A behavioral study on learning and memory abilities of pilocarpine-induced temporal lobe epilepsy rats of different injury types

Abstract

Objective To study the neurobehavioral manifestations of pilocarpine-induced temporal lobe epilepsy (TLE) rats in different kinds of learning and memory ability tests at chronic stage. Methods Thirty SD rats were randomized into TLE group (n=20) and control group (n=10). Intraperitoneal injection of lithium-pilocarpine (LIP) was performed in rats of the TLE group, and saline was given to the control group. Six weeks after modeling, rats were investigated in spatial, object, time and space combined episodic memory tests, and received 7.0 T MR imaging for structural images. Results Immediately after LIP treatment, 13 rats in the TLE group exhibited status epilepticus. Six weeks later, 11 of the 13 rats in the TLE group were observed spontaneous seizures. T2 images from MR imaging implied gray matter damage in the hippocampus in the TLE group and intact structure in the control group. The ranges of motion in the spatial memory, object memory and episodic memory in the control group were (90.56±19.9) m/min, (92.58±14.83) m/min and (94.20±30.99) m/min, respectively; those in the TLE group were (95.09±21.51) m/min, (117.10±44.38) m/min and (104.90±35.22) m/min; no significant differences were noted between the two groups (P>0.05). In the control group, more exploration time on novel location in the spatial test, novel object in the object test, familiar location-familiar object and novel location-novel object in the episodic test were showed than that on the other objects, with significant difference (P 0.05). Conclusion All spatial, object and episodic memory are impaired in chronic LIP-TLE rats. Key words: Temporal lobe epilepsy; Lithium-pilocarpine; Spatial memory; Object memory; Episodic memory