Effects of Transient Cerebral Ischemia in Gerbils on Working Memory Performance in the Delayed Nonmatching to Position Task Using a T-Maze.

Abstract

ABSTRACT-To examine the working memory performance, gerbils were tested in the delayed nonmatching to position task using a T-maze, and the effects of cerebral ischemia on the performance were examined. There were no significant differences between gerbils and rats in the alternation performance without delay and with the in terrun intervals ranging from 10 to 810 sec. These data suggest that this task is useful for assessing working memory in gerbils as well as in rats. Scopolamine (0.1 and 0.2 mg/kg) impaired the working memory performance in both species. Bilateral occlu sion of the common carotid arteries for 5 min severely impaired the choice accuracy in the gerbils 1 to 3 days after the operation. This memory impairment was observed even at the shortest interval. One month after the operation, partial behavioral recov ery was observed in the ischemic gerbils, in spite of a marked loss of the pyramidal cells in the hippocampus CA1 sector. These data indicate that the working memory performance is highly vulnerable to the cerebral ischemia and that the ischemic opera tion transiently but severely impairs the acquisition process of the working memory in gerbils.In recent years, an increasing number of studies have been performed on cerebral ischemia. Mongolian gerbils are well-known to develop reproducible morphologic damage in restricted brain regions by a simpler surgical operation (1), in comparison with the compa rable model using rats ref. 2). In addition, neurochemical and neuropathologi cal consequences of the forebrain ischemia have been well-elucidated in gerbils (1, 3, 4). For these reasons, gerbils have been the most commonly used animal for pharmacological evaluation of the protective effects of drugs against ischemia-induced injury. On the other hand, the behavioral consequences of the ischemic damage in these animals have been studied mainly using passive avoidance tasks (5, 6), which are relatively crude behavioral tests of memory. Brief bilateral occlusion of the common carotid arteries of gerbils can produce a marked loss of pyramidal cells in the hippocampus (1), the area that plays a critical role in working memory processes (7 13). However, little is known about the ischemia-induced changes in working memory in gerbils.In the present study, to evaluate working memory performance in gerbils, we employed

Laser-Doppler Scanning of Local Cerebral Blood Flow and Reserve Capacity and Testing of Motor and Memory Functions in a Chronic 2-Vessel Occlusion Model in Rats

“…Imamura et al 31 describe a partial recovery of learning and working memory of gerbils 4 weeks after a 5-minute BCO. In our experiment the possible negative effects of acetazolamide application on functional test scores have to be considered since significant deteriorations, particularly of forelimb grasping strength, were observed after anesthesia for lCBF measurement and acetazolamide test compared with the scores 1 day before those measurements.…”

Synaptic plasticity in hippocampal CA1 neurons and learning behavior in transient ischemia-loaded gerbils

“…1A). An opaque push-open door (5 cm wide and 4.5 cm high) was attached at the enof forebrain ischemia (16,19,22,32) to study the histology of cell death of hippocampal neurons (3,11,13,24,33) and cognitive impairments, including memory loss (1,2,25). Hippocampal synaptic plasticity is considered to be the cellular basis of learning and memory in the brain (10).…”