Monosodium glutamate daily oral supplementation: study of its effects on male reproductive system on rat model

Abstract

Monosodium glutamate (MSG) is widely used in food preparation industry and has been consumed regularly. Previous studies had reported on effects of MSG when given at extremely high dosages, the results are not applicable to human equivalent intake. Therefore, the present study aimed to evaluate the effect of MSG on sperm quality and changes in reproductive organs of adult male rats when taken at average human daily intake (ADI). Twenty-four adult male rats were randomly assigned into three groups; NC (Normal control), MSG60 and MSG120 where MSG was given orally at 60 mg/kg and 120 mg/kg to each respective group. All treatments were conducted for 28 consecutive days. MSG at estimated ADI of 120 mg/kg body weight resulted in a significant drop in sperm quality (p < 0.05) when compared to both control and MSG60 groups. A significant decrease in the weight of reproductive organs was also apparent (p < 0.05). Moreover, oxidative status evaluation showed that treatment of MSG induces oxidative stress in the testis, more severely at a dose of 120 mg/kg body weight. These findings are supported by alterations in the observed histology of reproductive organs. This study shows that an intake dose of 120 mg/kg body weight MSG could cause significant damage to the reproductive system.

Antioxidant and cytoprotective effects of Nigella sativa L. seeds on the testis of monosodium glutamate challenged rats

“…Although apoptosis is an essential prerequisite in maintaining the population of Leydig cells and testosterone levels 50 increased apoptosis leads to decline in testosterone production, which may increase germ cell apoptosis and the possibility of infertility 51 . However, other studies showed insignificant changes in testosterone levels following MSG challenge 7 , 52 . This differential response may be due to difference in the experimental design including the dose and duration of exposure.…”

“…This experimental schedule did not lead to permanent infertility, but the normal morphology of the testis would need a long time to be regained 9 . A dose-dependent differences in the response of reproductive hormone, testicular oxidative status and semen characteristics were noticed in a rat model compromised by MSG indicating that daily oral intake of the higher dose (120 mg/kg BW) for 28 days caused a significant damage to the reproductive performances 7 . Oral supplementation of rats at two age groups with three gradual doses of MSG every 48 h for 6 weeks adversely affected spermatogenesis by disrupting the hypothalamic-pituitary gonadal regulatory axis without direct cyto-toxicological effect on the testis 10 .…”

“…Ingestion of MSG only results in a transient increase in plasma glutamate level, because glutamate is well tolerated by the body through the neutralizing actions of some nutritional substrates intake in concomitant with food-incorporated MSG 5 , 6 . Nevertheless, presence of high amount of MSG in the processed foods 7 could predispose to health hazards. Several biological systems are sensitive to the high doses of MSG; however, the reproductive system is considered to be its primary target.…”

“…Several biological systems are sensitive to the high doses of MSG; however, the reproductive system is considered to be its primary target. This is owing to abundance of glutamate receptors 7 and polyunsaturated fatty acids and low content of antioxidant reserve 8 in seminiferous tubules (ST) and spermatozoa, making them more susceptible to its peroxidative and excitatory damage. Plenty of controversies still emerged about its testicular toxicity relative to differences in the age of experimental model, the dose of MSG and the duration of exposure providing a driving force for continuation in exploring this area of research with respect to the multifactorial nature of testicular impairment.…”

“…Its suppressive effect on hypothalamic–pituitary–gonadal axis adds another dimension by disrupting the hormonal commanding mechanisms. It has deteriorating effects on the oxidative status and histo-architecture of testis 7 along with its ability to trigger apoptosis in the germ cells 1 .…”