title: Role of autonomic nervous system in chronic CNS-mediated antidiabetic action of leptin.
abstract: This study tested whether ganglionic blockade or hepatic vagotomy attenuates the chronic central nervous system (CNS)-mediated antidiabetic and cardiovascular effects of leptin. Male Sprague-Dawley rats were instrumented with telemetry probes and arterial and venous catheters for determination of blood pressure (BP), heart rate (HR), blood sampling, and intravenous (iv) infusions. An intracerebroventricular (ICV) cannula was placed into the brain lateral ventricle for infusion of leptin or vehicle. After control measurements, streptozotocin (STZ) was injected iv (50 mg/kg) to induce diabetes, and 5 days later leptin (n= 6) or saline vehicle (n= 5) was infused ICV for 12 days via osmotic pumps. Beginning onday 6of leptin treatment, the ganglionic blocker hexamethonium (15 mg·kg-1·day-1iv) was infused, while leptin infusion was continued, to assess the role of the autonomic nervous system. Induction of diabetes was associated with increases in blood glucose (98 ± 7 to 350 ± 19 mg/dl), food intake (23 ± 3 to 43 ± 3 g/day), decreases in HR (-70 ± 11 beats/min), polyuria, and increased water consumption, which were all completely normalized by ICV leptin infusion. Although hexamethonium attenuated leptin's effect on HR, it failed to impair leptin's ability to restore euglycemia or to prevent the polyuria or increased water intake in STZ-diabetic rats. We also found that after pretreatment with hexamethonium (n= 8), ICV leptin infusion, during continued ganglionic blockade, completely normalized blood glucose in diabetic rats. In addition, selective hepatic vagotomy did not attenuate leptin's ability to restore euglycemia in diabetic rats. These results suggest that leptin's powerful chronic CNS antidiabetic actions are mediated primarily via nonautonomic mechanisms.
authors.affiliation: Department of Physiology and Biophysics, Mississippi Center for Obesity Research, Cardiovascular-Renal Research Center, University of Mississippi Medical Center, Jackson, Mississippi; and.|Barão de Mauá University Center, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Alexandre A
authors.initials: AA
authors.lastname: da Silva
authors.affiliation: Department of Physiology and Biophysics, Mississippi Center for Obesity Research, Cardiovascular-Renal Research Center, University of Mississippi Medical Center, Jackson, Mississippi; and.
authors.forename: John E
authors.initials: JE
authors.lastname: Hall
authors.affiliation: Department of Physiology and Biophysics, Mississippi Center for Obesity Research, Cardiovascular-Renal Research Center, University of Mississippi Medical Center, Jackson, Mississippi; and.
authors.forename: Sydney P
authors.initials: SP
authors.lastname: Moak
authors.affiliation: Department of Physiology and Biophysics, Mississippi Center for Obesity Research, Cardiovascular-Renal Research Center, University of Mississippi Medical Center, Jackson, Mississippi; and.
authors.forename: Jackson
authors.initials: J
authors.lastname: Browning
authors.affiliation: Department of Physiology and Biophysics, Mississippi Center for Obesity Research, Cardiovascular-Renal Research Center, University of Mississippi Medical Center, Jackson, Mississippi; and.
authors.forename: Haley J
authors.initials: HJ
authors.lastname: Houghton
authors.affiliation: Barão de Mauá University Center, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Giovana C
authors.initials: GC
authors.lastname: Micheloni
authors.affiliation: Department of Physiology and Biophysics, Mississippi Center for Obesity Research, Cardiovascular-Renal Research Center, University of Mississippi Medical Center, Jackson, Mississippi; and jdocarmo@umc.edu.
authors.forename: Jussara M
authors.initials: JM
authors.lastname: do Carmo
mesh_terms: D000818:Animals; D001341:Autonomic Nervous System / Q000187:drug effects / Q000503:physiopathology*; D001794:Blood Pressure / Q000187:drug effects*; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D003920:Diabetes Mellitus / Q000188:drug therapy* / Q000503:physiopathology*; D006339:Heart Rate / Q000187:drug effects*; D020738:Leptin / Q000008:administration & dosage* / Q000493:pharmacokinetics; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D016896:Treatment Outcome
chemical_list: D020738:Leptin
keywords: blood pressure; diabetes mellitus; glucose; heart rate; parasympathetic; sympathetic