Inhibition of oxidative phosphorylation in hepatic and cerebral mitochondria of sodium valproate-treated rats

Rats were treated with intraperitoneal injections of sodium valproate (VPA), either acutely, one injection VPA 200 mg/kg, or chronically, VPA 600 mg/kg/day for 5 days, and the oxygen consumption, MO2, of isolated hepatic and cerebral mitochondria measured. For hepatic mitochondria, Stade IV MO2 decreased by more than 20%, and Stage III MO2 by more than 50%, in the presence of succinate or glutamate-malate substrates. A decoupling agent intensified this inhibition. With cerebral mitochondria, the effects were similar but weaker, for pyruvate-malate or glutamate-malate substrates. These findings suggest that VPA, a short-chain fatty acid, may affect the properties of the internal mitochondrial membrane, although an action on substrate carriers, or on indispensable mitochondrial metabolites, is not excluded. Inhibition of oxidative phosphorylation cannot, however, alone account for hepatotoxicities seen in VPA-treated subjects. These are rare, whereas inhibition of mitochondrial respiration by VPA is consistently observed.     

Carnitine does not improve weight loss outcomes in valproate-treated bipolar patients consuming an energy-restricted, low-fat diet

Objectives:  Carnitine deficiency impairs fatty acid β -oxidation and may partly explain weight gain in valproate-treated patients. The aim of this study was to determine whether l -carnitine supplementation improves weight loss outcomes in bipolar patients taking sodium valproate.
Methods:  Sixty bipolar patients with clinically significant weight gain thought to be related to sodium valproate, who had been taking sodium valproate for ≥6 months, were randomized to l -carnitine (15 mg/kg/day) or placebo for 26 weeks, in conjunction with a moderately energy-restricted, low-fat diet. The primary outcome measure was weight change.
Results:  l -carnitine had no effect on mean weight loss compared with placebo (−1.9 kg versus − 0.9 kg) ( F  = 0.778, df = 1,58, p = 0.381). The number of people in each group able to lose any weight was identical (      = 0, p = 1.0); more patients in the carnitine group (nine versus five) achieved a clinically significant weight loss (≥5%) but this was not statistically significant (p = 1.0, Fisher's exact test).
Conclusions:  At the dose prescribed in this study carnitine supplementation did not improve weight loss outcomes in valproate-treated bipolar patients consuming an energy-restricted, low-fat diet.     

Carnitine treatment for stroke in rats

Changes in the concentrations of carnitine, long-chain acylcoenzyme A, and long-chain acylcarnitine in ischemic myocardium parallel those in ischemic brain. Since carnitine treatment reverses these changes and improves function in ischemic hearts, we examined whether carnitine given to rats before focal cerebral ischemia (produced by tandem right common carotid artery and middle cerebral artery occlusion) alters infarct volume in four separate experiments. Mannitol was used to control for the osmotic effect of carnitine on brain edema in one experiment. While carnitine was found to significantly decrease infarct volume compared with saline in one experiment (p less than 0.05, Student's t test), this result could not be replicated in the subsequent three experiments. Because the positive treatment effect was not reproducible despite similar experimental conditions, the result of the first experiment was attributed to a type I error. Mannitol also showed no significant effect on infarct volume. This study emphasizes the need for concurrent controls with each group of treated animals and the need for replicating the results of a single experiment when testing for drug efficacy in animal models of focal cerebral ischemia.     

Alterations of urinary acetylcarnitine in valproate-treated rats: the effect of L-carnitine supplementation.

Urinary excretion of acetylcarnitine was measured by high-performance liquid chromatography in two experimental groups of valproate-treated rats. In the urine of mature rats weighing 180 to 200 g treated with valproate (500 mg/kg/day), acetylcarnitine levels were higher than those in controls on days 4 and 7, while L-carnitine-supplemented rats showed lower levels than the valproate group. The valproate-treated rats showed an increased acetylcarnitine/acylcarnitine ratio on and after day 4, while the L-carnitine-supplemented rats showed no significant change compared to the controls on any days. In the urine of immature rats weighing 80 to 90 g treated with valproate (50 mg/kg/day), acetylcarnitine levels were increased after the 14th day of treatment. These results suggest that an increase in urinary acetylcarnitine occurs when small doses of valproate are administered for a longer time. We speculate that increased acetylcarnitine is not a product of beta-oxidation in mitochondria, because L-carnitine supplementation decreases the acetylcarnitine levels. Although the mechanism of acetylcarnitine excretion during valproate administration is not clear, L-carnitine supplementation is effective in decreasing the level of urinary acetylcarnitine and keeping the acetylcarnitine/acylcarnitine ratio normal.     

