Thakur Gurjeet Singh

Involvement of CCR-2 chemokine receptor activation in ischemic preconditioning and postconditioning of brain in mice

The present study has been designed to investigate the potential role of CCR-2 chemokine receptor in ischemic preconditioning as well as postconditioning induced reversal of ischemia-reperfusion injury in mouse brain. Bilateral carotid artery occlusion of 17 min followed by reperfusion for 24h was employed in present study to produce ischemia and reperfusion induced cerebral injury in mice. Cerebral infarct size was measured using triphenyltetrazolium chloride staining. Memory was evaluated using elevated plus-maze test and Morris water maze test. Rota rod test was employed to assess motor incoordination. Bilateral carotid artery occlusion followed by reperfusion produced cerebral infarction and impaired memory and motor co-ordination. Three preceding episodes of bilateral carotid artery occlusion for 1 min and reperfusion of 1 min were employed to elicit ischemic preconditioning of brain, while three episodes of bilateral carotid artery occlusion for 10s and reperfusion of 10s immediately after the completion of were employed to elicit ischemic postconditioning of brain. Both prior ischemic preconditioning as well as ischemic postconditioning immediately after global cerebral ischemia prevented markedly ischemia-reperfusion-induced cerebral injury as measured in terms of infarct size, loss of memory and motor coordination. RS 102895, a selective CCR-2 chemokine receptor antagonist, attenuated the neuroprotective effect of both the ischemic preconditioning as well as postconditioning. It is concluded that the neuroprotective effect of both ischemic preconditioning as well as ischemic postconditioning may involve the activation of CCR-2 chemokine receptors.

Pharmacological inhibition of inducible nitric oxide synthase attenuates the development of seizures in mice

The present study has been designed to pharmacologically expound the significance of inducible nitric oxide synthase in the pathophysiological progression of seizures using mouse models of chemically induced kindled epilepsy and status epilepticus induced spontaneous recurrent seizures. Pentylenetetrazole (40 mg kg(-1)) (PTZ) administration every second day for a period of 15 days was used to elicit kindled seizure activity in mice. Severity of kindled seizures was assessed in terms of a composite kindled seizure severity score (KSSS). Pilocarpine (100 mg kg(-1)) was injected every 20 min 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 induced the development of severe form of kindled seizures in mice. Further, pharmacological status epilepticus elicited a progressive evolution of spontaneous recurrent seizures in the animals. However, treatment of aminoguanidine, a relatively selective inhibitor of inducible nitric oxide synthase, markedly and dose dependently suppressed the development of both PTZ induced kindled seizures as well as pilocarpine induced spontaneous recurrent seizures. Therefore inducible nitric oxide synthase may be implicated in the development of seizures.

Modulation of leukotriene D4 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 40s. 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.

Pharmacological modulation of geranylgeranyltransferase and farnesyltransferase attenuates opioid withdrawal in vivo and in vitro.

Geranylgeranyltransferase and farnesyltransferase I, are noted to mediate a number of signal transduction cascades which are known to be involved in the causation of opioid withdrawal syndrome. GGTI-2133 and FTI-276 are selective modulators of geranylgeranyltransferase and farnesyltransferase subtype 1 respectively. Therefore, the present study investigated the effect of GGTI-2133 and FTI-276 on propagation of morphine dependence and resultant withdrawal signs in vivo, in sub-chronic morphine mouse model, and in vitro, in isolated rat ileum. Morphine was administered twice daily for 5 days following which a single day 6 injection of naloxone (8 mg/kg, i.p.) precipitated opioid withdrawal syndrome in mice. Withdrawal syndrome was quantitatively assessed in terms of withdrawal severity score and the frequency of jumping, rearing, fore paw licking & circling. Naloxone induced contraction in morphine withdrawn isolated rat ileum was employed as an in vitro model of opioid withdrawal syndrome. An isobolographic study design was employed to assess a potential synergistic activity between GGTI-2133 and FTI-276. GGTI-2133 and FTI-276 dose dependently attenuated naloxone induced morphine withdrawal syndrome both in vivo and in vitro. GGTI-2133 was also observed to exert a synergistic interaction with FTI-276. It is concluded that GGTI-2133 and FTI-276 attenuate the propagation of morphine dependence and reduce withdrawal signs possibly by a geranylgeranyl transferase; farnesyltransferase activation pathway linked mechanisms potentially in an interdependent manner.

