Adrenalectomy fails to alter radial maze performance of rats at retention intervals of 24 hours or less

Evidence suggests that the behavioral actions of adrenalectomy and glucocorticoid replacement therapy result from changes in the binding of corticosterone to specific receptors in the hippocampus. Efficient foraging for bait on the radial maze has been demonstrated to require a functionally intact hippocampal system. The present experiment examined the effect of adrenalectomy on the ability of rats to locate unexplored arms in the radial maze after various retention intervals midway through completion of the maze. Rats were very proficient at locating the unexplored arms after retention intervals of 3 hours or less; significantly more trials were required to locate all of the previously unvisited arms at retention intervals of 8 and 24 hours. However, adrenalectomy failed to alter maze performance at any retention interval tested. It was concluded that the neural substrates involved in the performance of this spatial/working memory task are not dependent upon the neuromodulatory effects of physiological levels of adrenal corticosteroids. The results are discussed in terms of behavior/contingency conflicts and innate versus learned responses as factors which may be important for revealing behavioral actions of adrenalectomy or corticosteroid therapy.