O efeito da fenilhidrazina sobre a obesidade induzida por glutamato monossódico (MSG)

Abstract

Obesity is characterized by an increase in fat mass, accompanied by a chronic inflammatory state, which has deleterious effects on iron homeostasis, a condition that seems to be related to maladjustments in the availability and recycling of iron, involving the liver and splenic tissue. Obese individuals have a higher incidence of anemia, so our question was trying to find out if the administration of an anemic agent could aggravate the pathophysiology of hypothalamic obesity? Thus, our objective was to evaluate the effect of the administration of the anemic agent phenylhydrazine (FHZ) on the adiposity and metabolic state of rats with hypothalamic obesity induced by monosodium glutamate. For this purpose, obesity was induced by the administration of monosodium glutamate (MSG; 4g/kg) in the neonatal period (n=20 male rats). In the same period, control rats (CON) received equimolar saline (n=20 male rats). At 70 days of life, part of CON and MSG animals received administration of FHZ (40mg/Kg) or saline (SAL; 0.9%) in three doses (0 h, 24 h, 32 h) forming four subgroups: CONSAL: saline control rats; CONFHZ: control rats treated with phenylhydrazine; MSGSAL: rats treated with monosodium glutamate receiving saline; MSGFHZ: rats treated with monosodium glutamate receiving phenylhydrazine (n=10/rats/group). From 72 to 90 days of life, body weight (g) and food intake (g/g) of all groups were evaluated. At 92 days of life, and after 12 hours of fasting, the animals were euthanized, blood was collected and plasma separated for biochemical analysis of iron, glucose, triglycerides and total cholesterol, as well as blood was collected in micro capillaries for analysis of the hematocrit (Hct). The White Adipose Tissue (TAB) deposits, as well as the Brown Adipose Tissue (TAM), spleen and liver were removed, cleaned and weighed, for histological analysis. The data went through the assumptions of normality and homoscedasticity, with the comparison between two groups made using the Student's t test, while the two-way Anova test with Tukey's post-test was used foranalyzes of four groups (p<0.05). Treated MSG rats showed higher adiposity, insulin resistance and hypertriglyceridemia, with normal levels of Hct and plasma iron compared to CON rats. MSGFHZ and CONFHZ rats showed reduced hematocrit and circulating iron as well as increased spleen weight, confirming the onset of hemolytic anemia. However, in the MSGFHZ group a greater impact was found on Hct and glycemia, with repercussions on adiposity. Thus, lower levels of subcutaneous TAB and TAM, associated with area reduction and fat deposition were found in MSGFHZ rats compared to the other groups. Therefore, MSG-obese rats do not show changes in Hct and plasma iron concentrations, being able to respond to the induction of hemolytic anemia, without worsening the metabolic state. However, anemia in these animals causes greater deleterious effects on Hct and blood glucose, resulting in a marked decrease in white and brown fat mass, suggesting a greater lipolytic effect.