Dynamics of protein uptake within the adsorbent particle during packed bed chromatography

Elevated osmolality and pCO(2) have been shown to alter sialylation in a protein-specific manner. In Chinese hamster ovary (CHO)MT2-l-8 cells, tPA sialylation changed only slightly from 40 to 250 mm Hg pCO(2), whereas neural cell adhesion molecule polysialic acid (NCAM PSA) content decreased by up to 70% at 250 mm Hg pCO(2), pH 7.2. NCAM PSA content also decreased with increasing NaCl or NH(4)Cl concentration. This suggests that PSA content is a sensitive indicator of conditions that may alter glycosylation. Amino acids and their derivatives have been used to protect hybridoma and CHO cell growth under hyperosmotic stress. We examined the impact of osmoprotectants on NCAM PSA content in CHO MT2-1-8 cells under hyperosmolality (up to 545 mOsm/kg) and at 195 and 250 mm Hg pCO(2). NCAM PSA content at 545 mOsm/kg was at least two-fold greater in the presence of glycine betaine or L-proline compared to that without osmoprotectant. Surprisingly, in the presence of 20 mM glycine betaine, PSA levels were 50-60% of the control level for osmolalities ranging from 320 to 545 mOsm/kg. Thus, glycine betaine inhibits NCAM polysialylation at osmolalities below 435 mOsm/kg and is beneficial at higher osmolalities. In contrast to glycine betaine, L-proline increased PSA content by 25-120% relative to the unprotected culture at < or =545 mOsm/kg. The decrease in NCAM PSA levels of CHO MT2-1-8 cells cultured at 195 mm Hg pCO(2)-435 mOsm/kg was not mitigated by the presence of 25 mM glycine betaine, glycine, or L-threonine, even though all of these compounds enhanced cell growth. At 250 mm Hg pCO(2), all osmoprotectants tested (20 mM L-threonine, L-proline, glycine, or glycine betaine) increased NCAM polysialylation, with 20 mM glycine betaine restoring NCAM PSA to near control levels. Thus, osmoprotectants may (partially) offset changes in glycosylation, as well as the inhibition of growth, in cells under environmental stress. Supernatant beta-galactosidase levels, which increase upon alkalization of acidic organelles, did not differ significantly under elevated pCO(2) and hyperosmolality from that at control conditions.     

The role of NCAM in auditory fear conditioning and its modulation by stress: a focus on the amygdala

Chronic stress in rodents was shown to induce structural shrinkage and functional alterations in the hippocampus that were linked to spatial memory impairments. Effects of chronic stress on the amygdala have been linked to a facilitation of fear conditioning. Although the underlying molecular mechanisms are still poorly understood, increasing evidence highlights the neural cell adhesion molecule (NCAM) as an important molecular mediator of stress‐induced structural and functional alterations. In this study, we investigated whether altered NCAM expression levels in the amygdala might be related to stress‐induced enhancement of auditory fear conditioning and anxiety‐like behavior. In adult C57BL/6J wild‐type mice, chronic unpredictable stress resulted in an isoform‐specific increase of NCAM expression (NCAM‐140 and NCAM‐180) in the amygdala, as well as enhanced auditory fear conditioning and anxiety‐like behavior. Strikingly, forebrain‐specific conditional NCAM‐deficient mice (NCAM‐floxed mice that express the cre‐recombinase under the control of the promoter of the α‐subunit of the calcium‐calmodulin‐dependent protein kinase II), whose amygdala NCAM expression levels are reduced, displayed impaired auditory fear conditioning which was not altered following chronic stress exposure. Likewise, chronic stress in these conditional NCAM‐deficient mice did not modify NCAM expression levels in the amygdala or hippocampus, while they showed enhanced anxiety‐like behavior, questioning the involvement of NCAM in this type of behavior. Together, our results strongly support the involvement of NCAM in the amygdala in the consolidation of auditory fear conditioning and highlight increased NCAM expression in the amygdala among the mechanisms whereby stress facilitates fear conditioning processes.     

