Optogenetic stimulation increases level of antiapoptotic protein Bcl-xL in Neurons

The antiapoptotic protein Bcl-xL is associated with several neuroplastic processes such as formation of synapses, regulation of spontaneous and evoked synaptic responses, and release of neurotransmitters. Dependence of expression on activity of neurons is characteristic for many proteins participating in regulation of neuroplasticity. Whether such property is exhibited by the Bcl-xL protein was analyzed using in vivo optogenetic stimulation of hippocampal glutamatergic neurons expressing channelrhodopsin ChR2H134 under CAMKIIa promoter in the adeno-associated viral vector, followed by immunohistochemical determination of the level of Bcl-xL protein in these neurons and surrounding cells. Increase in the level of early response c-Fos protein following illumination with blue light was indicative of activation of these hippocampal neurons. The optogenetic activation of hippocampus resulted in a significant increase in the level of antiapoptotic protein Bcl-xL in the photosensitive neurons as well as in the surrounding cells. The dependence of the level of expression of Bcl-xL protein on the activity of neurons indicates that this protein possesses one more important property that is essential for participation in neuroplastic processes in the brain.     

Effects of exposure to short-term heat stress on fitness components in Drosophila melanogaster

Effects of thermal stress on survival and reproductive success in ten recently collected isofemale lines of Drosophila melanogaster were compared for flies treated as follows: always held at 25° C, placed in an incubator set at 37° C for 120 min, or exposed to 40° C in an incubator for 90 min, with or without previous exposure to 37° C. Short-term exposure to the higher temperature greatly reduced adult survival, the mating frequency of males and females, and female fecundity, which was measured as offspring produced over ten days. Male fertility, measured as the progeny produced by a female mated once, differed little among treatments. Previous exposure to a high, but non-lethal, temperature before exposure to the higher one, improved survival of males and females, and improved offspring production of females. Genetic variation was present among lines for offspring production, but genetic variation for survival was not significant, and genotype by environment interactions for fitness components of females were small. These results indicated low genetic variation in thermal resistance in the studied population, such that a threshold for temperature stress probably exists, above which local extinction is more likely than the evolution of resistance.     

Gene expression in cortex and hippocampus during acute pneumococcal meningitis

Background  

Pneumococcal meningitis is associated with high mortality (~30%) and morbidity. Up to 50% of survivors are affected by neurological sequelae due to a wide spectrum of brain injury mainly affecting the cortex and hippocampus. Despite this significant disease burden, the genetic program that regulates the host response leading to brain damage as a consequence of bacterial meningitis is largely unknown.     

Effects of short-term cold exposure on pineal biosynthetic function in rats

In light of recent studies demonstrating stress-induced changes in pineal indoleamine metabolism, we tested the effect of acute cold stress on pineal biosynthetic function. Adult male rats were subjected to 30, 60, or 120 min of cold exposure (Ta = 2 degrees C) during either the light or dark phase of the daily photoperiodic cycle. Controls were kept at room temperature (22 +/- 2 degrees C). Animals were killed by decapitation and pineals were analyzed by radioimmunoassay for melatonin content and by radioenzymeassay for the activity of N-acetyltransferase (NAT). Cold exposure during the day elicited no significant changes in pineal indoleamine metabolism. Exposure to cold for 1 hr during the second hour after lights off slightly increased pineal melatonin content, without a concomitant change in NAT activity. Rats exposed to 2 hr of cold beginning 2 hr after lights off, however, displayed a 50% reduction in NAT activity, whereas pineal melatonin content remained unchanged. The paradoxical response of pineal NAT activity and melatonin content are not uncommon when rats are exposed to adverse stimuli.     

