Subacute Administration Research Articles

Modulation of histone deacetylase attenuates naloxone-precipitated opioid withdrawal syndrome

The present study has been designed to investigate the effect of selective inhibitors of histone deacetylase and/or N-acetyl-Asp-Glu-Val-Asp-al (Ac-DEVD-CHO), a selective interleukin-1β converting enzyme inhibitor, on the development of naloxone-induced opioid withdrawal syndrome both in vitro and in vivo and the effect of histone deacetylase inhibition on histone H3 acetylation in brain. Sub-acute morphine administration followed by a single injection of naloxone (8mg/kg, i.p.) was used to precipitate opioid withdrawal syndrome in mice. Behavioral observations were made immediately after naloxone treatment. Withdrawal syndrome was quantitatively assessed in terms of withdrawal severity score and frequency of jumping, rearing, fore paw licking and circling. Separately naloxone-induced contraction in morphine-dependent isolated rat ileum was employed as an in vitro model. An isobolographic study design was employed to assess potential synergistic activity between trichostatin A and Ac-DEVD-CHO. Brain histone acetylation status was examined by western blotting. Injection of naloxone precipitated a severe form of abstinence syndrome in morphine-dependent mice along with strong contracture in isolated rat ileum. Administration of tributyrin (1.5, 3 and 6g/kg, p.o.), trichostatin A (0.3, 1.0 and 3.0mg/kg, p.o.) and Ac-DEVD-CHO (0.3, 1.0 and 3.0mg/kg, p.o.) markedly and dose dependently attenuated naloxone-induced morphine withdrawal syndrome in vivo as well as in vitro in rat ileum. Trichostatin A was also observed to exert a synergistic interaction with Ac-DEVD-CHO. Western blot analysis revealed that multiple administration with the effective dose of tributyrin or trichostatin A in the in vivo experiments induced hyperacetylation of histone H3 in the mouse brain. Thus, it is proposed that histone deacetylase activation linked mechanism might be involved in the development of opioid dependence and the precipitation of its withdrawal syndrome.

Effects of subacute oral warfarin administration on peripheral blood granulocytes in rats

Warfarin affects mainly vitamin K dependent (VKD) processes, but the effects on some non-VKD-related activities such as tumor growth inhibition and mononuclear cell-mediated immune reactions were shown as well. In this study, the effect of subchronic (30days) oral warfarin (0.35mg/l and 3.5mg/l) intake on peripheral blood granulocytes in rats was investigated. Increase in prothrombin and partial thromboplastin time at high warfarin dose reflected its basic activity. Priming effect for respiratory burst was noted at both warfarin doses, while only high warfarin dose resulted in priming for adhesion, the rise in intracellular myeloperoxidase content/release and stimulation of nitric oxide production. Differential effects of high warfarin dose were noted on granulocyte cytokines IL-6 (lack of the effect), TNF-α (decreased release and mRNA expression) and IL-12 (increase in mRNA for IL-12 subunits p35 and p40). Changes in granulocytes seems not to rely on mitogen activated kinases p38 and ERK. Warfarin intake was associated with an increase in circulating IL-6, fibrinogen and haptoglobin and with changes in the activity of erythrocyte antioxidant enzymes superoxide dismutase and catalase. The effects of oral warfarin intake on peripheral blood granulocytes demonstrated in this study might be relevant for oral anticoagulant therapy strategies in humans.

Toxicological Evaluation of <i>Murraya Paniculata</i> (L.) Leaves Extract on Rodents

Problem statement: Present study was aimed to explore the acute and s ub-acute toxicities studies with orally administered 50% ethanolic leav es extract of Murraya paniculata . Approach: Acute toxicity (oral single dose, 50-2000 mg kg -1 ) includes any mortality and CNS and ANS toxicities in mice while, sub-acute toxicity (100, 200 and 400 mg kg -1 , orally and once daily for 28 days) includes any change in body weight, food and water intake and other biochemical, hematological and histopathological changes in tissues (liver, ki dney, spleen, stomach, heart and lung) in rats. Results: Acute oral administration of M. paniculata extract (2000 mg kg -1 , single dose) did not show any mortality and CNS and ANS toxicities. Similarly sub-acute oral administration (100, 200 and 400 mg kg -1 for 28 days) in rats did not show any change in bo dy weight, food consumption, water intake and biochemical, hematological and histopathological parameters compared to control untreated group. Conclusion: The conclusions of the present study indicate Murraya paniculata to be safe in its oral effective dose.

