Treatment Of Rat Brain Research Articles

The effects of endogenous melatonin on brain tissue oxidative stress induced by photoperiodic alterations and iron overloading in rats

Melatonin is a potent endogenously occurring antioxidant with the pleiotropic activities to neurodegenerative diseases associated with brain oxidative damage. In this study, we examined the prolonged photoperiodic alterations and iron (Fe) overload on melatonin production and brain oxidative stress in rats. The result showed that the 15 days of constant light (CL) exposure did not low the melatonin production but the 15 days of constant darkness (CD) significantly increased serum melatonin level in rats. The Fe treatment in both CL and CD conditions significantly reduced endogenous melatonin levels and increased brain tissue lipid peroxidation. Fe as a toxic transition metal can induce Fenton reaction to generated hydroxyl radical which can damage the neuronal cell membrane and impair the brain antioxidant system. In the current study, we observed the imbalanced antioxidant defense alterations upon Fe treatment in rat brain including the increased levels of alpha-tocopherol (α-T) and total thiols and the reduced melatonin level and catalase (CAT) activity. We speculated that the reduced melatonin level caused by Fe was due to its consumption since melatonin served as a metal chelator and antioxidant. Understanding these aspects enhances knowledge of brain Fe metabolism and its role in neurodegenerative disorders as well as the potential protective effects of melatonin on this metal.

Alterations in Synaptic Plasticity and Oxidative Stress Following Long-Term Paracetamol Treatment in Rat Brain.

Several studies have recently revealed that cognitive function can be affected by paracetamol (APAP) treatment. However, the exact impact of this drug treatment on learning and memory has not been clarified. This study aimed to investigate the effect of APAP treatment on the alteration of synapses and oxidative stress in the rat frontal cortex and hippocampus. APAP at a dose of 200mg/kgbw was fed to adult male Wistar rats through either acute (n = 10), 15-day (n = 10), or 30-day (n = 10) treatment regimens. The synaptic ultrastructure and proteins, synaptophysin (SYP) and postsynaptic density-95 (PSD-95), were monitored. The amount of protein carbonyl oxidation (PCO) and glutathione (GSH) levels were examined. Our results demonstrated that acute treatment with APAP had no effect on synapses and oxidative stress. However, the synapses obtained from rats with 15-day APAP treatment showed a marked shortening of active zones and widening of the synaptic cleft. Decrement of SYP and PSD-95 proteins were demonstrated in these rats as well. With 30-day APAP treatment, the alteration of the synaptic ultrastructure and proteins was more evident. Moreover, the depletion of GSH and the elevation of PCO levels were demonstrated in the rats treated with APAP for 30days. These results suggest that long-term APAP treatment can induce synaptic degeneration in the hippocampus and frontal cortex. The increase in oxidative stress in these brain areas may be due to the deleterious effect of this drug.

Lack of Regulatory Changes of µ-Opioid Receptors by 14-Methoxymetopon Treatment in Rat Brain. Further Evidence for Functional Selectivity

Here we have studied regulatory changes of µ-opioid receptors accompanying in vivo 14-methoxymetopon treatments of rats. Previously, this ligand has been shown to be an extremely potent, centrally acting µ-opioid specific analgesic with low physical dependence, tolerance, respiratory depression, constipation and other side effects. Our work shows that it is a highly potent full agonist of µ-opioid receptor coupled G-protein signaling in vitro, alike the well-known opioid agonist, etorphine. However, unlike etorphine, which desensitized and down-regulated the endogenous µ-opioid receptors, 14-methoxymetopon, given to rats intraperitoneally (i.p.) either acutely or chronically, did not change the binding or G-protein signaling of µ-opioid receptors in rat brain subcellular membranes. Thereby, these data provide further evidence that there is no direct relationship between the efficacy of the ligand in signaling and its ability to internalize or desensitize the receptor. Viewed collectively with published work, it is discussed that µ-opioid receptors display functional selectivity, also called 'biased agonism'. This concept implies that each ligand may induce unique, ligand-specific receptor conformation that can result in distinct agonist- directed trafficking and/or signal transduction pathways associated with the receptor. Ligand-specific signaling may open up new directions for designing potent analgesics that do not interact with unwanted signaling pathways, which mediate undesired side-effects, such as tolerance and dependence.

