Neurobehavioral deficit due to ischemic brain damage limited to half of the CA1 sector of the hippocampus

Abstract

It is well known that ischemia causes neuronal necrosis in selectively vulnerable sectors of the hippocampus. Since the hippocampus is involved in spatial navigation, learning, and memory, selective deficits in these areas may arise from ischemic brain damage. The objective of this study was to test whether a minimal ischemic insult, producing selective neuronal necrosis restricted to only a portion of the CA1 pyramidal cells of the hippocampus, could produce a detectable spatial navigation deficit. Male Wistar rats received 9 min of forebrain ischemia induced by carotid clamping and hypotension or sham operation with exposure of the carotid arteries. The rats were allowed to recover and were tested on a simple place task, a place learning-set task, and a pattern discrimination task in swimming pools paradigms. Subsequently, the rats were perfusion-fixed and their entire brains subjected to quantitative histopathologic analysis. Although both ischemic and sham-operated groups learned the simple place task, the learning-set task revealed defects in spatial navigation, reflected as increased errors and latency in the performance of the ischemic rats. In the subsequent pattern discrimination task, the ischemic group was superior to the control group, which perseverated by attempting to use a place strategy to solve the discrimination. Quantitative neuropathology revealed neuronal necrosis in the ischemia group limited to 50% of the CA1 zone of the hippocampus. Extrahippocampal damage consisted of rare cortical neuronal necrosis in 2 of 6 animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of Cortical Serotonin Depletion Induced by 3,4-Methylenedioxymethamphetamine (MDMA) on Behavior, Before and After Additional Cholinergic Blockade

“…However, once they found the platform, they remembered its location and performed as well as controls, as indicated by very low latenc ies in swimming to the hidden platform dur ing the last four to fIve trials on each day. This pattern of performance is similar to that obtained in rats with partial hippocampal CAl damage induced by ischemia (Auer et al 1989). Furthermore, after they had 4 days of experience on this task, MDMA-pretreated rats per formed at control levels (Fig.…”

Tacrolimus (FK506) reduces ischemia-induced hippocampal damage in rats: a 7- and 30-day study

“…Similar results have been observed following hypothermia in the gerbil model (20). Differential sensitivity of CA1 pyramidal cells to ischemia, decreasing from the septal to the temporal pole of the hippocampus, has been demonstrated by others (21,22). Since sensitivity to ischemia may vary within the same brain region, the neuroprotective efficacy of drugs will not necessarily be the same in different parts of the brain, or even within the same brain structure.…”

Hippocampal Tissue Transplants Reverse Lesion-Induced Spatial Memory Deficits in Zebra Finches (Taeniopygia guttata)

“…Lesions of the mHf can disrupt performance on many different behavioral tasks (O'Keefe and Nadel, 1978;Jarrard, 1993;Eichenbaum, 1996), some of which can be ameliorated through the implantation of neural tissue into the hippocampus. For example, cerebral ischemia produces a lesion of the CA1 cell field of the hippocampus, with corresponding learning and memory deficits in the water and radial maze tasks (Auer et al, 1989;Davis and Volpe, 1991). These deficits can be reversed by the transplantation of either fetal hippocampal (H) tissue or fetal CA1 cells into the lesioned hippocampus, but not by the grafting of other cell types (Onifer and Low, 1990;Netto et al, 1993).…”