The significance of blood and salivary oxidative stress markers and chemerin in gestational diabetes mellitus.

OBJECTIVE: Gestational diabetes mellitus (GDM) is a medical complication of pregnancy. The aim of this study was to evaluate the correlations between the salivary and blood levels of oxidative stress markers and an adipokine chemerin, which play a role in the pathogenesis of GDM. MATERIALS AND METHODS: Study groups (Control (n = 29), GDM (n = 22)) had been assessed clinically healthy oral hygiene, according to the age range between 25 and 40 years, BMI<30 kg/m2, who were non-smokers and who were not having systemic diseases. GDM was diagnosed using a 100 g OGTT. Saliva samples were collected without stimulation between 08.30 and 10.00 a.m.. Chemerin and TrxR levels were measured by ELISA. Malondialdehyde, sulfhydryl and NO levels were determined by spectrophotometric analysis. Statistical analysis were performed by Shapiro Wilk, Mann Whitney U, Student's t test. RESULTS: Blood pressure, BMI, and plasma chemerin, salivary chemerin, fasting glucose, LDL, triglyceride, CRP levels in GDM were not different when compared to Control. There were significant differences between Plasma TrxR and HDL levels. Also, significant differences between salivary TrxR and Malondialdehyde levels were observed in GDM. CONCLUSION: It was concluded that the optimal cut-off points for oxidative stress parameters and chemerin level can be used to distinguish between healthy pregnant and GDM.

Effects of leptin on stress-induced changes of caspases in rat gastric mucosa.

BACKGROUND: In this study, we investigated the effect of leptin on caspase-3, caspase-8, and caspase-9 immunoreactivity and lipid peroxidation in the stomachs of rats exposed to cold-restraint stress. METHODS: Thirty-two male Wistar Albino rats were used. Rats pretreated with leptin (10 microg/kg per day for 7 days) were restrained in a wire cage for 4 h at 4 degrees C. Spectrophotometric techniques were used for detection of malondialdehyde (MDA) and glutathione (GSH) levels, and immunoreactivity of caspases was investigated by immunohistochemistry. RESULTS: While the stomach MDA level of the cold-restraint stress group was increased significantly, the level of GSH was decreased when compared with the control group. Caspase-9 and caspase-3 immunoreactivities of the stress group were not changed, while caspase-8 immunoreactivity was decreased. Leptin administration prevented the increase in the MDA level and the decrease in the GSH content of the gastric mucosa in animals subjected to stress. Leptin administration produced no significant change in caspase-8 immunoreactivity but caused a decrease in caspase-3 immunoreactivity. CONCLUSIONS: Cold-restraint stress decreases the antioxidant capacity of stomach tissue while activating oxidants, and induces apoptosis by an increase in caspase immunoreactivity. The presence of leptin reverses these mechanisms and suppresses the apoptosis.

Effects of taurine in cellular responses to oxidative stress in young and middle-aged rat liver.

Aging is related with an increased cellular level of lipid peroxides and reactive oxygen species (ROS). The useful effects of taurine as an antioxidant in biological systems have been attributed to its capability to stabilize biomembranes, to scavenge ROS, and to decrease the peroxidation of unsaturated membrane lipids. The aim of the present study was to investigate the effects of taurine on malondialdehyde (MDA), glutathione (GSH), glutathione peroxidase (GPx), thioredoxin reductase (TR), and endothelial nitric oxide synthase (eNOS) in young and middle-aged rat liver. There was not a significant difference in liver MDA levels between the control groups of young and middle-aged rats (P > 0.05). However, liver GSH levels, and GPx and TR activities between the control groups of young and middle-aged rats were significantly different (P < 0.05). Liver MDA level was significantly lower in the taurine group of middle-aged rats (P < 0.05). Liver GSH levels, and GPx and TR activities were significantly increased in the taurine group of middle-aged rats when compared to the control group (P < 0.05). Liver MDA level was significantly lower in the taurine group of young rats than the ones in the control group (P < 0.05). Liver TR activity was significantly increased in the taurine group of young rats when compared to the control group (P < 0.05). Liver GPx activity was not statistically different between the taurine and the control groups in young rats (P > 0.05). Liver GSH levels were not different between the young taurine and the control groups (P > 0.05). Immunohistochemical studies exhibited no change in eNOS activity after taurine injection in young rats. However, in middle-aged rats, taurine lowered the eNOS reactivity to the same level found in young rats. These results suggested that exogenous taurine might play a role in aging by means of its reducing effects on free radical levels in parallel to an increase in the antioxidant capacity.

