Objective: To study plasma PP concentration during sham feeding in PD patients and healthy controls, as a measure of pancreatic vagal innervation.

Background:

Most patients with Parkinson’s disease (PD) experience signs of decreased parasympathetic function. Lewy pathology is present in the vagus nerve and the dorsal motor nucleus of the vagus very early in the disease course (Braak stage I). The pancreas is densely innervated by the vagus nerve, and the early peak (5-20 min) of the hormone Pancreatic Polypeptide (PP) after food intake or sham-feeding has been validated as a marker of vagal integrity. Thus, we aimed to study plasma PP concentration during sham feeding (chew-and-spit) in PD patients and healthy controls (HC), as a measure of pancreatic vagal innervation.

Methods:

Twenty-five early-to-moderate PD patients (H&Y 2 (1-3); 7 female) and 17 HC (5 female) were included. Blood sampling for analysis of PP, glucose, and insulin levels were performed before, during, and 20 minutes after a 5 minute sham feeding session with white bread and chocolate spread. Furthermore, faeces samples from all participants were analysed for pancreatic elastase enzyme levels as a marker of exocrine pancreatic function.

Results:

The PD group displayed significantly decreased plasma PP concentrations during the early phase after sham feeding compared to controls (p=0.012). No change in glucose and insulin levels were seen in any of the groups as an indicator of pure sham feeding without food ingestion. Also, no significant group difference was seen in pancreatic elastase levels (p=0.69).

Conclusions:

Early-to-moderate stage PD patients showed significantly decreased PP plasma concentrations after sham feeding – an indication of decreased vagal function. Exocrine pancreatic function measured by elastase in faeces was not significantly different in the patient group compared to controls.

 Glucose and insulin concentrations did not change in either group throughout the test, verifying that sham feeding was performed correctly without unintentional swallowing of food.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/pancreatic-polypeptide-plasma-levels-in-parkinsons-disease-a-marker-of-parasympathetic-denervation/