Corticotropin releasing-factor (CRF) increases extracellular GABA levels in the rat hypothalamus

We investigated the effect of the perfusion of corticotropin releasing-factor (CRF) on the extracellular levels of γ-aminobutyric acid (GABA) in the hypothalamic paraventricular nucleus in the rat using a microdialysis technique. Local perfusion of CRF (3 μM, 10 μM and 30 μM) caused significant increases in extracellular GABA levels in a dose dependent manner. Increases in GABA levels in this region caused by CRF were significantly reduced by the presence of [D-Phe12, Nle21,38, α-Me-Leu37]-CRF (12-41) (D-Phe CRF12-41, 1 μM), a CRF receptor antagonist. These findings suggest that CRF activates GABAergic neurons in the rat hypothalamic paraventricular nucleus via CRF receptors, which might be related to regulation of ACTH secretion in the anterior lobe of the pituitary.