Effect of Monosodium Glutamate on Some Endocrine Functions

Abstract

Neonatal female and male rats of the Sprague-Dawley strain were injected subcutaneously with a daily dose of MSG (2.2–4.2 mg/g body wt.) beginning on the 2nd day of life. The rats were autopsied at 40 and 110 days of age. At 40 days of age, the body weight and nasoanal lengths were significantly reduced in the MSG-treated rats. At 110 days, the body lengths of MSG-treated rats were approximately 10–12% shorter than those of control rats, and calculation of the ‘Lee’ index indicated a significant increase in carcass fat. Food consumption studies, carried out at 75 days of age, showed a significant hypophagia in some MSG-treated rats. Upon autopsy at 40 days of age, the absolute weights of the thyroid and adrenal glands of both sexes were significantly decreased from those of control rats; but when corrected for body weight, these differences were marginal. At 110 days, the absolute weights of the adrenal and thyroid glands of both sexes were significantly reduced from their respective control levels. Gonadal weights of MSG-treated rats were significantly reduced at 40 and 110 days of age. Size and weight of the anterior pituitary glands of both male and female MSG-treated rats were significantly reduced from control values. There was a marked decrease in growth hormone and luteinizing hormone content in the anterior pituitaries of male and female MSG-treated rats at 40 days. However, thyrotropin content of the anterior pituitary of MSG-treated male rats did not show any significant change from control levels at 40 days of age.

Serum luteinising hormone, testosterone and total cholesterol levels, libido and testicular histomorphology of male West African Dwarf goats orally or subcutaneously treated with monosodium l-glutamate

“…This finding is in agreement with the reports of Adamo and Ratner (1970) and Fernstrom (2000) who administered a 4 g/kg body weight single treatment to rats, but differs from that of Tafelski and Lamperti (1977) who administered 8 g/kg body weight to hamsters. It is thought that the possible reasons why Tafelski and Lamperti Redding et al (1971) who recorded a decrease in the pituitary content of LH in rats treated with MSG. It is thought that the significantly lower serum LH recorded in the MSG-treated groups at Days 14 and 28 of MSG administration may be as a result of reduced gonadotrophin-releasing hormone (GnRH) associated with the lesions on the arcuate nucleus of the hypothalamus that occurs in animals given MSG (Palkovits et al 1974;Pizzi et al 1977;Hawkins et al 1995;Raiten et al 1995;Igwebuike et al 2010;Igwebuike et al 2011).…”

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

“…In the MSG-treated mature animals, reduction of the growth hormone (6-8) and thyroid hormone (5)(6)(7)(8)(9) in the blood as well as an imbalance in the autonomic nervous system (5-9) were reported. Moreover, irreversible hypothalamic lesions by MSG histologically were manifested immediately after the treatment (18,19), suggesting possible functional disturbance in the hypothalamus-hypophysis system and a subsequent functional imbalance in the nervous, endocrine and metabolic systems.…”

“…In the same report, he mentioned that the animals with MSG-induced hypothalamic lesions became apparently obese in and after adolescence even without hyperphagia and that these MSG-induced obese animals remained short throughout their lives (1)(2)(3)(4). MSG-induced obese animals have been mainly investigated biochemically in order to clarify the mechanism of obesity (5)(6)(7)(8)(9) In the present study, the growth pattern of the visceral organs together with the changes in body weight gain, morphological findings and cell proliferative kinetics was investigated in MSG-induced obese mice. …”

Impact of transient correction of increased adrenocortical activity in hypothalamo-damaged, hyperadipose female rats

“…[1][2][3] MSG-induced partial hypothalamic denervation alters several neuroendocrine-metabolic functions. It has been proposed that early loss of hypothalamic neurotransmitters induced by MSG, namely in the ARC, 1,4,5 is responsible for such abnormalities. Among these, MSG animals develop a number of morphological, behavioral, and endocrine abnormalities.…”