The effect of thyroxine administration on lipid peroxidation in different tissues of rats with hypothyroidism

Thyroid dysfunctions bring about pathological changes in different organs of the body. Findings obtained from in vivo and in vitro studies point out that thyroid hormones have a strong impact on oxidative stress. The present study was conducted to demonstrate how high-dose thyroxin administration for one week affected oxidative damage formed in experimental hypothyroidism. The study was carried out with 30 Spraque-Dawley species male rats. The experimental animals were divided into 3 groups (Group 1, control; Group 2, hypothyroidism; Group 3, hypothyroidism + thyroxine administration). Malondialdehyde (MDA) and glutathione (GSH) levels were determined in cerebral, hepatic and cardiac tissues after the experimental period. MDA and GSH levels in cerebral, hepatic and cardiac tissues of hypothyroidism + thyroxine supplemented group were higher than those in the control and hypothyroidism groups (p<0.001). The same parameters were higher in the control group than those in the hypothyroidism group (p<0.001). The results of the present study show that hypothyroidism reduced the oxidative damage in cerebral, hepatic and cardiac tissues of rats. However, high-dose thyroxine administration in addition to induced hypothyroidism increased oxidative damage in the same tissues and that this damage could not be prevented despite the increase in the antioxidant system activity.     

Short-term thyroxine administration leads to lipid peroxidation in renal and testicular tissues of rats with hypothyroidism

Thyroid dysfunction brings about pathological changes in different organs of the body. The aim of the present study was to examine how experimental hypothyroidism and additional short-term high-dose thyroxine administration (one-week) affected lipid peroxidation in renal and testicular tissues of rats. The study was carried out on 30 male Spraque-Dawley rats. The experimental animals were divided into 3 groups as control, hypothyroidism and hypothyroidism + thyroxine administration. Both malondialdehyde (MDA) and glutathione (GSH) levels were lower in renal and testicular tissues of the hypothyroidism group than the control and hypothyroidism + thyroxine administration groups and the levels in hypothyroidism + thyroxine administration group were higher than those in the control and hypothyroidism groups (p < 0.001). Results of the study demonstrate that hypothyroidism reduced oxidant stress in kidney and testis tissues, but short-term, high-dose thyroxine administration in addition to hypothyroidism increased oxidant stress in the same tissues of rats.     

Specific protein markers in monolayer hepatocyte cultures from adult rats

By indirect immunofluorescence it has been shown that syntheses of protein A, ligandin, cytochrome P-450 PhB, and serum albumin persist in hepatocytes of adult rats during the first 2-3 days in culture. A surface protein--fibronectin--was also synthesized in cultured cells to be localized on the lower side of the free cell edge. On the 4-5th day of cultivation large regions of the lammelar cytoplasm appeared in hepatocytes accompanied by cell polarization. As a result, cells acquired a "fibroblast-like" form. During this period of cultivation, cells were characterized by the loss of cytochrome P-450 PhB, by a drastic decrease in protein A, and ligandin synthesis. At the same time, gamma-glutamyl transpeptidase, the protein characteristic of the embryonic stages, was revealed histochemically. Therefore, the impairment of tissue organization accompanying the transfer of hepatocytes into the vitro conditions results in gradual changes of their morphology, in a reduction or complete loss of some specific "adult" synthesis and activation of the "embryonic" synthesis.     

Age peculiarities in changes of free radical oxidation processes in the brain of rats with hypothyroidism

The objective of the present experiment was to study age peculiarities of free radical protein oxidation and lipid peroxidation in brain of 1.5-month-old and 12-month-old rats with drug-induced hypothyroidism. It has been shown that hypothyroidism in both 1.5-month and 12-month old rat is accompanied by the oxidative stress in the brain. It manifests by an increase of content of lipid peroxidation products and protein carbonyls in mitochondrial and microsomal fractions. Hypothyroidism decreases the prooxidant effect of exercises on the brain mitochondria.     

L-thyroxine and L-triiodothyronine in the cerebral tissues of the adult rat. Effect of hypothyroidism]

The L-thyroxine and L-triiodothyronine concentrations in several brain areas (cerebral cortex, brain stem, hypothalamus, total brain and hypophysis) in normal and hypothyroid rats have been studied. Results show that L-thyroxine values at tissue level are inferior in the hypothyroid group, although non-significant with respect to the control group, whereas L-triiodothyronine presents values similar to the hypothyroid group and its control in all the brain regions studied with the exception of hypophysis. These results show that in hypothyroid situations exist a compensatory mechanism for maintaining the adequate L-triiodothyronine levels in several brain areas, although the serum levels are strongly decreased in hypothyroid animals.     