Pentyl-4-yn-valproic acid enhances both spatial and avoidance learning, and attenuates age-related NCAM-mediated neuroplastic decline within the rat medial temporal lobe

2-N-Pentyl-4-pentynoic acid [pentyl-4-yn-valproic acid (VPA)] is an analogue of valproic acid that induces neuritogenesis and increases neural cell adhesion molecule (NCAM) prevalence in cultured neural cells. As memory consolidation involves synapse growth, aided by cell adhesion molecule function, we determined whether or not pentyl-4-yn-VPA had cognition-enhancing properties. Pentyl-4-yn-VPA (16-85 mg/kg) significantly improved water maze learning and task retention when given prior to each training session. Acute administration of pentyl-4-yn-VPA also influenced memory consolidation processes as, when given at 3 h post-passive avoidance training, the amnesia induced by scopolamine given 6 h post-training was prevented in a dose-dependent manner. Chronic administration of pentyl-4-yn-VPA (16.8 or 50.4 mg/kg) also significantly reduced escape latencies in the water maze task, 24 h following the last drug administration. This improved spatial learning was accompanied by enhanced neuroplasticity as the expression of NCAM polysialylated neurons in the infragranular zone of the dentate gyrus and in layer II of the perirhinal and piriform cortex was increased significantly following chronic drug treatment. The cognition-enhancing qualities of pentyl-4-yn-VPA, combined with its ability to attenuate the age-related loss of the NCAM polysialylation state, suggest that it may effectively slow the onset of cognitive decline.     

Effects of low doses of Li carbonate injected into mice. Functional changes in kidney seem to be related to the oxidative status

Effects of daily injections of lithium carbonate (20, 40 or 80 mg/kg body weight) during 14 and 28 days were investigated in Wistar mice. Attention was paid (1) to changes in concentrations of lithium, creatinine and urea in serum, (2) to level of oxidative stress by measuring lipids peroxidation level and catalase, superoxide-dismutase and glutathione-peroxidase activities, and (3) to changes in the histological structure of brain. The first intraperitoneal injection was followed by a transitory peak of lithium in the blood, reaching 0.25 mM and 1.1 mM and disappearing 6 and 12 h later for the 20 and 80 mg/kg doses, respectively. From the first to the last day of treatment, lithium concentrations in the blood, measured 12 h after the injections, increased from 0 to 0.11 mM (20 mg/kg dose) or 0.25 mM (80 mg/kg dose). The 80 mg/kg treatment induced a renal insufficiency evidenced by an increase of blood creatinine and urea levels. Lithium treatment was found to trigger an oxidative stress in kidney, but not in brain. In kidney, the lipid peroxidation level (TBARS) and the superoxide dismutase and catalase activities were increased. No change in glutathione peroxidase activity was detected. Histology of the brain cortex revealed interesting modifications: thicker neuronal cells and a denser network of dendrites, as compared to controls.     

Effects of Melatonin on Behavioral Reactions and on the Expression of NCAM in Rats

We studied the effects of i.p. injection of melatonin in pharmacotherapeutic doses and of constant illumination (a melatonin synthesis-suppressing factor) on the behavior of rats in the open-field test and on the content of the main isoforms of neural cell adhesion molecule (NCAM) in the hippocampus, cerebellum, and neocortex of these animals. In the studied brain structures of the rats kept under conditions preventing the melatonin synthesis, we observed suppression of the behavioral activity of animals and a decrease in the expression of the NCAM180 isoform. In rats injected with 10 mg/kg melatonin, changes in the behavioral activity were insignificant. In the hippocampus and neocortex of rats of this group, the NCAM180 content increased. Our experiments showed that melatonin can be involved in the control of balance of the expression of different NCAM isoforms. Such a balance is a crucial factor determining plastic rearrangements of the synaptic contacts.     

Behavioral reactions of rats and the contents of neurospecific proteins in their brain after single X-ray irradiation

