Transcriptional profiling of cortex and striatal tissue following chronic dosing of PDE10A inhibitor PF-02545920 in a Q175 homozygous knock-in mouse model of Huntington’s disease. Mus musculus

Huntington’s disease (HD) symptoms are driven to a large extent by dysfunction of the basal ganglia circuitry. HD patients exhibit reduced striatal phoshodiesterase 10 (PDE10) levels. Using HD mouse models that exhibit reduced PDE10, we demonstrate the benefit of pharmacologic PDE10 inhibition to acutely correct basal ganglia circuitry deficits. PDE10 inhibition restored corticostriatal input and boosted cortically driven indirect pathway activity. Cyclic nucleotide signaling is impaired in HD models and PDE10 loss may represent a homeostatic adaptation to maintain signaling. Elevation of both cAMP and cGMP by PDE10 inhibition were required for rescue. Phosphoproteomic profiling of striatum in response to PDE10 inhibition highlighted plausible neural substrates responsible for the improvement. Early chronic PDE10 inhibition in Q175 mice showed improvements beyond those seen with acute administration after symptom onset, including partial reversal of striatal deregulated transcripts and the prevention of the emergence of HD neurophysiological deficits. Overall design: Transcriptional profiling of cortex and striatal tissue following chronic dosing of either vehicle or the PDE10A inhibitor PF-02545920 (0.32, 1 and 3.2 mg/kg po qd) in the Q175 homozygous knock-in mouse model of Huntington’s disease (dosing from 5-weeks to 9 months of age).