title: Influence of microgravity on plasma levels of gastroenteropancreatic peptides: a case study.
abstract: BACKGROUND
  No data are available about the short- or long-term influences of microgravity in space on the release of gastroenteropancreatic peptides, although these peptides are involved in the regulation of gastrointestinal functions.
  
  
  METHODS
  Fasting plasma samples were gained during the EUROMIR-94 mission from a European Space Agency (ESA) astronaut who experienced no signs of space motion sickness in orbit. Plasma concentrations of nine gastroenteropancreatic peptides were measured with sensitive and specific radioimmunoassays.
  
  
  RESULTS
  Fasting plasma levels of motilin, pancreatic polypeptide (PP), vasoactive intestinal peptide (VIP), and secretin were increased and plasma level of cholecystokinin (CCK) was decreased by acute exposure of the astronaut to microgravity. Chronic (4 wk) exposure caused an enhancement of plasma CCK, motilin, neurotensin, VIP, and insulin whereas plasma concentrations of PP, secretin, gastrin, and somatostatin showed no changes. During the 25-d stay on MIR station plasma levels of CCK, motilin, and neurotensin increased. Short-time body rotations caused an elevation of plasma levels of PP but decreased plasma motilin.
  
  
  CONCLUSIONS
  As the influence of microgravity on the peptide levels was not uniform, an effect due to other factors (e.g., change in fluid balance or body weight) is unlikely. Moreover, adaptive changes of some peptides occurred during the stay in orbit. The release of PP and motilin seems to be very sensitive to rotation forces. These results have to be confirmed in more subjects in space to be able to link changes of gastroenteropancreatic peptide release to alterations of gastrointestinal functions.
authors.affiliation: Medizinische Klinik Innenstadt of the Ludwig-Maximilians-University of Munich, Germany. RL_Riepl@hotmail.com
authors.forename: Rudolf L
authors.initials: RL
authors.lastname: Riepl
authors.forename: Christian
authors.initials: C
authors.lastname: Drummer
authors.forename: Peter
authors.initials: P
authors.lastname: Lehnert
authors.forename: Rupert
authors.initials: R
authors.lastname: Gerzer
authors.forename: Bärbel
authors.initials: B
authors.lastname: Otto
mesh_terms: D000328:Adult; D005768:Gastrointestinal Hormones / Q000097:blood*; D006801:Humans; D018472:Hypogravity / Q000009:adverse effects*; D008297:Male; D009479:Neuropeptides / Q000097:blood*; D011863:Radioimmunoassay; D013026:Space Flight
chemical_list: D005768:Gastrointestinal Hormones; D009479:Neuropeptides