Multiple and interrelated functional asymmetries in rat brain.

Normal rats rotate (turn in circles) at night and in response to drugs (e.g. d-amphetamine) during the day. Rats with known circling biases were injected with [1,2-³H]-deoxy-d-glucose, decapitated and glucose utilization was assessed in several brain structures. Most structures showed evidence of functional brain asymmetry. Asymmetries were of three different kinds: (1) a difference in activity between sides of the brain contralateral and ipsilateral to the direction of rotation (midbrain, striatum); (2) a difference in activity between left and right sides (frontal cortex, hippocampus); and (3) an absolute difference in activity between sides that was correlated to the rate of either rotation (thalamus, hypothalamus) or random movement (cerebellum). Amphetamine, administered 15 minutes before a deoxyglucose injection in other rats, altered some asymmetries (striatum, frontal cortex, hippocampus) but not others (midbrain, thalamus, hypothalamus, cerebellum). Different asymmetries appear to be organized along different dimensions in both the rat and human brains.     

Effects of acute manganese chloride exposure on lipid peroxidation and alteration of trace metals in rat brain

Although manganese (Mn) is an essential element, exposure to excessive levels of Mn and its accumulation in the brain can cause neurotoxicity and extrapyramidal syndrome. We have investigated the differences in the accumulated levels of Mn, the degree of lipid peroxidation, and its effects on the levels of trace elements (Fe, Cu, and Zn) in various regions in the brain of rats having undergone acute Mn exposure. The rats in the dose—effect group were injected intraperitoneally (ip) with MnCl₂ (25, 50, or 100 mg MnCl₂/kg) once a day for 24 h. The Mn significantly accumulated (p<0.05) in the frontal cortex, corpus callosum, hippocampus, striatum, hypothalamus medulla, cerebellum, and spinal cord in each case. The rats in the timecourse group were ip injected with MnCl₂ (50 mg MnCl₂/kg) and then monitored 12, 24, 48, and 72 h after exposure. The Mn accumulated in the frontal cortex, corpus callosum, hippocampus, striatum hypothalamus, medulla, cerebellum, and spinal cord after these periods of time, In both the dose—effect and time-course studies, we observed that the concentration of malondialdehyde, an end product of lipid peroxidation, increased significantly in the frontal cortex, hippocampus, striatum, hypothalamus, medulla, and cerebellum. However, no relationship between the concentrations of Mn in the brain and the extent of lipid peroxidation was observed. In addition, we found that there was a significant increase (p<0.05) in the level of Fe in the hippocampus, striatum, hypothalamus, medulla, and cerebellum, but the Cu and Zn levels had not changed significantly. These findings indicated that Mn induces an increase in the iron level, which provides direct evidence for Fe-mediated lipid peroxidation in the rats' brains; these phenomena might play important roles in the mechanisms of Mn-induced neurotoxicology.     

Brain Regional Distribution of Glutamic Acid Decarboxylase, Choline Acetyltransferase, and Acetylcholinesterase in the Rat: Effects of Chronic Manganese Chloride Administration after Two Years

Abstract: Rats were treated chronically with manganese chloride from conception onward for a period of over 2 years in order to study the effects of manganese and aging on the activities of glutamic acid decarboxylase (GAD), choline acetyltransferase (ChAT), and acetylcholinesterase (AChE) in hypothalamus, cerebellum, pons and medulla, striatum, midbrain, and cerebral cortex (which included the hippocampus). Manganese-treated 2-month-old and 24- to 28-month-old rats and age-matched controls were studied. In control rats during aging the activities of GAD decreased in hypothalamus (19%), pons and medulla (28%), and midbrain (22%) whereas the activities of AChE decreased in all regions (20–48%), particularly in the striatum (44–48%). Changes in ChAT activities in aging were observed only in one region—a decrease (23%) in the striatum. Life-long treatment with manganese appeared to abolish partially the decreases in aging in AChE activities in hypothalamus, cerebellum and striatum, and striatal ChAT activity. Manganese treatment also seemed to abolish the age-related decreases in GAD activities, since GAD activities in various brain regions of manganese-treated senescent rats were not significantly different from those of control young rats. These results are discussed in relation to other metabolic changes associated with aging and manganese toxicity.     

