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

Disruptive consequences of monosodium glutamate on male reproductive function: A review

Monosodium glutamate (MSG) is one of the most extensively used flavour enhancers worldwide. Although it is widely regarded as a safe food additive with no recommended daily dosage, its over-consumption has been associated with notably pathophysiological events in various tissues and organs of the body. Previous studies have reported of the neuro- cardio- and hepato- toxic effects of its excessive exposure. Moreover, the food additive instigates metabolic dysfunction. It has been established that MSG damages male reproductive accessory organs like prostate glands and epididymis. In addition, it impairs serum enzymatic activities and serum levels of testosterone, gonadotropin-releasing hormone, luteinizing hormone and cholesterol. Reduced sperm count, sperm motility, sperm morphology, and sperm viability, imbalances in male reproductive hormones, alongside alteration in the histoarchitecture of the testes and other male reproductive tissues have also been connected with excessive exposure to MSG. Literature reports affirm the link between the over-consumption of MSG and reproductive organ weight and male sexual behaviour. This review article addresses the multi-systemic effects of exposure to MSG and the possible mechanism of action of the compound with a focus on the negative implications of the food additive on male reproductive functions and the possible role of natural antioxidants in male reproductive functions. carefully selected keywords were used during the literature search to gather credible and up-to-date information about the subject matter.

The Effects of Apocynin on Monosodium Glutamate Induced Liver Damage of Rats

Monosodium glutamate (MSG) is found in refined foods. Apocynin (APO) is a selective NADPH oxidase (NOX) inhibitor. The aim of this experimental study was to investigate possible effects of MSG and the curative effects of APO in rats. Twenty-eight male Sprague-Dawley rats were randomly divided into four groups (Normal control, APO, MSG and MSG + APO, n:7 for each group). The MSG and MSG + APO groups received 120 mg/kg MSG solution orally for 28 consecutive days. The APO and MSG + APO groups received 25 mg/kg APO solution orally for 5 days until the end of the experiment. At the end of the experiment, all rats were sacrificed and liver tissue and blood samples were taken for histological, ultrastructural, and biochemical analyses. In the MSG group, vacuolization and loss in glycogen content in the hepatocytes, leukocyte infiltration and fibrosis in the liver parenchyme and portal triads, were observed. Terminal deoxynucleotidyl transferase dUTP (TUNEL)-positivity and NADPH oxidase (NOX)-2-positivity were higher in the MSG group compared with the other experimental groups. The concentrations of alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), total bilirubin, malondialdehyde (MDA), and myeloperoxidase (MPO) were higher, whereas albumin, glutathione (GSH), and superoxide (SOD) levels were lower in the MSG group. All these data has been reversed in MSG + APO group. The histological and biochemical criteria indicated the prominent ameliorating effect of APO on MSG -induced liver injury.

Apocynin Ameliorates Monosodium Glutamate Induced Testis Damage by Impaired Blood-Testis Barrier and Oxidative Stress Parameters

BACKGROUND

the aim of this study was to investigate the effects of apocynin (APO) on hormone levels, the blood-testis barrier, and oxidative biomarkers in monosodium glutamate (MSG) induced testicular degeneration.

METHODS

Sprague Dawley male rats (150-200 g; n = 32) were randomly distributed into four groups: control, APO, MSG, and MSG + APO. MSG and MSG + APO groups were administered MSG (120 mg/kg) for 28 days. Moreover, the APO and MSG + APO groups received APO (25 mg/kg) during the last five days of the experiment. All administrations were via oral gavage. Finally, biochemical analyses were performed based on the determination of testosterone, follicle-stimulating hormone (FSH), luteinizing hormone (LH), malondialdehyde (MDA), glutathione (GSH), and superoxide dismutase (SOD), as well as light and transmission electron microscopic examinations, assessment of sperm parameters, ZO-1, occludin, NOX-2, and TUNEL immunohistochemistry were evaluated.