Phorbol ester-associated changes in ganglioside metabolism

The effect of phorbol esters on ganglioside metabolism in contact-inhibited Chinese hamster V79 cells was examined. Three phorbol esters of varying structure and tumor-promoting activity were used. Treatment of cells with tumor-promoting phorbol esters resulted in accumulation of gangliosides and increased incorporation of [1-¹⁴C]palmitate and [9-³H]sialic acid into gangliosides. Moreover, the phorbol esters were found to increase the activity of CMP-sialic acid: lactosylceramide sialyltransferase, the enzyme catalysing the first step in ganglioside biosynthesis. The magnitude of phorbol ester effects on V79 cell ganglioside metabolism correlated with the in vivo phorbol ester tumor-promoting activity.     

Evaluation of sphingolipids changes in brain tissues of rats with pentylenetetrazol-induced kindled seizures using MALDI-TOF-MS

Abnormal lipid metabolism has been implicated in the pathogenesis of many neural system diseases, including epilepsy. Pentylenetetrazol (PTZ)-induced kindling in rodents is considered a model of human absence epilepsy and myoclonic, generalized tonic-clonic seizure. In an effort to further understand the mechanism for PTZ-induced seizure, we analyzed crude lipids and sphingolipids in the cortex, hippocampus, and brain stem of normal and PTZ-rats using delayed extraction matrix-assisted laser desorption ionization time-of-flight mass spectrometry (DE MALDI-TOF-MS). It was found that phosphatidylcholines dominated the crude lipids in different tissues and there were no obvious differences in crude lipid profiles of different tissues between normal and PTZ-rats. However, ceramide, sphingomyelins, and ceramide-monohexoside were differently distributed in normal and PTZ-rats. Using the reference mass spectra method established in our laboratory, it was shown that sphingomyelins and ceramide-monohexoside levels were elevated in the brain tissues of PTZ-rats. Ceramide levels were found to be higher in brain stem than in cortex and hippocampus of normal rats, and PTZ caused a general decrease in ceramide levels. These data suggest that changes in sphingolipid metabolism contribute to PTZ-induced seizure.     

Morphologic and biochemical changes in the lymphoid and hematopoietic tissues of rats with Zajdela hepatoma

The growth of allogeneic ascites hepatoma is accompanied by involution of the thymus, leukemoid response and anemia. Tumor cells disseminate throughout the body appearing in many organs including the spleen, liver, bone marrow and lymph nodes. The activity of adenosine deaminase and the adenosine deaminase/purine nucleosidephosphorylase ratio decrease in the host thymus as well as in the cellular elements of the spleen. The above phenomena reflect the impairment of lymphocyte differentiation and presumably contribute to the decreased efficiency of the host immune response.     

MicroRNA在神经系统不同部位特异分布及其在神经损伤再生中的变化和作用

MicroRNA是一类内源性的非编码RNA,在mRNA转录后水平调节靶基因的表达.近年来国内外研究表明,生理条件下microRNA在神经系统存在特异性表达并发挥重要作用.而在神经系统损伤后,多种microRNA的分布和表达发生改变,从而对神经再生过程产生影响.microRNA的这一作用对临床诊断和治疗神经系统损伤意义重大.     

Behavioral changes in adult rats exposed to ELF magnetic fields

In two experiments, male rats that had been exposed to an ELF (0.5 Hz), 3–50 gauss rotating magnetic field (RMF) for 21–30 days, displayed significantly (p < 0.05) greater ambulatory behavior (activity) than the control group in an open field test, when removed from the RMF. In a third experiment rats were exposed to a different RMF apparatus (3–30 gauss), and tested in a different open field for longer duration. Again the RMF-exposed group displayed greater activity (p < 0.10) than the control group.

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Zusammenfassung In zwei Untersuchungen zeigten männliche Ratten,die einem ELF (0,5 Hz) 3–50 Gauss rotierenden magnetischen Feld (RMF) für 21–30 Tage ausgesetzt wurden, in einem Open-Field Test signifikant (p < 0,05) mehr Bewegungsaktivität als die Kontrollgruppe,nachdem sie von dem RMF entfernt wurden. In einer dritten Untersuchung wurden Ratten in einem anderen RMF Gerät gehalten und in einem anderen Open-Field für längere Zeit getestet. Wieder zeigte die Gruppe, die dem RMF ausgesetzt war, mehr Bewegungsaktivität (p < 0,10) als die Kontrollgruppe.

