Effect of Melatonin Administration on Mitochondrial Activity and Oxidative Stress Markers in Patients with Parkinson’s Disease

Mitochondrial dysfunction and oxidative stress are extensively linked to Parkinson’s disease (PD) pathogenesis. Melatonin is a pleiotropic molecule with antioxidant and neuroprotective effects. The aim of this study was to evaluate the effect of melatonin on oxidative stress markers, mitochondrial complex 1 activity, and mitochondrial respiratory control ratio in patients with PD. A double-blind, cross-over, placebo-controlled randomized clinical trial study was conducted in 26 patients who received either 25 mg of melatonin or placebo at noon and 30 min before bedtime for three months. At the end of the trial, in patients who received melatonin, we detected a significant diminution of lipoperoxides, nitric oxide metabolites, and carbonyl groups in plasma samples from PD patients compared with the placebo group. Conversely, catalase activity was increased significantly in comparison with the placebo group. Compared with the placebo group, the melatonin group showed significant increases of mitochondrial complex 1 activity and respiratory control ratio. The fluidity of the membranes was similar in the melatonin group and the placebo group at baseline and after three months of treatment. In conclusion, melatonin administration was effective in reducing the levels of oxidative stress markers and restoring the rate of complex I activity and respiratory control ratio without modifying membrane fluidity. This suggests that melatonin could play a role in the treatment of PD.

The effect of sulodexide on placental mitochondria function in rats with experimental preeclampsia

Substitution of drinking water for 1.8% NaCl in pregnant rats caused a pronounced increase in arterial pressure by 24,3% and urinary protein by 117% to day 21 of pregnancy. State 4 respiration of isolated placental mitochondria in the group of negative control was 3- and 1.5-fold higher with malate/glutamate and succinate as substrates than in placental mitochondria isolated from uncomplicated pregnant animals. This led to a decrease of the respiratory control ratio. These results suggest that development of experimental preeclampsia is accompanied by mitochondrial dysfunction through uncoupling of oxidative phosphorylation. Daily administration of sulodexide to females with experimental preeclampsia (EP) per os at a dose of 30 LE during the whole period of gestation decreased manifestations of the disease as evidenced by a slight increase in blood pressure (by 8,6%) and less pronounces increase in urinary protein (by 58,9%). Sulodexide decreased development of mitochondrial dysfunction in EP rats as shown a decrease of non-stimulated ADP respiration with malate/glutamate and succinate (4.5- and 2.5-fold, respectively) as compared with the negative control group and the corresponding increase in the respiratory control ratio (2.5- and 1.5-fold, respectively). Thus, sulodexide reduces uncoupling of oxidative phosphorylation and enhances the functional activity of mitochondria in EP animals, possibly due to its antioxidant and endotelioprotective effects.

Cardiac, skeletal, and smooth muscle mitochondrial respiration: are all mitochondria created equal?

Unlike cardiac and skeletal muscle, little is known about vascular smooth muscle mitochondrial respiration. Therefore, the present study examined mitochondrial respiratory rates in smooth muscle of healthy human feed arteries and compared with that of healthy cardiac and skeletal muscles. Cardiac, skeletal, and smooth muscles were harvested from a total of 22 subjects (53 ± 6 yr), and mitochondrial respiration was assessed in permeabilized fibers. Complex I + II, state 3 respiration, an index of oxidative phosphorylation capacity, fell progressively from cardiac to skeletal to smooth muscles (54 ± 1, 39 ± 4, and 15 ± 1 pmol·s−1·mg−1, P < 0.05, respectively). Citrate synthase (CS) activity, an index of mitochondrial density, also fell progressively from cardiac to skeletal to smooth muscles (222 ± 13, 115 ± 2, and 48 ± 2 μmol·g−1·min−1, P < 0.05, respectively). Thus, when respiration rates were normalized by CS (respiration per mitochondrial content), oxidative phosphorylation capacity was no longer different between the three muscle types. Interestingly, complex I state 2 normalized for CS activity, an index of nonphosphorylating respiration per mitochondrial content, increased progressively from cardiac to skeletal to smooth muscles, such that the respiratory control ratio, state 3/state 2 respiration, fell progressively from cardiac to skeletal to smooth muscles (5.3 ± 0.7, 3.2 ± 0.4, and 1.6 ± 0.3 pmol·s−1·mg−1, P < 0.05, respectively). Thus, although oxidative phosphorylation capacity per mitochondrial content in cardiac, skeletal, and smooth muscles suggest all mitochondria are created equal, the contrasting respiratory control ratio and nonphosphorylating respiration highlight the existence of intrinsic functional differences between these muscle mitochondria. This likely influences the efficiency of oxidative phosphorylation and could potentially alter ROS production.

Effect of hyperbaric oxygen therapy on liver function during intermittent ischemia

PURPOSE: To analyze the effects of hyperbaric oxygen therapy on liver function in rats previously subjected to ischemia and reperfusion. METHODS: A randomly distribution of 23 Wistar rats was conducted into three groups: SHAM, animals subjected to surgical stress without restricting blood flow by clamping the hepatic pedicle, IR, rats underwent hepatic vascular occlusion intermittently for two complete cycles of 15 minutes of ischemia followed by 5 min of reperfusion, IR / HBO, rats underwent hepatic pedicle clamping and thereafter exposed to hyperbaric oxygen pressure of 2 absolute atmospheres for 60 minutes. We evaluated liver function through mitochondrial function, determined by the stages 3 and 4 of respiration, respiratory control ratio (RCR) and mitochondrial permeability transition (Swelling). Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were also quantified . We analyzed the results using the Mann-Whitney test and were considered significant all results with p <0.05. RESULTS: There were significant differences between the results of stage 3 in SHAM vs IR group ; of the stage 4 in the groups IR vs SHAM and SHAM vs IR /HBO; of the Respiratory Control Ratio (RCR) in the group IR vs IR / HBO ; of alanine aminotransferase in the groups IR vs SHAM , SHAM vs IR/HBO and IR vs IR / HBO; aspartate aminotransferase in the groups SHAM vs IR and SHAM vs IR / HBO. CONCLUSION: The whole analysis of the mitochondiral function indicators permits us to conclude that the hyperbaric oxygen therapy acted as a protective agent of the mitochondrial function, minimizing the ischemia-reperfusion injury of the hepatic parenchyma.

