Discrete Regions Of Rat Brain Research Articles

Ang (1–7)/Mas receptor-axis activation promotes amyloid beta-induced altered mitochondrial bioenergetics in discrete brain regions of Alzheimer's disease-like rats

Renin Angiotensin System plays significant role in the memory acquisition and consolidation apart from its hemodynamic function in the pathophysiology of Alzheimer's disease (AD). It has been reported that Ang (1–7) ameliorates the cognitive impairment in experimental animals. However, the effect of Ang (1–7)/Mas receptor signaling is yet to be explored in Aβ42-induced memory impairment. Aβ42 was intracerebroventricularly injected into the male rats on day-1 (D-1) of the experimental schedule of 14 days. All the drugs were administered from D-1 to D-14 in the study design. Aβ42 significantly increased the escape latency during Morris water maze (MWM) test on D-10 to13 in the animals. Further, Aβ42 significantly decreased the time spent and percentage of total distance travelled in the target quadrant of the rats on D-14 in the MWM test. Aβ42 also significantly decreased the spontaneous alteration behavior on D-14 during Y-maze test. Moreover, there was a significant increase in the level of Aβ42, decrease in the cholinergic function (in terms of decreased acetylcholine and activity of cholinesterase, and increased activity of acetylcholinesterase), mitochondrial function, integrity and bioenergetics, and apoptosis in all the rat brain regions. Further, Aβ42 significantly decreased the level of expression of heme oxygenase-1 in all the rat brain regions. Ang (1–7) attenuated Aβ42-induced changes in the behavioral, biochemical and molecular observations in all the selected rat brain regions. However, A779, Mas receptor blocker, significantly abolished the beneficial effects of Ang (1–7) in Aβ42-induced cognitive deficit animals. These observations clearly indicate that the Ang (1–7)/Mas receptor activation could be a potential alternative option in the management of AD.

Prenatal exposure to valproic acid reduces social responses and alters mRNA levels of opioid receptor and pre-pro-peptide in discrete brain regions of adolescent and adult male rats

Altered social behaviours are a hallmark of several psychiatric and developmental disorders. Clinical and preclinical data have demonstrated that prenatal exposure to valproic acid (VPA), an anti-epileptic and mood stabiliser, is associated with impaired social responses, and thus provides a useful model for the evaluation of neurobiological mechanisms underlying altered social behaviours. The opioid system is widely recognised to regulate and modulate social behaviours, however few studies have examined if the endogenous opioid system is altered in animal models of social impairment. The present study examined social behavioural responses of adolescent and adult male rats prenatally exposed to VPA, and the expression of mRNA encoding opioid receptors and pre-pro-peptides in discrete brain regions. Adolescent and adult rats prenatally exposed to VPA spent less time engaging in social behaviours in the direct social interaction test and exhibited reduced sociability and social novelty preference in the 3-chamber sociability test, compared to saline-treated counterparts. The VPA-exposed adolescent rats exhibited significantly reduced kappa opioid receptor (oprk1) and pre-pro-dynorphin (pdyn) mRNA expression in the cerebral cortex, and reduced oprk1 and nociceptin/orphanin FQ (oprl1) mRNA expression in the hypothalamus. Adult rats prenatally exposed to VPA exhibited decreased mRNA expression of oprk1 and pdyn in hypothalamus, reduced pro-opiomelanocortin(pomc) in the striatum and an increase in delta opioid receptor (oprd1) mRNA in the amygdaloid cortex, when compared to saline-treated counterparts. Mu opioid receptor (oprm1) mRNA expression did not differ between saline and VPA-exposed rats in any region examined. The data demonstrate that impaired social behaviours in adolescent and adult rats prenatally exposed to VPA is accompanied by altered mRNA expression of opioid receptors and pre-pro-peptides in a region specific manner. In particular, both adolescent and adult VPA-exposed rats exhibit reduced oprk1-pdyn mRNA expression in several brain regions, which are associated with deficits in social behavioural responding in the model.

Age-related changes in the brain antioxidant status: modulation by dietary supplementation of Decalepis hamiltonii and physical exercise.

