Monosodium glutamate neonatal treatment induces cardiovascular autonomic function changes in rodents.
OBJECTIVE
The aim of this study was to evaluate cardiovascular autonomic function in a rodent obesity model induced by monosodium glutamate injections during the first seven days of life.


METHODS
The animals were assigned to control (control, n = 10) and monosodium glutamate (monosodium glutamate, n = 13) groups. Thirty-three weeks after birth, arterial and venous catheters were implanted for arterial pressure measurements, drug administration, and blood sampling. Baroreflex sensitivity was evaluated according to the tachycardic and bradycardic responses induced by sodium nitroprusside and phenylephrine infusion, respectively. Sympathetic and vagal effects were determined by administering methylatropine and propranolol.


RESULTS
Body weight, Lee index, and epididymal white adipose tissue values were higher in the monosodium glutamate group in comparison to the control group. The monosodium glutamate-treated rats displayed insulin resistance, as shown by a reduced glucose/insulin index (-62.5%), an increased area under the curve of total insulin secretion during glucose overload (39.3%), and basal hyperinsulinemia. The mean arterial pressure values were higher in the monosodium glutamate rats, whereas heart rate variability (>7 times), bradycardic responses (>4 times), and vagal (~38%) and sympathetic effects (~36%) were reduced as compared to the control group.


CONCLUSIONS
Our results suggest that obesity induced by neonatal monosodium glutamate treatment impairs cardiac autonomic function and most likely contributes to increased arterial pressure and insulin resistance.
Basic Health Sciences Institute, Physiology Department, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre/RS, Brazil.
Signorá Peres
SP
Konrad
Vera
V
Farah
Bruno
B
Rodrigues
Rogério Brandão
RB
Wichi
Ubiratan Fabres
UF
Machado
Heno Ferreira
HF
Lopes
Beatriz
B
D'Agord Schaan
Kátia
K
De Angelis
Maria Cláudia
MC
Irigoyen
D000818:Animals; D000831:Animals, Newborn; D062186:Arterial Pressure / Q000187:drug effects; D001341:Autonomic Nervous System / Q000187:drug effects* / Q000503:physiopathology; D002320:Cardiovascular Physiological Phenomena / Q000187:drug effects*; D004195:Disease Models, Animal; D005503:Food Additives / Q000009:adverse effects*; D006321:Heart / Q000187:drug effects* / Q000503:physiopathology; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D008297:Male; D009765:Obesity / Q000139:chemically induced* / Q000503:physiopathology; D051381:Rats; D017208:Rats, Wistar; D012970:Sodium Glutamate / Q000009:adverse effects*; D013997:Time Factors
D005503:Food Additives; D007328:Insulin; D012970:Sodium Glutamate