Effects of hyperbaric oxygen (HBO), as pre-conditioning in liver of rats submitted to periodic liver ischemia/reperfusion

PURPOSE: to assess the effect of hyperbaric oxygen (HBO) as pre-conditioning on periodic liver ischemia/reperfusion injury. METHODS: Thirty-six male Wistar rats were divided into 4 groups (SHAM, I/R , HBO-I/R and CONTROL). The surgical technique consisted of total clamping of the hepatic pedicle for 15 min followed by twice repeated reperfusion for 5 min (unclamping). HBO was applied in a collective chamber (simultaneous exposure of 4 rats) directly pressurized with oxygen at 2 ATA for 60 min. Hepatic mitochondrial function was determined using samples of the median lobe obtained after exactly 5 min of reperfusion for the analysis of mitochondrial respiration based on the determination of states 3 and 4, the respiratory control ratio and the transition of mitochondrial permeability (mitochondrial swelling).Data were analyzed by the Mann-Whitney test and the level of significance was set at p < 0.05. RESULTS: There was a statistically significant difference (p< 0.05) in state 3 between the CONTROL and I/R and HBO-I/R groups, in state 4 between the CONTROL and I/R and HBO-I/R groups; in respiratory control ratio (RCR) between the CONTROL and I/R and HBO-I/R groups and between the CONTROL and Sham groups, and in mitochondrial swelling between the CONTROL and I/R and HBO-/R groups and between the Sham and I/R and HBO-I/R groups. CONCLUSION: In this process of periodic ischemia and reperfusion, hyperbaric pre-conditioning did not improve significantly hepatic mitochondrial function.

Accumulation of Exogenous Amyloid-BetaPeptide in Hippocampal Mitochondria Causes Their Dysfunction: A Protective Role for Melatonin

Amyloid-beta(Aβ) pathology is related to mitochondrial dysfunction accompanied by energy reduction and an elevated production of reactive oxygen species (ROS). Monomers and oligomers of Aβ have been found inside mitochondria where they accumulate in a time-dependent manner as demonstrated in transgenic mice and in Alzheimer’s disease (AD) brain. We hypothesize that the internalization of extracellular Aβ aggregates is the major cause of mitochondrial damage and here we report that following the injection of fibrillar Aβ into the hippocampus, there is severe axonal damage which is accompanied by the entrance of Aβ into the cell. Thereafter, Aβ appears in mitochondria where it is linked to alterations in the ionic gradient across the inner mitochondrial membrane. This effect is accompanied by disruption of subcellular structure, oxidative stress, and a significant reduction in both the respiratory control ratio and in the hydrolytic activity of ATPase. Orally administrated melatonin reduced oxidative stress, improved the mitochondrial respiratory control ratio, and ameliorated the energy imbalance.

Preparation of Rat Gingival Mitochondria with an Improved Isolation Method

In order to establish a method of obtaining rat gingival mitochondria (Mt), Mt fractions were prepared in various combinations of homogenizing time with collagenase concentration. Rat gingival tissues were excised, minced, treated with collagenase, homogenized, and subjected to differential centrifugation rates. Both the respiratory control ratio (RCR) and adenosine diphosphate/oxygen (ADP/O) ratio of the Mt fraction prepared in a combination of 40, 50, or 60 sec homogenization with collagenase in a concentration range of 0.115%–0.130% (w/v) were measured. The values for the RCR and ADP/O ratio of the Mt fraction obtained in an optimal condition was and , respectively. These results suggest that Mt of fairly high quality can be obtained through this refined combination of the homogenizing time and collagenase concentration.

Protective role of pinacidil against adrenaline-induced myocardium injury in guinea pig liver mitochondria

We investigated the role of the ATP-sensitive potassium channel opener pinacidil and blocker glibenclamide on guinea pig liver mitochondrial function, and a possible significance of pinacidil in the pharmacological treatment during myocardium dystrophy. First, a series of experiments was performed to determine the effect of pinacidil and glibenclamide on mitochondrial oxygen consumption. We found that pinacidil increased the rate of mitochondrial respiration for FAD-generated substrate (succinate oxidation), but was most effective for α-ketoglutarate oxidation with enhancement of respiratory control ratio. Oxidation of FAD-generated substrate inhibited efficiency of phosphorylation for α-ketoglutarate oxidation in pinacidil-treated animals. Glibenclamide decreased the rate of respiration with the lowest value of efficiency of phosphorylation, especially for α-ketoglutarate oxidation. A second series of experiments was performed to determine the effects of pinacidil and glibenclamide on oxidative phosphorylation during adrenaline-induced myocardium dystrophy. The increase in respiratory control ratio and efficiency of phosphorylation for α-ketoglutarate oxidation was greater than for succinate oxidation in mitochondria of pinacidil-pretreated animals during myocardium dystrophy. Inhibitory analysis with malonate suggested that endogenous succinate increased oxidation of NADH-generated substrates in mitochondria. Pinacidil is mainly involved in the adrenaline-induced alterations of mitochondrial function due to elevation of phosphorylation efficiency for α-ketoglutarate oxidation and a decreased level of lipid peroxidation.