The synergistic effects of physical exercise and diet have profound benefits on brain function. The present study was aimed to determine the effects of exercise and Decalepis hamiltonii (Dh) on age-related responses on the antioxidant status in discrete regions of rat brain. Male Wistar albino rats of 4 and 18months old were orally supplemented with Dh extract and swim trained at 3% intensity for 30min/day, 5days/week, for a period of 30days. Supplementation of 100mg Dh aqueous extract/kg body weight and its combination with exercise significantly elevated the antioxidant enzyme activities irrespective of age. Age-related and region-specific changes were observed in superoxide levels, and protein carbonyl and malondialdehyde contents, and were found to be decreased in both trained and supplemented groups. Levels of total thiols, protein, and nonprotein thiols decreased with age and significantly increased in the SW-T(+100mg) groups. Our results demonstrated that the interactive effects of two treatments enhanced the antioxidant status and decreased the risk of protein and lipid oxidation in the rat brain.

Tissue specific differential response in metabolic activities of cerebrum, cerebellum, pons and medulla associated with thyroid dysfunction in sub-acute fluoride toxicity

Objectives: In this present in vivo study, we are trying to explore differential effects of fluoride on metabolic functions of four discrete regions of rat brain associated with thyroidal insufficiency. Methods: Male rats of Wistar strain (N=6) were orally fed with 20 mg/kg/day fluoride for 30 days. Results: The results showed that following fluoride exposure, total protein content depleted more significantly in cerebrum and medulla in comparison to cerebellum and pons. Due to less availability of protein in all those tissues especially in medulla the proleolytic enzyme activity was severely affected by fluoride. Change in acidic protein content after fluoride exposure was more in cerebrum than in medulla, pons and cerebellum, whereas basic protein reduced markedly in medulla followed by pons, cerebellum and cerebrum. Additionally, neutral protein depleted more adversely in cerebellum and medulla in comparison with pons and cerebrum. Both DNA and RNA contents were markedly reduced in medulla and pons as compared with cerebrum and cerebellum. Increased RNase activity may be a causative factor for decreased RNA content in those tissues after fluoride treatment. Additionally, protein carbonylation is pronounced in cerebrum as compared with other tissue which may be responsible for depleting acidic proteins in that region. The neurotransmitter level was markedly reduced in cerebellum followed by medulla, pons and cerebrum. Conclusion: Thus, it is suggested that fluoride altered metabolic homeostasis in cerebrum, cerebellum, pons, medulla and thyroid in a tissue specific manner. Moreover, it is further observed that among the studied brain regions medulla and pons were adversely affected in terms of their protein and nucleic acid metabolism, whereas cerebellum was severely depressed to synthesize neurotransmitters following fluoride exposure.

Evaluation of oxidant stress and antioxidant defense in discrete brain regions of rats exposed to 900 MHz radiation

In the current study, the effects of 900 MHz radio-frequency electromagnetic radiation (RF-EMR) on levels of thiobarbituric acid-reactive substances (TBARS), total antioxidants (TA), and glutathione S-transferase (GST) activity in discrete brain regions were studied in adolescent rats.Thirty-six male Wistar rats (6-8 weeks old) were allotted into three groups (n = 12 in each group). Control group (1) remained undisturbed in their home cage; sham group (2) was exposed to mobile phone in switch off mode for four weeks; RF-EMR-exposed group (3) was exposed to 900 MHz of RF-EMR (1 hr/day with peak power density of 146.60 µW/cm2) from an activated Global System for Mobile communication (GSM) mobile phone (kept in silent mode; no ring tone and no vibration) for four weeks. On 29th day, behavioral analysis was done. Followed by this, six animals from each group were sacrificed and biochemical parameters were studied in amygdala, hippocampus, frontal cortex, and cerebellum.Altered behavioral performances were found in RF-EMR-exposed rats. Additionally, elevated TBARS level was found with all brain regions studied. RF-EMR exposure significantly decreased TA in the amygdala and cerebellum but its level was not significantly changed in other brain regions. GST activity was significantly decreased in the hippocampus but, its activity was unaltered in other brain regions studied.RF-EMR exposure for a month induced oxidative stress in rat brain, but its magnitude was different in different regions studied. RF-EMR-induced oxidative stress could be one of the underlying causes for the behavioral deficits seen in rats after RF-EMR exposure (Fig. 5, Ref. 37).

Brain aging and AD-like pathology in streptozotocin-induced diabetic rats.

