Effects of Electroconvulsive Shock on Tetrahydrobiopterin and GTP-Cyclohydrolase Activity in the Brain and Adrenal Gland of the Rat

The effects of a single and repeated electroconvulsive shock (ECS) (300 mA, 0.2 s) on tetrahydrobiopterin (BH4) levels and GTP-cyclohydrolase activity in the brain and adrenal glands of rats were examined. Twenty-four hours after the last ECS treatment (one/day for 7 days), biopterin levels were significantly elevated in the locus coeruleus, hippocampus, frontal cortex, hypothalamus, ventral tegmental area, and adrenal gland. There were no changes in biopterin levels after a single application of ECS. GTP-cyclohydrolase activity was significantly increased in the locus coeruleus, frontal cortex, hippocampus, hypothalamus, and adrenal gland 24 h after repeated ECS and remained elevated in certain tissues up to 8 days after the last treatment. Kinetic analysis of adrenal and locus coeruleus GTP-cyclohydrolase 1 day after 7 days of ECS showed significant changes in both Km and Vmax values. These data suggest that the long-term increases in BH4 levels and GTP-cyclohydrolase activity after repeated ECS may play a part in the mediation of the antidepressant effects of ECS.     

Effects of Electroconvulsive Stimuli and MK-801 on Neuropeptide Y,Neurokinin A,and Calcitonin Gene-Related Peptide in Rat Brain

Rats were pretreated with 0.9% NaCl, or 0.1 or 1.0 mg/kg MK-801, an anticonvulsant and a psychotomimetic drug, and 60 minutes later given ECS or sham ECS. After six sessions the animals were sacrificed and neuropeptide Y (NPY-), neurokinin A (NKA-), and calcitonin gene-related peptide (CGRP-) like immunoreactivity (-LI) measured with radioimmunoassays. ECS increased NPY-LI in frontal cortex, striatum, occipital cortex and hippocampus, and NKA-LI in occipital cortex and hippocampus. MK-801 increased CGRP in a dose-response manner in frontal cortex, and NKA-LI in occipital cortex. Although the higher MK-801 dose reduced seizure duration by 50%, the ECS induced NPY-LI increase in striatum, occipital cortex and hippocampus, and NKA-LI in occipital cortex was not diminished. In contrast, there was a parallel decrease in seizures and NPY-LI and NKA-LI changes in frontal cortex and hippocampus, respectively. Investigation of neuropeptides in brain may contribute to understanding of the mechanisms of action of antide-pressive and antipsychotic treatments and of psychotomimetic drugs.     

Effects of chronic electroconvulsive shock on the expression of beta-adrenergic receptors in rat brain: immunological study

The purpose of the present study is to determine the effect of chronic electroconvulsive shock (ECS) on the expression of beta-adrenergic receptors in rat brain by Western blot using mAb beta CO2, a monoclonal antibody against beta-adrenergic receptors. Rats in ECS treated groups received maximal ECS (70 mA, 0.5 second, 60 Hz) through ear-clip electrodes for 12 consecutive days. The experiment was carried out in 14 discrete regions of brain. Chronic ECS reduced the expression of beta-adrenergic receptors in frontal cortex, temporal cortex, parietooccipital cortex, hippocampus and limbic forebrain, but not in other areas of brain. The regional specificity and the magnitude of the reduction of receptor expression are well correlated with those of the reduction of receptor ligand binding, which was determined using [3H]dihydroalprenolol. To the best of our knowledge, this is the first report to demonstrate that chronic ECS decreases the expression of receptor protein in specific regions of rat brain.     