Circadian variation in the acetylcholinesterase activity of specific rat brain areas

Abstract

Acetylcholinesterase (AChE) activity of the adenohypophysis, cerebellum, cerebral cortex, hypothalamus, amygdala, hippocampus, midbrain, pons, medulla oblongata and caudate nucleus was determined by a spectro‐photometric method in adult, male rats adapted toan LD 12:12cycle. Results of the study show that AChE activity is highest during the light phase and lowest during the dark phase of the cycle in all the brain areas studied except the adenohypophysis, cerebellum, hippocampus and hypothalamus. These findings expand earlier observations on the circadian variation in rat brain AChE activity and suggests a relationship with reported circadian variation in the acetylcholine levels of rat brain.     

Profile of acetylcholinesterase in brain areas of male and female rats of adult and old age

Inhibition of acetylcholinesterase (AChE)-metabolizing enzyme of acetylcholine, is presently the most important therapeutic target for development of cognitive enhancers. However, AChE activity in brain has not been properly evaluated on the basis of age and sex. In the present study, AChE activity was investigated in different brain areas in male and female Sprague-Dawley rats of adult (3 months) and old (18-22 months) age. AChE was assayed spectrophotometrically by modified Ellman's method. Specific activity (micromoles/min/mg of protein) of AChE was assayed in salt soluble (SS) and detergent soluble (DS) fractions of various brain areas, which consists of predominantly G1 and G4 molecular isoforms of AChE respectively. The old male rats showed a decrease (40-55%) in AChE activity in frontal cortex, striatum, hypothalamus and pons in DS fraction and there was no change in SS fraction in comparison to adult rats. In the old female rats the activity was decreased (25-40%) in frontal cortex, cerebral cortex, striatum, thalamus, cerebellum and medulla in DS fraction whereas in SS fraction the activity was decreased only in hypothalamus as compared to adult. On comparing with old male rats, old female rats showed increase in AChE activity in cerebral cortex, hippocampus and hypothalamus of DS fraction and decrease in hypothalamus of SS fraction. There was a significant increase in AChE activity in DS fraction of cerebral cortex, hippocampus, hypothalamus, thalamus and cerebellum in female as compared to male adult rats. However, no significant change in AChE activity was found in the SS fraction, except hypothalamus between these groups. Thus it appears that age alters AChE activity in different brain regions predominantly in DS fraction (G4 isoform) that may vary in male and female. These observations have significant relevance to age related cognitive deficits and its pharmacotherapy.     

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.     

Induction of apoptotic change in the rat hippocampus caused by ferric nitrilotriacetate

Abstract

Iron, a source of oxidative stress, plays a major role in the pathology of neurodegenerative disease. In Alzheimer's disease, the hippocampus is vulnerable to oxidative stress, leading to impairment in memory formation. In our previous study, a brain oxidative reaction was induced after intraperitoneal injection of ferric nitrilotriacetate (Fe-NTA). However, since only a small amount of iron reached the brain in the previous study, Fe-NTA was administered into the hippocampus using an osmotic pump in this study.

After continuous injection of Fe-NTA for 2 weeks, a high level of apoptotic change was induced in the hippocampus, in accordance with the iron localization. After injection for 4 weeks, the hippocampus was totally destroyed. A small amount of iron infiltrated into the cerebral cortex and the striatum, and deposition was observed at the choroid plexus and ependymal cells. However, no apoptotic reaction or clear tissue injury was observed in these areas. In addition, muscarinic acetylcholine receptors (M1, M2, and M4) were decreased in both the cortex and hippocampus while it increased in the striatum. Thus, the hippocampus is likely vulnerable to oxidative stress from Fe-NTA, and the oxidative stress is considered to bring the disturbance in the muscarinic acetylcholine receptors.     