Objective. Numerous epidemiological studies have linked diabetes mellitus (DM) with an increased risk of developing Alzheimer's disease (AD). However, whether or not diabetic encephalopathy shows AD-like pathology remains unclear. Research Design and Methods. Forebrain and hippocampal volumes were measured using stereology in serial coronal sections of the brain in streptozotocin- (STZ-) induced rats. Neurodegeneration in the frontal cortex, hypothalamus, and hippocampus was evaluated using Fluoro-Jade C (FJC). Aβ aggregation in the frontal cortex and hippocampus was tested using immunohistochemistry and ELISA. Dendritic spine density in the frontal cortex and hippocampus was measured using Golgi staining, and western blot was conducted to detect the levels of synaptophysin. Cognitive ability was evaluated through the Morris water maze and inhibitory avoidant box. Results. Rats are characterized by insulin deficiency accompanied with polydipsia, polyphagia, polyuria, and weight loss after STZ injection. The number of FJC-positive cells significantly increased in discrete brain regions of the diabetic rats compared with the age-matched control rats. Hippocampal atrophy, Aβ aggregation, and synapse loss were observed in the diabetic rats compared with the control rats. The learning and memory of the diabetic rats decreased compared with those of the age-matched control rats. Conclusions. Our results suggested that aberrant metabolism induced brain aging as characterized by AD-like pathologies.

Prosopis cineraria: A potential nootropic agent

Context: Prosopis cineraria (L.) Druce (Leguminosae), a plant of the Thar Desert of India and Pakistan is used traditionally by local people for the treatment of memory disorders and to arrest wandering of the mind.Objective: The study includes scientific validation of P. cineraria for nootropic activity. To elucidate the possible mechanism, the anticholinesterase activity was also investigated in different parts of the brain.Materials and methods: Methanol extract of P. cineraria stem bark (200, 400 and 600 mg/kg body weight p.o.) was administered once in a day for 7 days to rats and these rats were then subjected to Morris water-maze (MWM) test for spatial reference memory (SRM) and spatial working memory (SWM) versions of memory testing. The inhibitory effect of the extract on acetylcholinesterase (AChE) in discrete rat brain regions (prefrontal cortex [PFC], hippocampus [HIP] and amygdala [AMY]) was also investigated using acetyl thiocholine iodide and dithiobisnitrobenzoic acid reagent.Results and discussion: The oral administrations of methanol extract of P. cineraria in all doses tested, significantly (p < 0.05) improved both spatial reference and working memories in the MWM test in terms of decrease in escape latency during SRM and increase in time spent in the target quadrant during SWM probe trial. A ceiling effect was observed at 400 mg/kg. Pre-treatment for 7 days significantly inhibited the activity of AChE in the HIP, PFC and AMY.Conclusion: The extract exerted significant nootropic activity in the MWM test which may be attributed to the inhibition of brain AChE.

Increased cerebral oxidative damage and decreased antioxidant defenses in ovariectomized and sham-operated rats supplemented with vitamin A

Previous studies have linked oxidative stress with aging and aging-related processes, including menopause. Abnormalities in the redox state similar to those observed in menopausal women can be modeled experimentally with rat ovariectomy. The aim of the present study was to investigate the effects of vitamin A (retinol palmitate) supplementation (500 or 1,500IUkg(-1)day(-1) for 30days) on behavioral parameters and brain redox profile in ovariectomized (OVX) and sham-operated rats. Ovariectomy caused pronounced uterine atrophy and decreased locomotor/exploratory activity. Moreover, we found increased hypothalamic and frontal cortex superoxide dismutase/catalase (SOD/CAT) ratio and decreased hippocampal thiol content, accompanied by increased frontal cortex lipid oxidative damage (TBARS) in OVX rats. Vitamin A at 1,500IUkg(-1)day(-1) decreased exploratory behavior and decreased total hippocampal thiol content in sham-operated rats, increased hippocampal SOD/CAT ratio and decreased total antioxidant potential in the hippocampus of both sham and OVX groups, and increased cortical TBARS levels in OVX rats. Thus, vitamin A may induce a pro-oxidant state in discrete brain regions of sham-operated and OVX rats. These results suggest some caution regarding the use of high doses of vitamin A supplementation during menopause.