In vivo regulation of the serotonin-2 receptor in rat brain

Serotonin-2 (5-HT-2) receptors in brain were measured using [3H]ketanserin. We examined the effects of amitriptyline, an antidepressant drug, of electroconvulsive shock (ECS) and of drug-induced alterations in presynaptic 5-HT function on [3H]ketanserin binding to 5-HT-2 receptors in rat brain. The importance of intact 5-HT axons to the up-regulation of 5-HT-2 receptors by ECS was also investigated, and an attempt was made to relate the ECS-induced increase in this receptor to changes in 5-HT presynaptic mechanisms. Twelve days of ECS increased the number of 5-HT-2 receptors in frontal cortex. Neither the IC50 nor the Hill coefficient of 5-HT in competing for [3H]ketanserin binding sites was altered by ECS. Repeated injections of amitriptyline reduced the number of 5-HT-2 receptors in frontal cortex. Reserpine, administered daily for 12 days, caused a significant increase in 5-HT-2 receptors, but neither daily injections of p-chlorophenylalanine (PCPA) nor lesions of 5-HT axons with 5,7-dihydroxytryptamine (5,7-DHT) affected 5-HT-2 receptors. However, regulation of 5-HT-2 receptors by ECS was dependent on intact 5-HT axons since ECS could not increase the number of 5-HT-2 receptors in rats previously lesioned with 5,7-DHT. Repeated ECS, however, does not appear to affect either the high-affinity uptake of [3H]5-HT or [3H]imipramine binding, two presynaptic markers of 5-HT neuronal function. 5-HT-2 receptors appear to be under complex control. ECS or drug treatments such as reserpine or amitriptyline, which affect several monoamine neurotransmission systems including 5-HT, can alter 5-HT-2 receptors. While depleting 5-HT alone (5,7-DHT or PCPA) does not alter [3H]ketanserin binding to 5-HT-2 receptors, intact 5-HT axons are necessary for the adaptive up-regulation of the receptor following ECS.     

Cerebral Metabolic Responses to Electroconvulsive Shock and Their Modification by Hypercapnia

Abstract: Brain glucose metabolism was studied in paralyzed, ventilated rats given electroconvulsive shock (ECS) under normocapnic and hypercapnic conditions. Brains were obtained with a freeze-blowing apparatus. Rates of glucose utilization were determined with [2-¹⁴C]glucose and[³H]deoxyglucose as tracers. In normocapnic rats, ECS caused a large increase in the rate of glycolysis to 5–6 μmol/g/min. Brain lactate levels increased three- to fourfold. The stimulation of glucose metabolism was reflected in decreased brain glucose 6-phosphate concentration as early as 2–3 s after ECS. There were significant decreases in brain glucose and glycogen levels at 20 and 30 s after ECS. The decreases in endogenous brain glucose accounted for most of the increases in glucose utilization measured isotopically, implying that influx of glucose from blood into brain did not increase greatly over these time periods. Animals made hypercapnic by respiration with 10% CO₂ for 2 min prior to ECS were different in their metabolic responses to ECS in several ways. The increases in glycolyt-ic rate and lactate content of brain were half of those found in normocapnic rats. Brain glycogen and glucose concentrations did not change significantly in the hypercapnic rats during seizure activity. Thus, hypercapnia lessened the stimulation of glycolysis caused by ECS, but increased net influx of glucose from blood to brain. The mechanisms of these effects of hypercapnia are uncertain, but it is postulated that the effect on glycolytic activity is due to the acidosis and that the effect on glucose transport is due to an increase in capillary surface area.     

Effect of Electroconvulsive Shock on Mitochondrial Respiratory Chain in Rat Brain

It is well described that impairment of energy production has been implicated in the pathogenesis of a number of diseases. Although several advances have occurred over the past 20 years concerning the use and administration of electroconvulsive therapy (ECT) to minimize its side effects, little progress has been made in understanding its mechanism of action. In this work, our aim was to measure the activities of mitochondrial respiratory chain complexes II and IV and succinate dehydrogenase from rat brain after acute and chronic electroconvulsive shock (ECS). Our results showed that mitochondrial respiratory chain enzymes activities were increased after acute ECS in hippocampus, striatum and cortex of rats. Besides, we also demonstrated that complex II activity was increased after chronic ECS in cortex, while hippocampus and striatum were not affected. Succinate dehydrogenase, however, was inhibited after chronic ECS in striatum, activated in cortex and not affected in hippocampus. Finally, complex IV was not affected by chronic ECS in hippocampus, striatum and cortex. Our findings demonstrated that brain metabolism is altered by ECS.     

