Targeting the endocannabinoid system in the amygdala kindling model of temporal lobe epilepsy in mice.

The endocannabinoid system can be considered as a putative target to affect ictogenesis as well as the generation of a hyperexcitable epileptic network. Therefore, we evaluated the effect of a CB1 receptor agonist (WIN55.212-2) and of an inhibitor of the enzymatic degradation of the endocannabinoid anandamide (fatty acid hydrolase inhibitor URB597) in the amygdala kindling model of temporal lobe epilepsy. Only minor effects on seizure thresholds and seizure parameters without a clear dose-dependency were observed in fully kindled mice. When evaluating the impact on kindling acquisition, WIN55.212-2 significantly delayed the progression of seizure severity. In contrast, URB597 did not affect the development of seizures in the kindling paradigm. Analysis of cell proliferation and neurogenesis during the kindling process revealed that URB597 significantly reduced the number of newborn neurons. These data give first evidence that CB1-receptor activation might render a disease-modifying approach. Future studies are necessary that further analyze the role of CB1 receptors and to confirm the efficacy of CB1-receptor agonists in other models of chronic epilepsy.

The erythropoietin-derived peptide mimetic pHBSP affects cellular and cognitive consequences in a rat post-status epilepticus model.

PURPOSE: The selection of a minimal active sequence of erythropoietin allowed the design of peptide mimetics that exert beneficial effects in the central nervous system but lack an erythropoietic effect. Erythropoietin has been suggested as a promising therapeutic and prophylactic for epilepsies based on its neuroprotective, neuroregenerative, and antiinflammatory potency. Therefore, it is of particular interest to evaluate whether the nonerythropoietic erythropoietin-derived peptide pHBSP can affect epileptogenesis. METHODS: In a post-status epilepticus model in rats, we determined the effects of pHBSP and of recombinant human erythropoietin with short-term administration following status epilepticus. KEY FINDINGS: Both pHBSP and erythropoietin further enhanced the status epilepticus-associated increase in hippocampal cell proliferation. Thereby, pHBSP seemed to promote neuronal differentiation and survival resulting in a significant increase in neurogenesis. Neither pHBSP nor erythropoietin affected the number of animals exhibiting spontaneous recurrent seizures as well as the seizure frequency in the chronic phase. In the Morris water maze, pHBSP attenuated cognitive deficits in epileptic animals. SIGNIFICANCE: In conclusion, the helix B-derived erythropoietin peptide pHBSP can modulate the cellular and cognitive consequences of a status epilepticus. The impact of pHBSP on spatial learning might indicate that the peptide allows beneficial effects on epileptogenesis-associated cognitive deficits. However, it needs to be considered that learning deficits were not abolished by pHBSP and that the effects were not observed consistently until the end of the study. Therefore, adjustment of timing, duration, and dose of peptide administration might be necessary to further evaluate the efficacy of pHBSP.

The CNTF-derived peptide mimetic Cintrofin attenuates spatial-learning deficits in a rat post-status epilepticus model.

Ciliary neurotrophic growth factor is considered a potential therapeutic agent for central nervous system diseases. We report first in vivo data of the ciliary neurotrophic growth factor peptide mimetic Cintrofin in a rat post-status epilepticus model. Cintrofin prevented long-term alterations in the number of doublecortin-positive neuronal progenitor cells and attenuated the persistence of basal dendrites. In contrast, Cintrofin did neither affect acute status epilepticus-associated alterations in hippocampal cell proliferation and neurogenesis nor reveal any relevant effect on seizure activity. Whereas status epilepticus caused a significant disturbance in spatial learning in reversed peptide-treated rats, the performance of Cintrofin-treated rats did not differ from controls. The study confirms that Cintrofin comprises an active sequence mimicking effects of its parent molecule. While the data argue against an antiepileptogenic effect, they indicate a putative disease-modifying impact of Cintrofin.

Impact of the erythropoietin-derived peptide mimetic Epotris on the histopathological consequences of status epilepticus.

The design of peptide mimetics offers interesting opportunities to selectively include beneficial and exclude undesirable effects of a parent molecule. Epotris represents a novel erythropoietin mimetic, which lacks an erythropoietic activity. The present study evaluates the potential of this peptide to interfere with the histopathological consequences of electrical-induced status epilepticus in rats. The peptide attenuated status epilepticus-associated expansion of the neuronal progenitor cell population in a significant manner. Moreover, Epotris affected the number of persistent basal dendrites exhibited by neuronal progenitor cells. In contrast, hippocampal cell loss remained unaffected by administration of this peptide mimetic. Status epilepticus resulted in obvious microglial activation in different brain regions involved in seizure generation and spread. Epotris diminished the microglial response caused by prolonged seizure activity in the thalamus but not in other brain regions. The study renders support that the Epotris' sequences from binding site 2 in helix C of Epo play a role in receptor interaction and cytokine function. In addition, the data demonstrate that Epotris can exert limited in vivo effects on the cellular consequences of prolonged seizure activity. When considering further testing it should be taken in mind that Epotris administration only attenuated selected cellular consequences of status epilepticus and did not completely prevent cellular alterations.