We studied the behavior of rats in an open-field test and the contents of neurospecific proteins [neural cell adhesion molecule (NCAM) and glial fibrillary acidic protein (GFAP)] in the brain cortex, hippocampus, striatum, midbrain, cerebellum, andpons Varolii 1, 12, 24, 120, and 168 h after a single X-ray irradiation session (dose of 0.25 Gy). Within the postirradiation period, manifestations of the behavioral activity of the animals were mostly suppressed, and the parameters related to the emotional state of the animals were influenced to a greater extent. The dynamics of the NCAM and GFAP contents were complex and dissimilar in the brain structures under study, but it was possible to observe some general regularities. Within early periods of time, 12 h after irradiation, the NCAM content increased in the cortex, hippocampus, and cerebellum. In these structures, it reached approximately 220, 170, and 150%, respectively, as compared with the control, while it dropped to about 40% in thepons Varolii. Changes in the GFAP content reached their maximum 24 h after irradiation; this index dropped to 29, 44, 34, and 67% in the striatum,pons Varolii, midbrain, and cerebellum, respectively, while it increased to 380% in the hippocampus. Later time intervals were characterized by smoother changes in the contents of the above neurospecific proteins. Seven days after irradiation, the NCAM content did not differ from initial values in the striatum and cerebellum and was higher than the control in the neocortex, hippocampus, and midbrain. Within this period, the GFAP level in the cerebellum and midbrain was relatively normalized, but it increased in the hippocampus and decreased in the pons and striatum. Therefore, the greatest postirradiation shifts in the NCAM and GFAP levels were observed in the structures of the limbic system, and this can be correlated with the data on testing the rats in an open field.     

Studies on the Formation of 6-Hydroxydopamine in Mouse Brain After Administration of 2,4,5-Trihydroxyphenylalanine (6-HydroxyDOPA)

2,4,5-Trihydroxyphenylalanine (6-OH-DOPA) destroys central and peripheral noradrenergic neurons, while sparing dopaminergic neurons. Previous studies indicate that 6-OH-DOPA toxicity is mediated by the formation of 6-hydroxydopamine. However, levels of 6-hydroxydopamine in brain following peripheral administration of 6-OH-DOPA have not been documented. In the current study, 6-OH-DOPA and 6-hydroxydopamine were measured in brain by HPLC with electrochemical detection after intraperitoneal injection of 6-OH-DOPA. When mice were injected with 100 mg 6-OH-DOPA/kg, 6-hydroxydopamine levels in the striatum were highest (1.9 microgram/g) at 15 min and fell slowly to 24% of the peak value at 4 h. Experiments with reserpine indicated that the relatively stability of 6-hydroxydopamine was largely dependent upon storage in synaptic vesicles. Reserpine (10 mg/kg) lowered striatal 6-hydroxydopamine levels to 21.6% of control (non-reserpine-treated) values at 1 h, and to 8.9% of control values at 4 h. Levels of 6-hydroxydopamine in the striatum at 1 h were increased 113% by pargyline (100 mg/kg), 145% by alpha-methyldopahydrazine (carbidopa; 25 mg/kg), and 261% by pargyline and carbidopa together. Levels of dopamine in the striatum were unchanged at 2.5 h after 200 mg 6-OH-DOPA/kg (with pargyline and 50 mg carbidopa/kg), whereas levels of norepinephrine in the frontal cortex fell by 77%. At the same time, 6-hydroxydopamine levels were 8.8-fold higher in the striatum (5.54 micrograms/g) than in the cortex (0.63 micrograms/g).(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of valproic acid on hepatic and plasma levels of 15-F2t-isoprostane in rats

The mechanism by which valproic acid (VPA) induces liver injury remains unknown, but it is hypothesized to involve the generation of toxic metabolites and/or reactive oxygen species. This study's objectives were to determine the effect of VPA on plasma and hepatic levels of the F(2)-isoprostane, 15-F(2t)-IsoP, a marker for oxidative stress, and to investigate the influence of cytochrome P450- (P450-) mediated VPA biotransformation on 15-F(2t)-IsoP levels in rats. In rats treated with VPA (500 mg/kg), plasma 15-F(2t)-IsoP was increased 2.5-fold at t(max) = 0.5 h. Phenobarbital pretreatment (80 mg/kg/d for 4 d) in VPA-treated rats increased plasma and liver levels of free 15-F(2t)-IsoP by 5-fold and 3-fold, respectively, when compared to control groups. This was accompanied by an elevation in plasma and liver levels of P450-mediated VPA metabolites. Pretreatment with SKF-525A (80 mg/kg) or 1-aminobenzotriazole (100 mg/kg), which inhibited P450-mediated VPA metabolism, did not attenuate the increased levels of plasma 15-F(2t)-IsoP in VPA-treated groups. Plasma and hepatic levels of 15-F(2t)-IsoP were further elevated after 14 d of VPA treatment compared to single-dose treatment. Our data indicate that VPA increases plasma and hepatic levels of 15-F(2t)-IsoP and this effect can be enhanced by phenobarbital by a mechanism not involving P450-catalyzed VPA biotransformation.     