Evaluation of the cell death pathway and apoptosis-stunning effect relationship after low- and high-dose I-131 administrations in rat thyroid tissue.

OBJECTIVES: This study had two aims; (1) to describe the cell death pathway (apoptosis or necrosis) induced by a low and high dose of radioiodine (I-131) in rat thyroid tissue in in vivo conditions and (2) to determine the role of apoptosis in the development of "stunning effect" in the thyroid tissue with low and high doses of I-131 application. DESIGN: The experimental group consisted of 18 rats; low and high I- 131 doses with a 1-week interval were administered to this group. At first, low doses were injected intraperitoneally (i.p.) (net injected dose was 51.54 +/- 8.6 microCi). After 1 week of the low-dose injection, high doses were also injected (net injected dose was 934.9 +/- 211.8 microCi). Thyroidal I-131 uptakes for both low- and high-dose applications were calculated by using a gamma camera after 24 hours of injections. Immediately after the uptake calculation, thyroid tissues were resected. A control group of 10 rats was also included in the study; in this group, I-131 was not administered. Thyroid tissues of this group rats were also resected. DNA was extracted from thyroid tissues, and damage was examined with the "DNA ladder by agaroz gel electrophoresis." RESULTS: Thyroidal I-131 uptakes were calculated as 11.3% +/- 3.6% and 9.8% +/- 5.3% at the 24th hour after low- and high-dose I-131 applications, respectively. When the low- and high-dose uptake values were compared for each rat; a significant relationship was not found between thyroidal uptakes and injected low and high doses of I-131. When the chromosome images were examined, there was healthy DNA appearance in 1 rat; in 4 rats, only necrotic hyperfragmentations were observed; in 9 rats, both apoptotic specific fragmentations and necrotic hyperfragmentations were observed; and in 4 rats, apoptosis, necrosis, and healthy DNA appearances were seen together. In none of the rats, specific fragmentations concordant only with apoptosis was found. When the thyroidal uptake alterations were taken into consideration, significant difference was not found between first and second uptake calculations (p = 0.28). No significant relationship was also observed between thyroidal uptake alterations and apoptosis-necrosis-healthy DNA findings. Additionally, when we take into consideration the DNA results of only 13 of the rats that had reduced thyroidal uptake, a significant relationship could also not be observed between reduced uptake and apoptotic, necrotic, or healthy tissue findings. Interestingly, apoptotic and necrotic tissue or only necrotic, tissue findings were observed in the other 5 rats which had increased thyroidal uptake. CONCLUSIONS: Following I-131 administration, two types of cell death--both apoptosis and necrosis findings--have been observed in most of the rats. We think that the decreased uptake values are because of the probable stunning effect in thyroid tissue. We also investigated whether the stunning effect is related to apoptosis. According to our results, it can be concluded that the stunning effect is not related to tissue damage, cell decrease, or cell death. Alternatively, we think that this can be related to a radiation-induced reduction of iodine uptake/metabolism or a modified iodine transport mechanism. For further in vivo studies, this experimental model using normal rat thyroid tissue may be useful in investigating the cell death pathways induced by I-131 and its probable roles in the development of the stunning phenomenon.

The effect of systemic leptin administration on aorta smooth muscle responses in diabetic rats.

