Activity-stress induces atrophy of apical dendrites of hippocampal pyramidal neurons in male rats.

Recently, researchers have demonstrated the damaging effect of restraint-stress on hippocampal neurons. The purpose of the present study was to determine if a more chronic stressor, i.e., activity-stress (A-S), would also result in hippocampal dendritic atrophy. When activity-stress (n = 6) rats showed evidence of the criteria "stress symptoms" (after an average of 6 days), they were sacrificed and their brains were quickly removed, blocked, and placed in Golgi-Cox solution. Food-yoked control animals (n = 6) were sacrificed on the following day. Serial coronal sections (150 um) of the rostral hippocampus were cut so that the CA3 and CAI areas could be analyzed. Stressed short-shaft neurons were significantly shorter and had fewer branch points in CA1 and CA3 neurons than the control neurons. A similar nonsignificant trend was observed in long-shaft neurons. These data suggest that a short period of chronic stress (6 days as opposed to 21 days in prior studies) induces neuronal atrophy in the hippocampus.