Selenium induced anticonvulsant effect: A potential role of prostaglandin E1 receptor activation linked mechanism

PROJECT Selenium deficiency has been associated with enhanced propensity of seizures in man and laboratory animals. Therefore, the present study has been designed to investigate the anti-convulsant effect of sodium selenite and seleno-dl-methionine on pentylenetetrazole induced seizures in mice and the role of prostaglandin receptor activation in the proposed anticonvulsant effect of sodium selenite. PROCEDURE Sodium selenite (1, 3 and 10 mg kg(-1), i.p.) and seleno-dl-methionine (0.3, 1 and 3 mg kg(-1), i.p.) was used to evaluate the potential effect on pentylenetetrazole induced seizures in mice. Pentylenetetrazole induced seizures were assessed in terms of onset time of straubs tail phenomenon, jerky movements of the whole body and convulsions. Additionally, an isobolographic study design was used to examine the interaction between sodium selenite and celecoxib (a cyclooxygenase-2 inhibitor). Sodium selenite and seleno-dl-methionine significantly attenuated pentylenetetrazole induced seizures in mice. RESULTS Prior administration of misoprostol (a selective agonist of prostaglandin E(1) receptors) markedly attenuated the anticonvulsant effect of sodium selenite as well as seleno-dl-methionine in mice. However, the administration of misoprostol per se did not produce any behavioral changes. Further, sodium selenite was observed to exert a synergistic interaction with celecoxib. CONCLUSIONS Selenium induced reduction in seizure like behavior might be ascribed to the activation of a prostaglandin E(1) receptor activation linked mechanism. It is further proposed that sodium selenite exerts a synergistic anti-convulsant effect with celecoxib indicating the therapeutic usefulness of combining the two agents to treat epilepsy.

SU-6656, a Selective Src Kinase Inhibitor, Attenuates Mecamylamine-Precipitated Nicotine Withdrawal Syndrome in Mice

INTRODUCTION Src kinase is reported to regulate neuronal nicotinic acetylcholine receptor activity, which is among the principal receptor systems acted upon by nicotine. Src kinase is documented to mediate the pathogenesis of substance dependence. Therefore, the present study has been designed to investigate the effect of SU-6656, selective src kinase inhibitor, on the development of nicotine dependence in a mouse model of mecamylamine-induced nicotine withdrawal syndrome. METHODS Our experimental protocol consisted of administration of nicotine (2.5 mg/kg, subcutaneously), 4 times daily for 7 days. In order to precipitate nicotine withdrawal, mice were given 1 injection of mecamylamine (3 mg/kg, intraperitoneally), 1 hr after the last nicotine injection on the test day (Day 8). Behavioral observations were made for a period of 30 min immediately after mecamylamine treatment. Withdrawal syndrome was quantitated in terms of a composite withdrawal severity score (WSS), and withdrawal syndrome-related anxiety was assessed by elevated plus maze test results. RESULTS SU-6656 markedly and dose dependently (p < .01) attenuated mecamylamine-induced experimental nicotine withdrawal syndrome in mice measured in terms of WSS and anxiety score. CONCLUSIONS Thus, it is suggested that src kinase is involved in the development of nicotine dependence-induced precipitation of its withdrawal syndrome and thus may serve as a viable pharmacological target to tackle the problem of nicotine addiction.

Involvement of src-kinase activation in ischemic preconditioning induced protection of mouse brain.

AIMS To investigate the role of src-kinase in ischemic preconditioning induced reversal of ischemia and reperfusion induced cerebral injury in mice. MAIN METHODS Bilateral carotid artery occlusion of 17min followed by reperfusion for 24h was employed to produce ischemia and reperfusion induced cerebral injury in mice. Cerebral infarct size was measured using triphenyltetrazolium chloride staining using both by volume and by weight methods differently. Memory was evaluated using elevated plus maze test. Rota rod test was employed to assess motor incoordination. KEY FINDINGS Bilateral carotid artery occlusion followed by reperfusion produced cerebral infarction and impaired memory and motor co-ordination. Three preceding episodes of bilateral carotid artery occlusion for 1min and reperfusion of 1min (ischemic preconditioning) prevented markedly ischemia-reperfusion-induced cerebral injury measured in terms of infarct size (38.5±1.3% and 38.5±2.9% mean infarct of control animals was reduced to 24.3±1.2% and 23.5±1.8% of the preconditioning groups respectively), loss of memory (72.2±3.6 mean transfer latency time of control animals was reduced to 25.6±5.2 of the preconditioning group respectively) and motor coordination (78.3±17.6s mean falling down latency time of control animals was increased to a mean value of 180.9±6.5s of the preconditioning groups respectively). SU6656 (2mg/kg, ip) and PP1 (0.1mg/kg, ip), highly selective src-kinase inhibitors, attenuated this neuroprotective effect of ischemic preconditioning. SIGNIFICANCE Therefore, neuroprotective effect of ischemic preconditioning may be due to src-kinase linked mechanism.

