% purity from rat liver using a sucrose density gradient solution. Zero to 100 μmol/L tacrolimus was incubated with the mitochondrial fraction for 6 hours at 37°C. OFRs were evaluated by measuring the fluorescent product from the oxidation of an oxidant-sensitive 2,7-dichlorefluorescein using a VICTOR3 multilabel counter. Results The fluorescence units for OFR production were increased as the time of exposure to tacrolimus passed from 1 to 6 hours. The fluorescence units in 0.1 μmol/L tacrolimus were 6.0 × 10 5 at 1 hour, 7.8 × 10 5 at 2 hours, 9.0 × 10 5 at 3 hours, 10.0 × 10 5 at 4 hours, 11.1 × 10 5 at 5 hours, and 11.4 × 10 5 at 6 hours. However, the fluorescence units were similar although the tacrolimus concentration increases from 0.1 to 100 μmol/L. Conclusions The results in this experiment suggested that tacrolimus induced the production of OFRs depending on the exposure time.

Conjugated linoleic acid and hepatic lipogenesis in mouse: role of the mitochondrial citrate carrier

Conjugated linoleic acid (CLA) is able to reduce adiposity by affecting lipid metabolism. In particular, CLA administration to mice reduces body fat mass with a concomitant lipid accumulation in the liver. We investigated the effects of CLA on the activity of the mitochondrial citrate carrier (CIC), which is implicated in hepatic lipogenesis. The transport activity of the CIC, measured both in intact mitochondria and in the proteoliposomes, progressively increased with the duration of CLA feeding. An increase in the CIC activity of approximately 1.7-fold was found in 16 week CLA-treated mice with respect to control animals. A kinetic analysis showed a 1.6-fold increase in the V(max) of citrate transport but no change in the K(m) value. Western blot experiments revealed an increase of approximately 1.7-fold in the expression of CIC after CLA treatment. A strict correlation between the increase in CIC activity and the stimulation of the cytosolic lipogenic enzymes was also found. These data indicate that the CIC may play a role in the onset of hepatic steatosis in CLA-fed mice by supplying the carbon source for de novo fatty acid synthesis.

Oxidative stress in experimental liver microvesicular steatosis: Role of mitochondria and peroxisomes

Hepatic microvesicular steatosis is a clinical manifestation seen in a number of liver diseases. Although the role of mitochondrial beta-oxidation in the development of the disease has been well studied, information on lipid peroxidative damage in liver subcellular organelles is scarce. The present study looked at oxidative stress in hepatic peroxisomes and microsomes in microvesicular steatosis, using an animal model of the disease. Rats were given i.p. injections of sodium valproate (700 mg/kg bodyweight) to induce microvesicular steatosis, which was confirmed by histology. Oxidative stress was evident in liver in steatosis, accompanied by structural and functional alterations in hepatic mitochondria. Alterations in lipid composition, with decreased phosphatidyl choline and ethanolamine and increased lysophosphatidyl choline and ethanolamine, were seen. An increase in triglyceride content was also seen. In addition, increased lipid peroxidation was also evident in peroxisomes and microsomes from steatotic rats. Pretreatment with clofibrate results in partial reversal of changes produced by valproate. These results suggest that in addition to impaired mitochondrial beta-oxidation, oxidative stress is also seen in the hepatic peroxisomes and microsomes during microvesicular steatosis.

For Dioxin-induced Birth Defects, Mouse or Human CYP1A2 in Maternal Liver Protects whereas Mouse CYP1A1 and CYP1B1 Are Inconsequential

Dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin) induces cleft palate and hydronephrosis in mice, when exposed in utero; these effects are mediated by the aryl hydrocarbon receptor. The Cyp1a1, Cyp1a2, and Cyp1b1 genes are up-regulated by the aryl hydrocarbon receptor. To elucidate their roles in dioxin-induced teratogenesis, we compared Cyp1a1(-/-), Cyp1a2(-/-), and Cyp1b1(-/-) knock-out mice with Cyp1(+/+) wild-type mice. Dioxin was administered (25 microg/kg, gavage) on gestational day 10, and embryos were examined on gestational day 18. The incidence of cleft palate and hydronephrosis was not significantly different in fetuses from Cyp1a1(-/-), Cyp1b1(-/-), and Cyp1(+/+) wild-type mice. To fetuses carried by Cyp1a2(-/-) dams, however, this dose of dioxin was lethal; this effect was absolutely dependent on the maternal Cyp1a2 genotype and independent of the embryonic Cyp1a2 genotype. Dioxin levels were highest in adipose tissue, mammary gland, and circulating blood of Cyp1a2(-/-) mothers, compared with that in the Cyp1(+/+) mothers, who showed highest dioxin levels in liver. More dioxin reached the embryos from Cyp1a2(-/-) dams, compared with that from Cyp1(+/+) dams. Fetuses from Cyp1a2(-/-) dams exhibited a approximately 6-fold increased sensitivity to cleft palate, hydronephrosis, and lethality. Using the humanized hCYP1A1_1A2 transgenic mouse (expressing the human CYP1A1 and CYP1A2 genes in the absence of mouse Cyp1a2 gene), the teratogenic effects of dioxin reverted to the wild-type phenotype. These data indicate that maternal mouse hepatic CYP1A2, by sequestering dioxin and thus altering the pharmacokinetics, protects the embryos from toxicity and birth defects; substitution of the human CYP1A2 trans-gene provides the same protection. In contrast, neither CYP1A1 nor CYP1B1 appears to play a role in dioxin-mediated teratogenesis.

Prepartal Plane of Nutrition, Regardless of Dietary Energy Source, Affects Periparturient Metabolism and Dry Matter Intake in Holstein Cows

Previous research in our laboratory showed that dietary fat supplementation during the dry period was associated with decreased peripartum hepatic lipid accumulation. However, fat supplementation decreased dry matter (DM) intake and thereby confounded results. Consequently, 47 Holstein cows with body condition scores (BCS)≤3.5 at dry-off were used to determine whether source or amount of energy fed to dry cows was responsible for the decreased hepatic lipid content. Moderate grain- or fat-supplemented diets [1.50 Mcal of net energy for lactation (NEL)/kg] were fed from dry-off (60 d before expected parturition) to calving at either ad libitum (160% of NEL requirement) or restricted (80% of NEL requirement) intakes. Postpartum, cows were fed a single lactation diet for ad libitum intake and performance was measured for 105 d. Prepartum intakes of DM and NEL were significantly lower for feed-restricted cows as designed. During the first 21 d postpartum, previously restricted cows had higher intakes of DM and NEL. Body weights and BCS were lower prepartum for restricted cows but groups converged to similar nadirs postpartum. Restricted-fed cows had lower concentrations of glucose and insulin and increased concentrations of NEFA in plasma during the dry period. Peripartum NEFA rose markedly for all treatments but were higher postpartum for cows previously fed ad libitum. Plasma concentrations of NEFA and BHBA remained lower in cows restricted-during the dry period. Postpartum concentrations of total lipid and triglyceride in liver were lower in cows previously feed-restricted. Across dietary treatments, activity of carnitine palmitoyltransferase (CPT) in hepatic mitochondria was lowest at−21 d, highest at 1 d, and decreased at 21 and 65 d relative to parturition. The activity of CPT at d 1 tended to be higher for previously feed-restricted cows; thereafter, CPT activity declined more rapidly than in cows fed ad libitum. Nutrient intake during the dry period had more pronounced effects on peripartal lipid metabolism and DMI than did composition of the prepartum diet.

Stimulation Effect of Lithium on the Metabolic Activity of Liver Tissue Mitochondria Measured by Microcalorimetry

The effect of Li(I) on the metabolism of mitochondria isolated from Carassius auratus liver tissue was investigated by microcalorimetric method to provide evidence for mitochondria hypothesis of bipolar disorder (BPD) and to explore therapeutic mechanism of drug for treatment of BPD. Obvious stimulation induced by Li(I) on mitochondria metabolism was reflected by power-time (P-t) curves. The power-time curves of hepatic mitochondria metabolism without Li(I) could be divided into four parts: lag phase, active recovery phase, stationary phase, and decline phase. When Li(I) was added, the second heat peak occurred in a concentration-dependent sequence. Considering the first heat peak on the P-t curves, Li(I) in the range of therapeutic and lower concentration induced slight alterations in comparison with the characteristic heat peak observed in the control. However, Li(I) above the therapeutic concentration resulted in significant changes. Heat output increased with the concentration of Li(I), but the rate constant (k2) and the maximum heat power (Pmax2) for the second heat peak reached maximum value in the range of therapeutic concentration. Mechanism of activation of mitoKatp was suggested and discussed.