Acta Cirurgica Brasileira
On-line version ISSN 1678-2674
SOUZA, Fernando de et al. Effect of vagotomy in rats neonatally injected with monosodium glutamate: biometry study. Acta Cir. Bras. [online]. 2001, vol.16, n.1, pp. 32-45. ISSN 1678-2674. http://dx.doi.org/10.1590/S0102-86502001000100006.
The hypothalamus and autonomic nervous system exert strong influence in food intake. Hypothalamic lesion could cause neuroendocrine obesity. Hypothalamic obesity could be reproduced through ventromedial hypothalamic lesion in animals and attenuated that by subdiafragmatic vagotomy (VT). VT decreased food intake and insulinemia. Injection of monosodium glutamate (MSG) neonatally in rats produces adiposity, hyperphagia, without weight gain because it injures arcuate nucleus of the hypothalamus, site of growth hormone releasing hormone production. The purpose of this paper is to evaluate the MSG effect on weight, stature, Lee index (3 square root body weight/nasoanal length), gonadal fat (GF) and food intake in rats and the VT effect on these parameters. Fifty-two male Wistar rats were used, divided into two groups of twenty-six animals each. SALINA group was subcutaneously injected with saline solution 12.5% (1.25 mg/g body weight/dayly/5days) and MSG group was injected with MSG solution 24% (4 mg/g body weight/dayly/5 days), after the rats were born, in the posterior cervical region without adverse reaction. On the 30th day of life, the animals were divided into four groups and submitted to operation, sham operated groups (LAPSAL and LAPMSG) and vagotomized groups (VTSAL and VTMSG). On operation day, weight, nasoanal length (NAL) and Lee index were obtained. Food intake were obtained from the 30th day until 90th day. On 90th day, the animals were sacrificed and weight, NAL, Lee index and GF were obtained. Statistic analysis was performed by the Students t test. NAL was smaller and Lee index was greater in MSG group than in SALINA group on the 30th day. Weight gain and NAL were smaller and Lee index and GF were greater on the 90th day, and food intake from the 30th to 90th day period was greater in LAPMSG group than in LAPSAL group. Weight gain, Lee index and GF were smaller and NAL trended smaller in VTMSG group than in LAPMSG group on the 90th day. Food intake from the 30th to 60th day period was smaller and trended greater from the 60th to 90th day period in VTMSG group than in LAPMSG. Vagal regeneration could explain that food intake inversion. These results suggest that MSG injected neonatally increases food intake and adiposity, and decreases stature and weight gain from the 30th to 90th day period. VT performed on the 30th day decreases food intake in first 30 days and decreases weight gain, Lee index and GF in MSG injected rats.
Keywords : Obesity; Rats; MSG; Vagotomy.