In further support, RASGRF (Ras protein specific guanine nucleotide releasing factor)2, upregulated by RT, is associated with synaptic plasticity (Feig, 2011) and VIPR (vasoactive intestinal peptide receptor)1 may alleviate constipation in PD (Giancola et al., 2017) a distressing non-motor symptom affecting many individuals with PD (Pedrosa et al., 2018). Here, VIPR1 is linked to Parkinson disease.