A comparative proteomic analysis of the rat brain during rebound hyperphagia induced by space-restriction

Although neurochemical changes have been reported in the brain in animal models of binge eating, biochemical changes of specific proteins in the brain are unknown. Our aim was to elucidate brain proteins altered in rats during enhanced rebound hyperphargia. Rats were deprived of food for 22 h/day for 6 days, then allowed free access to food for 24 h in normal cages (rebound hyperphargia) or in space-restricted cages (enhanced rebound hyperphargia). Proteins extracted from the rat brain were separated by two-dimensional gel electrophoresis, and compared with those from control rats freely fed for 7 days in normal cages. Proteins expressed differently from controls were identified by N-terminal amino acid sequencing and mass fingerprinting using a MALDI-TOF mass spectrometer. Among proteins in the corpus striatum, frontal lobe, hippocampus and thalamus/hypothalamus, ubiquitin C-terminal hydrolase L1 and peroxiredoxin 2 decreased in the hippocampus and phosphatidylethanolamine-binding protein increased in the thalamus/hypothalamus of rats with the enhanced rebound hyperphargia induced by space-restriction. In this study, we first demonstrated that three brain proteins changed in rats during enhanced rebound hyperphagia. These proteins might have pathophysiologic relevance to binge eating. (Mol Cell Biochem 276: 21–29, 2005)     

Age related changes in weight and the concentrations of zinc and copper in the brain of the adult rat

Two groups of adult male rats aged 15 weeks and 49 weeks, 15 rats in each group, were analysed for the concentrations of the trace elements zinc (Zn) and copper (Cu) in serum, liver, kidney, and five parts of the brain (cortex, corpus striatum, hippocampus, midbrain + medulla, and cerebellum). All organs increased in weight from 15 weeks to 49 weeks. In all parts of the brain, except for corpus striatum, there was a significant increase of the weights. The dry weight (% of wet) increased in all parts of the brain. In serum, the Zn and Cu concentrations increased from 15 weeks to 49 weeks. In the liver, both concentrations decreased and in the kidney the concentrations increased with increasing age. The Zn concentrations increased in cortex and corpus striatum and decreased in cerebellum and hippocampus. The Cu levels increased in all parts of the brain with the largest changes in corpus striatum. For rats aged 49 weeks, a significant correlation was found between the Cu concentrations of corpus striatum or midbrain + medulla and the fluid consumption. The findings of the present study reveal a dynamic age-related pattern of changes in the concentrations of Zn and Cu in different organs of the adult rat. This stresses the need of age-matching as an important control in experiment studies.     

Level of delta sleep-inducing peptide (DSIP) in the brain of rats with different alcoholic motivation

Radioimmunoassay was used to measure the content of delta-sleep-inducing peptide (DSIP) in random-bred albino rats divided into groups according to the duration of ethanol anesthesia and the levels of 15% ethanol consumption under free-choice conditions. The concentration of the neuropeptide was assayed in intact brain, in the cortex of large hemispheres, medulla oblongata, thalamus and striatum. The short-sleeping rats manifested a statistically significant lowering of the DSIP content in intact brain homogenates, in the cortex of large hemispheres and striatum. On the contrary, thirty minutes after a single intraperitoneal injection of ethanol in a dose of 1 g/kg the DSIP content in the medulla oblongata, thalamus and striatum was found to be increased. The raising of the ethanol dose up to 2.5 and 4.5 g/kg was followed by a less significant increase in the neuropeptide content. Prolonged chronic alcoholization under free-choice conditions led after 12 months to the reduced DSIP content in the medulla oblongata, thalamus and striatum. The importance of DSIP for the pathogenesis of experimental alcoholism using rats with different levels of alcoholic motivation is discussed.     