Leptin produces effects in central nervous system and peripheral tissues via its specific receptors. Leptin also stimulates nitric oxide release in a concentration-dependent manner. In this study, our aim was to test the hypothesis that whether leptin has a modulatory role on endothelium or smooth muscle function in streptozotocin (STZ)-induced diabetic rats. Wistar-Albino rats were divided into four groups: 1 -- Control, 2 -- Diabetic, 3 -- Control + leptin and 4 -- Diabetic + leptin. Experimental diabetes was produced by intraperitoneal injection of a single dose of STZ (55 mg/kg). Diabetes was determined by increased fasting blood glucose level on the 7th day of the experiment. Leptin (0.1 mg/kg/day) was administered intraperitoneally for 5 days. At the end of the 5th day, thoracic aortas were isolated and phenylephrine (Phe)-induced contractions and acetylcholine (ACh)-induced relaxations of each group were estimated. In diabetic rats, Phe-induced contractility was increased (p < 0.05). Leptin pre-treatment increased the Phe-induced contractility significantly in aortic rings obtained from diabetic rats (p < 0.05). In normal rats, leptin administration produced only a slight and non-significant increase in Phe-induced contractions. Although the relaxant responses were decreased in diabetic rats, leptin administration enhanced the ACh-induced relaxation in both normal and diabetic animals significantly. As a conclusion; chronic leptin pre-treatment caused a significant increase both in Phe-induced contractions and ACh-induced Endothelial-Derived Relaxing Factor (EDRF)/Nitric oxide-mediated relaxations in the aortic rings isolated from streptozotocin-induced diabetic rats. This peptide hormone caused a significant increase in the relaxations obtained by ACh while not inducing a significant alteration in the contractile effect of Phe in control rats.

Effects of fasudil, a Rho-kinase inhibitor, on myocardial preconditioning in anesthetized rats.

The aim of this study was to examine the effects of fasudil, a Rho-kinase inhibitor, on ischemic preconditioning and carbachol preconditioning in anesthetized rats. The total number of ventricular ectopic beats was markedly augmented with fasudil at 0.3 mg/kg and depressed with fasudil at 10 mg/kg. Fasudil at 10 mg/kg also markedly decreased the ventricular tachycardia incidence. Ischemic preconditioning, induced by 5 min coronary artery occlusion and 5 min reperfusion, decreased the incidence of ventricular tachycardia and abolished the occurrence of ventricular fibrillation. The incidences of ventricular tachycardia and ventricular fibrillation in the fasudil (10 mg/kg) + ischemic preconditioning group were found to be similar to the ischemic preconditioning group. However, low doses of fasudil (0.3 and 1 mg/kg) appeared to prevent the antiarrhythmic effects of ischemic preconditioning. Carbachol (4 microg/kg/min for 5 min) induced marked reductions in mean arterial blood pressure, heart rate and abolished ventricular tachycardia. Marked reductions in ventricular ectopic beats and ventricular tachycardia were noted in the fasudil (10 mg/kg) + carbachol preconditioning group. Lactate levels were markedly reduced in the ischemic preconditioning group and this reduction was prominently inhibited with fasudil at 1 mg/kg. Ischemic preconditioning caused a marked decrease in plasma malondialdehyde levels. Fasudil (10 mg/kg), ischemic preconditioning and carbachol preconditioning each generated marked reductions in ischemic myocardial malondialdehyde levels. Decreases in infarct size were observed with fasudil (10 mg/kg) treatment, ischemic preconditioning and carbachol preconditioning when compared to control. These results suggest that low doses of fasudil (0.3 and 1 mg/kg) appeared to prevents the effects of ischemic preconditioning and carbachol preconditioning, but a high dose of fasudil (10 mg/kg) was able to produce cardioprotective effects on myocardium against arrhythmias, infarct size or biochemical parameters and mimic the effects of ischemic preconditioning in anesthetized rats.

