Correlation of the rat behavior after immobilization with structural reorganization in the motor cortex

Behavioral changes and accompanying morphological neuron-glia reorganization in the rat brain were compared after emotional stress. Wistar rats (n = 20) were stressed by the interrupted immobilization, which was carried out during one week 7-8 h daily. Behavioral immobilization of rats was accompanied by an increase in horizontal and vertical locomotors activity and in duration of the III and IV phases of grooming ("comfortable" grooming) in the "open field" test. The morphometric studies showed a statistically significant increase in the density of hypoxic neurons in the right neocortex of the experimental animals as compared with control. Hypoxic changes in neurons were of functional character. Experimental rats can be considered as a model of redistribution of functional brain activity with preferential intensification of the left brain hemisphere.     

Prior exposure to methylenedioxyamphetamine (MDA) induces serotonergic loss and changes in spontaneous exploratory and amphetamine-induced behaviors in rats

The substituted amphetamine 3,4 methylenedioxyamphetamine (MDA) is a popular recreational drug of abuse. Administration of MDA to experimental animals has been shown to induce damage to serotonergic axons and nerve terminals. However, there is a lack of information on whether these treatments can produce any long-term changes in behavioural performance particularly under stressful conditions. In the present study, MDA (7.5 mg/kg; i.p.) was administered twice daily to adult male Sprague Dawley rats for four days. Four weeks following the last dose, spontaneous behaviors of these animals were tracked and scored in a novel "open field" environment using an automated video registration and computer interpretation system. Changes in behavior were observed in MDA treated animals including reductions in exploratory oriented behaviors (locomotion and rearing) and increases in grooming behavior when compared to vehicle treated controls. MDA-treated animals also displayed an enhanced locomotor and stereotyped response to d-amphetamine (12 mg/kg; i.p.). Significant reductions in 5-HT concentrations (20-30%) were observed in the frontal cortex, amygdala, striatum, and hypothalamus as a result of MDA treatment. In addition, [3H] paroxetine binding was reduced by (40%) in the cortex of MDA treated rats indicating that the decrease in 5-HT concentrations were accompanied by a reduction in intact presynaptic 5-HT nerve terminals. Changes in behavioural performance in a novel "open field" environment and following d-amphetamine challenge might be considered as a behavioural model of serotonergic deficit induced by MDA. The findings of this study also suggest that MDA use may increase both the abuse potential, and the propensity to develop psychosis as a result of abusing other psychostimulants such as d-amphetamine.     

The effects of verbascoside on plasma lipid peroxidation level and erythrocyte membrane fluidity during immobilization in rabbits: a time course study

We studied the changes in the level of plasma lipid peroxidation indicated by malondialdehyde (MDA) level and erythrocyte membrane fluidity expressed by the value of order parameter (S) during single hindlimb immobilization of 21 days using thiobarbituric acid - reactive substances method and spin label electron spin resonance method, respectively. The impacts of verbascoside that has been proved its antioxidative activity on the measured parameters were examined. 11 New Zealand white rabbits were immobilized and divided into two groups. The rabbits in the verbascoside group were administrated with 0.8 mg/kg of verbascoside twice a day orally throughout the immobilization. The rabbits in the placebo group were treated with normal saline. In placebo group, the results showed that the level of MDA significantly increased on day 3, peaked on day 7, and was still significantly higher on day 14 of immobilization, compared with the value measured before immobilization. The value of S reached the highest on day 7 and subsequently lowered but still higher on day 14 than those measured before immobilization. Compared with placebo group, there were lower MDA level (P < 0.05, 0.001, and 0.05 for days 3, 7, and 14, respectively) and higher erythrocyte membrane fluidity (P < 0.05, 0.001, and 0.001 for days 3, 7, and 14, respectively) in verbascoside group. The data indicated that immobilization caused temporal changes of increase in plasma lipid peroxidation and decrease in erythrocyte membrane fluidity. Verbascoside might have the effects to moderate oxidative stress and erythrocyte membrane fluidity during immobilization.     

