Volume 17 Issue 8 - March 18, 2011 PDF
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Sexual Dimorphism in Stress-Induced Enhancement of Hippocampal CA1 Long-Term Depression during Puberty
Jia-Peng Chen, Chiung-Chun Huang and Kuei-Sen Hsu*
Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan
NCKU Landmark Project《A002》
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Females and males react differently to stress. Our previous studies revealed that acute stress facilitates the occurrence of long-term depression (LTD) in hippocampal CA1 area. However, it remains unknown whether sex differences exist in the effect of stress on LTD. Using an acute unpredictable and inescapable restraint tailshock stress paradigm, we report here that hippocampal slices from stressed male rats expressed larger LTD by low-frequency stimulation (LFS) than controls, whereas such effect was not observed in female rats during puberty. The facilitatory effect of stress on LTD was prevented when animals were submitted to bilateral adrenalectomy. However, no sex differences in the magnitude of LTD induced by direct application of N-methy-D-aspartate or a combination of LFS with the glutamate uptake inhibitor DL-threo-β-benzyloxyaspartate were observed in slices from naive rats. Female rats exhibited significantly higher basal but lower stress-evoked levels of plasma corticosterone than male rats. We also found that stress induces a profound decrease in the glutamate uptake in hippocampal synaptosomal preparations from male but not female rats. Furthermore, hippocampal slices from stressed male but not female rats showed an increase in the induction of LTD by paired-pulse LFS. Importantly, female rats that are masculinized with testosterone at birth respond to stress like male rats do, demonstrating an enhancement of LTD. In contrast, ovariectomized female rats failed to restore the ability of stress to facilitate LTD. These results reveal an obvious sex difference in stress-induced modification of hippocampal synaptic plasticity, which depends on organizational effect of testosterone during early development.
Figure 1. Male rats (left) expressed stress-induced enhancement of LTD in hippocampal CA1 area whereas female rats (right) did not.
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