Alterations of 3,4-dihydroxyphenylethylamine and its metabolite 3,4-dihydroxyphenylacetic produced in rat brain tissues after systemic administration of saxitoxin

We have measured the dopamine levels in some discrete rat brain regions after acute intraperitoneal administration of saxitoxin (STX). STX is one of the several toxins that causes paralytic shellfish poisoning (PSP). PSP is a serious public health concern through the world. Certain dinoflagellates are able of producing STX, a powerful neurotoxic compound, which blocks the voltage sensitive sodium channels, entailing to the appearance of the main symptoms of poisoning by PSP: muscular paralysis and respiratory depression. The goal in this study was to analyze the effect of STX on dopamine levels in discrete rat brain regions after its acute intraperitoneal administration. Different experimental periods were analyzed for STX doses (5 and 10μgkg−1 body weight). With low dose, experimental periods were: 30, 60 and 120min. With high dose, experimental period was just 30min. At the end of each experimental period, animals were sacrificed by cervical dislocation. Brains were removed and dissected in: hypothalamus, striatum, midbrain, brain stem, right and left hemispheres. This is to our knowledge, the first report in which a sublethal dose of STX administered intraperitoneally results in an acute alteration of dopamine (DA) production and its metabolite 3,4-dihydroxyphenylacetic acid (DOPAC).

The lumped constant of α-methyl- l-tryptophan is not influenced by drugs acting through serotonergic system

Lumped constant (LC) is a constant used to convert brain trapping constant of α-methyl- l-tryptophan (using α- 14C-methyl- l-tryptophan) into the constant for conversion of tryptophan into serotonin (5-hydroxytryptamine, 5-HT), which can be then used with certain assumptions in the calculation of the brain regional 5-HT synthesis rate. The aim of the present study was to investigate the acute effects of two drugs on the regional stability of the LC and possible effect on its value. Drugs used were a selective 5-HT reuptake inhibitor, fluoxetine, and a drug that releases 5-HT and inhibits 5-HT uptake, d, l-fenfluramine. The values of the LC from those experiments were compared with the value of LC obtained in the saline treated rats. KT is the constant for tryptophan conversion into 5-HT, which was measured by an autoradiographic method in more than twenty brain regions, using labelled tryptophan ( 14C-Trp) as tracer, after the fraction incorporated into proteins was removed. The trapping constant K α for α-methyl- l-tryptophan was also measured autoradiographically in a separate group of rats. All measurements were done in drug and saline (control) treated rats. The regional LC constants were calculated as the ratios between KT and K α. Statistical evaluation showed that the regional values in each of these three sets were normally distributed, and that the three sets of LC values calculated as the mean of logarithmic differences (saline 0.450 ± 0.055; fluoxetine 0.429 ± 0.091; d, l-fenfluramine 0.48 ± 0.09) did not differ significantly. The overall weighted mean value of the LC from all three sets of measurements was 0.452 ± 0.041, and this value was not significantly different from the LC value of 0.42 ± 0.07, i.e. value obtained in our previous studies. These results showed the unaltered LC value in discrete rat brain regions after treatment with fluoxetine or d, l-fenfluramine, and confirmed that the numerical value of the LC used in our previous studies was not altered by treatment with drugs affecting 5-HT transmission and 5-HT synthesis rate.

Estrogen receptor (ER) subtype agonists alter monoamine levels in the female rat brain

We assessed the effects of subtype-selective ER agonists on monoamine levels in discrete regions of the female rat brain. Ovariectomized (ovx) rats were treated for 4 days with vehicle, 17β-estradiol (E; 0.05 mg/kg), an ERβ agonist (C19; 3 mg/kg) or an ERα agonist (PPT; 3 mg/kg) and samples from brain regions were assessed for monoamines and metabolites. We also assessed effects of ERβ modulation on baseline and fenfluramine-induced release of monoamines in hippocampus using microdialysis. In the first study, E and the ERα agonist increased norepinephrine in cortex and all three ER ligands increased it in the ventral hippocampus. Changes in levels of the noradrenergic metabolite, MHPG and the dopaminergic metabolite, DOPAC were noted in brain areas of ER ligand-treated animals. E also increased levels of 5HIAA in three brain areas. In the microdialysis study, there were no differences among groups in baseline levels of monoamines. However, E and the ERβ agonist increased levels of the dopaminergic metabolite, HVA following fenfluramine. In summary, activation of the two nuclear ERs with selective agonists affects monoamine and metabolite levels in discrete brain areas, a number of which are known to play key roles in cognitive and affective function.