Regulation of NMDA Receptor Subunits after Acute Ethanol Treatment in Rat Brain

Tolerance to ethanol-induced inhibition of N-methyl-D-aspartate receptors (NMDARs) is thought to underlie the acute adaptive mechanisms against ethanol. To explore these compensatory upregulating mechanisms of NMDARs, we investigated the expression and phosphorylation of NMDAR subunits in vivo following an acute ethanol treatment. Male Sprague-Dawley rats were given 4g/kg ethanol, and the phospho-S896-NR1, NR2A and NR2B subunits of NMDAR were immunoblotted from the cerebral cortex and hippocampus. We also examined the mRNAs and ubiquitinated forms of the NR2A and NR2B subunits. Acute ethanol treatment increased phospho-S896-NR1 at 30min in the cerebral cortex and hippocampus, and the increase was maintained until 2h in the hippocampus. Ethanol increased total NR2A and NR2B expression at 30min in the cortex and hippocampus, and the NR2A increase was maintained until 2h in the hippocampus. The increased expression of the NR2A and NR2B subunits was not associated with statistically significant alterations in mRNA expression or protein ubiquitination. Acute ethanol treatment increased NR1 subunit phosphorylation and NR2A and NR2B subunit expression in the cerebral cortex and hippocampus of rats. These effects of ethanol on the NMDAR subunits may underlie the mechanisms that compensate for ethanol-induced inhibition of NMDARs. However, the regulation of NR2A and NR2B in this paradigm is not dependent on transcriptional changes.

Regulation of a2-adrenoceptor gene expression by chronic lithium treatment in rat brain

One of the approaches for the treatment of bipolar disorder involves the coadministration of lithium, a mood stabilizer, with α₂-adrenoceptor antagonists possessing an antidepressant effect. Since lithium accelerates the recovery of α₂(D)-adrenoceptors following their irreversible inactivation with N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ), our aim was to examine if it could be to some changes in Adra2A gene expression which codifies these adrenoceptors. Animals were treated with lithium chloride (120 mg/kg i.p.) or saline once a day for 10 days. A group of lithium- or saline-treated rats was killed 48 h after the last injection. The remaining animals were treated with EEDQ and were killed at 0.25, 4 and 14 days following this administration. Total RNA was extracted from cerebral cortex and Adra2A gene expression was measured by RT-QPCR. The results show that chronic lithium raised the Adra2A gene expression (P < 0.05), and after EEDQ administration this expression decreased to the basal level. No change in Adra2A gene expression was detected in the saline-treated group. However, EEDQ administration produced an insignificant increase in α₂-adrenoceptors mRNA levels followed by a progressive decrease until basal levels. Lithium produced an overexpression of the Adra2A gene after chronic treatment that made the neuron ready to produce α₂-adrenoceptors to deal with their inactivation.

Expression and subcellular localization of thymosin beta15 following kainic acid treatment in rat brain

Thymosin β15 (Tβ15) is a pleiotropic factor which exerts multiple roles in the development of nervous system and brain diseases. In this study, we found that the expressions of Tβ15 mRNA and protein were substantially increased in several brain regions including hippocampal formation and cerebral cortex, following kainic acid (KA)-evoked seizures in rat. Interestingly, a subset of cortex neurons exhibited nuclear Tβ15 immunoreactivity upon KA treatment. Furthermore, translocation of Tβ15 from cytosol to nuclei was observed in cultured neurons or HeLa cells during staurosporine (STS)-induced apoptosis, which was also verified by time-lapse imaging of YFP-tagged Tβ15. It appeared that localization of Tβ15 is restricted to the cytosol in normal condition by its G-actin-interacting domain, because site-directed mutagenesis of this region resulted in the nuclear localization of Tβ15 in the absence of STS treatment. To explore the role of nuclear Tβ15, we enforced Tβ15 to localize in the nuclei by fusion of Tβ15 with nuclear localization signal (NLS-Tβ15). However, overexpression of NLS-Tβ15 did not alter the viability of cells in response to STS treatment. Collectively, these results suggest that nuclear localization of Tβ15 is a controlled process during KA or STS stimulation, although its functional significance is yet to be clarified.