Prallethrin induced serum biochemical changes in Wistar rats

The present study was designed as a repeated dose 28-day oral toxicity study in rodent. All the rats were randomly divided into five groups (C1, C2, T1, T2 and T3) each containing 10 Wistar rats (5 male and 5 female). Group C1 served as control as no treatment was administered. Group C2 was administered groundnut oil (1ml/100g b.wt) and served as vehicle control. Group T1 was put on high dose 153.33mg/kg b.wt (LD50/3), while group T2 received intermediate dose of 92mg/kg b.wt (LD50/5), and group T3 was administered low dose of 46mg/kg b.wt (LD50/10) of Prallethrin suspended in 1ml/100g b.wt of groundnut oil. Blood samples were collected from all groups on the 7th, 14th, 21st and 28th day of the experiment for measurement of serum glucose, serum urea, serum triglyceride, serum cholesterol, serum aspartate aminotransferase (AST), serum alanine aminotransferase (ALT) and serum alkaline phosphatase (ALP). According to data obtained on the 7th day of the study, no statistically significant change in any of the treatment groups was observed as compared to the control group. On the 14th day of the study, in comparison to the control group, triglyceride level and ALP activity were found to be significantly increased in the group T1 female and group T1 male rats respectively. On the 21st day of the study, compared to the controls, significant increase in cholesterol and ALP levels were present in both T1 and T2 females and in addition to this total protein and triglycerides levels were also significantly increased in group T1 female rats. In group T1 male total protein, triglycerides, ALT and ALP activity was found to be increased significantly as compared to healthy control group. On the 28th day, all the recorded biochemical parameters were found to be significantly increased, except BUN and AST in group T1 female rats. In group T2 female rats, significantly increased cholesterol, ALT and ALP levels were observed. In group T3 female rats, none of the parameters were found to be significantly affected. Among male rats, only total protein level was found to be increased in groups T2 and T3. Whereas, total protein, triglyceride, ALT and ALP were significantly elevated in group T1 male rats at the end of the study. In conclusion, the results of this study demonstrate that subacute oral administration of Prallethrin; at dose levels of 1/3 LD50 and 1/5 LD50 for 28days induces moderate toxic effects on different biochemical parameters.

General and Electrophysiological Toxic Effects of Manganese in Rats following Subacute Administration in Dissolved and Nanoparticle Form

In an attempt to model occupational and environmental Mn exposures and their possible interaction, young male Wistar rats were exposed to Mn by oral administration in dissolved form (MnCl2 ·4H2O, 14.84 and 59.36 mg/kg b.w.) and by intratracheal application of MnO2 nanoparticles (2.63 mg/kg b.w.). After 3 and 6 weeks oral, or 3 weeks oral plus 3 weeks intratracheal, exposure, general toxicological, and electrophysiological tests were done. Body weight gain was significantly reduced after 6 and 3 plus 3 weeks exposure, but the effect of the latter on the pace of weight gain was stronger. Organ weights signalized systemic stress and effect on lungs. Changes in evoked electrophysiological responses (cortical sensory evoked potential and nerve action potential) indicated that the 3 plus 3 weeks combined exposure caused equal or higher changes in the latency of these responses than 6 weeks of exposure, although the calculated summed Mn dose in the former case was lower. The results showed the importance of the physicochemical form of Mn in determining the toxic outcome, and suggested that neurofunctional markers of Mn action may indicate the human health effect better than conventional blood Mn measurement.

Effects of betaine on lipopolysaccharide-induced memory impairment in mice and the involvement of GABA transporter 2