Relationships between tensile strength, ascorbic acid, hydroxyproline, and zinc levels of rabbit full-thickness incision wound healing.

PURPOSE: This work was carried out to follow up the healing of full-thickness incision wounds opened on the back skin of rabbits in order to gain insight into the periodical correlation among such factors as ascorbic acid, collagen (hydroxyproline), the zinc content, and tensile strength of wound tissue. The need to provide vitamin C or zinc supplements after such wound incisions is also discussed. METHODS: Full-thickness incision wounds and the ascorbic acid and hydroxyproline levels were measured in 24 rabbits by spectrophotometric methods on day 0 and on the 3rd, 5th, 7th, and 15th days after operation. The tensile strength was measured by a polygraph using a force displacement transducer. The zinc levels of the wounds were measured by atomic absorption spectrophotometry. RESULTS: The zinc and hydroxyproline levels reached the peak levels on the 5th day, but the tensile strength of wound increased sharply on the 7th day after wounding while the zinc levels did not change. These results indicated that in the first 7 days of wound healing, high levels of ascorbic acid, hydroxyproline, and zinc cumulation occurred in the wound tissue, and the tensile strength reached its highest level on the 15th day without any supplementation. CONCLUSION: The supplementation of zinc and/or ascorbic acid should therefore be given just at the beginning of the wounding period, especially if there is deficiency of these nutrients.

Effects of L-arginine and NG-nitro L-arginine methyl ester on lipid peroxide, superoxide dismutase and nitrate levels after experimental sciatic nerve ischemia-reperfusion in rats.

Nitric oxide (NO) has been reported to function in both cytoprotective and cytotoxic tissue ischemia-reperfusion (I/R). In this study, we evaluated the effects of L-arginine, the substrate for NO, and NG-nitro L-arginine methyl ester (L-NAME), NO synthase (NOS) inhibitor on super oxide dismutase (SOD) enzyme activity, malondialdehyde (MDA), a marker of lipid peroxidation, nitrate levels, and histopathological structure in rat sciatic nerve 2 h after ischemia, followed by 3 h of reperfusion. Reperfusion resulted in a significant increase in lipid peroxidation level and a decrease in nitrate level of the sciatic nerve. The increased level of lipid peroxidation was partly reduced by NOS inhibition. The decrease in sciatic nerve SOD level, observed in group subjected to I/R, was prevented by inhibition of NOS by L-NAME. These results were supported by histological findings that in the L-arginine-treated group, degenerations of both myelin sheath and axon were observed, while in the L- NAME-treated group, no pathological changes were detected. Our results suggested that excessive NO formation accelerates lipid peroxidation, as well as axonal degeneration on the early reperfusion period of the sciatic nerve.

Effects of vitamin E and electrical stimulation on the denervated rat gastrocnemius muscle malondialdehyde and glutathione levels.

Effects of vitamin E treatment and local electrical stimulation on progression of atrophy in the denervated rat gastrocnemius muscle were studied. Denervation was performed by right leg sciatic nerve axotomy. Electrical stimulation (3-10 mA ms(-1), 10 min per day for 7 days) was applied to the right gastrocnemius muscle starting from day 1 of denervation. The muscle samples were assayed for malondialdehyde (MDA) and glutathione levels, as well as the histological appearance after 8 days of denervation. MDA levels were markedly increased following denervation. However, electrical stimulation, vitamin E treatment (30 mg kg(-1), i.m., everyday for 7 days), and combination of electrical stimulation and vitamin E treatment markedly reduced MDA levels. Glutathione levels were significantly decreased in the denervation group. Electrical stimulation, vitamin E treatment, and electrical stimulation plus vitamin E treatment prevented these reductions in glutathione levels. In the vitamin E treatment group, glutathione levels were markedly higher than in the control group. These results indicate that electrical stimulation and vitamin E treatment alone, or in combination, were able to prevent the effects of denervation on muscle atrophy.