Decreased gene expression of glial and neuronal glutamate transporters after chronic antipsychotic treatment in rat brain

Post-mortem studies in schizophrenic patients revealed alterations in glutamate transporter gene expression. The question concerning a possible influence of chronic antipsychotic treatment on these gene expressions, however, remained open. In this study, 11 rats per group were treated with either haloperidol (1.5 mg/kg per day) or clozapine (45 mg/kg per day) over a period of 6 months in doses comparable to clinic application. Gene expression of glial glutamate transporter EAAT2 and the predominantly neuronal glutamate transporter EAAT3 were examined by in situ hybridization. Clozapine significantly downregulated EAAT2 in hippocampal CA1 and parietal cortex and EAAT3 in the cingulate cortex compared to the expression upon haloperidol treatment and controls. Additionally, clozapine decreased EAAT2 in temporal, cingulate and frontal cortex and downregulated EAAT3 in cingulate and infralimbic cortex, striatum and hippocampal CA1 and CA2 compared to controls. Haloperidol downregulated EAAT2 in cingulate and frontal cortex and reduced EAAT3 in nucleus accumbens, infralimbic cortex and hippocampal CA2. We hypothesize that glutamate transporter downregulation by neuroleptics increases glutamatergic action at the postsynaptic neuron and thereby may be related to beneficial antipsychotic effects and side effects.

Identification of a Novel Gene with RING-H2 Finger Motif Induced after Chronic Antidepressant Treatment in Rat Brain

Previously, we have identified 200 cDNA fragments as antidepressant related genes/ESTs. In this study, using these cDNAs, we developed our original cDNA microarray for rapid secondary screening of candidate genes as the novel therapeutic targets. With this microarray, we found that the expression of a novel gene, ADRG34, was significantly increased in rat hippocampus which had been chronically treated with a selective serotonin reuptake inhibitor antidepressant, sertraline. RT-PCR analysis also demonstrated the induction of ADRG34 at mRNA levels in rat hippocampus and the frontal cortex. This cDNA encoded 685 amino acid residues containing a RING-H2 finger motif at the carboxy-terminal. Sequence analysis of ADRG34 with the EMBL/GenBank database showed significant homology to mouse and human kf-1 gene. Our data suggest that ADRG34, a possible rat homologue of kf-1, may be one of the common functional molecules induced after chronic antidepressant treatment.

383. Differential cloning and DNA microarrays in depression research

Depression is one of the major psychiatric diseases. Although blockade by antidepressants of monoamine uptake into nerve endings is one of the cornerstones of the monoamine hypothesis of depression, there is a clear discrepancy between the rapid effects of antidepressants in increasing synaptic concentrations of monoamine and the lack of immediate clinical efficiency of antidepressant treatment. It is known that antidepressant effect is generally observed after repeated administration for several weeks. This delay could be explained at the molecular level by an action on gene transcription. Recently introduced technique, DNA microarray, enabled us to perform large-scale coordinate monitoring of gene expression during different functional states in normal and diseased samples, or in control and treated animals. This method of large-scale gene expression analysis creates a bridge between the molecular pharmacological approach and study at the systems level to understand the pathophysiology of depression and the mechanisms of action of the treatment. In addition to the gene expression monitoring, cDNA microarray can be used for gene discovery by probing enriched libraries derived from the experiments with differential cloning techniques, which includes Differential Display PCR, RNA fingerprinting, Suppressive Subtractive Hybridization, and Representational Difference Analysis. While screening of the common biochemical changes induced after antidepressant treatment in rat brain with these genome-pharmacological approach, we identified several interesting candidate genes and expressed sequence tags, ESTs. We believe that these molecules would be attractive target molecules for future antidepressant development with a new class of action in the brain.

437. Differential expression of newly identified gene with RING-H2 finger motif after chronic antidepressant treatment in rat brain

437. Differential expression of newly identified gene with RING-H2 finger motif after chronic antidepressant treatment in rat brain

Differential expression of a novel Rho-kinase homologue after chronic antidepressant treatment in rat brain

Differential expression of a novel Rho-kinase homologue after chronic antidepressant treatment in rat brain

Reduction of tyrosine kinase B and tyrosine kinase C inductions by treatment with neurotrophin-3 after transient middle cerebral artery occlusion in rat

Infarct volume and immunoreactivities for trkB and trkC in rat brain were compared at 24 h after 90 min of transient middle cerebral artery occlusion (MCAO) between animal groups with or without neurotrophin-3 (NT-3, 10 μg/250 g animal). Treatment of rat brain with topical application of NT-3 significantly reduced infarct volume ( P=0.02) and trkB and trkC inductions. These data suggest that NT-3 reduced the ischemic injury along with the reduction of trkB and trkC inductions.