Effects of exposure to short-term heat stress on male reproductive fitness in a soil arthropod

Ambient temperature is a key environmental factor influencing a variety of aspects of the ecology and evolution of ectotherms. Reproductive traits have been suggested to be more sensitive to thermal stress than other life history traits. This study investigated the direct and indirect effects of heat shock on male reproductive success in the widespread springtail Orchesella cincta. Male springtails were exposed to four temperature treatments: heat hardening (35.2 °C for 1 h), heat shock (37.2 °C for 1 h), heat hardening + heat shock (35.2 °C for 1 h, followed 15 h later by 37.2 °C for 1 h), and control (20 °C). The heat shock gene Hsp70 showed high expression in all the heat treatments, indicating that the treatments indeed induced thermal stress. Significant mortality was only found in the treatment with heat shock, both with and without heat hardening. A direct effect of heat treatment was found on time to first reproduction, which was significantly longer after heat shock (with or without heat hardening) than in the control treatment. There was no difference among treatments in the number of spermatophores produced in the first reproductive instar. Heat treatment also had indirect effects on male reproductive success. Females chose significantly more spermatophores from control males than from males that received heat shock, heat hardening or both. A high percentage of spermatophores produced by heat shocked males caused reproductive failure in females, but no significant differences among treatments were found.Our results suggest that not all traits were equally affected by the heat stress. Heat hardening did not protect reproductive traits against the negative effects of heat shock. The indirect effects of heat shock on reproduction may be equally important as the direct effects.     

Effects of adaptation to exposure to short-term stress on indices of resistance of energy metabolism and contractile function of the myocardium to acute hypoxic hypoxia and reoxygenation

Effect of preliminary adaptation to immobilization stress with progressive duration from 15 min. to 1 h (every second day, 8 sessions) on the resistance of indices of myocardial energy metabolism and contractile function to acute hypoxic hypoxia and subsequent reoxygenation was studied. It was shown, that adaptation to short-term stress exposure by some way provided the retention of activities of important enzymes like creatine-phosphokinase and phosphorylase under the harmful action of acute hypoxia and subsequent reoxygenation. At the same time, the ATP restoration and the CP super-restoration were observed during reoxygenation. This effect, in its turn, was accompanied by a more pronounced super-restoration of the heart contractile function than in control.     

噪声暴露对大鼠事件相关电位P300的影响及其海马水平的机制

目的：研究噪声暴露对大鼠事件相关电位（ERP）的影响及海马水平的机制。方法：雄性SD大鼠,随机均分为正常对照组（C组）、噪声暴露组（N组）。暴露条件：105dB白噪声2．5h／d×20d。观察试验过程中第0、7、14和20d ERP各波的峰潜伏期以及峰峰幅度值,并检测海马神经元尼氏体、NMDAR2B及胞内钙浓度的变化。结果：在实验第14d、第20d,噪声暴露组动物ERP P3a、P3和P3b的峰潜伏期显著增长,而且在噪声暴露20d后,大鼠海马齿状回以及CA1区尼氏体显著减少（P〈0．01）,齿状回、CA1及CA3区NMDAB2B的免疫反应强度显著降低（P〈0．01）,神经元胞内钙浓度显著升高（P〈0．01）。结论：噪声暴露可致事件相关电位的改变,这可能与其海马神经元尼氏体、NMDAR2B以及胞内钙的变化有关。     

Effects of short-term exposure to catecholestrogens on serum concentrations of gonadotrophins and metabolism of catecholestrogens in ovariectomized rats