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Resume Lors de deux essais, on a placé des rats mâles dans un champ magnétique tournant (CMT) de 3 à 50 gauss et des très basse fréquence (FTB) (0,5 Hz). Après 21 à 30 jours de ce traitement, on les a remis dans des conditions normales. Leur activité (marche) était plus élevée que celle d'un groupe de contrôle et cela de façon significative (p < 0,05). Dans un troisième essai, d'autres rats furent placés dans un autre appareil (3 à 30 gauss) et examinés ensuite dans un autre champ ouvert sur une plus longue période. Le groupe traité a déployé dans ce cas également une plus grande activité qu'un groupe de contrôle (p < 0,10).

     

pH-dependent changes of ganglioside biosynthesis in neuronal cell culture

Ganglioside biosynthesis was studied in primary cultured murine cerebellar cells after labeling with [14C]galactose. A shift in biosynthesis from "a"-series to "b"-series gangliosides was observed after lowering the pH of the culture medium from 7.4 to 6.2; this effect was fully reversible on changing back to pH 7.4. The observed regulatory effect of pH is in accordance with a recent model of ganglioside biosynthesis. Sialyltransferase II (ST II), the first enzyme for biosynthesis of "b"-series gangliosides, is more active at pH 6.2 than Gal-NAc-transferase, the first enzyme for synthesis of "a"-series gangliosides, which is more active than sialyltransferase II at pH 7.4.     

Specific impact of cardiovascular risk factors on coronary microcirculation in patients with subclinical hypothyroidism

BackgroundAlthough thyroid hormones have significant effect on cardiovascular system, the impact of subtle thyroid dysfunction such as subclinical hypothyroidism (SCH) remains to be determined. We investigated coronary flow reserve (CFR) in patients with subclinical hypothyroidism.MethodsThirty two subjects with SCH and eighteen control subjects with normal serum thyroid hormones and thyroid-stimulating hormone (TSH) levels were included in the study. TSH, free thyroxine, free triiodothyronine, glucose, insulin, HbA1c, cholesterol, triglyceride and plasma levels of C-reactive protein were measured. Coronary diastolic peak flow velocities in left anterior descending coronary artery were measured at baseline and after adenosine infusion. CFR was calculated as the ratio of hyperemic to baseline diastolic peak velocity.ResultsCFR values were not significantly different between the two groups (SCH 2.76±0.35 vs controls 2.76±0.42). There was a significant correlation of CFR with waist to hip ratio, hypertension, smoking habits, markers of glucose status (glucose level, HbA1c, insulin level, HOMA IR), cholesterol, LDL-cholesterol and triglyceride levels in SCH group, whereas only cholesterol level showed significant correlation with CFR in controls. There was no correlation between CFR and thyroid hormones.ConclusionsWe concluded that there is a different impact of cardiovascular risk factors on CFR in SCH patients compared to healthy control and that these two groups behave differently in the same circumstances under the same risk factors. The basis for this difference could be that the altered thyroid axis "set point" changes the sensitivity of the microvasculature in patients with SCH to known risk factors.     

幼鼠和成年大鼠心室肌细胞起搏电流的改变

目的:运用膜片钳全细胞技术和实时定量聚合酶链式反应(PCR),探讨幼鼠和成年大鼠心室肌细胞起搏电流(If)及超极化激活的环核苷酸门控通道(HCN)亚型的改变。方法:分离3d的幼鼠和成年大鼠的心室肌细胞;测定HCN1、HCN2、HCN3和HCN4 mRNA的表达;记录If并研究其特性。结果:在新生大鼠心室肌细胞记录到If并得到电流密度-电压曲线,其激活电压约为-75mV;实时定量PCR检测HCN1、HCN2、HCN3和HCN4 mRNA在总HCN mRNA的表达中所占比例分别为0.23%±0.01%、83.58%±0.04%、0.79%±0.01%和15.44%±0.01%。在成年大鼠心室肌细胞也记录到超极化激活、并可以被4mmol/LCsCl阻断的If,其激活电压约为-115mV;HCN1、HCN2、HCN3和HCN4 mRNA在总HCN mRNA中所占比例分别为0.72%±0.02%、91.58%±0.08%、0.27%±0.02%和7.12%±0.02%。HCN2∶HCN4为(13.06±0.21)∶1。结论:随着年龄的增长,大鼠心室肌细胞HCN2所占比例增加;If值减小,激活电压变负。