反复苯丙胺刺激对大鼠脑部蛋白羰基化的影响

目的:为了进一步研究苯丙胺神经毒性作用机制,我们对大鼠进行不同时长的反复苯丙胺刺激,检测大鼠部分脑区中蛋白羰基化的变化情况,我们的研究为苯丙胺的成瘾及治疗提供了新的理论依据。方法:分别对大鼠进行1d、3d、7d、10d及14d的苯丙胺反复刺激,进行旷场测试检测其活动量变化后,采用DNPH法检查的大鼠大脑前皮层、海马区、杏仁核三大脑区总蛋白的蛋白羰基化水平变化,探讨反复苯丙胺刺激对大鼠脑部蛋白羰基化的影响。结果:苯丙胺刺激7d及14d时,大鼠活动量出现了显著性增加,同时大鼠前皮层总蛋白的蛋白羰基化也出现了显著性增加,而海马区及杏仁核区域总蛋白的蛋白羰基化没有明显变化。结论:反复苯丙胺刺激能够增加大鼠活动量及大脑前皮层总蛋白蛋白羰基化水平。     

Interhemispheric relations of prefrontal cortical neurons in rats during emotional stimulation of increasing intensity

Unit activity of the prefrontal cortex of the right and left brain hemispheres of rats was recorded during intracranial stimulation of emotionally positive and negative brain structures. The neurons were divided according to their reaction to a change in food motivation: cells that decrease (M-neurons) and cells that increase their firing frequencies (R-neurons) after feeding. Three levels of stimulation current intensity were used. When stimuli of subthreshold intensity (evoking the behavioral reaction of smelling) were applied, the recorded neuronal activity was higher in the left hemisphere. During threshold emotionally positive or negative stimulation (producing approach behavior or freezing, respectively), activity of M-neurons was higher in the right hemisphere, whereas the left-side R-neurons were more active than the right-side ones. During strong emotionally positive stimulation producing self-stimulation, the firing frequency of both groups of neurons was higher in the left hemisphere. Strong emotionally negative stimulation that evoked behavioral avoidance to a greater extent activated the right hemisphere.     

Cerebral Processing of Prosodic Emotional Signals: Evaluation of a Network Model Using rTMS

A great number of functional imaging studies contributed to developing a cerebral network model illustrating the processing of prosody in the brain. According to this model, the processing of prosodic emotional signals is divided into three main steps, each related to different brain areas. The present study sought to evaluate parts of the aforementioned model by using low-frequency repetitive transcranial magnetic stimulation (rTMS) over two important brain regions identified by the model: the superior temporal cortex (Experiment 1) and the inferior frontal cortex (Experiment 2). The aim of both experiments was to reduce cortical activity in the respective brain areas and evaluate whether these reductions lead to measurable behavioral effects during prosody processing. However, results obtained in this study revealed no rTMS effects on the acquired behavioral data. Possible explanations for these findings are discussed in the paper.     

Sexual differentiation of mammalian frontal cortex

The pattern of distribution of the progesterone binding sites was examined in selected nuclei of the brain of male and female rat. In female rats the frontal cortex resulted to be the region with the highest concentration of 3H R5020 binding sites. However, in male rats the same region showed very little progestin binding activity. When female rats were androgenized via neonatal exposure to testosterone, the progestin binding activity of the frontal cortex became similar to that we observed in male rats. The present investigation indicates that sexual differentiation of the rat brain may include also brain regions not clearly involved in sex related functions like the frontal cortex.     

