Chronic exposure to alcohol during development alters the calcium currents of cultured cerebellar Purkinje neurons

The effect of chronic exposure to alcohol during development on the calcium currents of rat cerebellar Purkinje neurons was studied in a culture model system using voltage clamp techniques. The neurons were exposed to 30 mM alcohol (ethanol) during the main period of morphological and physiological development. The calcium currents were measured at the end of the treatment period, which lasted for 8–10 days. The currents were evoked by a series of depolarizing test commands from holding potentials of −62 mV and −90 mV. The evoked currents were qualitatively similar in control and alcohol-treated neurons and were comprised of a high threshold slowly inactivating calcium current and a low threshold rapidly inactivating calcium current. The low threshold current could be observed in isolation at test potentials ranging from −50 to − 30 mV. The mean peak amplitude of this current was significantly smaller in the alcohol-treated neurons compared to controls. At more depolarized test potentials, the high threshold current dominated the current response, which was characterized by an initial peak that slowly declined to a smaller relatively sustained level. The mean amplitude of the high threshold current at both peak and sustained levels was significantly larger in the alcohol-treated neurons compared to controls. Measurement of cell size indicated that alcohol-treated neurons were approximately 25% smaller than control neurons, a difference that could contribute to the smaller low threshold current observed in these neurons. These data show that chronic exposure to alcohol during the development can significantly influence the amplitude of calcium currents of the cultured Purkinje neurons. Alterations of these currents by alcohol could have multiple effects on the developing Purkinje neurons and may contribute to the structural and functional changes observed in animal models of fetal alcohol syndrome.