BackgroundBetaine (glycine betaine or trimethylglycine) plays important roles as an osmolyte and a methyl donor in animals. While betaine is reported to suppress expression of proinflammatory molecules and reduce oxidative stress in aged rat kidney, the effects of betaine on the central nervous system are not well known. In this study, we investigated the effects of betaine on lipopolysaccharide (LPS)-induced memory impairment and on mRNA expression levels of proinflammatory molecules, glial markers, and GABA transporter 2 (GAT2), a betaine/GABA transporter.MethodsMice were continuously treated with betaine for 13 days starting 1 day before they were injected with LPS, or received subacute or acute administration of betaine shortly before or after LPS injection. Then, their memory function was evaluated using Y-maze and novel object recognition tests 7 and 10-12 days after LPS injection (30 μg/mouse, i.c.v.), respectively. In addition, mRNA expression levels in hippocampus were measured by real-time RT-PCR at different time points.ResultsRepeated administration of betaine (0.163 mmol/kg, s.c.) prevented LPS-induced memory impairment. GAT2 mRNA levels were significantly increased in hippocampus 24 hr after LPS injection, and administration of betaine blocked this increase. However, betaine did not affect LPS-induced increases in levels of mRNA related to inflammatory responses. Both subacute administration (1 hr before, and 1 and 24 hr after LPS injection) and acute administration (1 hr after LPS injection) of betaine also prevented LPS-induced memory impairment in the Y-maze test.ConclusionsThese data suggest that betaine has protective effects against LPS-induced memory impairment and that prevention of LPS-induced changes in GAT2 mRNA expression is crucial to this ameliorating effect.

Toxicity studies of alkaloids of seeds of Datura stramonium and synthesis alkaloids in male rats

The effects of acute, subacute and chronic administration of alkaloids atropine and scopolamine, the main constituents of the active principle of Datura stramonium, with toxic properties, were studied in male Albino-Wistar rats. After acute i.p administration of dose 100 mg/kg (1/4 DL 50 ) of total alkaloids to the seeds of D. stramonium , there were no remarkable changes in general appearance and no deaths occurred in any experimental group. 24 h after total alkaloids of seeds, a significant reduction in tissues (liver, spleen and brain) was observed. The red blood cells (RBC), Hematocrit (HCT), Hemoglobin (HGB) and white blood cells (WBC) were significantly higher in the treated groups than the control group. There were no statistical differences in Glutamic-oxaloacetic transaminase (GOT), Glutamic-Pyruvic Transaminase (GPT) and alkaline phosphatase (ALP) observed between groups. Histological examination of liver showed no histopathological changes. Subacute study for four weeks showed no resulting mortality or signs of toxicity. The relative weight of kidneys showed a significant decrease, however, these doses of synthetic alkaloids (5.2 mg/kg of atropine and 2.6 mg/kg of scopolamine) produced significant increase of lungs in comparison with the control group. RBC, HBG, HCT and PLT values of control group were significantly higher than those of the treated group. The enzyme activities of GOT, GPT and ALP were significantly increased. The microscopic examination of liver showed normal conservative lobular architecture and necrotic areas. In chronic study, the synthetic alkaloids administered i.p at daily doses 4.2 mg/kg of atropine and 1.6 mg/kg of scopolamine, did not produce death, However the diarrhoea and hypoactivity were observed. The relative weight of liver was significantly less than that of the control group. The haematological analysis revealed a significant decrease in RBC, HCT, HBG and WBC and we observed manifold centrolobular necrotic areas, and blood congestion and dilated central veins in treated groups.

Acute and sub-acute toxicity studies of Passiflora nepalensis in rats

This study was designed to elucidate the toxicity of widely used plant Passiflora nepalensis Walp. (Passifloraceae) in rats. We have taken methanolic extract isolated from whole plant of Passiflora nepalensis and studied their toxic effects. Acute, sub-acute toxicities and LD50 values were determined in experimental rats. The external appearance of the dead animals, the appearance of the viscera, heart, lungs, stomach, intestine, liver, kidney, spleen and brain were carefully noted and any apparent and significant features or differences from the normal were recorded after acute treatment with methanolic extract of whole plant of Passiflora nepalensis (MPN). Following the sub-acute administration of MPN for fourteen days, the vital organ such as liver, kidney and heart were carefully evaluated by histopathological and biochemical studies and any apparent and significant changes or differences from the normal were recorded. Pathologically, neither gross abnormalities nor histopathological changes were observed. Oral administration of MPN at the doses of 40, 80, 160 and 320 mg/kg body wt for fourteen consecutive days to male and female rats did not induce any short term toxicity. Collectively, these data demonstrate that the methanolic extract of Passiflora nepalensis have a high margin of safety.

