Phosphodiesterase 9 inhibition prolongs the antiparkinsonian action of l-DOPA in parkinsonian non-human primates

pubmed.ncbi.nlm.nih.gov/354...

These results indicate that cGMP upregulation interacts with dopamine signaling to enhance the l-DOPA reversal of parkinsonian motor disability. Therefore, striatal PDE9 inhibition may be further explored as a strategy to improve motor responses to l-DOPA in PD.

[CaseyInsights]

Seems that PDE1 may do the same thing.

Here is Simon at The Science of Parkinson's on the nature of PDE1 , its effects and drugs being trialed to help .

scienceofparkinsons.com/201...

And this fun fact from that article -

A drug called Vinpocetine (a phosphodiesterase 1 inhibitor) was the only phosphodiesterase inhibitor that reduced alpha synuclein toxicity.