Abstract: Objective To observe the pyramidal neurons in the hippocampal CA1 area varying with time after heat stroke in rats. Methods Sprague-Dawley rats were divided into sham group (n=5) and heat stroke group (n=14), and the heat stroke group was divided into 7-day subgroup and 21-day subgroup (n=7 at each group) after heat stroke. Heat stroke group was established model of heat stroke. The brain tissues of rats were observed with Nissl staining to count the living pyramidal neurons in hippocampal CA1 area. Results The number of living pyramidal neurons in hippocampal CA1 area decreased in the heat stroke group (F=11.80, P<0.01), and decreased more in the 21-day subgroup than in the 7-day subgroup (P<0.05). Conclusion Pyramidal neurons in hippocampal CA1 area decrease with time after heat stroke, which may be associated with the learning and memory impairment.

Key words: heat stroke, hippocampus, pyramidal neuron, rats