Rat Brain Biogenic Amine Levels during Acute and Subacute Phosphamidon Treatment with Reference to Behavioral Tolerance

Organophosphate (OP) pesticides exert their toxic effects by cholinesterase inhibition and the consequent prolongation of the undesirable effects of accumulation of acetylcholine. However, sustained cholinesterase inhibition through sustained sub-acute administration of organophosphates leads to disappearance of the initial signs of toxicity, termed behavioral tolerance. The present study examines if the levels of amine neurotransmitter substances in rat brain regions are altered during acute and sub-acute treatment with an organophosphate pesticide. Phosphamidon under different time intervals was used with due reference to behavioral tolerance. Acute (1 day) and sub-acute (1 day, 7 days, 15 days) doses of phosphamidon were administered by oral intubation. Different brain regions were isolated at specific time intervals. The levels of epinephrine (EP), nor-epinephrine (NE), dopamine (DA) and serotonin (5-HT) and the activity levels of the enzyme monoamine oxidase (MAO) were determined at the specified time intervals under both acute and sub-acute dose treatments. The amine levels showed differential variations in different brain regions during acute and sub-acute treatments, implying regional changes in catecholamine and serotonin levels during the development of OP-induced behavioral tolerance. Monoamine oxidase activity was in general inhibited in all the brain regions under both acute and sub-acute treatments. The results indicate the involvement of noncholinergic mechanisms during behavioral tolerance. Key words : Behavioral tolerance, Biogenic amines, Phosphamidon, Rat brain

Modulation of leukotriene D 4 attenuates the development of seizures in mice

The present study has been designed to pharmacologically investigate the effect of Montelukast sodium, a leukotriene D 4 receptor antagonist, and 1,2,3,4, tetrahydroisoquinoline, a leukotriene D 4 synthetic pathway inhibitor, on the pathophysiological progression of seizures using mouse models of kindled epilepsy and status epilepticus induced spontaneous recurrent seizures. Pentylenetetrazole (40 mg kg −1) (PTZ) administration every second day for a period of 15 d was used to elicit chemically induced kindled seizure activity in mice. In a separate set of groups, fifty consecutive electroshocks were delivered to mice using corneal electrodes with continuously increasing intensity with an inter-shock interval of 40 s. Severity of kindled seizures was assessed in terms of a composite kindled seizure severity score (KSSS). Pilocarpine (100 mg kg −1) was injected every twenty minutes until the onset of status epilepticus. A spontaneous recurrent seizure severity score (SRSSS) was recorded as a measure of quantitative assessment of the progressive development of spontaneous recurrent seizures induced after pilocarpine status epilepticus. Sub-acute PTZ administration and electroshock induced the development of severe form of kindled seizures in mice. Severity of kindled seizures was assessed in terms of a composite kindled seizure severity score. Further, pharmacological status epilepticus elicited a progressive evolution of spontaneous recurrent seizures in the animals. However, Montelukast sodium, a leukotriene D 4 receptor antagonist, as well as 1,2,3,4, tetrahydroisoquinoline, a leukotriene D 4 synthetic pathway inhibitor, markedly and dose dependently suppressed the development of kindled seizures as well as pilocarpine induced spontaneous recurrent seizures. Therefore, leukotriene D 4 may be implicated in the pathogenesis of seizures.

Acute and subacute toxicity of chloroform and hexaneextracts of root of Xanthium strumarium

Xanthium strumarium Linn. is used in Indian and Chinese complementary medicines for its various therapeutic properties. There are reports stating that the plant is toxic and lethal to cattle and swine. We have studied the oral toxicity of chloroform and hexane soluble fractions of root extract of X. strumarium in Wistar rats. The toxicity determination was done according to the Organization for Economic Cooperation and Development guidelines. In the acute study with a single oral dose of extracts at 5 g/kg body weight, there was no mortality or signs of toxicity. In the subacute study, none of the blood elements were significantly affected in male and female rats after 28 days. Acute and subacute administration of chloroform and hexane soluble fractions of root did not produce any adverse reactions or any significant changes in organ weight, mortality, and the body weights as compared to untreated controls. Administration of these extracts did not alter the hepatic and renal function, and did not produce any change in the hematological parameters. The study indicates that acute and subacute administration of X. strumarium did not produce any toxicity to rats as evident from weight change, mortality, and limited biochemical and histopathological analysis. Hence, the extracts are considered as unclassified and are found to be safe.

