Serum somatostatin in early-stage Parkinson's disease

Objective - To compare levels of plasma digestive hormones in patients with and without nausea or vomiting during initial treatment of early-stage Parkinson's disease (PD). Methods - This was a 3-week, open-label, randomized study of treatment with an antiparkinson drug in untreated PD patients. We measured the levels of plasma digestive hormones before (baseline) and 3 weeks after administration of an antiparkinson drug. Results - Mean value of serum somatostatin at baseline was significantly increased in PD patients compared with the control group (P < 0.01). Serum somatostatin levels were significantly increased after treatment in subjects who experienced nausea or vomiting (P < 0.01). However, significant increase in serum somatostatin levels after treatment was not observed in PD patients without nausea or vomitting. Conclusion - Serum somatostatin in early-stage PD patients before treatment was increased compared with healthy subjects. The nausea and vomiting induced by antiparkinson drugs may be related to uncontrolled somatostatin secretion through central vagus nerve dysfunction.