磷水平与丛枝菌根真菌对桔梗生长及品质的影响

明确不同磷水平条件下接种丛枝菌根真菌(AMF)对桔梗质量与产量的影响.采用盆栽法,设计P0(20 mg/kg)、P1(50 mg/kg)、P2(80 mg/kg)、P3(140 mg/kg)共4个磷水平,同一磷水平分别接种摩西斗管囊霉(Funneliformis mosseae,FM)、根内根孢囊霉(Rhizophag...     

The role of liver glutathione in the acute toxicity of retrorsine to rats.

(1) Two procedures have been used to change the glutathione concentration in the livers of male rats. The glutathione level is increased to about double that of the controls, 0.5 h after the administration of cysteine (200 mg/kg, i.p.) and to about 25% that of controls, 1 h after the administration of 2-chloroethanol (30 mg/kg, i.p.). (2) The acute LD50 of retrorsine to rats (42 mg/kg) is increased by pretreatment with cysteine to 83 mg/kg and decreased by pre-treatment with chloroethanol to 23 mg/kg. In all three groups, deaths are accompanied by haemorrhagic centrilobular necrosis of the liver. (3) 2 h after the administration of retrorsine to rats (60 mg/kg), the levels of pyrrolic metabolites in the livers of animals pre-dosed with cysteine or chloroethanol are respectively about 60% and 200% those of rats given no pre-treatment. (4) Neither in the normal nor in the pre-treated rats dose retrorsine (60 mg/kg) cause a detectable fall in liver glutathione concentration 0.5-4 h after dosing. By 24 h, the glutathione concentration in the livers of the retrorsine-dosed rats is higher than those of the corresponding controls. There was no significant change in the liver weights of the treated rats relative to the controls. (5) Treatment of rats with retrorsine (60 mg/kg) causes a fall in the liver concentrations of cytochrome P-450, 24 h after dosing. This loss of cytochrome P-450 is increased in rats pre-treated with chloroethanol. The concentrations of cytochrome b5 in the same animals are not significantly reduced.     

Complex role of 5-HT in the regulation of TSH secretion in the male rat

The role of 5-hydroxytryptamine (5-HT) in the regulations of TSH secretion was studied in male rats using both peripheral and central administration of the drugs. Basal TSH levels were not modified by moderate doses of 5-HT (subcutaneously) or its precursors or antagonists (intraperitoneally) given 1 h before decapitation. The cold-stimulated TSH secretion was decreased by L-tryptophan (L-TRP, 400 mg/kg i.p.), quipazine (10 mg/kg i.p.) and 5-HT (1 or 5 mg/kg s.c. or i.v.) as well as by p-chlorophenylalanine (pCPA, 20 or more mg/kg i.p.) when the drugs were given 1 h before sampling. pCPA (100-400 mg/kg i.p.) was active 24-48 h after the injection but repetitive administration did not affect TSH levels. 5-HT (5 mg/kg s.c.) was effective also in pinealectomized animals. L-TRP and 5-hydroxytryptophan potentiated the TRH-stimulated TSH secretion when given 1 h before killing. 5-HT (10 microgram/rat) infused into the third ventricle enhanced the cold-stimulated TSH secretion when given 30-45 min before sampling. When injected into the medial basal hypothalamus, 50-HT (1-10 microgram/rat) had no effect on basal or stimulated TSH levels. The results suggest: (1) 5-HT does not play any role in the regulation of basal TSH secretion; (2) in the cold-stimulated TSH secretion 5-HT has a stimulatory action evidently inside the blood-brain barrier and also an inhibitory effect obviously outside this barrier.     

Effect of Melatonin on Cognitive Ability of Rats and Expression of NCAM in the Brain Structures in Streptozotocin-Induced Diabetes

We studied a protective effect of a course injections of melatonin on cognitive deficiency in rats with streptozotocin-induced diabetes (STZD). The mean time necessary for the fulfillment of the Morris' water test in animals with STZD after 7 days of testing was three times greater than the corresponding index in the control group. Rats with STZD, which were injected with 10 mg/kg melatonin daily for 21 days after introduction of STZ, demonstrated a significantly lower level of cognitive deficiency ((in these rats the mean time necessary for the test fulfillment was only 48% greater than that in the control animals). In rats with STZD, substantial changes in the content of NCAM isoforms in the brain structures (significant decreases in the NCAM180 content in the hippocampus, neocortex, and cerebellum, and in that of NCAM140 in the cerebellum) were observed. Course injections of melatonin into the rats with STZD promoted significant normalization of the composition of NCAM isoforms in the structures under study. The data obtained indicate that control of expression of separate NCAM isoforms can be one of the mechanisms through which melatonin prevents the development of cognitive deficiency in diabetic animals.     

