Purkinje cell degeneration elevates eupneic and hypercapnic ventilation in rats

Area of Science:

• Neuroscience
• Respiratory Physiology

Background:

• The fastigial nucleus (FN) in the cerebellum is crucial for respiratory facilitation, particularly during hypercapnia.
• Purkinje cells (PCs) in the cerebellum provide inhibitory input to the FN.

Purpose of the Study:

• To investigate the role of Purkinje cells (PCs) in modulating eupneic and hypercapnic ventilation.
• To test the hypothesis that PC degeneration increases ventilation by disinhibiting the FN.

Main Methods:

• Experiments were conducted on normal and PC-degenerated rats under both awake and anesthetized conditions.
• Ventilatory parameters (tidal volume [VT] and breathing frequency [f]) were measured using whole-body plethysmography during normoxia and hypercapnia (5% CO2).
• Fos protein immunocytochemistry was used to assess neuronal activity in PCs and the FN.

Main Results:

• PC degeneration significantly increased both eupneic and hypercapnic ventilation in awake and anesthetized rats.
• The increase in ventilation was mainly due to elevated tidal volume (VT), with minimal changes in breathing frequency (f).
• Fos expression was high in PCs of normal rats but absent in PC-degenerated rats; conversely, FN Fos expression was low in normal rats and high in PC-degenerated rats.

Conclusions:

• Cerebellar Purkinje cells (PCs) exert an inhibitory influence on respiratory control.
• The FN's role in ventilation is modulated by inhibitory input from PCs.
• PC degeneration leads to increased ventilation through disinhibition of FN neuronal activity.