Fine structural changes in the rat arcuate nucleus by forced running stress.

The forced running stress in male rats induced some fine structural changes in the arcuate nucleus. By inducing stress for 2 days, the number of multilamellar astrocytic wrappings and endoplasmic reticular (ER) whorls increased significantly. After a stress of 12 days, half of the rats remained inactive for several weeks, and the other half regained their normal activity. In the inactive group, the ER whorls were partially degenerated at 2 weeks after the stress. These degenerative changes remained for 14 weeks after the stress with the increased lysosomes and the disorganization of r-ER. These findings may suggest that long-term stress induces degenerative changes in the arcuate nucleus neurons and that some of these changes persist with some aging-like morphological changes.