Role of free radicals in stress-induced neurobehavioural changes in rats

Effect of restraint stress (RS) and its modulation by antioxidants were evaluated on elevated plus maze (EPM) and open field (OF) tests in rats. Restraint stress (RS for 1 hr) reduced the number of open arm entries, as also the time spent on open arms indicating enhanced anxiogenic response in the EPM test as compared to normal non RS group of rats. Pretreatment with ascorbic acid (100 and 200 mg/kg) and alpha-tocopherol (30 and 60 mg/kg) attenuated these RS-induced effects. In the OF test, RS-reduced (a) ambulations; and (b) rearings, whereas an increase was seen in (a) latency of entry and (b) number of fecal boluses. The RS-induced changes in OF parameters were reversed after pretreatment with the antioxidants, (ascorbic acid and alpha tocopherol). Biochemical data showed that RS enhanced MDA levels in both serum and brain, and these were attenuated after pretreatment with the antioxidants. The pharmacological and biochemical results indicate that free radicals might be involved in such stress-induced neurobehavioural effects.     

Effect of neurotensin on the behavior of rats with damaged serotoninergic neurons under immobilization stress

It was shown that the immobilization of animals has led to reducing of vertical and horizontal locomotor activity in the "open field" and decreasing of number of conditioned food-procuring reactions into T-maze. The damages of serotoninergic neurons produced via local injections of selective neurotoxin 5, 7-dihydroxytriptamine into dorsal raphe nucleus intensified behavior alterations. Neurotensin administrations reduced effects of neurotoxin: the rats locomotor activity and quantity of conditioned reactions into T-maze were kept at the phone level just after immobilization as well as next two days. The results indicate the important protective significance of neurotensinergic brain structures for ensuring of adaptive behavior of animals with damaged serotoninergic neurons under emotional stress conditions. It is supposed that neurotensin normalizing influences on behavior is connected to a restoration of balance of dopamine-and serotoninergic brain structures interaction.     

Rhythmic organization of compulsory swimming and its relation to the behavioral characteristics of rats

Seconds' biorhythms manifesting themselves during protracted swimming were studied in 52 white outbred rats of both sexes. In rats with higher rhythm frequency short immobilization periods dominated in swimming. They had shorter immobilization time. These rats relearned easier the direction of avoidance reaction in Y-maze, were more mobile in the open field, more often washed up, more rarely defecated and urinated. The seconds' rhythms may be used for evaluation of the ability of animals for adaptation to changing behavioural situation.     

Psychotropic effects of glutamic acid diethyl ester in mice

In 1 hour after intraperitoneal injection glutamic acid diethyl ester (GED) in doses 200 and 500 mg/kg decreased locomotor activity and exploratory patterns of mice in "open field" test. GED in doses 100 and 200 mg/kg diminished the immobilization period of animals in forced swimming test, that proves the reversal interaction of glutamatergic and catecholaminergic systems in CNS. Glutamate receptors antagonist--GED in doses 100-200 mg/kg disrupted passive avoidance reaction at 30 min before acquisition and retrieval, therefore glutamate receptors are involved into fixation and retrieval of memory engram.     

重金属污染土壤原位化学固定修复研究进展

重金属污染土壤原位化学固定修复是通过添加不同外源物质固定土壤中重金属元素,达到降低重金属迁移性和生物有效性的一种重要方法.由于操作方便和效果快速,使其在污染土壤治理过程中有着不可代替的作用,尤其对于耕作土壤中的面源污染.许多具有俘获土壤中重金属离子能力的自然物质和工业副产品如磷矿石、泥炭土、石灰和有机肥等都可用在实地的固定修复中.采用实验室评价和实地应用评价,一方面可以评估这些固定物质在土壤中对重金属离子的固定效率;另一方面可以评估重金属的溶出、释放和生物毒性等生态风险.本文对原位修复过程中采用的不同固定物质的来源和分类进行了概述,对化学固定过程的机理进行了探讨,同时阐述了重金属污染土壤化学固定修复应用过程中的实验室评价和实地应用评价方法,分析了化学固定修复的局限性并提出了今后的发展方向.     

Immobilization of soil nitrogen as a possible method for the restoration of sandy grassland

Abstract. Experiments were designed to test the applicability of nitrogen immobilization as a means of accelerating the recovery of an endemic open sandy grassland (Festucetum vaginatae danubiale) on old fields in the Great Hungarian Plain. Effects of various carbon sources (sucrose, starch, cellulose and sawdust) and their combinations in different quantities were studied in laboratory microcosms. Carbon addition decreased nitrogen availability in all cases, the intensity and timing of change being dependent on the type of carbon source applied. The combination of 2 g each of sucrose and polysaccharides (starch, cellulose, sawdust) per kg soil was found to be the most effective, as sucrose decreased available nitrogen content of soil intensively and the polysaccharides maintained the immobilized nitrogen for a longer period. In a follow‐up experiment, sucrose and sawdust were selected for field application to test their effectiveness in immobilizing N and accelerating restoration. The field experiment was established to test the importance of abiotic site differences in the immobilization of soil nitrogen. Selected sites were located along an elevation, moisture and productivity gradient. Soil organic matter, microbial biomass‐C and decomposition rate varied between sites depending on the elevation gradient. At two sites with lower soil moisture and organic matter levels carbon addition increased microbial activity and nitrogen immobilization significantly.     