Role of catalase on the hypoxia/reoxygenation stress in the hypoxia-tolerant Nile tilapia

The specific contribution of each antioxidant enzyme to protection against the reoxygenation-associated oxidative stress after periods of hypoxia is not well understood. We assessed the physiological role of catalase during posthypoxic reoxygenation by the combination of two approaches. First, catalase activity of Nile tilapias (Oreochromis niloticus) was 90% suppressed by intraperitoneal injection of 3-amino-1,2,4-triazole (ATZ, 1g/kg). In ATZ-injected fish, liver GSH levels, oxidative stress markers, and activities of other antioxidant enzymes remained unchanged. Second, animals with depleted catalase activity (or those saline-injected) were subjected to a cycle of severe hypoxia (dissolved O(2) = 0.28 mg/l for 3 h) followed by reoxygenation (0.5 to 24 h). Hypoxia did not induce changes in the above-mentioned parameters, either in saline- or in ATZ-injected animals. Reoxygenation increased superoxide dismutase activity in saline-injected fish, whose levels were similar to ATZ-injected animals. The activities of glutathione S-transferase, selenium-dependent glutathione peroxidase, and total-GPX and the levels of GSH-eq, GSSG, and thiobarbituric acid reactive substances remained unchanged during reoxygenation in both saline- and ATZ-injected fish. The GSSG/GSH-eq ratio in ATZ-injected fish increased at 30 min of reoxygenation compared with saline-injected ones. Reoxygenation also increased carbonyl protein levels in saline-injected fish, whose levels were similar to the ATZ-injected group. Our work shows that inhibition of liver tilapia catalase causes a redox imbalance during reoxygenation, which is insufficient to induce further oxidative stress. This indicates the relevance of hepatic catalase for hypoxia/reoxygenation stress in tilapia fish.     

Noradrenergic Inhibition and α2-Adrenergic Stimulation of Melatonin Secretion in the Pigeon

Adrenergic regulatory mechanisms of melatonin synthesis and secretion were studied in the pigeon in vivo. Late-afternoon intraperitoneal injection of noradrenaline (NA; 1 mg/kg) resulted in a significant decrease in plasma melatonin levels in 3 h. The same effect was seen after phenylephrine treatment (1 mg/kg i.p.), indicating that an alpha 1-adrenergic mechanism may mediate the inhibition. Propranolol treatment had no effect on plasma melatonin levels, supporting this concept. Detomidine (1 mg/kg i.p.), an alpha 2-adrenergic agonist, increased melatonin levels. This stimulatory effect was blocked by yohimbine, an alpha 2-adrenergic antagonist. However, yohimbine alone had no effect on the plasma melatonin levels, suggesting that alpha 2-adrenergic transmission is not primarily responsible for the nocturnal stimulation of melatonin synthesis and secretion in the pigeon.     

Effect of direct and indirect dopamine agonists on brain extracellular ascorbate levels in the striatum and nucleus accumbens of awake rats

Systemic administration of direct and indirect dopamine agonists resulted in increased extracellular ascorbic acid levels in the striatum and, to a lesser degree, in the nucleus accumbens as measured by in vivo voltammetry. Intraperitoneal d-amphetamine sulfate (5mg/kg) increased ascorbate concentrations in striatal extracellular fluid. Amphetamine also increased extracellular ascorbate levels in the nucleus accumbens although more gradually and to a lesser extent. Intraperitoneal phenethylamine hydrochloride (20 mg/kg) following pargyline hydrochloride pretreatment (20 mg/kg) increased extracellular ascorbate levels in the striatum significantly above the small increase seen in the nucleus accumbens. The direct acting dopamine agonists Ly-141865 and Ly-163502 when given i.p. at 1 mg/kg, resulted in increased extracellular ascorbate concentrations in both brain areas, again with a significantly greater effect in the striatum. These results indicate that brain extracellular ascorbate levels can be modulated by dopaminergic neuro-transmission and that this modulation is quantitatively different in different dopamine-containing brain structures.     

