Postnatal lead exposure alters spontaneous cerebellar Purkinje neuron discharge.
The effects of early postnatal lead administration on the spontaneous activity of cerebellar Purkinje neurons were studied electrophysiologically in adult male Sprague-Dawley rats. Newborn rat litters were divided into three groups and injected daily from Day 1 to Day 20 after birth with 8 mg NaAc/kg, 1 mg PbAc/kg, or 8 mg PbAc/kg intraperitoneally. Purkinje neurons in all three groups showed regular and sustained discharge. However, the mean spontaneous firing rate was significantly lower in the 8-mg PbAc/kg group (26.13 +/- 1.28 Hz) compared to the NaAc controls (32.39 +/- 1.93, P greater than 0.01). Furthermore, the distribution of the firing rates of the Purkinje cells were different in the two groups, with an obvious loss of faster firing cells in the 8-mg PbAc/kg group. No differences were seen between the 1-mg PbAc/kg group and the NaAc controls. As the 8-mg PbAc/kg group weighed significantly less than the NaAc group, malnourished animals were produced by using oversized litters, to control for any changes caused by the lower body weight. However, when compared to concomitantly raised controls, no changes could be seen in Purkinje cell discharge in the malnourished animals. It is concluded that neonatal exposure to lead can cause permanent changes in spontaneous Purkinje cell discharge.