Levetiracetam Inhibits both ryanodine and IP3 receptor activated calcium induced calcium release in hippocampal neurons in culture

Abstract

Epilepsy affects approximately 1% of the population worldwide, and there is a pressing need to develop new anti-epileptic drugs (AEDs) and understand their mechanisms of action. Levetiracetam (LEV) is a novel AED and despite its increasingly widespread clinical use, its mechanism of action is as yet undetermined. Intracellular calcium ([Ca 2+ ] i ) regulation by both inositol 1,4,5-triphosphate receptors (IP3R) and ryanodine receptors (RyR) has been implicated in epileptogenesis and the maintenance of epilepsy. To this end, we investigated the effect of LEV on RyR and IP3R activated calcium-induced calcium release (CICR) in hippocampal neuronal cultures. RyR-mediated CICR was stimulated using the well-characterized RyR activator, caffeine. Caffeine (10mM) caused a significant increase in [Ca 2+ ] i in hippocampal neurons. Treatment with LEV (33μM) prior to stimulation of RyR-mediated CICR by caffeine led to a 61% decrease in the caffeine induced peak height of [Ca 2+ ] i when compared to the control. Bradykinin stimulates IP3R-activated CICR-to test the effect of LEV on IP3R-mediated CICR, bradykinin (1μM) was used to stimulate cells pretreated with LEV (100μM). The data showed that LEV caused a 74% decrease in IP3R-mediated CICR compared to the control. In previous studies we have shown that altered Ca 2+ homeostatic mechanisms play a role in seizure activity and the development of spontaneous recurrent epileptiform discharges (SREDs). Elevations in [Ca 2+ ] i mediated by CICR systems have been associated with neurotoxicity, changes in neuronal plasticity, and the development of AE. Thus, the ability of LEV to modulate the two major CICR systems demonstrates an important molecular effect of this agent on a major second messenger system in neurons.

Development of status epilepticus, sustained calcium elevations and neuronal injury in a rat survival model of lethal paraoxon intoxication

“…We have shown these drugs to target RyR/ IP 3 receptors and also produce an antiepileptogenic response following SE-like injury (Deshpande et al , 2008a; Nagarkatti et al , 2008). As shown in Fig.…”

“…This study will evaluate the effects of POX induced SE on the development of the Ca 2+ plateau and neuronal damage to determine if the POX SE model produces similar effects on these processes as seen with pilocarpine and DFP SE. We will also investigate the contribution of ryanodine receptor (RyR) or inositol trisphosphate receptor (IP 3 R)-dependent regulation of [Ca2+] i towards the maintenance of the Ca2+ plateau utilizing select inhibitors that have been shown to lower elevated Ca 2+ levels following SE (Nagarkatti et al , 2008; Nagarkatti et al , 2010). Being able to reverse the Ca 2+ plateau after survival of POX SE with the Ca 2+ induced Ca 2+ release (CICR) inhibitors could provide new targets for the development of agents to reverse the Ca 2+ plateau and offer a unique insight into the pathophysiology of POX toxicity.…”

Levetiracetam protects hippocampal neurons in culture against hypoxia-induced injury

“…Studies in neuron cultures have focused on efforts to explain the mechanisms of LEV action which have a putative neuroprotective effect. Some studies have confirmed that LEV inhibits ryanodine and IP3 receptors in hippocampal culture [32]. These receptors are responsible for excessive accumulation of Ca 2+ in the cytoplasma of neurons.…”

“…These receptors are responsible for excessive accumulation of Ca 2+ in the cytoplasma of neurons. This is an important stage in the process of cell death [32]. Another experiment found that LEV modulates AMPA receptors in cortical neuronal cultures and leads to impairment of postsynaptic potential in these cells [33].…”

Keppra a magical antiepileptic medication

“…2 It also reduces the release of calcium from intraneuronal stores, which leads to changes in the levels of intraneuronal calcium. 3 LEV also partially inhibits N-type calcium channels, which also leads to changes in the levels of intraneuronal calcium. 4 Additionally, it opposes the activity of the negative allosteric modulators zinc and ß-carbolines on GABA-and glycin-gated currents.…”