Hypothalamic control of liver glycogen metabolism in adult and aged rats

The regulatory function of the hypothalamus in the metabolism of liver glycogen was investigated by analyzing the changes in the activities of the rate-limiting enzymes implicated in glycogen breakdown (glycogen phosphorylase) and synthesis (glycogen synthetase), after electrical stimulation of the ventromedial hypothalamic nucleus (VMH) and the lateral hypothalamic nucleus (LH) of rats. Electrical stimulation of the VMH induced rapid and marked increase in the content of the active form of phosphorylase in the liver, but it did not affect the synthetase. Stimulation of the LH, on the other hand, caused an increase in the level of the active form of synthetase, but produced little change in the phosphorylase activity. The concentration of insulin in the portal blood decreased significantly on stimulation of the VMH, but did not change appreciably on stimulation of the LH. The ability of the hypothalamus to control liver glycogen metabolism was found to be impaired in 2-year-old rats: the magnitude and duration of the early increase in active phosphorylase in response to VMH stimulation were reduced, and the response of synthetase to LH stimulation was slow.The results are discussed from the viewpoint that the VMH and LH are the centers for controlling irect neural and neural-hormonal regulations of liver glycogen metabolism. It is concluded that the VMH-splanchnic nerve pathway is an important neural component for controlling glycogenolysis and glucose output by the liver, and that the LH-vagal pathway is an opposing neural component for controlling glycogenesis in the liver.     

高压氧对脑缺血性老龄大鼠海马神经元超微结构的影响及线粒体形态计量分析

目的观察高压氧(Hyperbaric Oxygen,HBO)对老龄大鼠脑缺血/再灌注(Cerebral Ischemia/Reperfusion,CI/R)后海马神经元超微结构的影响.方法建立老龄大鼠不完全性脑缺血动物模型.不进行HBO处置正常对照组(A组)、脑缺血30min再灌注6h(B组)、12h(C组)、24h(D组)、48h(E组)、12d(F组)和22d(G组).HBO处置组将大鼠按不同的再灌注时程暴露于0.25MPa(2.5ATA)高压氧环境中,每天1次,每次给氧30min×2(间歇10min),连续10次(1疗程)和20次(2疗程).1疗程组老龄正常对照组(A1组)、缺血30min再灌注6h(B1组)、12h(C1组)、24h(D1组)、48h(E1组);2疗程组老龄正常对照组(A 2组)、缺血30min再灌注6h(B2组)、12h(C2组)、24h(D2组)、48h(E2组).用透射电镜观察海马神经元的超微结构,通过计算机图像分析系统对线粒体形态计量分析.结果 A组、A1组和A2组海马的超微结构基本正常;CI/R 6h组1疗程和2疗程超微结构改变不明显;CI/R 24h组1疗程线粒体肿胀、嵴模糊,部分粗面内质网扩张、脱颗粒,2疗程后基本恢复正常;CI/R 48h组1疗程体积缩小,细胞核内异染色质增多、边聚,核周间隙增宽,线粒体肿胀、密度降低、嵴模糊,核糖体减少,2疗程同1疗程基本相同;CI/R 24h组、CI/R 48h组、CI/R 12d和22d组神经元细胞浆空化,部分神经元坏死,可见凋亡细胞.与A组比较,E组、F组、G组、E1组和E2组线粒体体密度、数密度、比表面和嵴膜表面密度明显减少(P＜0.05),线粒体平均体积和平均截面积明显增大(P＜0.05),B1组和B2组各参数与A组无明显差异.结论脑缺血再灌注24h以内,HBO对海马神经元具有保护性作用,脑缺血再灌注24h后,HBO对海马神经元的保护性作用不明显.     

