Effect Of Inescapable Footshock On Expression Of C-Fos-like Immunoreactivity In The Hippocampus Of Rates With Learned Helplessness

Part One Effect of Footshock on Expression of c-Fos-like Immunoreactivity in the Hippocampus CA3 of RatesObjective: To study the effect of foot shock on the expression of c-Fos at CA3 of rats in different time. According to the time pattern of c-Fos expression, we'll further investigate c-Fos expression at the hippocampus of Learned Helplessness rat.Methods: The distribution of c-Fos neurons within CA3 of rats was mapped with the immunohistochemical method after foot shock at the time of 0min, 60min,120min, 240min.Results: The rates that didn't receive foot shock showed little FLI in CA3. The rates that received footshock showed FLI in CA3 in the manner of time dependent. The time course of c-Fos protein induction is that, c-Fos levels generally peaked at 1~2 hours poststress, and by 4 hours were markedly returned to basal levels in CA3.Conclusions:The expression of c-Fos in normal rats were always at the low level. After rats received footshock, FLI at CA3 express in the manner of time dependent. The reason for this phenomenon perhaps is that stress caused the neurotransmitters and biochemistry changes trigger the expression of c-Fos. The experiment proved that c-Fos expression was a excellent functional anatomical mapping tool to identify cells and extended circuitries that becames activatted in response to footshock. This experiment also provides the reason to investigate c-Fos expression in the right time in further study.Part Two Effect of Inescapable Footshock on Expression of c-Fos-like Immunoreactivity in the Hippocampus of Rates with Learned HelplessnessObjective: To estabilish the depression model of Learned Helplessness (LH) in rats, and to study the effect of inescapable foot shock on the expression of c-Fos protein at the hippocampus of LH rats.Methods: We used inescapable footshocks to establish the depression model of LH in rats. The distribution of c-Fos neurons with in the hippocampus of LH rats was mapped with the immunohistochemical method after the inescapable foot shock. Results:The trials that LH rats failed to escape were obviously more than those of normal and non-LH rats. The LH rates showed significantly lower FLI in the hippocampus dentate gyrus after the inescapable footshock ( P<0.05).Conclusions: We established the depression model of LH in rats successfully. Fos protein is considered to be indicative of activities of neurons, the decreased expression of c-Fos protein in dental gyrus of LH possibly indicates alterations of activities of neurons in that area, and it is important for the LH. The reason for the alterations perhaps are the changes of neurotransmitter and neurotrophins in depression model. To further study the reason of the changes, it perhaps will provide a new method for the treatment of depression.