The role of glucocorticoids at the corticosterone level after stress in the early ontogeny of gray rats]

Norway rats were subjected to stress procedure of saline or hydrocortisone injections. The saline-treated rats revealed an increased level of the plasma corticosterone as opposed to hydrocortisone-treated ones. The modification of adrenocortical function with the stress in early postnatal life seems to be connected with changes in hypothalamic catecholamine synthesis and can be prevented with exogenous glycocorticoids.     

The age-related inhibition of motor excitation of the spinal cord in the early postnatal ontogeny of rats

In the experiments on the developing albino rats it was investigated the influence of the lesion of dorsolateral funiculus of the spinal cord on the age-related inhibition of the spontaneous periodic motor activity and late long-lasting discharges evoked by stimulation of n. tibialis controlateralis and recorded in m. gastrocnemius. The relative hyperactivity and increased duration of long-lasting discharges after the end of the second week was observed independently of the age of operated animal (3, 5, 10, 12 days after birth).     

Attenuation of early hyperglycaemia induced by streptozocin in fasting rats

Early hyperglycaemia induced by streptozocin was studied in fasting rats. It was found that the early hyperglycaemia was attenuated, the hypoglycaemia was prolonged, and the initiation of the permanent hyperglycaemia was delayed. The early hyperglycaemia induced by streptozocin was further attenuated in carbon tetrachloride pretreated fasting rats. It was speculated that the appearance of the early hyperglycaemia was liver related.     

The ontogeny of feeding in rats: III. Thermal determinants of early ingestive responding.

High ambient temperatures (38°C) stimulated high spontaneous levels of activity and high frequencies of behaviors normally associated with ingestion (mouthing and probing), particularly in young, 3- and 6-day-old Charles River CD rat pups (Exp I). The level of spontaneous behavior was highly correlated with body temperature and also depended on deprivation condition. Temperature played an important role in determining responses to food stimuli as well. When Ss were fed by oral infusion (Exp II) or by placing milk on the floor beneath them (Exp III), warm ambient temperatures were required for active ingestion. In Exp IV, body temperature and ambient temperature were manipulated independently to assess their relative importance for Ss' feeding behavior. Ss with a low (29°C) or normal (34°C) core temperature at the start of testing were fed in either a 24°C or a 34°C ambience. Regardless of body temperature, Ss' levels of intake, activity, mouthing, and probing were higher in a warm than in a cool ambience. Therefore, the suppressed ingestive behavior of Ss fed at cool temperatures occurred not simply because Ss became hypothermic and inactive. Perceived warmth appears to be a significant contextual cue that regulates pups' responses to food stimuli. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cornea stress test--evaluation of corneal endothelial function in vivo by contact lens induced stress

Changes in the NHS have supported the idea of targeting health services to those in greatest need. This has meant that health visitors are increasingly having to identify 'vulnerable' families in need of increased health visiting intervention. This paper reports on a qualitative study undertaken in order to explore the ways in which health visitors plan and organize their work in relation to the concept of vulnerability. Focus groups and semi-structured interviews were carried out with health visitors from two separate geographical areas, one an inner city area and the other suburban, in order to explore the criteria by which health visitors define vulnerability and decide to increase their levels of intervention to particular families. It was found that vulnerability was extremely difficult to define but that the health visitors used criteria which were appropriate to the particular localities in which they worked to identify vulnerable families and to increase their levels of intervention to those families. Health visitors were targeting their services within a framework of a basic minimum service to all and were assessing the health needs of individuals or families rather than planning their work on the basis of community or practice profiles.     

The role of cortical serotonin in anxiety and locomotor activity in Wistar rats.

The brain's serotonergic system is known to play an important role in the modulation of anxiety. While the role of serotonin (5-HT) in subcortical structures is well investigated, little is known about the function of cortical 5-HT. The present series of studies used local injections of the serotonergic neurotoxin, 5,7-dihydroxytryptamine (5,7-DHT), into the medial prefrontal cortex (mPFC), entorhinal cortex (EC), or occipital cortex (OccC) of rats to chronically reduce 5-HT neurotransmission in these brain areas. The animals were tested for anxiety-like behavior on the elevated plus-maze and open field. An 82% depletion of 5-HT from the mPFC increased anxiety-like behavior, while no general motor effects were evident. In contrast, a 63% 5-HT-depletion of the EC or a 78% 5-HT-depletion of the OccC did not have any effects on emotional or exploratory behaviors. These findings are in line with a proposed role of 5-HT in the mPFC in the modulation of anxiety- and stress-mediated behavior and demonstrate a functional differentiation between different cortical 5-HT projections. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The possible mechanisms of the participation of the central cholinoreactive systems in regulating spontaneous motor activity in the early ontogeny of rats

In experiments on 0-16-day rat puppies, studies have been made of the effects of activation of N-cholinoreceptors during injections of nicotine, inactivation of N-cholinoreceptors by ganglerone, as well as combination of ganglerone and DOPA on the spontaneous periodic motor activity. It was shown that activation of N-cholinoreceptors results in the reactions which were earlier described for newborn rats during injection of exogenous catecholamines, i.e. the increase in motor activity and the onset of rhythmic components in the latter. Experiments with spinalization and DOPA injection showed that the potentiating effect of nicotine is realized via the descending catecholaminergic systems. Therefore, central N-cholinoreactive systems are mature already in newborn animals exhibiting from the very first day of postnatal life modulatory effects on catecholaminergic neurones in the brain stem.     