A morphometric study of muscle mitochondria in cytochrome c oxidase deficiency

Quantitative analysis of mitochondrial size and its percentage of total fibre volume in different muscle fibre types was performed on biceps brachii muscles of controls aged from 9 months to 10 years, and patients aged from 8 months to 14 years, with cytochrome c oxidase (CCO) deficiency confirmed by both histochemical and biochemical analyses. The disease was classified into 2 subgroups: one not containing ragged-red fibres (RRF) (group I), and one containing RRF (group II). Relationship between type 1 and 2 fibres in mitochondrial size and percentages of total fibre volume showed significant differences in the controls and group I. A comparison of the controls and group I did not show significant differences in mitochondrial size, but abnormally enlarged mitochondria were occasionally observed in the latter. In group I, statistical differences were observed in mitochondrial percentage of total fibre volume, though these differences remained in the control range, suggesting the presence of mild morphological changes in mitochondria on electron microscopy. In group II, mitochondrial size and its percentage of total fibre volume were markedly increased in both type 1 and 2 fibres, with no statistical differences observed between the 2 fibre types.     

Alterations of mitochondria in metabolic diseases. Carnitine deficiency, carnitine palmitoyltransferase deficiency and beta oxidation

Recently a number of defects of fatty acid transport and beta-oxidation have been described. Primary carnitine deficiency presents itself as muscle carnitine deficiency, systemic carnitine deficiency or a cardiomyopathic subtype. Another abnormality of fatty acid transport is due to inner carnitine palmitoyl transferase deficiency, usually associated with a myoglobinuric phenotype. Long chain, medium and short chain acyl-CoA-dehydrogenase defects are usually associated to Reye's syndrome, encephalopathy, organic aciduria and secondary carnitine deficiency.     

Carnitine stimulation of pyruvate dehydrogenase complex (PDHC) in isolated human skeletal muscle mitochondria

L-carnitine stimulated CO2 production from 1-14C pyruvate in mitochondria from human skeletal muscle nearly twofold. A comparable increase in the pyruvate dehydrogenase complex (PDHC) activity was seen. Moreover, in the presence of L-carnitine and at pyruvate concentration greater than 0.25 mM, this effect was associated with a marked increase of acetylcarnitine synthesis. Deoxycarnitine, an inhibitor of carnitine acetyltransferase (CAT), partially reversed the effect of carnitine on PDHC activity. The stimulatory effect of carnitine on PDHC activity in human mitochondria is mediated by the modulation of the intramitochondrial acetyl-CoA/CoASH ratio.     

Functional and morphometric study of the liver in motor neuron disease

Summary In routine liver function tests, 23 of 44 patients with motor neuron disease (MND) had abnormal findings, and there was disturbance of unconjugated bilirubin metabolism in 10 of the 33 patients tested. Liver-biopsy specimens from 10 MND patients were compared by electron microscopic examination with specimens from age-matched controls who had chronic persistent hepatitis. The MND patients had a higher incidence of intramitochondrial inclusions, less abundant mitochondria in a given area of cytoplasm and enlarged mitochondria. Electron-probe X-ray microanalysis of hepatocytic lysosomes found copper in 8 of 13 MND patients, but not in the controls. These findings suggest that the pathogenetic processes in MND may involve not only motor neurons but also hepatic cells.     

Dehydroepiandrosterone (DHEA) treatment stimulates oxidative energy metabolism in the cerebral mitochondria from developing rats

Effects of treatment with dehydroepiandrosterone (DHEA) (0.2 or 1.0mg/kg body weight for 7 days) on oxidative energy metabolism in cerebral mitochondria from developing and young adult rats were examined. Treatment with DHEA did not change the body weight of developing rats but resulted in increase in the brain weight in 5 week group. In young adult rats the body weight increased following treatment with 1.0mg DHEA. State 3 and state 4 respiration rates with all the substrates increased following DHEA treatment, the effect being more pronounced in the developing rats. State 4 respiration rates were stimulated to variable extents. Contents of cytochromes aa(3) and b increased following DHEA treatment and once again the effect was more pronounced in the developing rats. DHEA treatment marginally changed the content of cytochromes c+c(1). In the developing rats the ATPase activity and the levels of dehydrogenases increased significantly by DHEA treatment. Results of our studies have shown that treatment with exogenous DHEA accelerates the process of maturation of cerebral mitochondria thus emphasizing the role of DHEA in brain development in postnatal life.     

