Role of glutamate and its receptors in migraine with reference to amitriptyline and transcranial magnetic stimulation therapy.

Glutamate plays an important role in migraine pathogenesis but there is paucity of studies on glutamate in migraine subtypes, effect of treatment on glutamate levels and the changes in glutamate receptors. In this study we report the glutamate levels and changes in glutamate receptors following amitriptyline (AMT) or repetitive Transcranial Magnetic Stimulation (rTMS) therapy. One hundred and fifty migraine patients having more than 4 migraine attacks per month were included. Thirty patients were treated with AMT and 120 with rTMS; 24 patients received 3 sessions, 36 received single session of rTMS and 60 patients received sham stimulation. The severity of headache was assessed by VAS score, Migraine Index (MI) and frequency of headache. Good outcome was defined by 50% improvement in headache frequency; severity and MI. Plasma glutamate level were measured by enzyme linked immunosorbant assay and relative expression of NR2B and mGluR3 receptors by real time polymerase chain reaction. The changes in these parameters before and after treatment were measured and correlated with the clinical parameters. Glutamate levels (P = 0.006) and NR2B receptor expressions (P < 0.001) were significantly higher in migraine patients compared to the controls. Chronic migraine patients had higher glutamate level (P = 0.05). Glutamate and NR2B receptor declined after treatment (P < 0.001). There was a decline in glutamate levels following rTMS (P = 0.03), sham stimulation (P = 0.05) and AMT treatment (P = 0.003). NR2B receptors also declined after rTMS (P = 0.005) and AMT treatment (P = 0.01). It can be concluded that migraine is associated with high plasma glutamate and NR2B receptor which decline following AMT or rTMS therapy.

Memory and Learning Dysfunction Following Copper Toxicity: Biochemical and Immunohistochemical Basis.

The prototype disease of Cu toxicity in human is Wilson disease, and cognitive impairment is the presenting symptom of it. There is no study correlating Cu-induced excitotoxicity, apoptosis, and astrocytic reaction with memory dysfunction. We report excitotoxicity, apoptosis, and astrocytic reaction of the hippocampus and frontal cortex with memory dysfunction in rat model of Cu toxicity. Thirty-six rats were divided into group I (control) and group II (100 mg/kgBwt/day CuSO4 orally). Y-maze was performed for memory and learning at 0, 30, 60, and 90 days. Frontal and hippocampal free Cu concentration, oxidative stress markers [glutathione (GSH), total antioxidant toxicity (TAC), and malondialdehyde (MDA)], and glutamate were measured by atomic absorption spectroscopy, spectrophotometry, and ELISA, respectively. N-methyl-D-aspartate receptors (NMDARs) NR1, NR2A, and NR2B were done by real-time polymerase chain reaction. Immunohistochemistry for caspase-3 and glial fibrillary acidic protein (GFAP) were done and quantified using the ImageJ software. The glutamate level in hippocampus was increased, and NMDAR expression was decreased at 30, 60, and 90 days in group II compared to group I. In the frontal cortex, glutamate was increased at 90 days, but NMDARs were not significantly different in group II compared to group I. Caspase-3 and GFAP expressions were also higher in group II compared to group I, and these changes were more marked in hippocampus than frontal cortex. These changes correlated with respective free tissue Cu, oxidative stress, and Y-maze attention score. Cu toxicity induces apoptosis and astrocytosis of the hippocampus and frontal cortex through direct or glutamate and oxidative stress pathways, and results in impaired memory and learning.

Temporal kinetics of organ damage in copper toxicity: A histopathological correlation in rat model.

Excess of copper is toxic to different organs. We aim to study the histopathological changes of liver, kidney, and brain following oral CuSO4 exposure for different duration and doses in rat model. Fifty-four males Wistar rats (205 ± 10 g) were included and divided into control (group-I) and experimental (group-II and III) arms. An oral dose of 100 and 200 mg/kgBWt/Day CuSO4 was given to group-II and III respectively and group-I received normal saline by gavage. Six rats from each group were sacrificed on days 30, 60 and 90 for biochemical and histopathological examinations. The histopathological changes were graded on 1-5 scores and correlated with respective laboratory parameters. The organ functions were worsened in experimental group with increasing dose and time. Histopathological study revealed edema, hemorrhage, necrosis and fibrosis/gliosis in experimental group. The worst histopathological severity score ranged from 4 to 5(median 5) in liver, 3-5(median 4) in kidney and 4-5(median 5) in brain. The edema and hemorrhage were more marked at 30 days and fibrosis/gliosis at 90 days. In conclusion, high-dose Cu toxicity results in structural damage to liver, kidney, and brain that correlates with organ dysfunction, Cu, GSH, TAC, and MDA concentrations. Liver damage is more severe and occurs earlier than other organs.

Role of Oxidative Stress in the Worsening of Neurologic Wilson Disease Following Chelating Therapy.

