Steroid suppression of axon sprouting in the hippocampal dentate gyrus of the adult rat: dose-response relationship.

Various doses of adrenal steroids were given to adult male rats for 8 days following unilateral ablation of the entorhinal cortex in order to test their effects on axon sprouting. Seven days after termination of the steroid treatment the brains were analyzed for changes in the outgrowth of the commissural-associational fiber plexus in the hippocampal dentate gyrus. Analysis of the data revealed a dose-dependent suppression of the reactive fiber growth in this region of the hippocampus. Deoxycorticosterone had no suppressive effect, indicating that suppression was not related to mineralocorticoid properties. On the other hand dexamethasone, a synthetic glucocorticoid devoid of mineralocorticoid properties, had a maximal effect. These results suggest that glucocorticoids and their anti-inflammatory effects may have a significant influence on the response of the nervous system to damage.