促红细胞生成素对颅脑损伤后线粒体ATP酶活性及自由基代谢的影响

目的 探讨重组促红细胞生成素(mEPO)对大鼠颅脑损伤后脑组织线粒体ATP酶、超氧化物歧化酶(SOD)的活性及丙二醛(MDA)水平的影响. 方法 建立大鼠自由落体脑挫裂伤模型,伤后立即腹腔注射rhEPO,采用生化检测的方法 分别测定治疗后6 h、12 h、24 h和48 h及各自损伤对照组大鼠脑组织线粒体ATP酶和SOD的活性以及MDA水平. 结果 rhEPO治疗后12 h、24 h和48 h大鼠脑组织线粒体ATP酶和SOD活性均明显高于各自时间点损伤对照组.而MDA水平则明显低于各自时间点损伤对照组,差异均有统计学意义(P<0.05). 结论 rhEPO可以通过影响线粒体功能而减轻大鼠创伤性脑损伤后的继发性脑损害,从而改善预后.     

Choroid plexus and ageing in rats: a morphometric and ultrastructural study

Choroid plexuses (CP) are intraventricular structures involved in the production of cerebrospinal fluid (CSF) and in the synthesis and transport of numerous CSF components. Age-related modifications of the CP structure are still ill defined. We performed an ultrastructural and morphometric study of ageing CP in nine Sprague-Dawley rats 6, 18 and 30 months of age. Epithelial cells of CP villi were cubic in shape at 6 months, more dome-like at 18 months, and significantly flattened at 30 months of age. Epithelial basement membranes were thin and regular at 6 months, significantly thicker at 18 months and thicker and irregular at 30 months. Intravillous stroma increased nonhomogeneously with age. The ageing of CP in rats is characterized morphologically by epithelial atrophy, irregular fibrosis of the stroma and a thickening of epithelial basement membranes. These modifications suggest an alteration of secretory and filtrating functions in ageing CP.     

Physiological growth is associated with esophageal morphometric and biomechanical changes in rats

Esophageal geometry and biomechanical changes were studied during physiological growth in rats aged 1-32 weeks. Histological examination was done after the biomechanical study. The esophageal dimensions increased many-fold from 1-32 weeks, e.g. the weight per unit length increased six-fold and the wall cross-sectional area increased eight-fold. The inner and outer circumferential length of the mucosa and muscle, and the thickness and area of the layers increased as function of age. The opening angle was approximately 140 degrees at age 1 and 2 weeks and gradually decreased to approximately 80 degrees after 16 weeks. The circumferential and longitudinal stress-strain curves were exponential. The circumferential stress-strain curves shifted from left to the right up to 4 weeks of age (P < 0.001) where after no further change was observed, i.e. the esophagus became more compliant during the first 4 weeks of life. The longitudinal stress-strain curves shifted from left to the right up to 16 weeks of age (P < 0.001), i.e. the esophagus became more compliant longitudinally during the first 16 weeks of life. Bi-axial stress-strain analysis with determination of mechanical tissue constants showed that the esophagus was stiffer in the longitudinal direction than in the circumferential direction. In conclusion, a pronounced morphometric and biomechanical remodelling was observed in the rat esophagus during physiological growth. The observed changes likely reflect the development of the physiological function of the esophagus since for other tissues the function dictates the form of the tissue, and growth and remodelling depend on the mechanical loading.     

