engleski

Effect of dihydroergotoxine treatment on the passive avoidance task in rats with lesions of the nucleus basalis magnocellularis

The basal forebrain cholinergic systems and their respective terminal fields in the hippocampus and neocortex have a major role in the performance of behavioral tasks related to learning and memory. It has been found that a reduction in cholinergic function in the telencephalon in old age and in dementia of the Alzheimer type is a result of dysfunction in the basal forebrain cholinergic system, particularly in the nucleus basalis. Dihydroergotoxine (DHE) is widely used drug for the treatment of senile cerebral insufficiency. It has been found that mentioned drug has a stimulatory effect on choline acetyl transferase level in the frontal and parietal cortex in rats with lesions of the nucleus basalis magnocellularis (NBM) which bring about a marked cortical cholinergic deficit. Anesthetized male Wistar rats weighing 350-480 g were placed in a stereotaxic apparatus. The coordinates for bilateral electrolytic NBM lesions were: 1.8 mm anterior, 2.5 mm lateral and 8 mm ventral with bregma as 0. The site of the lesion was histologically verified. Fifteen days later the passive avoidance task according to the procedure of Ashford and Jones (1975) was performed. A total of four consecutive daily sessions were given. Used DHE-methanesulfonate doses were: 0.1 mg/kg ; 1 mg/kg ; 10 mg/kg and 50 mg/kg. All the tested doses were given intraperitoneally once per day, one hour before the passive avoidance experiment starting in the course of four behavior testing days. In agreement with the findings reported in the literature, the results of our experiments show that bilateral electrolitic lesions of the NBM impaired the passive avoidance task in the rat. DHE at the dose of 0.1 mg/kg slightly, but not significantly improved the performance of behavioral task during all experimental days. The other tested DHE doses were ineffective in reversing the memory deficits in rats with lesions of the NBM.

dihydroergotoxine; NBM lesions; passive avoidance

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