Acute and subacute toxicity of Cassia occidentalis L. stem and leaf in Wistar rats

Cassia occidentalis L. (syn. Senna occidentalis; Leguminosae) has been used as natural medicine in rainforests and tropical regions as laxative, analgesic, febrifuge, diuretic, hepatoprotective, vermifuge and colagogo. Herein, we performed a pre-clinical safety evaluation of hydroalcoholic extract of Cassia occidentalis stem and leaf in male and female Wistar rats. In acute toxicity tests, four groups of rats (n=5/group/sex) were orally treated with doses of 0.625, 1.25, 2.5 and 5.0 g/kg and general behavior, adverse effects and mortality were recorded for up to 14 days. In subacute toxicity assays, animals received Cassia occidentalis by gavage at the doses of 0.10, 0.50 or 2.5 g/kg/day (n=10/group/sex) for 30 days and biochemical, hematological and morphological parameters were determined. Cassia occidentalis did not produce any hazardous symptoms or death in the acute toxicity test, showing a LD(50) higher than 5 g/kg. Subacute treatment with Cassia occidentalis failed to change body weight gain, food and water consumption and hematological and biochemical profiles. In addition, no changes in macroscopical and microscopical aspect of organs were observed in the animals. Our results showed that acute or subacute administration of Cassia occidentalis is not toxic in male and female Wistar rats, suggesting a safety use by humans.

Immunoactive Profile of Aqueous Extracts of Desmodium adscendens in Mice

The pharmacological effects of aqueous extracts of Desmodium adscendens on selected immunological parameters were studied. This study deals with the evaluation of impact on the acute, subacute, and subchronic oral administrations of aqueous extracts of D. adscendens on both cellular and humoral immunity. The flow cytometry technique was used to determine the number of granulocytes, monocytes, and total lymphocytes, particularly TCD4+, TCD8+ and NK cells. The enzyme-linked immunosorbent assay method was used to measure the concentration of immunoglobulins (A, E, and G). The results clearly demonstrated that the aqueous extracts of D. adscendens affect the immune system. It decreased the counts of the total lymphocytes, particularly TCD4+, TCD8+, and NK cells, decreased the humoral immunity, and increased the monocyte counts. Aqueous extracts of D. adscendens have potentially strong effects on both cellular and humoral immunity, thus explaining its extensive traditional uses.

On the Cover

Genus Aesculus includes about 16 species of primarily temperate trees and shrubs worldwide, of which six are native to North America. 1 Farrar J.L. Trees of the Northern United States and Canada. in: Iowa State University Press, Ames, IA1995: 156-159 Google Scholar , 2 Brown C.L. Kirkman L.K. Trees of Georgia and Adjacent States. in: Timber Press, Portland, Oregon1990: 194-199 Google Scholar , 3 Sibley D.A. The Sibley Guide to Trees. in: Alfred A. Knopf, New York2009: 326-331 Google Scholar Horse chestnut, Aesculus hippocastanum, is native to Greece and Albania, but is widely cultivated throughout Europe, Canada, and northeastern United States. 1 Farrar J.L. Trees of the Northern United States and Canada. in: Iowa State University Press, Ames, IA1995: 156-159 Google Scholar , 3 Sibley D.A. The Sibley Guide to Trees. in: Alfred A. Knopf, New York2009: 326-331 Google Scholar , 4 Polunin O. Flowers of Europe: A Field Guide. in: Oxford University Press, London1969: 234-235 Google Scholar Ohio or fetid buckeye, A. glabra, is found throughout the eastern states and up into southern Ontario; and red buckeye, A. pavia, is found throughout the southeastern states. 1 Farrar J.L. Trees of the Northern United States and Canada. in: Iowa State University Press, Ames, IA1995: 156-159 Google Scholar , 2 Brown C.L. Kirkman L.K. Trees of Georgia and Adjacent States. in: Timber Press, Portland, Oregon1990: 194-199 Google Scholar , 5 Phillips R. Trees of North America and Europe. in: Random House, New York1978: 79-82 Google Scholar Horse chestnut and buckeye are planted frequently as ornamentals due the large showy flowers. The large seeds are not edible, but have been used to feed livestock; they are 5% oil, and the starch has been used for stiffening. 4 Polunin O. Flowers of Europe: A Field Guide. in: Oxford University Press, London1969: 234-235 Google Scholar The wood is used for turnery, utensil and bush handles. 1 Farrar J.L. Trees of the Northern United States and Canada. in: Iowa State University Press, Ames, IA1995: 156-159 Google Scholar , 4 Polunin O. Flowers of Europe: A Field Guide. in: Oxford University Press, London1969: 234-235 Google Scholar Escin, a mixture of triterpene saponins extracted from A. hippocastanum seeds, protects against oxidative stress effects, has antitumor activity against hepatocellular carcinoma, and has anti-inflammatory effects synergistic with glucocorticoids. 6 Küçükkurt I. Ince S. Keleş H. et al. Benefical effects of Aesulus hippocastanum L. seed extract on the body's own antioxidant defense system on subacute administration. J Ethnopharmacol. 2010; 129: 18-22 Crossref PubMed Scopus (49) Google Scholar , 7 Zhou X.Y. Fu F.H. Li Z. Dong Q.J. He J. Wang C.H. Escin, a natural mixture of triterpene saponins, exhibits antitumor activity against hepatocellular carcinoma. Planta Med. 2009; 75: 1580-1585 Crossref PubMed Scopus (44) Google Scholar , 8 Xin W. Zhang L. Sun F. et al. Escin exerts synergistic anti-inflammatory effects with low doses of glucocorticoids in vivo and in vitro. Phytomedicine. 2010; (Epub) Google Scholar

