Quantification of cerebellar hemispheric purkinje cell linear density: 32 ET cases versus 16 controls

Abstract

Although essential tremor (ET) is among the most prevalent neurological diseases, its precise pathogenesis is not understood. Purkinje cell loss has been observed in some studies and is the focus of interest and debate. Expressing these data as Purkinje cells/layer length allows one to adjust for the inherent curved nature of the cerebellar folia. Capitalizing on the Essential Tremor Centralized Brain Repository, we quantified Purkinje cell linear density in cases versus controls. Free-floating 100-μm parasagittal cerebellar hemispheric sections were subjected to rabbit polyclonal anti-Calbindin D28k antibody, and 10 random fields/brain were selected for quantification of Purkinje cells/mm(-1) Purkinje cell layer. Purkinje cell linear density was lower in 32 ET cases than in16 controls (1.14 ± 0.32 vs. 1.35 ± 0.31/mm(-1) , P = 0.03). Purkinje cell linear density was inversely associated with torpedo count (r = -0.38, P = 0.028). The current sample of ET cases demonstrates a reduction in Purkinje cell number relative to that of controls. Greater Purkinje cell axonal remodeling (torpedoes) was found in individuals who had the most Purkinje cell drop out. The role of Purkinje cell loss in the pathogenesis of this disorder merits additional study.

Keywords: Purkinje cell; brain; cerebellum; essential tremor; neurodegenerative; pathology; pathophysiology.

Figure 1

100 μm parasagittal cerebellar hemispheric sections were subjected to rabbit polyclonal anti-Calbindin D28k antibody. Three controls (A, B, C) and three ET cases (D, E, F). Purkinje cell linear density was 1.77 per mm⁻¹ (A), 1.59 per mm⁻¹ (B), 1.27 per mm⁻¹ (C), 0.96 per mm⁻¹ (D), 0.79 per mm⁻¹ (E), 0.63 per mm⁻¹ (F). Torpedoes are also evident in ET cases. Magnification 100×. The panels were chosen to represent a full range of linear density values, starting with a very high value (1.77 PC/mm⁻¹) and then, at intervals of 0.20 – 0.30 PC/mm⁻¹, arriving at a very low value (0.63 PC/mm⁻¹). The width of the intervals was chosen to result in 6 panels (A – F). The three top panels are from controls and represent the values seen in 2/3 of controls. Similarly 2/3 of cases had values that were below the value shown in panel C.

Figure 2

Purkinje cell linear density was lower in 32 ET cases than 16 controls (1.14 ± 0.32 vs. 1.35 ± 0.31 per mm⁻¹, p = 0.03). The curves represent the distribution of data points.