Depolarization-induced release of corticotropin-releasing factor (CRF) in primary neuronal cultures of the amygdala

Abstract

The 41-amino acid neuropeptide, corticotropin-releasing factor (CRF) is distributed throughout the central nervous system and appears to play a pivotal role in stress, anxiety and depression. CRF is present in high concentrations in the limbic brain region, the amygdala, an area important in emotional and autonomic responses to stress. In this report, primary neuronal cultures of amygdala from fetal rat brains (E18–E19) were used to study depolarization-induced CRF release. Immunocytochemical analyses of the cultures revealed a bead-like distribution of CRF immunoreactivity (CRFir) in about 1% of the neurons. Time course studies showed that 56 mM KCl-evoked CRF release occurred with an initial burst during the first minute that was maintained over 30 min; basal CRF release slightly increased over a 30-min period. CRF release in response to depolarization increased with increasing cell density and with increasing days in culture. Multiple serial incubations alternating basal and depolarizing conditions caused a depletion of the releasable pool of CRF. Potassium-evoked CRF release was calcium-dependent. These data suggest that primary neuronal cultures of fetal rat amygdala are an effective model system to study CRF release in this brain region.