RELEASE OF BETA-ENDORPHIN FROM RAT HYPOTHALAMUS INVITRO

The rate of release of β-endorphin-like immunoreactivity (β-EI) from rat hypothalamic slices was increased 3- to 4-fold over the spontaneous release during exposure to a depolarizing concentration of potassium ions. This augmented outflow was abolished in the absence of calcium. The amount of β-EL released from slices exposed to a second pulse of potassium was reduced by approximately 50% compared to that in the first. 70% of the potassium-induced released immunoreactive material migrated on a calibrated Sephadex G-50 column like synthetic human β-endorphin. These findings are discussed in terms of a neuronal release of β-endorphin and may be taken as supportive evidence for a neurotransmitter and/or neurohormonal role of β-endorphin in the hypothalamus. © 1979.