Alterations of tubulin function caused by chronic antidepressant treatment in rat brain.

1. Antidepressants have been used clinically for many years; however, the neurochemical mechanism for their therapeutic effect has not been clarified yet. Recent reports indicate that chronic antidepressant treatment directly affects the postsynaptic membrane to increase the coupling between the stimulatory GTP-binding (G) protein, Gs, and adenylyl cyclase. Tubulin, a cytoskeletal element, is involved in the stimulatory and inhibitory regulation of adenylyl cyclase in rat cerebral cortex via direct transfer of GTP to G proteins. In this study, we investigated whether the functional change of the adenylyl cyclase system caused by chronic antidepressant treatment involves an alteration of tubulin function in the regulation of adenylyl cyclase activity. 2. Male Sprague-Dawley rats were treated once daily with amitriptyline or saline by intraperitoneal injection (10 mg/kg) for 21 days, and their cerebral cortex membranes and GppNHp-liganded tubulin (tubulin-GppNHp) were prepared for what. 3. GppNHp-stimulated adenylyl cyclase activity in cortex membranes from amitriptyline-treated rats was significantly higher than that in control membranes. Furthermore, tubulin-GppNHp prepared from amitriptyline-treated rats was more potent than that from control rats in the stimulation of adenylyl cyclase activity in the cortex membranes of the controls. However, there was no significant difference in manganese-stimulated adenylyl cyclase activity between control and amitriptyline-treated rats. 4. The present results suggest that chronic antidepressant treatment enhances not only the coupling between Gs and the catalytic subunit of adenylyl cyclase but also tubulin interaction with Gs in the cerebral cortex of the rat.

Developmental changes in calpain activity, GluR1 receptors and in the effect of kainic acid treatment in rat brain

The cellular distribution of calpain activation and glutamate receptor 1 (GluR1) subunits of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors and their alterations following kainic acid-induced seizure were evaluated during postnatal development using antibodies specific for spectrin breakdown product and the C-terminus of GluR1 subunits. In the first postnatal week, most brain regions exhibited high levels of calpain activity that progressively decreased during the following weeks. The highest levels of spectrin breakdown product immunoreactivity were observed in the somata and proximal dendrites of hippocampal pyramidal cells, non-pyramidal neurons in stratum oriens, and cortical neurons. In general, during the first two postnatal weeks, kainic acid treatment induced a decrease in spectrin breakdown product immunoreactivity in neuronal cell bodies and an increase in dendritic fields. Obvious elevation in spectrin breakdown product immunoreactivity in selective non-pyramidal cells in stratum oriens started at postnatal day 14, and was further evidenced by postnatal day 21. Likewise, massive calpain activation in subpopulations of neurons in some thalamic nuclei, amygdala, and pyriform cortex was observed after the third postnatal week. GluR1 subunits were highly expressed throughout the forebrain in the first postnatal week, further increased during the second postnatal week, decreased thereafter, and reached adult levels after postnatal day 21. In cortex, intense GluR1 immunostaining was found in the somata and proximal processes of pyramidal and non-pyramidal neurons, with the non-pyramidal neurons in layers IV through VI exhibiting the densest immunolabelling. In the first two postnatal weeks, the somata of hippocampal pyramidal neurons exhibited intense GluR1 immunostaining that became more dendritic in the subsequent developmental period. While hilar cells exhibited a similar developmental pattern as CA regions, the molecular layer of dentate gyrus exhibited weak immunoreactivity from postnatal day 7 to postnatal day 14. The early increase in GluR1 immunoreactivity in hippocampal pyramidal layer following kainic acid treatment occurred throughout the developmental period, while the later decrease in CA regions, amygdala, and pyriform cortex was observed only in postnatal day 21 animals. The combined immunocytochemical studies of spectrin breakdown product localization and GluR1 expression indicate that calpain activation might play an important role in synaptic formation, developmental regulation of synaptic plasticity, and neuronal vulnerability to excitotoxicity during postnatal development. Moreover, calpain-mediated modulation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors might underlie these processes.

