Morphological and cell proliferative study on the growth of visceral organs in monosodium L-glutamate-treated obese mice.

Abstract

SummaryThe growth pattern of visceral organs was investigated in monosodium L-glutamate (MSG)-treated obese mice with hypothalamic lesions. Male Jcl-ICR strain mice were subcutaneously injected with MSG, 2mg/g of body weight daily, for five days after birth. The MSG-treated mice became obese after 4 weeks of age. According to patterns of weight gain compared with those in the control mice, the visceral organs in the MSG-treated mice were classified into three groups as follows: The first group of organs (heart, lungs, spleen, pancreas, kidneys, testes, brain and submandibular glands) remained absolutely lower in weight throughout their growth. The second group of organs (liver and stomach) was low in weight until 12 weeks of age, but became identical to that of the control mice after 16 weeks of age. The third group of organs (epididymal fat, small intestine and colon) showed lower weight until 4 weeks of age and were significantly heavier than those in the control mice after 8 weeks of age. The heart in the first group of organs apparently had hypertrophic muscle cells after 8 weeks of age and became significantly hypoplastic due to decreased cell production as was revealed by the continuous suppression of mitotic activity and DNA synthesis by [3H]thymidine autoradiography. The liver in the second group of organs became significantly hypoplastic due to decreased cell production and showed the same weight with the control mice due to the development of fatty liver. The small intestine in the third group of organs became hypoplastic due to decreased cell production in the crypts until 4 weeks of age, and became hypertrophic and hyperplastic by the acceleration of cell production in the crypts from 4 to 8 weeks of age. From these findings, in the MSG-treated mice with specific growth patterns of visceral organs, it is suggested that low energy expenditure results in a relatively excessive energy supply and leads to obesity, because most of the important organs with major physiological functions became 395

Effects of the neonatal treatment with monosodium glutamate on myenteric neurons and the intestine wall in the ileum of rats

“…30 Body weight and nasoanal length were reduced in the MSG group. Smaller weight and corporal length, 9,[15][16][17][18]29,31 a higher Lee's index, 9,14,15,18,19,22 and higher weights of the periepididimal and retroperitoneal adipose tissues [16][17][18]20 are characteristic of this obesity model.…”

“…Obesity in the adult rats of the MSG group was confirmed by higher values of Lee's index and by higher weights of periepididimal and retroperitoneal adipose tissues, results that are also in agreement with previous findings. 7,11,[14][15][16][17][18][19][20]29 The obesity in this experimental model is due to the interference of the glutamate with the maturation of the hypothalamic nuclei, which regulate energy homeostasis. There is a consensus that the arcuate nucleus lesion is responsible for metabolic alterations related to the accumulation of energy.…”

“…One study reported no change in the intestinal villi in the jejunum of rats, but a possible acceleration of intestinal absorption due to hyperplasia, verified in the crypts of rats more than 8 weeks of age, was pointed out. 14 The possibility that these functional adaptations of the intestine are mechanisms that maintain obesity in this experimental model 17,20 led us to perform morphometric measurements of elements of the ileum wall of adult rats treated with MSG in the neonatal period.…”

“…neonatally with MSG. 7,8,11,[14][15][16][17][18][19][20] MSG-induced obesity may or may not be accompanied by an increase in food intake. There are reports of normophagia, 11,21,22 hyperphagia, 21 and hypophagia.…”

Efeito da indução de obesidade neuroendócrina sobre a hemodinâmica sistêmica e a função ventricular esquerda de ratos normotensos

“…Além do mais, nesses animais, também há menor sensibilidade aos efeitos anabólicos da insulina (23). Achados semelhantes aos nossos já foram relatados em outros estudos (24,25), confirmando que o tratamento com MSG pode se acompanhar de redução da massa de ventrí-culo esquerdo.…”