title: Plasma pancreatic polypeptide levels are associated with differences in body fat distribution in human subjects.
abstract: OBJECTIVE
  Pancreatic polypeptide (PP) is produced by the F-cells of the pancreas, and its plasma concentration has been used as a marker of parasympathetic activity. Recent work in rodents suggests that there is both sympathetic and parasympathetic innervation of white adipose tissue and that parasympathetic activity is anabolic resulting in lipid accumulation. We have examined whether in humans increased PP levels are associated with increased intra-abdominal fat (IAF), and thereby insulin resistance.
  
  
  METHODS
  We measured PP levels in 177 non-diabetic subjects (75 male/102 female; age 32-75 years) 3 min after an i.v. glucose bolus during a frequently sampled intravenous glucose tolerance test. IAF and s.c. fat (SCF) areas were measured by CT scan. The insulin sensitivity index (S (I)) was quantified using Bergman's minimal model.
  
  
  RESULTS
  PP levels were higher in men than in women (96.2 +/- 72.2 vs 76.1 +/- 55.0 pg/ml, mean +/- SD, p = 0.037), as was IAF area (124.7 +/- 67.4 vs 83.0 +/- 57.7 cm(2), p < 0.001). While PP levels were significantly associated with IAF (r = 0.16, p = 0.031), WHR (r = 0.30, p < 0.001) and age (r = 0.37, p < 0.01), they were not associated with SCF (r = 0.02, p = 0.829). The association between PP and IAF was not independent of age and/or sex. S(I) was negatively associated with PP levels (r = -0.17, p = 0.026) and IAF area (r = -0.65, p < 0.001). The association between S(I) and PP disappeared after adjusting for IAF area, indicating that S(I) was not a major determinant of PP levels.
  
  
  CONCLUSIONS
  In humans, age and sex may modulate the association between plasma PP level and IAF area, suggesting that they may be determinants of parasympathetic activity and thus IAF accumulation.
authors.affiliation: Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, VA Puget Sound Health Care System, Harborview Medical Center, University of Washington, Seattle, WA 98108, USA. tongj@u.washington.edu
authors.forename: J
authors.initials: J
authors.lastname: Tong
authors.forename: K M
authors.initials: KM
authors.lastname: Utzschneider
authors.forename: D B
authors.initials: DB
authors.lastname: Carr
authors.forename: S
authors.initials: S
authors.lastname: Zraika
authors.forename: J
authors.initials: J
authors.lastname: Udayasankar
authors.forename: F
authors.initials: F
authors.lastname: Gerchman
authors.forename: R H
authors.initials: RH
authors.lastname: Knopp
authors.forename: S E
authors.initials: SE
authors.lastname: Kahn
mesh_terms: D000005:Abdomen / Q000033:anatomy & histology; D000273:Adipose Tissue / Q000033:anatomy & histology*; D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000378:metabolism; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D008297:Male; D008875:Middle Aged; D010191:Pancreatic Polypeptide / Q000097:blood*
chemical_list: D001786:Blood Glucose; D007328:Insulin; D010191:Pancreatic Polypeptide