Rosmarinic acid prevents lipid peroxidation and increase in acetylcholinesterase activity in brain of streptozotocin‐induced diabetic rats

We investigated the efficacy of rosmarinic acid (RA) in preventing lipid peroxidation and increased activity of acetylcholinesterase (AChE) in the brain of streptozotocin‐induced diabetic rats. The animals were divided into six groups (n = 8): control, ethanol, RA 10 mg/kg, diabetic, diabetic/ethanol and diabetic/RA 10 mg/kg. After 21 days of treatment with RA, the cerebral structures (striatum, cortex and hippocampus) were removed for experimental assays. The results demonstrated that the treatment with RA (10 mg/kg) significantly reduced the level of lipid peroxidation in hippocampus (28%), cortex (38%) and striatum (47%) of diabetic rats when compared with the control. In addition, it was found that hyperglycaemia caused significant increased in the activity of AChE in hippocampus (58%), cortex (46%) and striatum (30%) in comparison with the control. On the other hand, the treatment with RA reversed this effect to the level of control after 3 weeks. In conclusion, the present findings showed that treatment with RA prevents the lipid peroxidation and consequently the increase in AChE activity in diabetic rats, demonstrating that this compound can modulate cholinergic neurotransmission and prevent damage oxidative in brain in the diabetic state. Thus, we can suggest that RA could be a promising compound in the complementary therapy in diabetes. Copyright © 2013 John Wiley & Sons, Ltd.     

Neuroprotective Effect of Etomidate in the Central Nervous System of Streptozotocin-Induced Diabetic Rats

It is well known that hyperglycaemia due to diabetes mellitus leads to oxidative stress in the central nervous system. Oxidative stress plays important role in the pathogenesis of neurodegenerative changes. In the present study we investigated the possible neuroprotective effect of etomidate against streptozotocin-induced (STZ-induced) hyperglycaemia in the rat brain and spinal cord. A total of 40 rats were used in this study. Rats were divided into four groups: sham-control, diabetic, diabetic-etomidate treated and vehicle for etomidate treatment group. Diabetes mellitus was induced by a single injection of streptozotocin (60 mg/kg body weight). Three days after streptoztocin injection, etomidate (2 mg/kg) was injected intraperitoneally for etomidate group and lipid emulsion (10%) for vehicle group was injected with corresponding amount intraperitoneally every day for 6 weeks. Six weeks after streptozotocin injection, seven rats from each group were killed and brain, brain stem and cervical spinal cord were removed. The hippocampus, cortex, cerebellum, brain stem and spinal cord were dissected for the biochemical analysis (the level of malondialdehyde [MDA], total nitrite, reduced glutathione [GSH], and xanthine oxidase [XO] activity). STZ-induced diabetes resulted in significantly elevation of MDA, XO and nitrite levels in the hippocampus, cortex, cerebellum, brain stem and spinal cord of the rats (P < 0.05) while etomidate treatment provided significantly lower values (P < 0.05). This study demonstrated that etomidate have neuroprotective effect on the neuronal tissue against the diabetic oxidative damage.     

Motor functions but not learning and memory are impaired upon repeated exposure to sub-lethal doses of methyl parathion

Summary Our previous work showed that repeated exposure to methyl parathion (MP) caused a prolonged inhibition of acetylcholinesterase (AChE) activity (∼80%) and down-regulation of M₁ and M₂ muscarinic receptors (up to 38%) in rats at brain regions, including frontal cortex, striatum, hippocampus and thalamus. In the present neurobehavioral study, we found this repeated MP treatment had suppressant effects on rat’s locomotor activity. However, we observed no evidence of long-term effects of MP on associative learning and memory. Our data demonstrated that repeated exposure to MP caused some functional deficits in CNS, but motor activity and associative learning/memory process might differ in the sensitivity to its toxic effect. The motor dysfunctions in MP-treated rats may be mediated via reciprocal balance between cholinergic and dopaminergic systems at striatum following cholinergic over-stimulation. Our findings also suggest that the CNS deficits induced by repeated exposure to MP or other organophosphate (OP) pesticides cannot be attributed entirely to the inhibition of AChE. To accurately assess the neuro-toxic risk by occupational exposure to sub-lethal doses of MP, novel biomarkers besides in vivo anticholinesterase potency are needed.     