Possible GABAergic Modulation in the Protective Effect of Zolpidem in Acute Hypoxic Stress-induced Behavior Alterations and Oxidative Damage

Hypoxia is an environmental stressor that is known to elicit alterations in both the autonomic nervous system and endocrine functions. The free radical or oxidative stress theory holds that oxidative reactions are mainly underlying neurodegenerative disorders. In fact among complex metabolic reactions occurring during hypoxia, many could be related to the formation of oxygen derived free radicals, causing a wide spectrum of cell damage. In present study, we investigated possible involvement of GABAergic mechanism in the protective effect of zolpidem against acute hypoxia-induced behavioral modification and biochemical alterations in mice. Mice were subjected to acute hypoxic stress for a period of 2 h. Acute hypoxic stress for 2 h caused significant impairment in locomotor activity, anxiety-like behavior, and antinocioceptive effect in mice. Biochemical analysis revealed a significant increased malondialdehyde, nitrite concentrations and depleted reduced glutathione and catalase levels. Pretreatment with zolpidem (5 and 10 mg/kg, i.p.) significantly improved locomotor activity, anti-anxiety effect, reduced tail flick latency and attenuated oxidative damage (reduced malondialdehyde, nitrite concentration, and restoration of reduced glutathione and catalase levels) as compared to stressed control (hypoxia) (P < 0.05). Besides, protective effect of zolpidem (5 mg/kg) was blocked significantly by picrotoxin (1.0 mg/kg) or flumazenil (2 mg/kg) and potentiated by muscimol (0.05 mg/kg) in hypoxic animals (P < 0.05). These effects were significant as compared to zolpidem (5 mg/kg) per se (P < 0.05). Present study suggest that the possible involvement of GABAergic modulation in the protective effect of zolpidem against hypoxic stress.     

M受体对吗啡戒断大鼠脊髓和脑干NMDA受体基因表达及中脑导水管周围灰质中谷氨酸释放的调节

应用鞘内注射反义寡脱氧核苷酸技术和RT—PCR反应,观察毒蕈碱型乙酰胆碱受体(muscarinic acetylcholine receptor,M)对吗啡依赖大鼠脊髓和脑干NMDA受体NR1A和NR2A mRNA表达和中脑导水管周围灰质区(periaqueductal grey,PAG)中谷氨酸释放的影响。结果显示,吗啡依赖大鼠脊髓NR1A和NR2A mRNA表达明显升高,而脑干中NR1A和NR2A mRNA表达没有显著变化;注射纳洛酮后1h,吗啡戒断大鼠脊髓和脑干中NR1A和NR2A表达显著高于依赖组,经NMDA受体拮抗剂MK801(0．125mg／kg,i．p．)、M受体拮抗剂东莨菪碱(0．5mg／kg,i．p．)、M1受体拮抗剂呱伦西平(10mg/kg,i．p．)和NOS抑制剂L-NAME(10mg／kg,i．p．)处理后,脊髓和脑干中NR1A和NR2A基因表达都较戒断组明显减少。在纳洛酮激发前24h鞘内注射NR1A和M2受体的反义寡脱氧核苷酸(4μg／只),戒断症状评分值及脊髓和脑干的NR1A mRNA的表达均较对照组明显减少。吗啡依赖大鼠在纳洛酮注射前24h鞘内注射M2受体反义寡脱氧核苷酸(4μg/只),可以明显减少PAG内透析液中谷氨酸含量。上述结果提示：NMDA受体的基因表达和谷氨酸释放参与吗啡戒断过程,而这种表达受到M受体的调节。     

Effect of butorphanol,midazolam or ketamine on romifidine based sedation in horses during standing cheek tooth removal

Background

Standing surgery, especially dental procedures, are commonly performed in horses. This leads to an increasing demand for reliable sedation protocols. Therefore, it was the purpose of this study to investigate the influence of butorphanol, midazolam or ketamine on romifidine based sedation in horses during cheek tooth removal.

