Pilocarpine-induced seizures produce alterations on choline acetyltransferase and acetylcholinesterase activities and deficit memory in rats

Abstract

In the present study, we investigated the effect of seizures on rat performance in the Morris water maze task, as well as on choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) activities in rat hippocampus. Wistar rats were treated with 0.9% saline (i.p., control group) and pilocarpine (400 mg/kg, i.p., pilocarpine group). After the treatments all groups were observed for 1 h. The changes on reference and working spatial memory caused by pilocarpine administration were observed in seized rats. The ChAT and AChE activities were measured using spectrophotometric methods and the results compared to values obtained from saline animals. Its activities were also determined after behavioral task. Results showed that seizures alter reference memory when compared to saline-treated animals. In the working memory task, we observed a significant day's effect with significant differences between control and pilocarpine-induced seizures. In pilocarpine group, it was observed a significant decreased in ChAT and AChE activities, when compared to control group. Our findings suggest that seizures caused cognitive dysfunction and a decrease of ChAT and AChE activities that might be related, at least in part, to the neurological problems presented by seizures induced by pilocarpine.

Fig. 1

Numbers of crossings and rearings in the open field task after pilocarpine-induced seizures. Male rats (250–280 g, 2-month-old) were treated with a single dose of pilocarpine (400 mg/kg, intraperitoneal, i.p., n = 14) and the control animals with 0.9% saline (i.p., n = 14). Results are mean ± SEM for the number of animals shown inside in parentheses. The differences in experimental groups were determined by the analysis of variance. ^a  P < 0.0001 as compared with control group (ANOVA and Student–Newman–Keuls test)

Fig. 2

Hippocampal choline acetyltransferase (ChAT) activity of adult rats after pilocarpine-induced seizures. Male rats (250–280 g, 2-month-old) were treated with a single dose of pilocarpine (400 mg/kg, intraperitoneal, i.p., n = 6) and the control animals with 0.9% saline (i.p., n = 9). Animals were observed for 1 h and then killed. Results are mean ± SEM for the number of animals shown inside in parentheses. The differences in experimental groups were determined by analysis of variance. ^a  P < 0.05 as compared to control animals (t-Student–Neuman–Keuls test)

Fig. 3

Hippocampal acetylcholinesterase (AChE) activity of adult rats after pilocarpine-induced seizures. Male rats (250–280 g, 2-month-old) were treated with a single dose of pilocarpine (400 mg/kg, intraperitoneal, i.p., n = 6) and the control animals with 0.9% saline (i.p., n = 9). Animals were observed for 1 h and then killed. Results are mean ± SEM for the number of animals shown inside in parentheses. The differences in experimental groups were determined by the analysis of variance. ^a  P < 0.05 as compared to control animals (t-Student–Neuman–Keuls test)

Fig. 4

Western blot analysis of acetylcholinesterase (AChE) in hippocampus of adult rats. Male rats (250–280 g, 2-month-old) were treated with a single dose of pilocarpine (400 mg/kg, intraperitoneal, i.p.) and the control animals with 0.9% saline (i.p.). Animals were observed for 1 h and then killed, showing one representative experiment of n = 5