65-70 - Distribution of fos expression induced by long-acting haloperidol decanoate treatment in rat brain

65-70 - Distribution of fos expression induced by long-acting haloperidol decanoate treatment in rat brain

2118 Tissue plasminogen activator mRNA induction after methamphetamine treatment in rat brain

Oat protein isolate is nutritious but with poor processing functionality. Pleurotus ostreatus β-glucan with good processing functionality can be conjugated with oat protein isolate via Maillard reaction, leading to an improved utilization of protein in food industry. Therefore, we produced conjugate with oat protein isolate and Pleurotus ostreatus β-glucan via Maillard reaction under controlled dry-heating conditions. The formation of conjugates with high molecular weight was identified by a new band of sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The analysis of amino acid composition showed that cysteine and lysine were the dominant Maillard reaction sites of oat protein isolate and Pleurotus ostreatus β-glucan. Changes in spatial configuration of conjugates caused reduction in their surface hydrophobicity of proteins and intrinsic fluorescence intensity. Fourier transform infrared spectroscopy analysis of conjugates suggested that Maillard reaction could cause the C=O stretching vibration, as well as the C-H and N-H deformation vibration. Circular dichroism analysis indicated that the secondary structure of conjugates was altered by decreasing the contents of α-helix and β-sheet and increasing the contents of β-turn and random coil. The surface structure of conjugates was loose and porous using scanning electron microscope. Furthermore, Maillard reaction could improve the solubility, emulsifying property and thermal stability of oat protein isolate. Our findings confirm the potential of protein-carbohydrate conjugate formed by Maillard reaction, to improve the application of instable but valuable proteins in food industry.

P-Chlorophenylalanine-reversible reduction of σ binding sites by chronic imipramine treatment in rat brain

Repeated treatment with imipramine (10 mg/kg intraperitoneally (i.p.), once daily for 14 days) caused a decrease in the B max, without affecting the K d, of [ 3H]DTG (1,3-di-o-tolylguanidine) binding to the haloperidol-sensitive σ sites in the striatum, hippocampus and cerebral cortex of the rat. A similar reduction was observed after chronic administration of a selective serotonin uptake inhibitor, fluoxetine (10 mg/kg i.p., twice daily for 14 days), but not of a selective norepinephrine uptake inhibitor, desipramine (10 mg/kg i.p., once daily for 14 days). Neither a single injection of imipramine (10 mg/kg i.p.) nor addition of imipramine or fluoxetine into the binding assay medium mimicked the changes in the maximal binding of brain σ sites induced by chronic treatment with these drugs. Finally, depletion of brain serotonin by means of repeated administration of p-chlorophenylalanine, which produces inhibition of the amine synthesis, blocked the ability of repeated imipramine treatment to reduce the maximal number of [ 3H]DTG binding sites in the striatum and hippocampus. The present results suggest that cerebral serotonergic transmission may play a role in the regulation of cerebral σ binding sites in the rat.

Inositol 6 g daily may be effective in depression but not in schizophrenia

AbstractInositol is an important precursor for second messenger synthesis and has been reported to be reduced by lithium treatment in rat brain and in human CSF in depression. An open trial of 6 g/day in 11 depressed patients resistant to previous treatment led to major improvement in nine patients. The enzyme synthesizing inositol has been reported to be elevated in schizophrenia, suggesting an attempted compensation for possible inositol deficiency. A controlled double‐blind crossover trial in 10 chronic schizophrenic patients of 6 g/day of inositol for 30 days did not reveal any benefit.

NGFI-A mRNA induction after methamphetamine treatment in rat brain

NGFI-A mRNA induction after methamphetamine treatment in rat brain

Regulation of G proteins by chronic antidepressant drug treatment in rat brain: tricyclics but not clorgyline increase G oα subunits

The effect of long-term (3-week) administration of various antidepressant drugs on the steady-stack concentrations of G protein α subunits, G sα, G iα, and G oα, has been investigated in rat brain using an enzyme-linked immunosorbent assay. Tricyclic antidepressants and clorgyline decreased G sα and, to a lesser extent, G iα in several brain regions, while G oα was increased by tricyclics but not clorgyline. We conclude that long-term treatment with antidepressant drugs exerts differential effects on G protein α subunits, and that antidepressant efficacy may potentially be based on functional modifications of signal transduction.