Stress and the Brain: A Paradoxical Role for Adrenal Steroids

This chapter discusses paradoxical effects of adrenal steroids in the hippocampus. Stress is common in everyday life and is blamed for many problems. There is mounting evidence that stressful experiences exacerbate disease processes. Adrenal steroids represent only one of several neurochemical systems that mediate the delicate balance between hippocampal function and dysfunction. To explore the role of endogenous corticosterone (CORT) release in dendritic atrophy evoked by stress, the steroid synthesis inhibitor cyanoketone was used to reduce the magnitude of CORT secretion in response to restraint stress. Another important issue is the relationship between the atrophy of CA3c neurons induced by repeated CORT treatment or repeated restraint stress and the loss of pyramidal neurons that has been reported after both 12 weeks of CORT treatment and severe social stress. Repeated restraint stress in rats for 3 weeks causes changes in the hippocampal formation, including atrophy of the dendrites of CA3c pyramidal neurons, as well as suppression of serotonin 1A (5-HT_1A) receptor binding.