Sequence quality is maintained after multiple displacement amplification of non-invasively obtained macaque semen DNA

Whole genome amplification protocols are revolutionizing the fields of molecular and conservation biology as they open the possibility of obtaining a large number of copies of a complete genome from minute amounts of sample. Multiple displacement amplification (MDA) is a whole genome amplification technique based on the properties of the phi29 DNA polymerase, which leads to a uniform representation of the genome with very low error rates. In this study we performed MDA on 28 macaque DNA samples extracted from blood or non-invasively collected semen from which we obtained mitochondrial control region sequences both before and after MDA. The length of the readable sequences was longer for the original samples than for the MDA products, but the number of unresolved positions was comparable both before and after MDA. We conclude that the MDA technique is useful for increasing the amount of DNA for sequencing mitochondrial regions in the case of non-invasively collected semen samples.     

Immobilization and hybridization by single sub-millisecond electric field pulses, for pixel-addressed DNA microarrays

Single square voltage pulses applied to buried electrodes result in dramatic rate increases for (1) selective covalent bonding (immobilization) of single-stranded DNA (ssDNA) probes to a functionalized thin film SiO₂ surface on a plastic substrate and (2) hybridization of ssDNA to the immobilized probe. DNA immobilization and hybridization times are 100 ns and 10 μs, respectively, about 10⁹ times faster than the corresponding passive reactions without electric field. Surface coverage is comparable. Duration, magnitude and slew rate of the voltage pulse are all key factors controlling the rates of ssDNA immobilization and hybridization. With rise times of 4.5 ns, pulses shorter than 1 ms and voltages below 1 V are effective. The ssDNA adsorbed on the surface is reoriented by the rapidly changing electric field. This reduces steric barriers and speeds the immobilization and hybridization reactions. These results open the way for pixel-addressed microarrays driven by silicon microelectronics circuits.     

Changes in the catecholamine content of brain structures in rats subjected to immobilization stress

The changes in DOPA and catecholamine (adrenaline, noradrenaline, dopamine) levels were investigated in noradrenaline- and dopamine-synthesizing brain nuclei of Wistar rats after prolonged immobilization stress on catecholamine analyzer (BAS, USA) using HPLC technique. Distinct DOPA and catecholamine changes were observed in locus ceruleus + nucleus subceruleus (1. c + n. sc) and substantia nigra at any stage after immobilization (right after immobilization and 15 and 30 days later). The most prominent alterations in noradrenaline content were detected in 1. c + n. sc. 30 days after immobilization NA level in these nuclei was 1.5 times higher, as compared to the control one. It is suggested that the increasing noradrenaline level in 1. c + n. sc. plays a defensive role in survival of rats after immobilization stress.     

The effects of hormonal and circadian cycles, stress, and activity on levels of cyclic AMP and cyclic GMP in pituitary, hypothalamus, pineal and cerebellum of female rats

Cyclic AMP and cyclic GMP levels were measured in the anterior and posterior pituitary, hypothalamus, pineal and cerebellum of female rats sacrificed during proestrus, metestrus and diestrus. In the first experiment rats were sacrificed by microwave irradiation between 0900 and 1100, between 1600 and 1800 and between 2100 and 2300. Cyclic AMP and cyclic GMP levels did not vary in any region tested as a function of the estrous cycle except for slightly elevated cyclic GMP levels in the posterior pituitary during proestrus. However the time of day at which the animals were sacrificed affected levels of cyclic AMP in the hypothalamus and cerebellum and levels of cyclic GMP in the cerebellum. In a second experiment female rats were all sacrificed between 2130 and 2330 during proestrus and diestrus. In this experiment rats were sacrificed either immediately upon removal from the home cage or after 10 min of immobilization stress, or after 10 min of open field activity. No differences in pituitary cyclic nucleotides were seen between proestrous and diestrous animals. However, stressed animals showed large cyclic AMP increases in the pituitary, and activity increased cyclic GMP levels in the cerebellum and pineal.     