Biocompatible gellan gum‐reduced gold nanoparticles: cellular uptake and subacute oral toxicity studies

Currently gold nanoparticles are being explored for drug delivery and other biomedical applications; therefore it is necessary to study the fate of such nanoparticles inside the body. The objective of the present study was to investigate the cellular uptake and toxicity of the gold nanoparticles synthesized using a microbial polysaccharide, gellan gum, as a capping and reducing agent. The cellular uptake of gold nanoparticles was studied on mouse embryonic fibroblast cells, NIH3T3 and human glioma cell line, LN-229. The cellular uptake study indicated that the gellan gum-reduced gold nanoparticles were located in cancer cells (LN-229) while no uptake was observed in normal mouse embryonic fibroblast cells (NIH3T3). The toxicity of the gold nanoparticles was evaluated by carrying out subacute 28 day oral toxicity studies in rats. Subacute administration of gum-reduced gold nanoparticles to the rats did not show any hematological or biochemical abnormalities. The weight and normal architecture of various organs did not change compared with control. The current findings, while establishing the specific uptake of nanoparticles into cancerous cells, also demonstrates that the gellan gum-reduced gold nanoparticles are devoid of toxicity in animals following oral administration.

Effects of subacute administration of protein powder on the histology of rat kidneys

Effects of subacute administration of protein powder on the histology of rat kidneys

The Protective Effect of ENA Actimineral Resource A on CCl4-Induced Liver Injury in Rats

ENA Actimineral Resource A (ENA-A) is alkaline water that is composed of refined edible cuttlefish bone and two different species of seaweed, Phymatolithon calcareum and Lithothamnion corallioides. In the present study, ENA-A was investigated as an antioxidant to protect against CCl(4)-induced oxidative stress and hepatotoxicity in rats. Liver injury was induced by either subacute or chronic CCl(4) administration, and the rats had free access to tap water mixed with 0% (control group) or 10% (v/v) ENA-A for 5 or 8weeks. The results of histological examination and measurement of antioxidant activity showed that the reactive oxygen species production, lipid peroxidation, induction of CYP2E1 were decreased and the antioxidant activity, including glutathione and catalase production, was increased in the ENA-A groups as compared with the control group. On 2-DE gel analysis of the proteomes, 13 differentially expressed proteins were obtained in the ENA-A groups as compared with the control group. Antioxidant proteins, including glutathione S-transferase, kelch-like ECH-associated protein 1, and peroxiredoxin 1, were increased with hepatocyte nuclear factor 3-beta and serum albumin precursor, and kininogen precursor decreased more in the ENA-A groups than compared to the control group. In conclusion, our results suggest that ENA-A does indeed have some protective capabilities against CCl(4)-induced liver injury through its antioxidant function.

