Protein malnutrition modifies medullary neuronal recruitment in response to intermittent stimulation of the baroreflex.
Protein malnutrition after weaning changes the neurotransmission in neural pathways that organize cardiovascular reflexes in rats. The present study evaluates whether protein malnutrition alters the expression of c-fos protein (immediate-early gene expression) in central areas involved in the control of cardiovascular reflexes after intermittent stimulation of the baroreflex. The main nuclei we focused were paraventricular hypothalamus (PVH); nucleus tract solitarii (NTS); rostral ventromedial medulla (RVMM); rostral (RVLM) and caudal ventrolateral medulla (CVLM). Male Fisher rats at 28 days were submitted to two different isocaloric diets during the subsequent 35 days: control (CT) (15% protein) and malnourished (MN) (6% protein). thirtymin of intermittent (every 3 min) baroreflex stimulation was performed by infusing phenylephrine (Phe-0.25 mM) or, as control, 0.9% NaCl (Sal). Following ninety minutes, animals were anesthetized and perfused. The removed brains were sectioned (35 μm) and used for c-fos immunohistochemistry. Images were analyzed using the software Leica Q Win. Despite not altering the baseline MAP, malnutrition increased baseline HR and expression of c-fos in RVMM. Increases in c-fos expression after intermittent stimulation of baroreflex were evident in the PVH, medial NTS and CVLM in both dietary protocols. Current data further revealed a differential neuronal recruitment to stimulation of baroreflex in the caudal commissural and rostral NTS and RVLM of MN. We conclude that protein malnutrition modifies the cardiovascular control and the pattern of central response to baroreflex stimulation.
Department of Biological Sciences, Institute of Exact and Biological Sciences, Federal University of Ouro Preto-UFOP, Ouro Preto, MG 35400-000, Brazil.
Míriam Carmo
MC
Rodrigues-Barbosa
Cláudia Martins
CM
Carneiro
Lisandra Brandino
LB
de Oliveira
Fernanda Cacilda Santos
FC
Silva
Carlos Henrique
CH
Xavier
Luciano
L
Gonçalves Fernandes
Deoclécio Alves
DA
Chianca
D000704:Analysis of Variance; D000818:Animals; D017704:Baroreflex / Q000187:drug effects / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D004195:Disease Models, Animal; D006339:Heart Rate / Q000502:physiology; D008297:Male; D044342:Malnutrition / Q000473:pathology* / Q000503:physiopathology; D008526:Medulla Oblongata / Q000473:pathology*; D009474:Neurons / Q000473:pathology*; D010656:Phenylephrine / Q000494:pharmacology; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D016760:Proto-Oncogene Proteins c-fos; D014662:Vasoconstrictor Agents; D010656:Phenylephrine