STRESS INCREASES BRAIN-DERIVED NEUROTROPIC FACTOR MESSENGER-RIBONUCLEIC-ACID IN THE HYPOTHALAMUS AND PITUITARY

Brain-derived neurotropic factor (BDNF) is a member of the nerve growt h factor family that is important for neuronal survival and plasticity . We recently demonstrated that stress decreases BDNF messenger RNA (m RNA) levels in the hippocampus, which raises the possibility that BDNF may play a role in regulation of the hypothalamic-pituitary-adrenal a xis. The purpose of this study was to determine whether BDNF expressio n is present and influenced by stress in other brain areas relevant to control of the hypothalamic-pituitary-adrenal axis. Using in situ hyb ridization, we found that BDNF mRNA is present in the parvocellular po rtion of the hypothalamic paraventricular nucleus (PVN), the lateral h ypothalamus, and the anterior and neurointermediate lobes of the pitui tary in rats. Acute (2-h) or repeated immobilization stress increased BDNF mRNA in all of these areas. This was in distinct contrast to stre ss-induced decreases in extrahypothalamic areas, including the basolat eral amygdala, claustrum, and cingulate cortex as well as the hippocam pus. BDNF was expressed in both CRF and TRH neurons in the PVN. Reduci ng glucocorticoid or thyroid negative feedback increased BDNF mRNA in the PVN and anterior pituitary, but not in the neurointermediate lobe. These results suggest that BDNF is a stress-responsive intercellular messenger that may be an important component of the stress response.