Role of AVP in mediating the altered core temperature response to a simulated open field in pregnant rats.

Near the term of pregnancy, rats have an attenuated core temperature response on exposure to a novel environment (e.g., a simulated open field) compared with that observed early in pregnancy or in nonpregnant rats. The present experiments were carried out on 26 nonpregnant and 26 pregnant rats to test the hypothesis that arginine vasopressin, functioning as an endogenous antipyretic substance in the central nervous system, mediates this attenuated core temperature response. Exposure to a simulated open field after intracerebroventricular (ICV) vehicle produced a significant increase in core temperature in both nonpregnant and pregnant animals, the magnitude and duration of which were greater in the nonpregnant rats. In nonpregnant rats, exposure to a simulated open field after ICV vasopressin V(1)-receptor antagonist altered the pattern of the core temperature response but not the core temperature index compared with that observed on exposure to a simulated open field after ICV vehicle. In pregnant animals, ICV vasopressin V(1)-receptor antagonist did not alter the core temperature response to a simulated open field compared with that observed after ICV vehicle. Thus our data do not support the hypothesis that a pregnancy-related activation of arginine vasopressin attenuates the core temperature response to a simulated open field in rats near the term of pregnancy.     

Behavioral activity and stress reaction of the pituitary-adrenocortical axis in rat with prenatal inhibition of testosterone metabolism

The effects of maternal administration of the aromatase inhibitor, 1,4,6-androstatrien-3,17-dione (ATD), during the last week of gestation on stress reaction of the hypothalamic-pituitary-adrenal axis (HPA) and behavior in a novel environment (open field) and the anxiety level in the elevated plusmaze, were studied in male and female adult offspring. The results showed that parental inhibition of brain testosterone metabolism decreases the basic level of corticosterone in male rats and prolongs hormonal stress reaction of the HPA axis in both sexes. Prenatally treated rats demonstrated significant elevation of the anxiety level and emotionality. There was no sexual dimorphism in behavioral response to a novel environment such as locomotor activity, the time of immobilization, the total duration of grooming reaction, and the anxiety level, between control male and treated female rats. These data suggest a prenatal inhibition of the brain testosterone metabolism after the stress reaction of HPA axis and formation of sexual dimorphism in the anxiety and behavioral response to a novel environment in adulthood.     

Noninvasive monitoring of deterioration in skeletal muscle function with forearm cast immobilization and the prevention of deterioration

BACKGROUND: In this research inactivity was simulated by immobilizing the forearm region in a plaster cast. Changes in skeletal muscle oxidative function were measured using near-infrared spectroscopy (NIRS), and the preventative effect of the training protocol on deterioration of skeletal muscle and the clinical utility of NIRS were examined. METHODS: Fourteen healthy adult men underwent immobilization of the forearm of the non-dominant arm by plaster cast for 21 days. Eight healthy adult subjects were designated as the immobilization group (IMM) and six were designated as the immobilization + training group (IMM+TRN). Grip strength, forearm circumference and dynamic handgrip exercise endurance were measured before and after the 21-day immobilization period. Using NIRS, changes in oxidative function of skeletal muscles were also evaluated. Muscle oxygen consumption recovery was recorded after the completion of 60 seconds of 40% maximum voluntary contraction (MVC) dynamic handgrip exercise 1 repetition per 4 seconds and the recovery time constant (TcVO2mus) was calculated. RESULTS: TcVO2mus for the IMM was 59.7 +/- 5.5 seconds (average +/- standard error) before immobilization and lengthened significantly to 70.4 +/- 5.4 seconds after immobilization (p < 0.05). For the IMM+TRN, TcVO2mus was 78.3 +/- 6.2 seconds before immobilization and training and shortened significantly to 63.1 +/- 5.6 seconds after immobilization and training (p < 0.05). CONCLUSIONS: The training program used in this experiment was effective in preventing declines in muscle oxidative function and endurance due to immobilization. The experimental results suggest that non-invasive monitoring of skeletal muscle function by NIRS would be possible in a clinical setting.     

