Fig. 1.

Neonatal PCP administration does not modify the cytoarchitecture of the cerebellum and the spontaneous activity of PCs. (A) Experimental design. PCP (10 mg/kg) or vehicle is injected subcutaneously in mouse pups at P7, P9, and P11. Morphological and electrophysiological analyses are performed at P30. (B) Parasagittal cerebellar sections from the vermis of P30 mice were immunolabeled with an anti-calbindin antibody to stain PCs in their entirety and reveal cerebellar cytoarchitecture. Quantification of the mean area of cerebellar slices showed no significant differences between the two conditions (mean ± SEM; vehicle: n = 12 animals; PCP: n = 12; P = 0.0962, Student’s t test). Representative images from PCs and their dendritic tree in lobule VI reveal similar morphology in sections from P30 vehicle- and PCP-treated animals. Quantification of the thickness of the molecular layer (ML) in the lobule VI, measured as the length from the beginning of the primary dendrite of PCs in the Purkinje cell layer (PCL) to the upper extremity of the ML, reveals no significant difference between vehicle- and PCP-treated animals (lobule VI is shown here; mean ± SEM; vehicle: n = 14 animals; PCP: n = 16 animals; P = 0.964, unpaired Student’s t test). (Scale bars: Upper, 1,000 µm; Lower, 50 µm.) (C) High-density MEAs were used to record PC spontaneous spiking in acute cerebellar slices from P30 mice. An example of the recorded electrical activity in a cerebellar slice from a vehicle-treated mouse is shown with each pixel representing one channel and units showing high activity in red and low activity in blue. A representative trace of recordings from one channel is shown for each condition. Spike sorting using the SpyKING CIRCUS software allowed for estimation of the mean firing rate and mean interspike interval (ISI) CV and CV2. No significant difference was detected in any of these parameters (mean ± SEM; vehicle: n = 7 animals; PCP, n = 9 animals; unpaired Student’s t test).