Effects of octanoate on rat brain and liver mitochondria

Octanoate increased state 3 and state 4 respiration in rat liver mitochondria. The respiratory control rates decreased because state 4 was disproportionately affected. The ADP:O ratio was not affected. Octanoate produced a fall in the protonmotive force (delta p) of 30 mV during state 3 and state 4. The mitochondrial inner membrane proton conductance (Cm,H+) increased twofold during state 4. Similar effects were observed in polarographic assays of brain mitochondria, but measurements of delta p and Cm,H+ were not possible. Octanoate produces loose coupling in isolated mitochondria. This effect may play a role in the pathogenesis of Reye's syndrome.     

The hypothalamus and liver metabolism

Summary The results of our experiments on the influence of the hypothalamus upon liver metabolism in rabbits can be summarized as follow. The hypothalamus regulates the blood glucose and serum lipid content. By electrical stimulation of theb-sympathetic zone (the medial hypothalamic area), the liver glycogen decreases remarkably, while electrical stimulation of the c-parasympathetic zone (the lateral hypothalamic area) causes an insignificant change. The hypothalamus can also have a considerable effect upon the protein metabolism of the liver. The activities of tryptophan pyrrolase, tyrosine transaminase and alanine transaminase in rabbit liver are elevated by electrical stimulation of the sympathetic zone in normal rabbits and even in adrenalectomized rabbits. When the splanchnic nerve is stimulated electrically, the activities of glycogen phosphorylase, glucose-6-phosphatase and tryptophan pyrrolase of rabbit liver increase markedly. These results suggest that the hypothalamic influence upon liver enzymes is of neural nature.

---

Zusammenfassung Die vorliegenden experimentellen Ergebnisse über den Einfluß des Hypothalamus auf den Leberstoffwechsel bei Kaninchen können folgendermaßen zusammengefaßt werden: Der Hypothalamus regelt den Blutzucker- und Serumlipidgehalt. Durch elektrische Reizung derb-sympathischen Zone (des medialen Bereiches des Hypothalamus) sinkt der Glykogengehalt der Leber merklich ab, während eine elektrische Reizung der c-parasympathischen Zone (des lateralen Bereiches des Hypothalamus) nur zu unbedeutenden Veränderungen führt. Der Hypothalamus kann ebenfalls erheblich auf den Eiweißstoffwechsel der Leber einwirken. Die Aktivitäten der Tryptophan-Pyrrolase, Tyrosin-Transaminase und der Alanin-Transaminase in der Kaninchenleber werden durch elektrische Reizung der sympathischen Zone bei normalen und sogar bei adrenalektomierten Kaninchen erhöht. Wurde der Nervus splanchnicus elektrisch gereizt, so stiegen die Aktivitäten der Glykogen-Phosphorylase, der Glukose-6-Phosphatase und der Tryptophan-Pyrrolase in der Kaninchenleber deutlich an. Diese Ergebnisse lassen vermuten, daß der Hypothalamus die Leberenzyme auf neuralem Weg beeinflußt.

---

Résumé L'hypothalame et le métabolisme du foie. Le résultat de nos expériences concernant l'influence de l'hypothalame sur le métabolisme du foie chez les lapins peut être résumé comme suit. L'hypothalame règle le glucose du sang et les lipides contenus dans le sérum. Par stimulation électrique de la zone sympathétique B (l'aire hypothalamique moyenne) le glycogène du foie décroît considérablement tandis que la stimulation électrique de la zone parasympathétique C (l'aire hypothalamique latérale) provoque un changement insignifiant. L'hypothalame peut exercer aussi un effet considérable sur le métabolisme de la protéine du foie. Les activités de la pyrrolase de tryptophane, de la transaminase de tyrosine et de la transaminase d'alanine dans le foie des lapins, sont accrues par la stimulation électrique de la zone sympathétique des lapins normaux et même chez les lapins dont on a enlevé les capsules surrénales. Dans le cas où le nerf splanchnique est stimulé électriquement, les activités de phosphorylase de glycogène, de phosphatase de glucose 6 et de pyrrolase de tryptophane du foie de lapin augmentent sensiblement. Ces résultats suggèrent une nature neurale de l'influence de l'hypothalame sur les enzymes du foie.

---

---

With 1 Figure