Effects of prenatal disturbance in the brain testosterone metabolism on anxiety level and behavior of rats in a novel environment

The effects of maternal administration of the aromatase inhibitor 1,4,6-androstatrien-3,17-dione (ATD) during the last week of gestation on formation of behavior in a novel environment were studied in male and female offspring. The "open field" and the elevated plus-maze tests were used. The results showed that there were a significant elevation of the anxiety level and emotionality in ATD-treated 30-day-old female rats, whereas at the age of 90 days, the elevation of these behavioral parameters was observed both in males and females. There was no a sexual dimorphism in behavioral response to a novel environment such as locomotor activity, time of immobilization, total duration of grooming reaction, and anxiety level between adult control male and treated female rats. These data suggest that prenatal inhibition of the brain testosterone metabolism alters the formation of sexual dimorphism of the anxiety and behavioral response to a novel environment in adulthood.     

Influence of extremely-low-frequency magnetic field on antioxidative melatonin properties in AT478 murine squamous cell carcinoma culture

Effects of melatonin, extremely-low-frequency magnetic field (ELF-MF), and their combination on AT478 murine squamous cell carcinoma line were studied. Manganese superoxide dismutase (MnSOD), copper-zinc superoxide dismutase (Cu/ZnSOD), and glutathione peroxidase (GSH-Px) were used as markers of cells antioxidative status, and malondialdehyde (MDA) level was used as a marker of lipid peroxidation. After melatonin treatment, antioxidative enzyme activities were increased and MDA level was decreased. Application of ELF-MF on treated cells caused an increase of both superoxide dismutases activity and MDA level, but influence of ELF-MF on GSH-Px activity was negligible. All enzyme activity in culture medium containing melatonin (10⁻³, 10⁻⁴, 10⁻⁵ M) after exposure to ELF-MF were significantly diminished compared to cells treated only with melatonin. Also MDA levels after combined treatment with melatonin and ELF-MF were significantly decreased. Observed changes were statistically significant (p<0.05). These results strongly suggest that ELF-MF attenuates antioxidative actions of melatonin on cellular level.     

Electrospun polyvinyl alcohol/bovine serum albumin biocomposite membranes for horseradish peroxidase immobilization

Electrospinning, a simple and versatile method to fabricate nanofibrous supports, has attracted attention in the field of enzyme immobilization. Biocomposite nanofibers were fabricated from mixed PVA/BSA solution and the effects of glutaraldehyde treatment, initial BSA concentration and PVA concentration on protein loading were investigated. Glutaraldehyde cross-linking significantly decreased protein release from nanofibers and BSA loading reached as high as 27.3% (w/w). In comparison with the HRP immobilized into the nascent nanofibrous membrane, a significant increase was observed in the activity retention of the enzyme immobilized into the PVA/BSA biocomposite nanofibers. The immobilized HRP was able to tolerate much higher concentrations of hydrogen peroxide than the free enzyme and thus the immobilized enzyme did not demonstrate substrate inhibition. The immobilized HRP retained ⿼50% of the free enzyme activity at 6.4 mM hydrogen peroxide and no significant variation was observed in the KM value of the enzyme for hydrogen peroxide after immobilization. In addition, reusability tests showed that the residual activity of the immobilized HRP were 73% after 11 reuse cycles. Together, these results demonstrate efficient immobilization of HRP into electrospun PVA/BSA biocomposite nanofibers and provide a promising immobilization strategy for biotechnological applications.     

Effects of two types of restraint stress on spontaneous behavior of Sprague-Dawley and Lewis rats.

The purpose of this study was to evaluate the action of two types of stressors in Sprague-Dawley (S-D) and Lewis (LEW) rats differing in their hypothalamic-pituitary-adrenal axis activity on locomotion and rearing in an open space. Exposure to restraint immobilization alone (IMO) or this immobilization combined with cold water (22 degrees C) immersion (IMO+C) lasted for 1 h and started 2 or 5 h before the test. To evaluate the acute and persisting effects of both stressors, four trials were performed in one-week intervals; rats were exposed to the stressors in trial 1 and 3. While in LEW rats both acute stressors produced reduction of locomotion and rearing in all stressed groups, S-D rats responded with a decrease of both parameters only after IMO+C presented 2 h before testing. Neither strain displayed a changed performance one week after the first stress exposure. One week after the second stress exposure rats of both strains exhibited a tendency to an increase of both parameters reaching the significance in several experimental groups. The findings indicate: a) the IMO+C produced stronger behavioral alteration than IMO alone; b) the behavioral responses to stressors were more pronounced in LEW compared to S-D strain; c) change from the reduction of activity to its increase may be interpreted as bi-directional manifestation of long-term effects of immobilization stress.