Mild steel welding fume causes manganese accumulation and subtle neuroinflammatory changes but not overt neuronal damage in discrete brain regions of rats after short-term inhalation exposure

Serious questions have been raised by occupational health investigators regarding a possible causal association between neurological effects in welders and the presence of manganese (Mn) in welding fume. Male Sprague–Dawley rats were exposed by inhalation to 40 mg/m 3 of gas metal arc-mild steel (MS) welding fume for 3 h/day for 10 days. Generated fume was collected in the animal chamber during exposure, and particle size, composition, and morphology were characterized. At 1 day after the last exposure, metal deposition in different organ systems and neurological responses in dopaminergic brain regions were assessed in exposed animals. The welding particles were composed primarily of a complex of iron (Fe) and Mn and were arranged as chain-like aggregates with a significant number of particles in the nanometer size range. Mn was observed to translocate from the lungs to the kidney and specific brain regions (olfactory bulb, cortex, and cerebellum) after MS fume inhalation. In terms of neurological responses, short-term MS fume inhalation induced significant elevations in divalent metal ion transporter 1 (Dmt1) expression in striatum and midbrain and significant increases in expression of proinflammatory chemokines (Ccl2, Cxcl2) and cytokines (IL1β, TNFα) in striatum. In addition, mRNA and protein expression of glial fibrillary acidic protein (GFAP) was significantly increased in striatum after MS fume exposure. However, the 10-day MS welding fume inhalation did not cause any changes in dopamine and its metabolites or GABA in dopaminergic brain regions nor did it produce overt neural cell damage as assessed by histopathology. In summary, short-term MS welding fume exposure led to translocation of Mn to specific brain regions and induced subtle changes in cell markers of neuroinflammatory and astrogliosis. The neurofunctional significance of these findings currently is being investigated in longer, more chronic welding fume exposure studies.

Role of Glutathione monoester on age-related neurochemical alterations in rat brain

It is quite apparent that the incidence of neurodegenerative diseases in both men and women increases in a logarithmic fashion with age and begins to rise much more rapidly after the age of 60. Brain aging is accompanied by structural and functional changes at cellular and tissue levels such as increase in free radical generation, lowered antioxidant defenses, decrease in number of neurons, decrease in the activities of enzymes, (g) decrease in impulse transmission. The present study was aimed to assess the neuromodulatory role of Glutathione monoester (GME) when administered intraperitoneally (12mg/kg body weight) for 20 days on acetylcholine esterase (AchE) activity, levels of neurotransmitters such as dopamine, serotonin, norepinephrine and rotorod behavioral analysis in discrete brain regions of young and aged male albino Wistar rats. Age-related decrease (p<0.05) in acetylcholine esterase activity, neurotransmitter levels and also decrease in sensorimotor performance was observed. GME administration was effective in restoring these neuronal parameters in aged rat brain regions. Thus GME act as a neuromodulator in discrete brain regions of aged rats.

Effects of Systemic Administration of Saxitoxin on Serotonin Levels in Some Discrete Rat Brain Regions

The present study is related with the toxicity of Saxitoxin (STX), a neurotoxic compound, produced by certain dinoflagellates. Its main toxicological activity is observed through the blockage of the sodium channels. It might originate a reduction of the amplitude and speed of conduction of the action potentials by the peripheral and central nerves, as well as weakening of the skeletal muscular contraction. The aim of this study was to analyze the effect of STX on serotonin (5-HT) levels in some discrete rat brain regions after acute intraperitoneal (i.p.) administration of 5 and 10 microg Kg(-1) STX body weight. 5-HT levels were analyzed at 30, 60 and 120 min after the administration of 5 microg Kg(-1) of STX, and 30 min after administration of 10 microg K(-1) of the toxin. Animals were sacrificed by cervical dislocation and the brains were removed and dissected in seven regions. Tissue samples were analyzed by using a chromatographic technique with electrochemical detection (HPLC/ED). Our results suggest that systemic administration of the STX reaches the brain producing alterations in neurotransmission increasing the levels of 5-HT in all the brain regions studied. With respect to the serotonin metabolite, 5-hidroxiindoleacetic acid (5-HIAA), we observed an increase in its levels in all the brain regions studied with the high dose of toxin, whereas different alterations were observed with the low dose of toxin.