Effects of valproate on neurotransmission associated with ryanodine receptors

To clarify the antiepileptic mechanisms of valproate (VPA), we determined the effects of acute and sub-acute administrations of VPA on ryanodine receptor (RyR)-associated hippocampal releases of GABA and glutamate using microdialysis, as well expression of mRNA and protein of RyR subtypes in the rat hippocampus. Acute administration of therapeutic-relevant VPA did not affect the hippocampal extracellular levels of GABA or glutamate, whereas sub-acute administration increased GABA level without affecting that of glutamate. Perfusion with ryanodine increased the hippocampal extracellular level of glutamate (ryanodine concentration range: 1–1000 μM) concentration-dependently; however, that of GABA was increased by 1–100 μM ryanodine concentration-dependently but the stimulatory effects of 1000 μM ryanodine on GABA release was not observed. Both acute and sub-acute administrations of therapeutic-relevant VPA inhibited ryanodine-induced responses of hippocampal extracellular glutamate level without affecting that of GABA. Especially, both acute and sub-acute administrations of VPA prevented the breakdown of GABA release induced by 1000 μM ryanodine. Sub-acute administration of therapeutically-relevant dose VPA weakly increased RyR mRNA expression but we could not detect the changes of RyR protein expression in rat hippocampus. These results suggest that VPA inhibited the neurotransmitter release associated with RyR without affecting the expression of RyR protein. Therefore, the antiepileptic action of VPA seems to be mediated, at least in part, by an increase in basal GABA release and inhibition of RyR-associated glutamate release.

2-Phenylethylamine, a constituent of chocolate and wine, causes mitochondrial complex-I inhibition, generation of hydroxyl radicals and depletion of striatal biogenic amines leading to psycho-motor dysfunctions in Balb/c mice

Behavioral and neurochemical effects of chronic administration of high doses of 2-phenylethylamine (PEA; 25–75 mg/kg, i.p. for up to 7 days) have been investigated in Balb/c mice. Depression and anxiety, as demonstrated respectively by increased floating time in forced swim test, and reduction in number of entries and the time spent in the open arms in an elevated plus maze were observed in these animals. General motor disabilities in terms of akinesia, catalepsy and decreased swimming ability were also observed in these animals. Acute and sub-acute administration of PEA caused significant, dose-dependent depletion of striatal dopamine, and its metabolites levels. PEA caused dose-dependent generation of hydroxyl radicals in vitro in Fenton's reaction in test tubes, in isolated mitochondrial fraction, and in vivo in the striatum of mice. A significant inhibition of NADH-ubiquinone oxidoreductase (complex-I; EC: 1.6.5.3) activity suggests the inhibition in oxidative phosphorylation in the mitochondria resulting in hydroxyl radical generation. Nissl staining and TH immnunohistochemistry in brain sections failed to show any morphological aberrations in dopaminergic neurons or nerve terminals. Long-term over-consumption of PEA containing food items could be a neurological risk factor having significant pathological relevance to disease conditions such as depression or motor dysfunction. However, per-oral administration of higher doses of PEA (75–125 mg/kg; 7 days) failed to cause such overt neurochemical effects in rats, which suggested safe consumption of food items rich in this trace amine by normal population.

Effects of curcumin on pentylenetetrazole-induced anxiety-like behaviors and associated changes in cognition and monoamine levels.

The purpose of the present study was to estimate the protective effects of curcumin against anxiety and memory impairment, which are often comorbid in patients with anxiety disorders who are on standard anxiolytic therapy. The effects of curcumin on brain monoamine levels were also determined. We used the elevated plus maze (EPM), a standard animal model of anxiety, to determine the effects of subacute administration (14 days) of curcumin at doses of 5 and 10 mg/kg (p.o.) against pentylenetetrazole (PTZ; 20 mg/kg, i.p.)-induced anxiety-like behavior, followed by an evaluation of the effects of curcumin on cognitive deficits induced by PTZ using the passive avoidance retention task. Rats were exposed to the passive avoidance learning task before the initiation of treatment, and the effects on memory retention were studied 24 h after the EPM trial. A marked increase in the time spent in the open arms, an index of anxiety, and an increase in the step-down latency, an index of memory retention, were observed in curcumin-treated rats. Curcumin increased the levels of serotonin, norepinephrine, and dopamine in various regions of the rat brain. These results confirm the anxiolytic and memory-retentive effects of curcumin, and alterations in brain monoamine levels may have contributed to the present findings.