THE EFFECTS OF PENTOBARBITONE-SODIUM ANAESTHESIA, SHOCK AVOIDANCE CONDITIONING AND ELECTRICAL SHOCK ON ACETYLCHOLINESTERASE ACTIVITY AND PROTEIN CONTENT IN REGIONS OF THE RAT BRAIN

Abstract— Pentobarbitone sodium anaesthesia was found to produce an increase in protein content in some regions of the rat brain, i.e. posterior cortex, caudate nucleus, and a decrease in protein content in the ventral cortex.
Acetylcholinesterase expressed in terms of wet weight was found to increase in the cerebellum, medulla, and to decrease in the medial cortex, hippocampus, thalamus and caudate nucleus. The changes in activity were not explicable in terms of a direct effect of the anaesthetic on the enzyme. A decrease in protein content of rat brain was observed in the frontal cortex, ventral cortex, hippocampus and caudate nucleus after electrical shocks. Following shock avoidance conditioning procedure (shuttle-box), decreases in protein content were observed in the medial cortex, posterior cortex, cerebellum and ventral cortex; in the thalamus an increase in protein content was observed.
Changes in AChE activity were observed following footshock in the frontal cortex and medulla where there was an increase in activity and in the caudate nucleus, hypothalamus, thalamus, and olfactory tubercle where there was a decrease in activity.
Following shock avoidance conditioning the activity of the AChE increased in posterior cortex, hippocampus, thalamus and hypothalamus and the activity of the enzyme decreased in the ventral cortex.     

REGIONAL BIOSYNTHESIS OF ACETYLCHOLINE IN BRAIN FOLLOWING FORCED ORAL CHRONIC BARBITONE TREATMENT TO RAT

Rats received a solution of sodium barbitone as their only drinking fluid for 33 and 42–44 weeks. In three groups (A3, A12 and A30) the barbitone solution was withheld and replaced by water 3, 12 and 30 days respectively before death. Two other groups consisted of animals drinking barbitone until death (B) and untreated controls (C). Abstinence convulsions were recorded by jiggle cages. Thirty nmol of tritium-labelled choline ([³H]Ch) were injected i.v. and the rats were killed by decapitation 1 min later. A significantly higher content of tritium-labelled acetylcholine ([³H]ACh) was found in the cerebellum + medulla oblongata + midbrain of rats receiving barbitone until death (group B) (+22%) and abstinent for 3 days (+54%) (group A3) compared with group C. The [³H]ACh content was also significantly increased in the hippocampus + cortex of rats abstinent for 3 days (+23%). In the striatum no significant effect on [³H]ACh content was found in any of the groups. The ratio [³H]ACh/[³H]Ch was significantly increased in the cerebellum + medulla oblongata + midbrain of rats in group B and A3 and in the hippocampus + cortex in group A3. These results might indicate an increased turnover of ACh. The effect of long-term barbitone treatment on the enzyme activities of brain choline acetyltransferase and acetylcholinesterase was also studied but no significant effect was found.     

Biochemical alterations induced by nickel oxide nanoparticles in female Wistar albino rats after acute oral exposure

Context: Nickel oxide (NiO) nanoparticles (NPs) with appropriate surface chemistry have been widely used for their potential new applications in biomedical industry. Increased usage of these NPs enhances the chance of exposure of personnel involved in the work place.

Objective: This study was designed to assess the ability of NiO NPs to cause biochemical alterations post-acute oral exposure in female Wistar rats.

Materials and methods: Rats were administered with 125, 250, and 500?mg/kg doses of NiO NPs for haematological, biochemical, and histopathological studies. Biodistribution patterns of NiO NPs in female Wistar rats were also monitored.

Results: NiO NPs caused significant (p?Conclusions: This study revealed that exposure to nanosized NiO particles at acute doses may cause adverse changes in animal biochemical profiles. Further, the in vivo studies on toxicity evaluation help in biomonitoring of the potential contaminants.     