The role of oxidative stress in rhinovirus induced elaboration of IL-8 by respiratory epithelial cells

A direct correlation has been reported between the severity of symptoms associated with rhinovirus infection and the concentration of interleukin-8 in nasal secretions. The purpose of these studies was to examine the mechanism of rhinovirus-induced IL-8 elaboration. Rhinovirus infection induced oxidative stress in Beas-2b cells and the concentration of H2O2 in supernatant media from rhinovirus challenged cells was 12.5 +/- 6.1 microM 1 h after challenge compared to 0.7 +/- 0.3 microM in supernatant from control cells. N-acetyl cysteine inhibited RV-induced NF-kappaB activation and IL-8 elaboration. IL-8 concentrations were 36 +/- 2 pg/ml and 10 +/- 1 pg/ml 6 h after virus challenge in untreated and NAC-treated (30 mM NAC) cells, respectively. Despite the effects of NAC on IL-8 elaboration and NF-kappaB activation, RV stimulated increases in supernatant H2O2 were not altered by NAC. These data suggest that RV stimulation of IL-8 in respiratory epithelium is mediated through production of oxidative species and the subsequent activation of NF-kappaB.     

Visual function measured by reflex modification in rats with inherited retinal dystrophy.

Two experiments, with 16 Ss, examined developmental changes in visual function in the Royal College of Surgeons (RCS) rat with inherited retinal degeneration (retinal dystrophy) by studying the inhibition of acoustic startle reflexes by visual prestimuli. Compared with a congenic strain of nondystrophic rat, RCS Ss showed an increase in the interstimulus interval between the inhibitory prestimulus and the eliciting stimulus that produced maximal inhibition, a result suggesting a decrease in the speed of processing. The amount of inhibition also decreased over time, which suggests a progressive loss of visual function. Simultaneous presentation of auditory and visual prestimuli was used to demonstrate that the changes in inhibition were related to alterations in visual function and that auditory function was not impaired. Results show that reflex modification is a suitable test for evaluating visual dysfunction in rats. ( 27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of stress and articulatory difficulty in children's early productions.

Interactions between stress level and articulatory difficulty as influences on children's early words were investigated in an elicited imitation task. Thirty-two 26-month-old children were asked to imitate nonsense-word stimuli containing target syllables that varied in articulatory difficulty and level of stress. Both factors had significant effects on aspects of the children's imitations, although the relative contributions of each differed for whole word avoidance, syllable omissions, and accuracy of production. Implications of these differential effects for accounts of children's early productions are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The early evaluation of induced osteoarthritis in rats with 99Tcm-pertechnetate scans

Osteoarthritis was induced in 30 adult rats by serial injection of papain (3.5 mg kg-1) into the right knee on days 1, 4 and 7 of the study, with equal volumes of normal saline being injected into the left knee as a control. The severity of the induced arthritis was observed after the subcutaneous injection of 37 MBq kg-1 (1 mCi kg-1) 99Tcm-pertechnetate in the neck 24 h and 1, 2, 4, 6 and 8 weeks after the first intra-articular injection of papain. The ratio of radioactivity in the right compared with the left knee of each rat was measured as an index of the severity of osteoarthritis. After the scans, X-rays of both knees were obtained. At each state of progression, a rat was sacrificed and bilateral knee sections were performed for further pathological evaluation. The results were then compared with the changes in the radioactivity ratio and the X-rays. The radioactivity ratio of the knees reached a peak approximately 25 min after the subcutaneous injection of 99Tcm-pertechnetate and this value was chosen as the index of the severity of osteoarthritis. Marked differences in radioactivity in the left and right knees were observed as early as 24 h after the first intra-articular injection of papain. The radioactivity ratio increased with time, which correlated well with pathological changes. Joint space narrowing was not found on X-ray until 4 weeks post-injection. The results showed that the 99Tcm-pertechnetate scans correlated well with the pathological changes and that this method can detect osteoarthritis earlier than joint X-rays. It is suggested that a 99Tcm-pertechnetate scan is a useful means of evaluating early changes in induced osteoarthritis in rats.     

The nootropic correction of disorders in learning and memory processes induced by extreme exposures

Experiments on rats demonstrated that the low-intensity electromagnetic field (12.6 cm, 2375 MHz, power density 1 mW/cm2), motion sickness, and electroconvulsive shock provoked the retrograde amnesia in the passive avoidance test. The oxyracetam (100 mg/kg, i.p.), aniracetam (50 mg/kg, i.p.), nooglutil (50 mg/kg, i.p.), meclofenoxate (50 mg/kg, i.p.), pyracetam (200 mg/kg, i.p.), and GABA (200 mg/kg, i.p) prevented the memory-impairing effect of all these extreme factors. On the contrary, the N-acetylglycinamide, semax, and other nootropic drugs were effective only under one or two extreme conditions.     

