The hypothalamic arcuate nucleus plays an important role in the gating system controlling the secretion of hypothalamic neurons. In order to analyze this gating mechanism, arcuate neurons from rats aged 21–22 days were cultured in a chemically defined medium. Addition of nerve growth factor to this medium increased the survival of the arcuate neurons. Neuron characterization was done with the Lucifer Yellow liposome technique and neurofilament immunocytochemistry. Electrophysiological information was obtained with the patch-clamp technique by whole-cell recordings and single-channel measurements. This qualitative inventory demonstrated the presence of at least five types of conductances: a sodium conductance, two potassium conductances, a calcium-activated conductance, presumably determined by potassium, and a leakage conductanc