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2023, Volume 31, Issue 2

Original Article

Challenges in reproducing the standard lithium Pilocarpine model of temporal lobe epilepsy in wistar rats: troubleshooting strategies

Asha Rao, Tulika Gupta, Ashish Kumar Kakkar, Shammy Chandel, Ashish Jain, Lekha Saha, Ranjana Bharti, Ujjwaljit Kaur, Navneet Singla

Pages : 65-81


Introduction: Animal model of temporal lobe epilepsy (TLE) provide an essential platform to study the disease pathophysiology, and disease modifying management protocols. Lithium –pilocarpine model is one of the most favored model. Many practical difficulties have been encountered while creating this model in this study as well as by other authors. We have systematically attempted to compile all issues and their possible solutions in establishment of Li-Pi model of status epilepticus in wistar rats, to provide a dependable protocol with improved seizure induction rates and lower mortality rates.

Materials and Methods: Young small size male wistar rats (100-150gm) were injected with lithium chloride (LiCl) (127 mg/kg, i.p.), followed by methyl scopolamine (1mg/kg, i.p.) after 18-22 hrs. Precisely after 30 minutes, dose of pilocarpine (i.p.) was administered. Post seizures, diazepam (10 mg/kg) was injected to reduce seizures severity and to increase survival rate and rats were fed glucose (10% of body weight) through oral gavage. Model creation was validated by histological examination of hippocampus. The rats which did not develop seizures, were reutilized for the model generation after drug wash-out period of 48 hours.

Results: Initial model creation was unsuccessfully attempted in 75 rats. Standard described protocol of three incremental doses of pilocarpine (10mg/kg, maximum of 30mg/kg) did not elicit epilepsy. Loading dose of 30mg/kg pilocarpine caused stage 1 epilepsy in 60% rats; second dose of pilocarpine (30mg/kg), caused stage 2 epilepsy in 70% rats. Successful TLE model creation was seen in 33 out of 57 rats, using proposed modification in which 2 incremental doses of pilocarpine (30mg/kg each) were followed by 3 doses of 10mg/kg each; 6 rats died.

Conclusions: The study provides a detailed procedure for lithium pilocarpine model creation and various pitfalls encountered. Modified pilocarpine dosage led to improved seizure induction rates (58%) and lower mortality rates (10%).

Keywords: Epilepsy animal model; Status epilepticus; lithium-pilocarpine; Animal mortality

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