Does ghrelin increase during nausea?

The appetite stimulating hormone ghrelin is mainly secreted from the stomach was found to reduce emesis in a chemotherapy induced nausea model in ferrets when given intra-peritoneally. The mechanism of its anti-emetic activity is not yet clear. Therefore, we investigated ghrelin levels during motion sickness induced nausea. Methods: Eight healthy male subjects (24.8±1.4 years) being susceptible to vection were recruited to our test procedure. To induce nausea a slow rotation procedure (120° per s) around the vertical axis for 1min with head movements was used. After a break (1min) rotation was repeated until nausea forced the subject to stop. Standardized nausea ratings (using a sum score) and blood sampling was performed before and immediately after the rotation procedure. Plasma levels of ghrelin, ACTH, antidiuretic hormone (ADH), and pancreatic polypeptide (PP) were determined by radioimmunoassays. Results: During the rotation period each subjects developed nausea. Rotation time was between 60 an 300 seconds (145.9±29.6 seconds). ACTH levels (from 53.9±13.1 to 124.6±24.0 pg/mL) and ADH (from 0.4±0.04 to 20.2±5.3 pg/mL) were both significantly increased after the rotation period (P=0.012). PP was also significantly increased during nausea development (from 12.6±2.7 to 18.0±2.6 pmol/L; P=0.05). In contrast, ghrelin levels did not change significantly (before rotation: 387.1±35.2 pg/mL; after rotation: 382.3±36.7 pg/mL). Conclusions: While ACTH, ADH, and PP were significantly increased, no endogenous ghrelin release was found during motion sickness induced nausea. To understand the ability of ghrelin to reduce chemotherapy induced nausea merits further investigations.