糖尿病大鼠模型额叶神经元内生长抑素表达的原位杂交研究

研究生长抑素神经元在糖尿病大鼠模型额叶表达的变化。SD大鼠腹腔注射链脲佐菌素建立速发型糖尿病大鼠模型,4周时运用原位杂交组织化学方法检测大鼠额叶生长抑素mRNA阳性神经元的变化,并与正常大鼠比较。糖尿病大鼠成模4周时大脑额叶生长抑素mRNA阳性神经元显著减少,其单位面积内的阳性细胞数、阳性细胞的光密度及阳性细胞平均细胞面积均比正常大鼠相同区域减少,两者差异有显著性意义(P<0.01)。本研究表明糖尿病大鼠额叶生长抑素神经元mRNA表达的减少,可能是糖尿病患者发生痴呆等糖尿慢性脑病的相关因素之一。     

Pentylenetetrazol-induced seizures and kindling: changes in free fatty acids,superoxide dismutase,and glutathione peroxidase activity

The whole brain free fatty acid (FFA) level, as well as the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPX) were determined in the frontal cortex, cerebellum, hippocampus, and pons-medulla region of the single pentylenetetrazol (PZT)-treated and PZT-kindled Hannover-Wistar rats. PZT administration in the convulsive dose caused significant increase of the brain FFA content. Decreased SOD activity was detected in the frontal cortex of PZT-kindled rats, whereas decreased GPX activity was found in the frontal cortex and cerebellum of all treated rats, as well as in the hippocampus and pons-medulla of PZT-kindled rats. Kindling caused distinctive change of antioxidative defense in the frontal cortex, hippocampus, and pons-medulla region.     

Electroconvulsive seizures increase levels of pGlu-Glu-Pro-NH2 (EEP) in rat brain

We have previously reported that electroconvulsive seizures (ECS) increases the level of prepro-TRH-derived peptides in hippocampus, amygdala and pyriform cortex but not the striatum of male rats and that this increase is significantly correlated with reduced immobility (increased swimming) in the Porsolt forced swim test. An abstract by Mabrouk and Bennett published in 1993 described increased locomotor activity in rats following IP injection of TRH (pGlu-His-Pro-NH2) and EEP (pGlu-Glu-Pro-NH2). We have examined the effect of three daily transcorneal ECS on the levels of EEP in various brain regions and their correlation with results from the Porsolt forced swim test. The EEP level (ng/g wet weight) was measured by RIA in 6 brain regions: amygdala (AY), hippocampus (HC), pyriform cortex (PYR), anterior cortex (AC), striatum (STR) and motor cortex (MC). ECS significantly increased EEP levels in AY, HC and PYR. The increased swim behavior following ECS, as measured in the Porsolt test, correlated significantly with the EEP levels in HC and MC within individual subjects. Intraperitoneal (IP) injection of EEP (1.0 mg/kg) resulted in a rapid and sustained rise in EEP levels throughout the brain and a clearance half-time from blood of 2.0 h. Intracardiac injection of 0.5 mg EEP resulted in a peak EEP level in CSF at 2 h followed by a t1/2 of 0.35 h. A 3 compartment model for EEP transport from blood into CSF and then brain was developed. This model revealed a 1.75 h delay in the transit time of EEP from blood to CSF followed by rapid clearance from the CSF but long retention time within various brain tissues. We conclude that (1) ECS significantly increases EEP levels in limbic regions, but not in striatum, of the rat brain, (2) EEP, like TRH, is a potential mediator of the antidepressant effect of ECS and (3) EEP, after IP or IV administration, is readily taken up by, and has a long residence time in, brain tissue.     

Chronic electroconvulsive shock decreases (+/-) 1-(4-iodo-2,5-dimethoxyphenyl)-2-aminopropane hydrochloride (DOI)-induced wet-dog shake behaviors of dexamethasone-treated rats

Electroconvulsive shock (ECS) therapy is considered to be an effective treatment for depression, but its mechanism of action is still unknown. We investigated the effect of chronic ECS in rats treated for 14 days with dexamethasone (Dex), a glucocorticoid receptor agonist. Chronic injection of sesame oil decreased body weight change and increased serotonin (5-HT)-2A receptor number and DOI (5-HT-2A, 2C receptor agonist)-induced wet-dog shake (WDS) behaviors. Dex treatment for 14 days decreased body weight of rats, but repeated ECS did not reverse this decrease. Dex also abolished plasma corticosterone levels, and ECS failed to restore these levels. These results indicate that chronic ECS does not antagonize the effect of Dex. The treatment with Dex increased 5-HT-2A receptor binding density of rat frontal cortex and the number of DOI-induced WDS behaviors. Chronic ECS reduced the enhanced WDS behaviors by Dex but had little effect on receptor density. These results suggest that chronic ECS might suppress 5-HT-2A receptor function at the postreceptor signaling level rather than at the receptor itself, without changing HPA axis function in Dex-treated rats.     

