Hippocampal-Dependent Spatial Memory in the Water Maze is Preserved in an Experimental Model of Temporal Lobe Epilepsy in Rats

Abstract

Cognitive impairment is a major concern in temporal lobe epilepsy (TLE). While different experimental models have been used to characterize TLE-related cognitive deficits, little is known on whether a particular deficit is more associated with the underlying brain injuries than with the epileptic condition per se. Here, we look at the relationship between the pattern of brain damage and spatial memory deficits in two chronic models of TLE (lithium-pilocarpine, LIP and kainic acid, KA) from two different rat strains (Wistar and Sprague-Dawley) using the Morris water maze and the elevated plus maze in combination with MRI imaging and post-morten neuronal immunostaining. We found fundamental differences between LIP- and KA-treated epileptic rats regarding spatial memory deficits and anxiety. LIP-treated animals from both strains showed significant impairment in the acquisition and retention of spatial memory, and were unable to learn a cued version of the task. In contrast, KA-treated rats were differently affected. Sprague-Dawley KA-treated rats learned less efficiently than Wistar KA-treated animals, which performed similar to control rats in the acquisition and in a probe trial testing for spatial memory. Different anxiety levels and the extension of brain lesions affecting the hippocampus and the amydgala concur with spatial memory deficits observed in epileptic rats. Hence, our results suggest that hippocampal-dependent spatial memory is not necessarily affected in TLE and that comorbidity between spatial deficits and anxiety is more related with the underlying brain lesions than with the epileptic condition per se.

CXCR4 Antagonist AMD3100 Suppresses the Long-Term Abnormal Structural Changes of Newborn Neurons in the Intraventricular Kainic Acid Model of Epilepsy

“…Similar to the descriptions from previous reports, the seizures were characterized by brief tonic-clonic episodes with forelimb automatisms with rearing and falling [28]. On post-SE day 72, spontaneous EEG seizures were frequently observed in rats subjected to kainic acid.…”

Blockade of p75 Neurotrophin Receptor Reverses Irritability and Anxiety-Related Behaviors in a Rat Model of Status Epilepticus

“…However, its mRNA expression was significantly reduced at 2 nd and 3 rd weeks, when compared to the first week of SE induction ( † † † p < 0.001). The mRNA expressions of p75NTR and pro-NGF were normalized to GAPDH and were expressed as mean ± SD, n = 4. which is consistent with previous published reports [50][51][52] that demonstrated SE induction is associated with decreased anxiety in the elevated plusmaze, as evidenced by longer time spent and higher number of entries in arms. Similar to our finding, Detour and colleagues [50] found that in the elevated plus maze, epileptic rats exhibited a significant higher number of entries and the time spent in open arms, suggesting a reduction in the anxiety-related behavior.…”

Reversal Effect of Coriandrum sativum Leaves Extract on Learning and Memory Deficits Induced by Epilepsy in Male Rat

“…Our data showed a reduction of learning acquisition; however it was only a transient reduction in water maze task. One study demonstrated a prominent reduction of memory in Sprague dawley but not Wistar rats (28), which shows strain dependency. Another study revealed that memory impairment is more probably related to lesion comorbidity rather than epilepsy itself (28).…”

“…One study demonstrated a prominent reduction of memory in Sprague dawley but not Wistar rats (28), which shows strain dependency. Another study revealed that memory impairment is more probably related to lesion comorbidity rather than epilepsy itself (28). Retrieval data demonstrated a delayed impairment, one week later, on the time of probable structural lesion.…”