Effect of l -NAME microinjected into the nucleus tractus solitarius on jejunal glucose and electrolyte absorption in anesthetized rats

• Published in: Brain research Vol. 1359; pp. 107 - 115
• Main Authors: Nogueira, Marcelo Coelho, Haibara, Andréa Siqueira, Borges, Elizabeth Lage
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 04-11-2010; Elsevier
• Subjects: Animals; Autonomic nervous system; Autonomic Nervous System - drug effects; Autonomic Nervous System - physiology; Biological and medical sciences; Electrolytes - metabolism; Enzyme Inhibitors - pharmacology; Fundamental and applied biological sciences. Psychology; Glucose - metabolism; Jejunum - metabolism; Male; Microinjections; Neurology; NG-Nitroarginine Methyl Ester - pharmacology; Nitric oxide; Nitric Oxide - metabolism; Peripheral nervous system. Autonomic nervous system. Neuromuscular transmission. Ganglionic transmission. Electric organ; Rats; Rats, Wistar; Solitary Nucleus - drug effects; Solitary Nucleus - metabolism; Sympathectomy; Vagotomy; Vertebrates: nervous system and sense organs; NO; nitric oxide; heart rate; GLUT2; l-NAME; glucose transporter 2; SGLT1; mean arterial pressure; nucleus tractus solitarius; HR; NTS; vasoactive intestinal peptide; NOS; N G-nitro- l-arginine-methyl-ester; Autonomic nervous system; VLM; ventrolateral medulla; nitric oxide synthase; VIP; MAP; sodium/glucose co-transporter 1; Nitric oxide; Rat; Rodentia; Central nervous system; Glucose; Encephalon; Solitary nucleus; Vertebrata; Mammalia; Absorption; Electrolyte; Animal
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2010.08.079

Abstract The aim of the present study was to investigate the effects of NG -nitro- l -arginine-methyl-ester ( l -NAME) microinjected into the rostral nucleus tractus solitarius (NTS) on jejunal glucose, sodium and potassium absorption. Male Wistar rats (210–250 g, n = 6–12) were anesthetized and submitted to midline laparotomy to expose and isolate 20 cm of jejunal loop and perform a subdiaphragmatic truncal vagotomy or sympathectomy. Either 0.9% NaCl or l -NAME (10 nmol 100 nl − 1 ) was microinjected into the rostral NTS using a stereotaxic instrument. Tyrode solution (pH 8) containing twice the usual concentrations of glucose, sodium and potassium was infused (0.5 ml min−1 ) into the jejunal loop and samples were taken at 10-min intervals during the 40-min experiment. Results were expressed by the difference between influx and efflux. l -NAME into the NTS increased glucose absorption and decreased potassium absorption when compared to the saline group (38.8 ± 3.8 vs. 50.3 ± 3.3 mg/dl and 0.6 ± 0.01 vs. 0.4 ± 0.03 mM, respectively; p < 0.05). Sympathectomy inhibited the glucose absorption caused by l -NAME alone (50.3 ± 3.3 vs. 30.7 ± 4.6 mg/dl; p < 0.05), whereas vagotomy inhibited the l -NAME effect on potassium absorption (0.40 ± 0.02 vs. 0.70 ± 0.05; p < 0.05). Moreover, increased sodium absorption was observed only in the group that received 30 nmol of l -NAME into NTS (33.0 ± 4.2 vs. 48.4 ± 3.9). In conclusion, the results suggest the participation of endogenous nitric oxide (NO) in the NTS in modulating intestinal glucose and potassium absorption mediated by the autonomic nervous system.