The hypothalamic paraventricular nucleus and carotid receptors modulate hyperglycemia induced by hemorrhage.
The aim of this study was to assess the role of cholinergic transmission in the paraventricular nucleus of the hypothalamus (PVN) and carotid body receptors in mediating a rise in plasma glucose levels in response to hemorrhagic hypotension in rats. Methylatropine (1x10(-9) mol) or 0.15 M NaCl (0.2 microl) was injected into the PVN of Wistar rats weighing 250-300 g bearing a chronic jugular catheter for blood sampling and hemorrhage (1.2 ml/100 g/2 min). Polyethylene cannulae (PE-10) were inserted into the left femoral artery for cardiovascular monitoring. In the other experimental protocol, hemorrhage was performed on rats submitted to bilateral carotid receptor denervation (H-CD). The results show that the hyperglycemic response to hemorrhage was decreased by either methylatropine (H-MA) treatment or bilateral carotid receptor denervation (10.3+/-0.4 mM, control, n=15 vs. 7.7+/-0.2 mM, H-MA, n=12, and 7.6+/-0.3 mM, H-CD, n=5, p<0.01). Furthermore, methylatropine did not affect the recovery of blood pressure after hemorrhage-induced hypotension, suggesting that the metabolic and pressor adjustments have different efferent pathways. Our data demonstrate that cholinergic input from the PVN and carotid receptors (chemo- and/or baroreceptors) might participate in the same neural pathway activated by hemorrhage-induced hypotension that produces hyperglycemia.
Silveira
Simonton Andrade
SA
Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, ICB-UFMG, 6627 Av. Antonio Carlos, 31270-901 Belo Horizonte, MG, Brazil.
Viana Lima
Nilo Resende
NR
Haibara
Andréa Siqueira
AS
Coimbra
Cândido Celso
CC
D000818:Animals; D001286:Atropine Derivatives; D001786:Blood Glucose / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D002339:Carotid Arteries; D002344:Carotid Body / Q000503:physiopathology*; D003714:Denervation / Q000379:methods; D006339:Heart Rate / Q000187:drug effects; D006470:Hemorrhage / Q000139:chemically induced / Q000150:complications*; D006943:Hyperglycemia / Q000139:chemically induced / Q000209:etiology*; D008297:Male; D008845:Microinjections / Q000379:methods; D008954:Models, Biological; D010286:Paraventricular Hypothalamic Nucleus / Q000503:physiopathology; D051381:Rats; D017208:Rats, Wistar; D012965:Sodium Chloride / Q000494:pharmacology; D013223:Statistics as Topic; D013997:Time Factors
D001286:Atropine Derivatives; D001786:Blood Glucose; D012965:Sodium Chloride; C006649:methylatropine