Equimolar amounts (36.8 nmol) of estradiol and the two catecholestrogens (CE's) 4-hydroxyestradiol (4-OHE2) and 2-hydroxyestradiol (2-OHE2) were injected subcutaneously to ovariectomized adult rats. Serum levels of both LH and FSH were determined at short-term intervals. Moreover, serum levels of the administered steroids and their main free and conjugated metabolites were monitored. Serum levels of the injected steroids reached peak values at different time points: estradiol between 60 and 240 min, CE's between 30 and 60 min. Peak height also differed significantly: with estradiol highest (1500 pg/ml), followed by 4-OHE2 (540 pg/ml) and then 2-OHE2 (135 pg/ml) (ratio 11:4:1). This mirrored the different MCR's of the steroids: CE's, especially 2-OHE2, were rapidly and extensively methylated and/or - to a lesser degree - conjugated. Estradiol remained mainly unchanged. LH-serum levels in steroid treated animals showed - irrespective of the steroid used - a uniform reaction pattern: they were significantly depressed 60 to 240 min after injection and - with the exception of estradiol treated rats - reached pretreatment levels again 480 min after injection. Ultra-short (15 min) effects were not observed. FSH serum levels in CE treated animals were not significantly altered, only E2 application led to a significant but small decrease in FSH levels 240 and 480 min after its injection. In conclusion, neither the effect of 4-OHE2 nor that of 2-OHE2 corresponded to the different MCR's or the MCR-corrected affinities for the classical estrogen receptor. A non-genomic mechanism may be responsible for this impaired effect of CE's.     

The antiapoptotic protein Bcl-xL is dispensable for the development of effector and memory T lymphocytes

The antiapoptotic protein Bcl-x(L) is induced in activated T lymphocytes upon costimulation through CD28, 4-1BB, and OX40. Bcl-x(L) is also highly enriched in memory T lymphocytes. Based on this body of evidence, it was thought that Bcl-x(L) plays an essential role in the generation of effector and memory T lymphocytes. We report that mice with a conditional deletion of Bcl-x in T lymphocytes develop a normal CD8(+) T cell response to Listeria monocytogenes infection. Furthermore, Bcl-x conditional knockout mice exhibit normal T-dependent humoral immune responses. These results indicate that Bcl-x is dispensable for the generation of effector and memory T lymphocytes and suggest that costimulation of T lymphocytes promotes their survival through a Bcl-x(L) independent mechanism.     

Regulation of uteroglobin/Clara cell protein expression after acute lung exposure to an organophosphoreted insecticide

Uteroglobin (UG) or Clara cell protein (CC16), the main secretory product of bronchiolar Clara cells, plays an important protective role in the respiratory tract against inflammatory processes. In the lung, protein secretion is regulated by glucocorticoids, but also proinflammatory cytokines, such as interferon-gamma (IFN-) and TNF-, have been found to modulate the expression of this peptide. We have previously demonstrated that the acute exposure to an organophosphoreted insecticide induces an enhanced production of UG/CC16 by Clara cells. In the present report, we worked with intact and adrenalectomised (ADX) animals to study the mechanism involved in the UG/CC16 increase caused by the insecticide and the role played by a glucocorticoid (dexamethasone; DEX). In intact rats we found that DEX treatment could not reproduce such an increase of UG/CC16 synthesis with pharmacological doses. In ADX rats, even though glucocorticoid deprivation provoked a strong inhibition of UG/CC16 synthesis, the exposure to the organophosphoreted insecticide stimulated the synthesis of the protein, shown by the great accumulation of secretory granules in the cytoplasm of Clara cells and the increase of UG/CC16 detected by immunocytochemistry and western blot. These results imply that glucocorticoids are not essential to trigger the increase of UG/CC16 in response to an injury, and they also suggest an involvement of other molecules associated with inflammation. In coincidence with these observations, we have found that IFN-, a proinflammatory cytokine, increased after insecticide exposition in both groups, intact and ADX, mainly in ADX rats. The stimulation of UG/CC16 synthesis occurring during inflammatory processes of the respiratory tract caused by acute inhalation of a toxicant appears to be functional without the intervention of glucocorticoids and mediated by IFN- as a mechanism for local control of the inflammatory response.     