RESULTS

MSG increased both the oxidative stress level and apoptosis, decreased cell proliferation, and caused degeneration in testis morphology including in the blood-testis barrier. Administration of apocynin reversed all the deteriorated morphological and biochemical parameters in the MSG + APO group.

CONCLUSIONS

apocynin is considered to prevent testicular degeneration by maintaining the integrity of the blood-testis barrier with balanced hormone and oxidant/antioxidant levels.

Testicular Effect of Selenium Nanoparticles on Monosodium Glutamate Induced Alteration in Male Albino Rats

<b>Background and Objective:</b> The flavor enhancer Monosodium Glutamate (MSG) is mostly utilized in Asian and West African cuisines, especially in West African and Asian dishes. However, due to its availability, largely without labeling, in many food products, unintentional overuse of this food additive may occur. The objective of this study was to find out how selenium nanoparticles affected the toxicity of MSG in male albino rats' testicles. <b>Materials and Methods:</b> As 35 Wistar male rats partitioned into 5 groups: G1: Control rats, G2: Received Se-NPs at 0.4 mg kg¹ b.wt., orally, G3: Injected with MSG at a daily dose of 4 g kg¹ b.wt., intraperitoneally (IP), G4: Ingested a daily oral dose of Se-NPs for 7 successive days and on the 7th day, received the first dose of MSG IP 4 g kg¹ b.wt., then received both treatments till the end of the study and G5: Administered a daily oral dose of 4 g kg¹ MSG, followed by Se-NPs at a daily dose of 0.4 mg kg¹ b.wt., the experiment continued for 28 days. Serum testosterone hormone, Follicle Stimulating Hormone (FSH), Luteinizing Hormone (LH), the levels of serum lipid peroxidation (MDA), reduced Glutathione (GSH), Glutathione Peroxidase (GSH-Px), superoxide dismutase (SOD) and Lactate Dehydrogenase (LDH) were estimated and samples from testis were separated for histological analysis. <b>Results:</b> The MSG treatment induced a significant decline in the values of serum testosterone, FSH, LH, GSH, GSH-Px and SOD. It also increased the values of serum MDA and LDH and spermatic arrest. While, the administration of Se-NPs orally before MSG treatment resulted in a decline in the values of serum MDA and LDH, an elevation in the values of serum GSH, GSH-PX and SOD, testosterone, FSH, LH and reappearance of sperm. <b>Conclusion:</b> The use of Se-NPs as a protector exhibited more improvement in values of estimated hormones and oxidative stress markers than using it as a therapy.

Effect of bromelain on sperm quality, testicular oxidative stress and expression of oestrogen receptors in bisphenol-A treated male mice

Bisphenol A (BPA) as an endocrine-disrupting chemical (EDC) with low estrogenic activity increases oxidative stress and testicular damage. Bromelain is a mixture of different thiol endopeptidases and other components with many uses as a natural anti-inflammatory enzyme. The present study aimed to evaluate the effect of bromelain on male reproductive failure induced by BPA. A total of 60 healthy adult male mice were randomly divided into six groups (n = 6), including control, bromelain (70 mg/kg), BPA (5 and 600 mg/kg), and BPA (5 and 600 mg/kg) + bromelain. BPA and bromelain were administrated orally for 35 days. Then, the epididymis and testes were removed to evaluate sperm parameters, oxidative stress markers, serum levels of testosterone concentrations, and oestrogen receptors expression. The BPA significantly (P < 0.05) decreased sperm count, motility, viability, and normal sperm morphology, as well as testosterone levels, oestrogen receptors alpha (ERα) and beta (ERβ), GPx, CAT, and SOD activity than control. Also, BPA significantly (P < 0.05) increased the sperm anomalies, and MDA concentration. Co-administration of bromelain + BPA caused a significantly (P < 0.05) increase sperm count, normal sperm morphology, testosterone levels, expression of ERα and ERβ, and GPx, CAT, and SOD activity than the BPA group (P < 0.05). Also, Bromelain significantly (P < 0.05) decreased sperm anomalies and MDA concentration than control. Based on the results of this study, it appears that BPA causes side effects on male reproduction. While, bromelain has the potential to reduce the side effects of BPA on the male reproductive system.

