Corticotropin-releasing factor modulates basal and stress-induced excitatory amino acid release in the locus coeruleus of conscious rats.

The in vivo interactions between corticotropin-releasing factor (CRF) and excitatory amino acid (EAA) release in the locus coeruleus (LC) were studied. Superfusion of the LC with CRF (0.1 microM) led to a prolonged increase in the release rate of aspartate and, to a lesser extent, of glutamate. The CRF antagonist alpha-helical CRF9-41 (1 microM) had no effect on basal EAA release but abolished the enhanced aspartate and glutamate release induced by noise stress (95 dB). Tail pinch-induced EAA release was not influenced by alpha-helical CRF9-41. Results demonstrate a facilitatory action of CRF on in vivo EAA release in the LC. Furthermore, modulation by CRF of stress-induced EAA release in the LC depends on the nature of stress.