Developmental autoregulation of calcium currents in mammalian central neurones

The influence of calcium currents expressed at early stages on the subsequent development of calcium currents was studied in embryonic rat hypothalamic neurones in culture. Voltage-activated calcium currents and spontaneous fluctuations of intracellular free calcium concentration ([Ca2+]i) were monitored. Acute application of nickel chloride (0.1 mM) to 6- to 7-day-old cultures strongly reduced calcium currents and [Ca2+]i fluctuations. When cultures were maintained for 6-7 days in the presence of NiCl2 (0.05-0.1 mM), expression of the low voltage-activated current was strongly inhibited; this treatment did not affect high voltage-activated currents. Our results suggest that spontaneous activation of calcium currents early during development promotes calcium influx that regulates expression of calcium current in mature neurones.