Farede Filaman Perforasyon Yöntemi ile Oluşturulan Subaraknoid Kanama Modelinde Donepezilin Beyin Hasarına Etkisi

Abstract

Introduction and objective: Spontaneous subarachnoid hemorrhage is a pathology that causes high mortality and morbidity and the most common cause is aneurysms. Even if the patients survive the bleeding moment, mortality and severe morbidities may develop during hospital follow-up. Although increased intracranial pressure is blamed as the cause of brain damage and associated mortality in the hyperacute period, an increase in brain damage is observed in a significant portion of the patients and additional neurological deficits and deaths are observed. It is thought that excessive increase of glutamate, an excitatory neurotransmitter, stimulates N-methyl-D-aspartate (NMDA) receptors, increasing calcium influx into the cell and causing apoptosis. Neurotoxicity (excitotoxicity) caused by excessively increased glutamate is a mechanism that has been shown to be effective in many pathologies (trauma, ischemia, neurodegenerative diseases, etc.) and causes brain damage. It has been shown that the amount of glutamate is increased in the measurements made in the cerebrospinal fluid of patients with subarachnoid hemorrhage, and it is thought that excitotoxicity has an important share in neuron damage in these patients. Agents such as NMDA antagonists and glutamate release blockers have been tried to stop neuronal damage by preventing glutamate excitotoxicity in various pathologies but could not be used due to inadequate results and side effects in clinical studies. Donepezil is not a direct glutamate antagonist but an acetylcholinesterase blocker and its net effect is to increase the amount of acetylcholine. Increased acetylcholine stimulate α7 nicotinic acetylcholine receptors (α7-nAchR), and stimulation of this receptor reduces glutamate excitotoxicity by internalizing glutamate receptors on the cell surface. However, it doesn’t impair glutamate neurotransmission in synapses, so it can be considered that it doesn’t have the negative effects of the agents used for glutamate antagonism. The human side effect profile of donepezil, an agent developed for the treatment of Alzheimer's, is also well known. Donepezil has been tested in animal models for trauma and ischemia alongside Alzheimer's, but there are no studies showing its efficacy in subarachnoid hemorrhage. In our study, the neuroprotective effects of Donepezil on subarachnoid hemorrhage were investigated.

Materials and methods: Five groups of Swiss albino mice were used in the experiments. A total of 32 mice were used, with 7 for each of the sham, control, low-dose donepezil treatment, high-dose donepezil treatment groups and 4 for the naive group used for standardization of TUNEL / MAP-2 staining. A filament perforation model was used to induce subarachnoid hemorrhage in mice. Donepezil administered intraperitoneally at doses of 1.8 mg / kg and 5.6 mg / kg to the treatment groups 2 hours and 24 hours after subarachnoid hemorrhage, and 0.9% saline solution per kg is given to the control and Sham groups at the same volume. Neurological evaluations of all subjects were made at the 2nd hour, 24th hour and 48th hour, and after the 48th hour examination, the mice were sacrificed and perfused with 4% formaldehyde solution, then their brains were placed in formaldehyde solution. The slides prepared from the brains were stained by immunohistochemical methods, and the data obtained by neurological examination and evaluation of the slides compared between the groups. Conclusion: In the subarachnoid hemorrhage model created by filament perforation method in mice, low dose donepezil (1.8 mg/kg /day) reduced apoptosis after subarachnoid hemorrhage and showed a protective effect. This effect was not observed with the administration of high dose donepezil (5.6 mg/kg/day).