title: Essentiality of portal vein receptors in hypoglycemic counterregulation: direct proof via denervation in male canines.
abstract: A major issue of in the treatment of diabetes is the risk of hypoglycemia. Hypoglycemia is detected both centrally and peripherally in the porto-hepatic area. The portal locus for hypoglycemic detection was originally described using the "local irrigation of the liver" approach in a canine model. Further work using portal vein denervation (DEN) in a rodent model characterized portal hypoglycemic sensing in detail. However, recent controversy about the relevance of rodent findings to large animals and humans prompted us to investigate the effect of portal DEN on the hypoglycemic response in the canine, a species with multiple similarities to human glucose homeostasis. Hypoglycemic hyperinsulinemic clamps were performed in male canines, before (PRE) and after (POST) portal vein DEN or sham surgery (CON, control). Insulin (30 pmol/kg·min) and glucose (variable) were infused to slowly decrease systemic glycemia to 50 mg/dL over 160 minutes. The average plasma glucose during clamp steady state was: 2.9 ± 0.1 mmol DEN-PRE, 2.9 ± 0.2 mmol DEN-POST, 2.9 ± 0.1 mmol CON-PRE, and 2.8 ± 0.0 mmol CON-POST. There were no significant differences in plasma insulin between DEN and CON, PRE and POST experiments. The epinephrine response to hypoglycemia was reduced by 62% in DEN but not in CON. Steady-state cortisol was 46% lower after DEN but not after CON. Our study shows, in a large animal model, that surgical disconnection of the portal vein from the afferent pathway of the hypoglycemic counterregulatory circuitry results in a substantial suppression of the epinephrine response and a significant impact on cortisol response. These findings directly demonstrate an essential role for the portal vein in sensing hypoglycemia and relating glycemic information to the central nervous system.
authors.affiliation: Diabetes and Obesity Research Institute (V.I., A.V.B.C., O.O.W., D.S., M.S.I., J.L.B., H.M., R.N.B.) and Department of Surgery (M.B., R.E.), Cedars Sinai Medical Center, Los Angeles, California 90048; and Department of Animal Resources (E.K.), University of Southern California, Los Angeles, California 90033.
authors.forename: Viorica
authors.initials: V
authors.lastname: Ionut
authors.forename: Ana Valeria B
authors.initials: AV
authors.lastname: Castro
authors.forename: Orison O
authors.initials: OO
authors.lastname: Woolcott
authors.forename: Darko
authors.initials: D
authors.lastname: Stefanovski
authors.forename: Malini S
authors.initials: MS
authors.lastname: Iyer
authors.forename: Josiane L
authors.initials: JL
authors.lastname: Broussard
authors.forename: Hasmik
authors.initials: H
authors.lastname: Mkrtchyan
authors.forename: Miguel
authors.initials: M
authors.lastname: Burch
authors.forename: Ram
authors.initials: R
authors.lastname: Elazary
authors.forename: Erlinda
authors.initials: E
authors.lastname: Kirkman
authors.forename: Richard N
authors.initials: RN
authors.lastname: Bergman
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002395:Catecholamines / Q000378:metabolism; D003714:Denervation / Q000379:methods*; D004285:Dogs; D004837:Epinephrine / Q000097:blood; D005947:Glucose / Q000378:metabolism; D015309:Glucose Clamp Technique; D006706:Homeostasis; D006854:Hydrocortisone / Q000378:metabolism; D007003:Hypoglycemia / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D007328:Insulin / Q000378:metabolism; D008297:Male; D009638:Norepinephrine / Q000097:blood; D011169:Portal Vein / Q000294:innervation* / Q000378:metabolism / Q000473:pathology*; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D002395:Catecholamines; D007004:Hypoglycemic Agents; D007328:Insulin; D005947:Glucose; D006854:Hydrocortisone; D009638:Norepinephrine; D004837:Epinephrine