Acetylcholinesterase activity in brain slices of rats subjected to cooling

The acetylcholinesterase (AChE) activity is studied in rat slices of the cerebral cortex, corpus striatum, hypothalamus and medulla oblongata of rats during hypothermia (20 degrees C) and also 1 and 7 days after the posthypothermal period. Cooling of animals down to 20 degrees C is accompanied by an increase in the AChE activity in the brain both under incubation temperature of 20 degrees and 37 degrees C. Under prolonged hypothermia the AChE activity in the investigated brain regions, except for corpus striatum, returns to the control level. By the 7th day of posthypothermal period the AChE activity in corpus striatum, hypothalamus and medulla oblongata does not restore completely. The most substantial changes in the AChE activity both under hypothermia and posthypothermal period occur in corpus striatum, which obviously reflects its complicated functional role.     

Regional increase of cyclic GMP by atrial natriuretic factor in rat brain: markedly elevated response in spontaneously hypertensive rats

Atrial natriuretic factor (ANF)-responsive areas in rat brain were examined by measuring ANF-stimulated cyclic GMP production in rat brain slice preparations. The medulla oblongata, thalamus, and pituitary gland responded most sensitively, the septum, hypothalamus, pons, midbrain and olfactory bulb responded moderately, but neocortex, cerebellum, striatum and hippocampus were unresponsive to ANF. The most responsive regions in spontaneously hypertensive rats brains showed 2 to 5 times higher cyclic GMP production than those from the control Wistar-Kyoto rats. These findings provide evidence for biological action of ANF on brain tissues, and indicate the action of ANF produced in the brain.     

Acetylcholinesterase Activity in Rats Experimentally Demyelinated with Ethidium Bromide and Treated with Interferon Beta

The ethidium bromide (EB) demyelinating model was associated with interferon beta (IFN-β) to evaluate acetylcholinesterase (AChE) activity in the striatum (ST), hippocampus (HP), cerebral cortex (CC), cerebellum (CB), hypothalamus (HY), pons (PN) and synaptosomes from the CC. Rats were divided into four groups: I control (saline), II (IFN-β), III (EB) and IV (EB and IFN-β). After 7, 15 and 30 days rats (n = 6) were sacrificed, and the brain structures were removed for enzymatic assay. AChE activity was found to vary in all the brain structures in accordance with the day studied (7–15–30 days) (P < 0.05). In the group III, there was an inhibition of the AChE activity in the ST, CB, HY, HP and also in synaptosomes of the CC (P < 0.05). It was observed that IFN-β per se was capable to significantly inhibit (P < 0.05) AChE activity in the ST, HP, HY and synaptosomes of the CC. Our results suggest that one of the mechanisms of action of IFN-β is through the inhibition of AChE activity, and EB could be considered an inhibitor of AChE activity by interfering with cholinergic neurotransmission in the different brain regions.     

Oxidative Stress in a Model of Toxic Demyelination in Rat Brain: The Effect of Piracetam and Vinpocetine

We studied the role of oxidative stress and the effect of vinpocetine (1.5, 3 or 6 mg/kg) and piracetam (150 or 300 mg/kg) in acute demyelination of the rat brain following intracerebral injection of ethidium bromide (10 μl of 0.1%). Results: ethidium bromide caused (1) increased malondialdehyde (MDA) in cortex, hippocampus and striatum; (2) decreased total antioxidant capacity (TAC) in cortex, hippocampus and striatum; (3) decreased reduced glutathione (GSH) in cortex and hippocampus (4); increased serum nitric oxide and (5) increased striatal (but not cortical or hippocampal) acetylcholinesterase (AChE) activity. MDA decreased in striatum and cortex by the lower doses of vinpocetine or piracetam but increased in cortex and hippocampus and in cortex, hypothalamus and striatum by the higher dose of vinpocetine or piracetam, respectively along with decreased TAC. GSH increased by the higher dose of piracetam and by vinpocetine which also decreased serum nitric oxide. Vinpocetine and piracetam displayed variable effects on regional AChE activity.