Amisulpride-Induced Seizurogenic Effect: A Potential Role of Opioid Receptor-Linked Transduction Systems

Abstract:  This study was designed to investigate the role of opioid receptors, gamma‐aminobutyric acid (GABA) receptors, mast cells and histamine receptors (H1 subtype) in the seizurogenic effect of amisulpride on mice. A single injection of amisulpride (180 mg/kg) was employed to evaluate the seizurogenicity of the drug in mice. Seizures were assessed in terms of a composite seizure severity score (SSS), time of the onset of straub‐like tail, onset of jerky movements of whole body, convulsions and death. Amisulpride administration (180 mg/kg) induced a significant pro‐convulsant effect in mice as measured in terms of the SSS (21.12 ± 2.71) and a significant decrease in the time latency of the onset of straub‐like tail (132.45 ± 12.31), jerky movements of whole body (153.28 ± 14.12), convulsions (184.97 ± 13.11) and death (100%). Moreover, prior administration of naloxone, cetrizine, sodium cromoglycate and gabapentin, respectively, attenuated this seizurogenic activity that amisulpride exerted on mice (p < 0.05). Therefore, it may be suggested that amisulpride exerts a seizurogenic effect on mice possibly via an opioid receptor activation‐dependent release of histamine from the mast cells and a simultaneous inhibition of GABA release.

Involvement of cyclic adenosine diphosphoribose receptor activation in ischemic preconditioning induced protection in mouse brain

The present study has been designed to expound the significance of cyclic adenosine diphosphoribose receptor activation in ischemic preconditioning induced reversal of ischemia and reperfusion induced cerebral injury in mice. Bilateral carotid artery occlusion of 17 min followed by reperfusion for 24 h was employed in present study to produce ischemia and reperfusion induced cerebral injury in mice. Cerebral infarct size was measured using triphenyltetrazolium chloride staining. Memory was evaluated using Morris water-maze test. Rota-rod test was employed to assess motor incoordination. Bilateral carotid artery occlusion followed by reperfusion produced cerebral infarction and impaired memory and motor co-ordination. Three preceding episodes of bilateral carotid artery occlusion for 1 min and reperfusion of 1 min (ischemic preconditioning) prevented markedly ischemia-reperfusion-induced cerebral injury measured in terms of infarct size, loss of memory and motor coordination. 8-Bromo-cyclic adenosine diphosphate ribose (2 mg/kg, ip), an antagonist of cyclic ADP-ribose receptor, attenuated the neuroprotective effect of ischemic preconditioning. It is concluded that neuroprotective effect of ischemic preconditioning may be due to the adenosine diphosphoribose receptor activation.

Modulation of muscarinic system with serotonin-norepinephrine reuptake inhibitor antidepressant attenuates depression in mice.

Objective: Several studies suggest that muscarinic receptor antagonist scopolamine is a rapidly acting antidepressant for the treatment-resistant depression. Therefore, this study was carried out to investigate the possibility of synergistic potential of scopolamine with antidepressants for the treatment of depression without memory impairment in mice. Materials and Methods: Antidepressants such as citalopram, duloxetine, fluvoxamine, and venlafaxine at their median effective dose that is 12.5, 42.8, 17.5, 15.7 mg/kg p.o., respectively, were evaluated in combination with scopolamine 0.2 mg/kg intraperitoneally for the synergistic potential for ameliorating depression in Swiss albino mice. A battery of tests including forced swim test (FST) and tail suspension test (TST) were performed in all the groups comprising vehicle control, scopolamine, antidepressants per se, and the combinations of antidepressants with scopolamine. This was followed by the locomotor activity and memory tests. Results: Behavioral studies indicated that only antidepressant venlafaxine with scopolamine resulted in 95.5% and 93.6% reduction in immobility time compared to the vehicle control in FST and TST, respectively. This is significant (P < 0.0001) synergistic hyper-additive antidepressive-like effect compared to scopolamine per se and venlafaxine per se treatment effects in antidepressant paradigms. All the data were evaluated using the one-way analysis of variance followed by individual comparisons using Tukeys post-hoc test. Control open field studies demonstrated no significant increase in general locomotion after co-administration of the compounds. Step down avoidance paradigm confirmed that scopolamine at the selected dose has no cognition deficit in any mice. Conclusions: The dose of scopolamine selected for synergistic potential has no detrimental effect on memory. The present results suggest the concoction of scopolamine with venlafaxine for enhanced synergistic antidepressive effects with the reduction of dose.