[Development of electrical activity of hypothalamic cells in culture]

The development of the electrical activity of hypothalamic cells was studied using intracellular and patch clamp recording technics on cultured hypothalamic neurones from 14 days mouse embryos. After 24 h of incubation, 15% of recorded cells were spontaneously active. During the first five days of culture this ratio increased exponentially to reach 95% at day 5. Between the 5th and the 9th day the spontaneous activity progressively decreased although the majority of cells remained excitable. Spontaneous activity reappeared after the 9th day and was underlain by a synaptic potential activity. During the first five days of culture, only a TTX sensitive inward current was observed in all cell tested. A calcium inward current appeared after the first week of incubation. It was recorded on 40% of cells at day 11th and in 80% of cells tested after a month of incubation. Our results show that electrical activity of cultured hypothalamic neurones develop in three stages. A first stage characterized by a spontaneous electrical activity without post synaptic potential, an intermediate stage during which a Calcium inward current appeared corresponding to synaptic contact development and a third stage during which post synaptic potential activity was observed, corresponding to synaptic contact maturation.