气管滴注大气可吸入颗粒物对大鼠的系统性氧化应激作用

目的:探讨大气可吸入颗粒物对大鼠的氧化应激作用.方法:将24只体重为320～360 g的雄性Wistar大鼠随机分为4组,即生理盐水对照组和颗粒物低、中、高剂量组(3.75、7.5、15 mg/kg).染毒采用一次性气管滴注颗粒物,24 h后处死动物,测定血液中的超氧化物歧化酶(superoxide dismutase,SOD)活性和丙二醛(malondialdehyde,MDA)含量,以及心肺组织中SOD活性、MDA和蛋白羰基(protein carbonyl)的含量.结果:与对照组相比,各染毒组大鼠血液中SOD活性降低,中、高剂量组的差异有统计学意义(P＜0.05);血液中MDA含量升高,高剂量组的差异有统计学意义(P＜0.05);各染毒组大鼠心肺组织高剂量组的SOD活性降低,且差异有统计学意义(P＜0.05);肺脏MDA水平升高,中、高剂量组的差异有统计学意义(P＜0.05);心脏MDA水平升高,高剂量组的差异有统计学意义(P＜0.05);肺脏蛋白羰基含量升高,高剂量组的差异有统计学意义(P＜0.05),心脏蛋白羰基含量无明显改变.结论:大气可吸入颗粒物能引起大鼠体内氧化和抗氧化系统的失衡,产生氧化应激效应,膜脂质较蛋白质更易受到氧化应激的作用.     

Effects of fluoxetine on the development of lung metastases induced by operative stress in rats

Experiments were performed in order to evaluate the effects of fluoxetine, a selective inhibitor of neural serotonin transporter antidepressant, on the development lung metastases in rats subjected to laparotomy and injected (i.v.) with 10(4) Walker 256 (W-256) carcinosarcoma cells. The number of metastatic nodules on the surface of the lungs, as well as the percentage-area of metastases in the frontal section through pulmonary hilus were increased in rats subjected to sham-surgery or laparotomy. Treatment with fluoxetine (5 mg/kg) partially reversed those adverse effects of surgery, but the difference was clearer when it was administered before surgery was performed. Survival periods were also assessed and fluoxetine was found to decrease the lethality of rats exposed to surgery.     

Oxidative stress in diabetic rats induced by streptozotocin: protective effects of melatonin

Two years after Kurt Schneider had finalised his thesis qualifying him as a lecturer at Cologne University, he completed his doctorate dissertation in philosophy, also at Cologne University. His advisor was Max Scheler. Schneider published the results of his researches in a short monograph. It appears that at this time Scheler's phenomenology began to influence psychiatry. However, Kurt Schneider made only passing references to Max Scheler in this regard. Nevertheless, Scheler's influence on Schneider remained noticeable even in his most famous book "Clinical Psychopathology". Years after their academic contacts, Scheler, on several occasions, asked Schneider's advice concerning his psychically disturbed son Wolfgang. Schneider's diagnosis amounted to a case of a severely psychopathic personality. He informed Max Scheler on this and, subsequently, Wolfgang Scheler was interdicted, i.e. legally incapacitated.     

Microstructures induced by a stress gradient in a nickel-based superalloy

The evolution of the microstructure of single crystals of a nickel-based superalloy during high temperature (1323 K, 1050°C) creep in bending has been studied. Bending provides both tensile and compressive stress gradients; consequently the effects of varying stress conditions on the evolution of the morphology of the γ′ precipitates can be determined from a single specimen. The morphological changes were analysed by scanning electron microscopy using image analysis techniques and by transmission electron microscopy, then described by dimensionless parameters. We discuss the dependence of the morphological changes in the superalloy on the stresses acting in the sample (magnitude and sign). We also discuss the driving mechanisms for the observed morphological changes.     

The role of stress hormones in exercise-induced suppression of alveolar macrophage antiviral function

We hypothesized that a previously observed exercise-induced suppression of alveolar macrophage antiviral resistance results from increases in corticosterone and/or epinephrine. Mice (CD-1) were run to fatigue on a treadmill (exercise), or placed in Plexiglas lanes above the treadmill (control). The role of corticosterone was assessed by further dividing mice into groups receiving one of the following treatments; sham surgery, adrenalectomy, or adrenalectomy plus corticosterone replacement. Macrophage antiviral function was suppressed in the exercised mice compared to the control mice. However, macrophage antiviral function was not suppressed in the exercised mice that underwent adrenalectomy or adrenalectomy plus corticosterone replacement. We tested whether another adrenal factor (epinephrine) may be involved by dividing mice into exercise and control groups treated with either saline or propranolol. Macrophage antiviral function was again suppressed in the saline-treated exercised mice compared to saline-treated control mice, but no differences were found between the exercised mice receiving propranolol, control mice receiving propranolol, or saline-treated control mice. Isoproterenol, when added to alveolar macrophages in culture, also suppressed antiviral resistance. These findings suggest that decreased macrophage antiviral function following exercise may be due to increased release of adrenal catecholamines.