title: Effect of diet-induced obesity and experimental hyperinsulinemia on insulin uptake into CSF of the rat.
abstract: We examined the hypothesis that the uptake of plasma insulin into cerebrospinal fluid (CSF) is saturable in two rat models. Dietary obese and control female Osborne Mendel rats received 24-h infusions of vehicle or insulin. CSF insulin levels in cafeteria- and chow-fed rats were comparable at all levels of plasma insulin (4.5 +/- 2.8, 7.6 +/- 2.4, and 23.9 +/- 6.4 microU/ml in cafeteria diet vs. 4.5 +/- 0.9, 6.8 +/- 1.1, and 17.0 +/- 4.0 microU/ml in chow rats). CSF insulin uptake as a percentage of plasma insulin decreased with increased plasma insulin in both groups. A similar relationship was observed in Wistar rats receiving 6-day infusions of vehicle or insulin (plasma insulin = 55 +/- 12 vs. 365 +/- 98 microU/ml; CSF/plasma insulin ratio = 0.022 +/- .007 vs. 0.013 +/- .006, respectively). Hyperinsulinemic Wistar rats did not demonstrate decreased brain capillary insulin binding vs. vehicle-infused controls. The results suggest that a saturable transport process contributes insulin transport into CSF in normal rats and that this process is not altered by moderate diet-induced obesity or hyperinsulinemia per se.
authors.affiliation: Department of Psychology, University of Washington, Seattle 98195.
authors.forename: P A
authors.initials: PA
authors.lastname: Israel
authors.forename: C R
authors.initials: CR
authors.lastname: Park
authors.forename: M W
authors.initials: MW
authors.lastname: Schwartz
authors.forename: P K
authors.initials: PK
authors.lastname: Green
authors.forename: A J
authors.initials: AJ
authors.lastname: Sipols
authors.forename: S C
authors.initials: SC
authors.lastname: Woods
authors.forename: D
authors.initials: D
authors.lastname: Porte
authors.forename: D P
authors.initials: DP
authors.lastname: Figlewicz
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight / Q000502:physiology; D002196:Capillaries / Q000378:metabolism; D004032:Diet; D005260:Female; D006946:Hyperinsulinism / Q000134:cerebrospinal fluid*; D007328:Insulin / Q000097:blood / Q000134:cerebrospinal fluid*; D008297:Male; D009765:Obesity / Q000134:cerebrospinal fluid* / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar
chemical_list: D001786:Blood Glucose; D007328:Insulin