Methods

Forty horses presented for tooth extraction were divided in four groups using matched pair randomization. Group R was sedated with romifidine (bolus 0.03 mg/kg, followed by a constant rate infusion (CRI) 0.05 mg/kg/h) and group RB with romifidine (same dose) and butorphanol (0.02 mg/kg; CRI 0.04 mg/kg/h). Group RM received romifidine (same dose) and midazolam (0.02 mg/kg; CRI 0.06 mg/kg/h) whereas group RK was administered romifidine (same dose) and ketamine (0.5 mg/kg; CRI 1.2 mg/kg/h). If sedation was not adequate a top up bolus of romifidine (0.01 mg/kg) was administered. The quality of sedation and the conditions for tooth extraction, the level of ataxia, chewing, head and tongue movement were evaluated by using a scoring system. The investigator was blinded to the applied sedation protocol. Furthermore, serum cortisol concentrations before, during and after the procedure were analyzed to gain more information about the stress level of the horses.

Results

Horses in group RM showed significantly less chewing and tongue activity compared to horses sedated with romifidine alone or with butorphanol additionally, but also significantly higher levels of ataxia. The quality of sedation was significantly better if romifidine was administered in combination with ketamine compared to romifidine alone. Furthermore, horses of group RK needed less additional romifidine boli compared to all other groups. Blood cortisol concentrations during surgery in groups RB and RM remained unchanged. Horses of group R showed higher cortisol concentrations during sedation compared to horses of groups RB and RM.

Conclusion

Romifidine alone at an initial bolus dose of 0.03 mg/kg followed by a constant rate infusion of 0.05 mg/kg/h was insufficient to obtain an adequate level of sedation and led to increased stress levels, whereas the addition of butorphanol inhibited the stress response. The combination of romifidine with either midazolam or ketamine improved sedation quality and surgical conditions.

     

Effect of Chronic N-Acetyl Cysteine Administration on Oxidative Status in the Presence and Absence of Induced Oxidative Stress in Rat Striatum

Antioxidants have possible therapeutic value in neurodegenerative disorders, although they may have pro-oxidant effects under certain conditions. Glutathione (GSH) is a key free radical scavenger. N-acetylcysteine (NAC) bolsters GSH and intracellular cysteine and also has effective free radical scavenger properties. The effects of chronic NAC administration (50 mg/kg/day, 500 mg/kg/day, 1500 mg/kg/day × 21 days) on cellular markers of oxidative status was studied in striatum of healthy male Sprague-Dawley rats as well as in animals with apparent striatal oxidative stress following chronic haloperidol treatment (1.5 mg/kg/day × 3 weeks). In non-haloperidol treated animals, NAC 50 and 500 mg/kg did not affect oxidative status, although NAC 1,500 mg/kg significantly increased striatal superoxide levels, decreased lipid peroxidation and increased consumption of reduced glutathione (GSH). Haloperidol alone evoked a significant increase in superoxide and lipid peroxidation. All NAC doses blocked haloperidol induced increases in superoxide levels, while NAC 500 mg/kg and 1,500 mg/kg prevented haloperidol-associated lipid peroxidation levels and also increased the GSSG/GSH ratio. NAC may protect against conditions of striatal oxidative stress, although possible pro-oxidative actions at high doses in otherwise healthy individuals, e.g. to offset worsening of neurodegenerative illness, should be viewed with caution.     

长时程增强诱导和维持过程中海马CA1区神经细胞粘附分子蛋白水平与mRNA表达的变化

既往研究发现,神经细胞粘附分子(neural cell adhesion molecules,NCAM)对海马CA1区突触传递长时程增强(longterm potentiation,LTP)的诱导和维持极为关键。本文采用原位杂交法和Western blot法,观察了大鼠海马腑片LTP诱导和维持过程中NCAM mRNA和蛋白水平的动态变化过程。结果显示,强直刺激诱发fEPSP斜率升高10 min时,海马CA1区NCAM mRNA染色阳性神经元数量显著增加(76.6±11.5个),NCAM蛋白水平亦明显升高(7.190±0.64任意单位/50μg蛋白)。强直刺激诱发fEPSP斜率升高1 h时,NCAM mRNA染色阳性神经元数量为73.3±14.0个,NCAM蛋白量为9.031±0.71任意单位/50 μg蛋白;与强直刺激后10 min比较,NCAM mRNA表达无显著变化,而NCAM蛋白水平变化明显。NMDA受体特异阻断剂AP-5在损害LTP的同时,显著抑制NCAM mRNA和蛋白的增加。实验结果表明,在大鼠海马LTP诱导和维持过程中,NCAM mRNA增强的表达相对稳定,而NCAM蛋白水平呈现先低后高的变化。