Reorganization of the morphology of hippocampal neurites and synapses after stress-induced damage correlates with behavioral improvement
Section snippets
Animals and treatments
Male Wistar rats (Gulbenkian Institute of Science, Oeiras, Portugal) were used in this study. All studies were performed in accordance with the European Communities Council Directives of 24 November 1986 (86/609/ECC) and Portuguese Act no. 129/92. Animals were maintained under standard laboratory conditions (light/dark cycle of 12/12 h; temperature at 22°C; free access to food and drink). The following groups (n=10), were formed by random pooling animals from different litters aged two months:
Behavioral performance
Place learning. The overall repeated-measures ANOVA showed that rats in all groups progressively improved their ability to locate the platform over the 12 days of training (F5,225=97.23, P<0.0005). Although the main effect of treatment on the performance of rats in place learning was non-significant, ANOVA revealed a significant group × trial block interaction (F20,225=1.69, P<0.05). Post hoc comparisons showed that STR rats swam significantly longer distances to find the platform than CONT, on
Stress induces neuritic degeneration
The present stochastic analysis of the dendrites of the main hippocampal neuronal populations confirmed previous reports that stress results in CA3 apical dendrite atrophy.40., 68. Specifically, we found that stress induces a widespread reduction of the total dendritic length and a reduction in the distal dendritic branching density as a consequence of the shorter length of the terminal segments. However, in contrast to other reports,63 we did not detect increases in the number of thorny
Acknowledgements
This work was supported by PRAXIS/2/2.1./SAU/1338/95.
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