Effects of zinc on the induction of metallothionein isoforms in hippocampus in stress rats

Metallothioneins (MTs) are involved in the cellular metabolism of zinc and in cytoprotection against stress factors. Hippocampus plays a specific role in the body's response to stressors. The present study was conducted to evaluate the effects of zinc on the expression of metallothionein isoforms in the hippocampus of stress rats. The animal model of psychologic stress was developed by restraint for 4 weeks. Wistar rats were randomly assigned to 6 groups: control group, zinc-deficient group, zinc-supplemented group, and the corresponding 3 stress groups. Three separate diets of different zinc contents (1.73 ppm, 17.7 ppm, and 41.4 ppm, respectively) were used in this study. Compared with the control group, the stress groups had higher inductions of MTs and MT-1 and MT-3 mRNA in hippocampus. On the one hand, the expressions of MTs and their mRNAs in hippocampus were downregulated in the zinc-deficient group; however, their expressions were evidently enhanced in the stress zinc-deficient group. MT induction in the zinc-supplemented group was increased. Furthermore, the stress zinc-supplemented group had a more significant yield of MTs and their mRNAs. In addition, the levels of plasma cortisol, interleukin-6 (IL-6), IL-1, and nitric oxide (NO) were increased clearly in the zinc-deficient group and the stress groups. The results suggest that zinc deficiency may decrease and zinc supplementation may increase the expressions of MTs and their mRNAs in hippocampus; moreover, stress can increase their expressions dramatically. The impairment of stress on the body may be involved with the nutrition status of zinc, and zinc deficiency can lower the body's adaptability to stress.     

NMR structural investigation of the mitochondrial outer membrane protein VDAC and its interaction with antiapoptotic Bcl-xL

Bcl-2 family proteins are essential regulators of cell death and exert their primary pro- or antiapoptotic roles at the mitochondrial outer membrane. Previously, pro- and antiapoptotic Bcl-2 proteins have been shown to interact with the voltage-dependent anion channel (VDAC) of the outer mitochondrial membrane. VDAC is a 283-residue integral membrane protein that forms an aqueous pore in the outer mitochondrial membrane, through which metabolites and other small molecules pass between the cytosol and intermembrane space. The essential life-sustaining function of VDAC in metabolite trafficking is believed to be regulated by proteins of the Bcl-2 family. The protective role of antiapoptotic Bcl-xL may be through its interaction with VDAC. Here, VDAC has been expressed, purified, and refolded into a functional form amenable to NMR studies. Various biophysical experiments indicate that micelle-bound VDAC is in intermediate exchange between monomer and trimer. Using NMR spectroscopy, gel filtration, and chemical cross-linking, we obtained direct evidence for binding of Bcl-xL to VDAC in a detergent micelle system. The VDAC-interacting region of Bcl-xL was characterized by NMR with chemical shift perturbation and transferred cross-saturation. The interaction region was mapped to a putative helical hairpin motif of Bcl-xL that was found to insert into detergent micelles. Our results suggest that Bcl-xL can bind to one or two VDAC molecules forming heterodimers and heterotrimers. Our characterization of the VDAC/Bcl-xL complex offers initial structural insight into the role of antiapoptotic Bcl-xL in regulating apoptotic events in the mitochondrial outer membrane.     

低氟铝长期与高氟铝短期暴露后大鼠骨生长的比较研究

目的观察不同剂量氟铝联合摄入时间长短对大鼠纵向骨生长及骨代谢的影响。方法48只8周龄体重170~190g清洁级SD大鼠,随机分成正常对照,低氟铝和高氟铝组,且分别设45d和90d组。进行胫骨近端生长板和干骺端松质骨的骨形态计量学分析。结果与正常组比较,高氟铝组生长板增厚,45d组软骨细胞层次清楚,排列整齐,形态无异常,而90d组软骨细胞拥挤,潴留;低氟铝(45d和90d)组干骺端次级小梁骨矿化周长、骨形成率、成骨细胞周长都增加,且骨吸收周长在90d组增加;上述骨代谢指标在高氟铝45d组均增加,90d组均降低。结论高氟铝短期暴露刺激软骨生长,长期抑制纵向骨生长。低氟铝短期暴露只增加次级小梁骨形成,低氟铝长期与高氟铝短期暴露均可刺激小梁骨形成,增加骨吸收,高氟铝长期抑制骨形成和吸收。     