Patients with neurologic Wilson disease (NWD) may worsen on treatment, but there is no study evaluating the role of oxidative stress. We report the role of plasma glutathione (GSH), total antioxidant capacity (TAC) and malondialdehyde (MDA) in the worsening of NWD following treatment. Fifty-one treatment-naïve NWD patients were subjected to detailed clinical evaluation. The severity of NWD was noted, and dystonia was measured by Burke-Fahn-Marsden (BFM) score. Their hematological, serum chemistry, ultrasound abdomen and cranial MRI changes were noted. Plasma GSH, TAC and MDA, serum free copper (Cu) and 24-h urinary Cu were measured at admission and at 3 and 6 months after treatment. The patients were considered worsened if there was one or more grade deterioration in severity scale, >10 % deterioration in BFM score or appearance of new neurologic signs. The median age of the patients was 11 (5-37) years, and 12 were females. Following treatment, 25 patients improved, 12 worsened, and 14 had stationary course. The worsened group at 3 months had lower GSH (1.99 ± 0.17 vs. 2.30 ± 0.30 mg/dl; P = 0.004) and TAC (1.59 ± 0.12 vs. 1.82 ± 0.17 mmol Trolox equivalent/L; P = 0.001) and higher MDA (5.24 ± 0.22 vs. 4.34 ± 0.46 nmol/ml; P < 0.001) levels compared to the improved group. These changes were associated with increased serum free Cu (41.81 ± 3.31 vs. 35.62 ± 6.40 µg/dl; P = 0.02) and 24-h urinary Cu (206.42 ± 41.61 vs. 121.99 ± 23.72 µg/24 h; P < 0.001) in the worsened compared to the improved group. All the patients having worsening were on penicillamine. Worsening following chelating treatment in NWD may be due to oxidative stress which is induced by increased serum free Cu. These results may have future therapeutic implication and needs further study.

Spectrum of hypokalaemic periodic paralysis in a tertiary care centre in India.

BACKGROUND: Acute flaccid paralysis is a common neurological emergency with diverse causes and variable outcome. There is a paucity of reports documenting the spectrum of hypokalaemic paralysis in neurological practice. OBJECTIVE: To report the clinical features, aetiology, and outcome of patients with hypokalaemic paralysis in a tertiary care teaching hospital in India. METHODS: Consecutive patients with acute flaccid paralysis with hypokalaemia from 2008 to 2010 were included in the study. Patients with Guillain-Barré syndrome, porphyria, polio and non-polio enterovirus infection and myositis were excluded. Detailed clinical examination, urinalysis, renal function tests, arterial blood gas analysis, thyroid hormones, and electrocardiogram were carried out. Patients received intravenous or oral potassium supplementation and their underlying causes were treated. RESULTS: Thirty patients aged 17-52 years, including three females, were included. Secondary causes of hypokalaemic paralysis were present in 13 patients and included thyrotoxic paralysis in five and renal tubular acidosis (RTA) and Gitelman syndrome in four each. All the patients had quadriparesis and 10 had severe weakness (MRC grade <2). Tendon reflexes were reduced in eight and brisk in four patients. Respiratory paralysis was present in six patients and one needed artificial ventilation. Fifteen patients had severe hypokalaemia (<2 mmol/l), four had acidosis, and six had alkalosis. The secondary group had more severe hypokalaemia and needed longer time to recover. CONCLUSION: 43.3% of patients with hypokalaemic paralysis had a secondary cause for their condition. Patients with severe hypokalaemia with acidosis or alkalosis should be investigated for secondary causes as their management differ.

Imbalance in oxidant/antioxidant system in different brain regions of rat after the infection of Japanese encephalitis virus.

The imbalance in redox equilibrium is associated with several viral diseases however its role in Japanese encephalitis (JE) has not been reported. In the present study, we report the status of oxidant/antioxidant system in different brain regions in rat model of JE. Twelve days old Wistar strain rats were inoculated intracerebrally with a dose of 3x10(6)pfu of JE virus (JEV). The activity of manganese superoxide dismutase (Mn-SOD), catalase (CAT), glutathione peroxidase (GPx) and the levels of reduced glutathione (GSH) and malonaldialdehyde (MDA) were estimated in corpus striatum, frontal cortex, thalamus and midbrain on 0, 10 and 20 days post-inoculation (dpi). A significant increase in MDA levels in striatum (p<0.01), cortex (p<0.01), thalamus (p<0.01) and midbrain (p<0.01) was observed in JEV infected rats on 10 and 20dpi compared to controls. The activity of CAT, GPx and the levels of GSH were significantly decreased in all the brain regions studied on 10 and 20dpi compared to controls. However, the activity of Mn-SOD in striatum (p<0.01), cortex (p<0.05), thalamus (p<0.01) and midbrain (p<0.01) were significantly increased on 10 and 20dpi in JEV infected rats compared to controls. The activity of Mn-SOD and MDA levels were significantly increased whereas the activity of CAT, GPx and GSH levels were significantly decreased in all the brain regions studied as the disease progressed from 0 to 20dpi. The maximum alteration in oxidant/antioxidant balance was observed in thalamus and midbrain. The results of the present study demonstrate that antioxidant defense mechanism is impaired after the infection of JE virus suggesting its critical role in cellular injury in brain regions. The findings could be beneficial to understand the role of oxidative stress in the pathogenesis of JE and therapeutic interventions.

Some observations on the tropism of Japanese encephalitis virus in rat brain.

The clinical picture of viral encephalitis is determined by the affinity and persistence of the virus to different brain regions. Therefore, the present study was aimed to investigate the neuropathological changes following Japanese encephalitis virus (JEV) infection in rat at different time points. Twelve days old Wistar rats were infected by intracerebral inoculation of JEV. Presence of JEV antigen was detected in thalamus, striatum, cortex and mid brain on 3, 6, 10 and 20 days post inoculation (d.p.i.). Histopathological changes were also studied in different brain regions at different time points. The highest expression of JEV antigen was found on 6 dpi in all the brain regions studied. JEV antigen was maximum in thalamus on 6 d.p.i. and mid brain on 10 d.p.i. JEV antigen, however, was almost undetectable on 20 d.p.i. in all the regions. The classical pathological changes such as cellular infiltration, perivascular cuffing, meningeal disruption, neuronal damage, neuronal shrinkage, and plaque formation were observed up to 10 d.p.i. The present study reveals high affinity of JEV to thalamus, brainstem and striatum. Rat model of JEV infection may serve as a useful model for studying mechanism of cell injury and recovery in JE.