The effects of synthetic and endogenous imidazoline binding site ligands on neuronal activity in discrete brain regions of naive and restraint-stressed rats

We have mapped Fos expression to investigate brain regions activated by synthetic selective I 2 (BU224) and endogenous (harmane) imidazoline binding site ligands in naive and restraint-stressed rats. Systemic administration of BU224 or harmane to naive rats increased Fos-like immunoreactivity (FLI) in the hypothalamic paraventricular nucleus (PVN), hippocampal dentate gyrus (DG), central and medial nuclei of the amygdala (CeA, MeA) and the locus coeruleus (LC). FLI in restraint-stressed rats was increased in all 5 regions by harmane, and in the CeA, MeA and LC by BU224. Dual-labelling of FLI cells in the PVN of naive rats showed an increase in the number of corticotrophin-releasing-factor-containing cells (CRF) activated by BU224 and harmane. Several CRF-containing neurons in the PVN expressed α 1-adrenoceptors and were densely surrounded by catecholaminergic axons and terminals. Our results provide a functional neuroanatomical framework which may explain the stimulatory effects of imidazoline ligands on basal and stress-induced neuronal and neuroendocrine activity.

Differential changes of neuroactive amino acids in samples obtained from discrete rat brain regions after systemic administration of saxitoxin

Aspartic acid, glutamic acid, γ-amino-n-butyric acid (GABA) and 2-aminoethanesulfonic acid are neuroactive amino acids. They are found in the central rat nervous system. Here, we have studied if a relationship exists between the presence of saxitoxin (STX) a paralytic poisoning shellfish (PSP) and the neuroactive amino acids. Samples of striatum (S), hypothalamus (H), mid brain (MB), frontal cortex (FC), brain stem (BS), right hemisphere (RH) and left hemisphere (LH) of rat brain were collected and analyzed for neuroactive amino acids (AAn t) by Aswad method (1984). Experiments, consisting of intraperitoneal injection of SXT (5 and 10 μg kg −1 body weight) to young male rats, evoked significant changes in AAn t above basal values. Aspartic and glutamic acid significantly increased for RH and LH (after 30 min the increased was 116% and 210%, P ≤ 0.001 over basal values, respectively). On the other hand, aspartic, glutamic, taurine and GABA significantly decreased for S (after 30 min the decreased was 77.4%; 84%; 93.8% and 95.3%, P ≤ 0.001 over basal values, respectively). These results suggest that STX alters AAn t. It is produced at least in part, because STX blocks voltage-gated sodium channels and this blockade could decrease AAn t release by exocytotic dependent mechanism of depolarization.

Development and validation of an RP‐HPLC method for the estimation of adenosine and related purines in brain tissues of rats

A new, rapid and sensitive RP-HPLC method with UV spectrophotometric detection was developed and validated for the concomitant estimation of adenosine and related purines in rat brain tissue preparations. The HPLC system consisted of C-18 column with UV-photodiode-array detection ranging from 210 to 400 nm, facilitating the online confirmation of peak purity. The column temperature was maintained at 30 degrees C and the injection volume was 20 muL. Elution with an isocratic mobile phase consisting of water/methanol/acetonitrile (88:5:7 by volume) at a flow rate of 0.8 mL/min yielded sharp, utmost-resolved peaks of adenosine (Ade), inosine (Ino), hypoxanthine (Hypoxan) and adenine (Adn) within 10 min. The method was validated with respect to the linearity, accuracy, precision, sensitivity, selectivity and stability. The method was also employed to estimate the naturally occurring purines in discrete regions of rat brain. A new protocol developed for tissue preparation utilizing H(2)SO(4) and Tris buffer gave well-resolved peaks and high component recoveries (>96%) which eliminated the need of an internal standard. The results show that the method for the determination of Ade, Ino, Hypoxan and Adn by RP-HPLC described here has good linearity, accuracy, precision, sensitivity, selectivity and is simple and rapid to perform.