Oxidative stress in the hippocampus after pilocarpine-induced status epilepticus in Wistar rats

The role of oxidative stress in pilocarpine-induced status epilepticus was investigated by measuring lipid peroxidation level, nitrite content, GSH concentration, and superoxide dismutase and catalase activities in the hippocampus of Wistar rats. The control group was subcutaneously injected with 0.9% saline. The experimental group received pilocarpine (400 mg.kg(-1), subcutaneous). Both groups were killed 24 h after treatment. After the induction of status epilepticus, there were significant increases (77% and 51%, respectively) in lipid peroxidation and nitrite concentration, but a 55% decrease in GSH content. Catalase activity was augmented 88%, but superoxide dismutase activity remained unaltered. These results show evidence of neuronal damage in the hippocampus due to a decrease in GSH concentration and an increase in lipid peroxidation and nitrite content. GSH and catalase activity are involved in mechanisms responsible for eliminating oxygen free radicals during the establishment of status epilepticus in the hippocampus. In contrast, no correlations between superoxide dismutase and catalase activities were observed. Our results suggest that GSH and catalase activity play an antioxidant role in the hippocampus during status epilepticus.     

Different susceptibility of prefrontal cortex and hippocampus to oxidative stress following chronic social isolation stress

Chronic oxidative stress plays an important role in depression. The aim of present study was to examine the stress-induced changes in serum corticosterone (CORT) levels, cytosolic protein carbonyl groups, malondialdehyde (MDA), reduced glutathione (GSH), nitric oxide (NO) and total superoxide dismutase (SOD) activity in the prefrontal cortex versus hippocampus of male Wistar rats exposed to acute (2 h of immobilization or cold), chronic (21d of social isolation) stress, and their combination (chronic + acute stress). The subcellular distribution of nuclear factor-κB (NF-κB) and cytosolic cyclooxygenase 2 (COX-2) protein expressions were also examined. Depressive- and anxiety-like behaviors were assessed via the forced swim, sucrose preference, and marble burying tests in chronically isolated rats. Although both acute stressors resulted in elevated CORT, increased MDA in the prefrontal cortex and NF-κB activation accompanied by increased NO in the hippocampus were detected only following acute cold stress. Chronic isolation resulted in no change in CORT levels, but disabled appropriate response to novel acute stress and led to depressive- and anxiety-like behaviors. Increased oxidative/nitrosative stress markers, likely by NF-κB nuclear translocation and concomitant COX-2 upregulation, associated with decreased SOD activity and GSH levels, suggested the existence of oxidative stress in the prefrontal cortex. In contrast, hippocampus was less susceptible to oxidative damage showing only increase in protein carbonyl groups and depleted GSH. Taken together, the prefrontal cortex seems to be more sensitive to oxidative stress than the hippocampus following chronic isolation stress, which may be relevant for further research related to stress-induced depressive-like behavior.     

Increased enzymatic activity of antioxidant protection of the heart in the adaptation of rats to short-term stress exposure

It has been shown that adaptation to short-term emotional-painful stresses leads to an increase in antioxidant enzyme activities but does not change vitamin E content in the myocardium. The most labile enzyme was catalase (35% increase). During stress in nonadapted animals the enzyme activity decreased, as compared to the control, while in the group of adapted animals with subsequent stress the activity was even higher than in the control. During initiation of lipid peroxidation in the heart homogenates in vitro there was a 3-fold increase and a 1%-fold decrease in the oxidation intensity in rats exposed to stress and in adapted animals, respectively. The role of adaptation activation of cardiac antioxidant system in the prevention of stress-induced heart damage is discussed.