Stimulation of the amygdala by glutamate facilitates corticotropin-releasing factor release from the median eminence and activation of the hypothalamic-pituitary-adrenal axis in stressed rats.
The role of the amygdala in the regulation of hypothalamic release of corticotropin-releasing factor (CRF) was investigated. Microinjection of glutamate (50 nmol) into the amygdala resulted in increased plasma corticosterone in male rats previously subjected to a 14-day unpredictable stressor paradigm (p < or = 0.05 vs. saline-injected controls). A long-lived increase in corticosterone levels was also observed in rats which were urethane-anesthetized (1.35 g/kg) 3 h prior to glutamate microinjection (p < or = 0.01 vs. saline-injected controls). These effects on plasma corticosterone were observed despite the presence of high basal levels of corticosterone. Furthermore, microperfusion of glutamate (3-300 microM) into the amygdala of urethane-anesthetized rats resulted in a dose-dependent increase in CRF release from the median eminence, as assessed by in vivo microdialysis (p < or = 0.025 vs. basal). These results indicate a facilitating role for the amygdala in stress-induced increases in CRF release and subsequent adrenocortical activation.
Gabr
R W
RW
Department of Pharmacology and Toxicology, Robert C Byrd Health Science Center, West Virginia University School of Medicine, Morgantown 26506-9223, USA.
Birkle
D L
DL
Azzaro
A J
AJ
D000311:Adrenal Glands / Q000378:metabolism*; D000679:Amygdala / Q000187:drug effects*; D000818:Animals; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism*; D018698:Glutamic Acid / Q000494:pharmacology*; D007030:Hypothalamo-Hypophyseal System / Q000378:metabolism*; D008297:Male; D017551:Microdialysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013312:Stress, Physiological; D013997:Time Factors
D018698:Glutamic Acid; D003346:Corticotropin-Releasing Hormone