VIP and Parkinson disease: This study aims to examine the effects of rTMS treatment on constipation symptoms in Parkinson’s disease by measuring constipation-related clinical scores and serum levels of key gut-brain peptides (5-HT, BDNF, VIP) and a panel of pro-inflammatory (IL-6, IFN-γ, TNF-α) and anti-inflammatory (IL-4, IL-10) cytokines before and after a 14 days intervention.