Estimation of adenosine and its major metabolites in brain tissues of rats using high-performance thin-layer chromatography–densitometry

A new, rapid and sensitive high-performance thin-layer chromatographic (HPTLC) method with densitometry was developed and validated for the concomitant estimation of purines like adenosine (Ade) and its major metabolites, inosine (Ino) and hypoxanthine (Hypoxan) in rat brain tissue preparations. The HPTLC method was chosen in order to generate better resolution and evade the tedious and prolonged sample preparation methods necessarily performed with HPLC methods when analyzing biological samples. In this method the planar chromatography was executed on aluminum plates pre-coated with silica gel 60 F254. Elution was performed with a two-step gradient mobile phase consisting of solvent A [n-butanol/water/acetonitrile/10% ammonia solution/glacial acetic acid (5:2:4:1:0.5, v/v)] and solvent B [n-butanol/chloroform/acetonitrile/10% ammonia solution/glacial acetic acid (5:4:2:1:0.5, v/v)]. The quantitative analysis of purines was performed based on the peak areas obtained from the reflectance scanning densitometry, performed at 258nm. The spectral scan was done from 200 to 300nm which facilitated the spectral analysis of peaks for purity and spectral matching. The method was validated in terms of linearity, accuracy, precision, sensitivity, selectivity and repeatability. The method was successfully employed to estimate the endogenous purines in discrete regions of rat brain. A novel protocol developed for the tissue preparation utilizing 0.1M HCl and 0.15M NaOH solutions made in 60% (v/v) methanol resulted in well-resolved peaks and high component recoveries. The results for the first time show that this method established for the flexible estimation of Ade, Ino and Hypoxan by planar chromatography has good linearity, accuracy, precision, sensitivity, selectivity and is simple, rapid and moreover, economical to produce maximum resolution in brain tissue preparations.

Age-associated alterations of lipofuscin, membrane-bound ATPases and intracellular calcium in cortex, striatum and hippocampus of rat brain: protective role of glutathione monoester

Brain aging has become an area of intense research and a subject of much speculation fueled largely from the widely recognized fact that age is the biggest risk factor in most neurodegenerative diseases and age-related increase of reactive oxygen species is particularly detrimental to postmitotic tissues. In the present study, we have evaluated the possible role of glutathione monoester (GME), when administered intraperitoneally (12mg/kg body weight) for 20 days on age-associated changes in the levels of lipofuscin, Na+K+, Mg2+, Ca2+ ATPase activities and intracellular calcium levels in discrete brain regions of young and aged male albino Wistar rats. An age-associated increase in lipofuscin, intracellular calcium in cortex, striatum and hippocampus was observed and contradictorily, a decrease in the activities of membrane-bound enzyme activities was also observed. Supplementation of GME brought these changes to near normalcy. Thus, GME improves neuronal antioxidant status, thereby effectively attenuating any putative increase in oxidative stress with age.

Effects of chronic treatment with citalopram on cannabinoid and opioid receptor-mediated G-protein coupling in discrete rat brain regions

There is growing interest in investigating the mechanisms of action of selective serotonin reuptake inhibitors (SSRIs), beyond their association with the serotonergic system, due to their wide therapeutic potential for disorders including depression, pain and addiction. The aim of this study was to investigate whether chronic treatment with the SSRI, citalopram, alters the functional coupling of G(i/o)-associated cannabinoid type 1 (CB(1)) and mu-opioid receptors in selected areas of rat brain implicated in psychiatric disorders and pain. Using an autoradiographic approach, the effects of the cannabinoid receptor agonist, HU210 (in the presence or absence of the CB(1) receptor antagonist AM251), or the mu-opioid receptor agonist, [D: -Ala(2),N-Me-Phe4,Gly(5)-ol]-enkephalin (DAMGO; in the presence or absence of the mu-opioid receptor antagonist D: -Phe-Cys-Tyr-D: -Trp-Orn-Thr-Pen-Thr-NH(2)), on [(35)S]GTPgammaS binding in discrete brain regions of citalopram-treated (10 mg kg(-1) day(-1) for 14 days by subcutaneous minipump) and control rats were investigated. The HU210-induced increase in [(35)S]GTPgammaS binding observed in the hypothalamic paraventricular nucleus of control rats was abolished after chronic treatment with citalopram. Reduced response to HU210 in rats receiving chronic treatment with citalopram was also observed in the hippocampus and medial geniculate nucleus. Citalopram had no significant effect on DAMGO-induced [(35)S]GTPgammaS binding in the brain regions investigated, with the exception of the medial geniculate nucleus where a modest impairment was observed. These data provide evidence for reduced cannabinoid receptor-mediated G-protein coupling in the hypothalamus, hippocampus and medial geniculate nucleus of rats chronically treated with citalopram, effects which may, in part, underlie the mechanism of action of SSRIs.