Metabonomic alterations in hippocampus, temporal and prefrontal cortex with age in rats

The metabolic changes in hippocampus, temporal cortex and prefrontal cortex in SD rats along with aging were explored using a metabonomic approach, which based on high resolution “magic angle spinning” ¹H NMR spectroscopy. The metabolite profiles were analyzed by partial least squares-discriminant analysis, and the results showed that the metabolites of the above three brain regions in old rats were dramatically different from that in the adult and young rats. The old rats showed increased myo-inositol and lactate in all of the three brain regions, and decreased N-acetylaspartate in temporal and frontal cortex, Glutamate–GABA level became imbalance in temporal cortex of old rats. In addition, compared with the adult female rats, male rats had higher levels of N-acetylaspartate, taurine, and creatine in temporal or frontal cortex. The age-related metabolic changes may indicate the early functional alterations of neural cells in these brain regions, especially the temporal cortex. The gender-related metabolic changes suggest the significance of the hormonal regulation in brain metabolism. Our work highlights the potential of metabolic profiling to enhance our understanding of biological mechanisms of brain aging.     

Effect of beta-phenylethylamine on evoked potentials of the neostriatum of rats]

The effect of intraperitoneal (70 mg/kg) and local (39 ug) administration of beta-phenylethylamine (beta-PEA) on evoked potentials (EP) in the caudate nucleus upon stimulation of substantia nigra zona compacta (SNC) and frontal cortex in rats has been studied. beta-PEA, glutamate and haloperidol were injected into the caudate nucleus by means of a system consisting of a pushpull cannule and an electrode for simultaneous registration of EP. Specificity in the effect of the drugs on EP in response to stimulation of the cortex and substantia nigra was revealed. The intraperitoneal injection of beta-PEA induced, comparatively to the application, more rapid and potent decrease in the amplitude of the component (N2-P2) as a result of the substantia nigra stimulation and slightly influenced the EP amplitude in stimulation of the frontal cortex. It was established using haloperidol that the component (N2-P2) of EP in response to the substantia nigra stimulation is of dopaminergic neuron function in the nigro-neostrital system of the rat brain.     

Brain NADH and jumping behavior in the rat

The effects of either the reduced Nicotinamide Adenine Dinucleotide (NADH) microinjected into the brain or amphetamine injected peritoneally on jumping behavior were observed in 68 rats. The enhanced jumps in the group with amphetamine are the greatest among the three experimental groups. The enhanced effect of NADH microinjected into the caudate nucleus is stronger than those of NADH in the frontal cortex. The effects of extra NADH in the frontal cortex on the jumps are dose-dependent. NADH concentrations in the brain of rats with amphetamine increased immediately after behavioral procedure. The increased concentrations in the brain from both extra and intra sources are related to the enhanced jumps of rats.     

The effects of acute ethanol exposure and ageing on rat brain glutathione metabolism

Abstract

Binge alcohol consumption in adolescents is increasing, and it has been proposed that immature brain deals poorly with oxidative stress. The aim of our work was to study the effect of an acute dose of ethanol on glutathione (GSH) metabolism in frontal cortex, hippocampus and striatum of juvenile and adult rats. We have observed no change in levels of glutathione produced by acute alcohol in the three brain areas studied of juvenile and adult rats. Only in the frontal cortex the ratio of GSH/GSSG was increased in the ethanol-treated adult rats. GSH levels in the hippocampus and striatum were significantly higher in adult animals compared to young ones. Higher glutathione peroxidase (GPx) activity in adult rats was observed in frontal cortex and in striatum. Our data show an increased GSH concentration and GPx activity in different cerebral regions of the adult rat, compared to the young ones, suggesting that age-related variations of total antioxidant defences in brain may predispose young brain structures to ethanol-induced, oxidative stress-mediated tissue damage.