Apocynin reduces cytotoxic effects of monosodium glutamate in the brain: A spectroscopic, oxidative load, and machine learning study

Herein, we examined the modulatory effects ofApocynum (APO) on Monosodium Glutamate (MSG)-induced oxidative damage on the brain tissue of rats after long-term consumption of blood serum components by biochemical assays, Fourier transform infrared spectroscopy(FTIR), and machine learning methods. Sprague-Dawley male rats were randomly divided into the Control, Control + APO, MSG, and MSG + APO groups (n = 8 per group). All administrations were made by oral gavage saline, MSG, or APO and they were repeated for 28 days of the experiments. Brain tissue and blood serum samples were collected and analyzed for measurement levels ofmalondialdehyde (MDA),glutathione (GSH),myeloperoxidase (MPO), superoxide dismutase (SOD) activity, and Spectroscopic analysis. After 29 days, the results were evaluated using machine learning (ML). The levels of MDA and MPO showed changes in the MSG and MSG + APO groups, respectively. Changes in the proteins and lipids were observed in the FTIR spectra of the MSG groups. Additionally, APO in these animals improved the FTIR spectra to be similar to those in the Control group. The accuracy of the FTIR results calculated by ML was 100%. The findings of this study demonstrate that Apocynin treatment protectsagainst MSG-induced oxidative damage by inhibitingreactive oxygen speciesand upregulatingantioxidant capacity, indicating its potential in alleviatingthe toxic effects of MSG.

The protective effect of L-carnitine on testosterone synthesis pathway, and spermatogenesis in monosodium glutamate-induced rats

Background

Monosodium glutamate (MSG) is a food ingredient that is increasingly used commercially. MSG leads to oxidative stress, consequently suppressing steroid hormone production that causes defects in male reproductive system. This study aimed to evaluate the effect of L-carnitine as an antioxidant on testicular damage in MSG-induced male rats.

Methods

Sixty adult male Spargue-Dawley rats were randomly divided into six groups of ten as follows: control (water), sham (normal saline), L-carnitine (200 mg/kg b.w), MSG (3 g/kg b.w), MSG + L-carnitine 100 (3 g/kg b.w of MSG and 100 mg/kg b.w of L-carnitine), and MSG + L-carnitine 200 (3 g/kg b.w of MSG and 200 mg/kg b.w of L-carnitine). The treatment was administered by oral gavage for six months. Serum levels of Malondialdehyde (MDA), Total Anti-oxidant Capacity (TAC), LH, FSH, testosterone, and mRNA expressions of Star, Cyp11a1, and Hsd17b3 genes, and histological and stereological changes were assessed.

Results

L-carnitine led to a significant decrease in the level of MDA and a significant rise in the serum levels of TAC, LH, FSH, and mRNA expression of Star and Cyp11a1 compared to the MSG group (p < 0.05). Furthermore, stereological results indicated a significant increment in the number of sexual lineage cells, the total volume of the testis, length, diameter, and volume of seminiferous tubules, the height of the germinal epithelium, sperm count, and sperm motility (p < 0.05) in MSG + L-carnitine 200 compare to MSG group.

Conclusion

The study’s findings demonstrated that L-carnitine due to its anti-oxidant properties, ameliorated the reproductive abnormalities in the male rats exposed to MSG.

Bisphenol A and Its Analogues Deteriorate the Hormones Physiological Function of the Male Reproductive System: A Mini-Review

BPA is identified as an endocrine-disrupting chemical that deteriorates the physiological function of the hormones of the male reproductive system. Bisphenol F (BPF), bisphenol S (BPS), and bisphenol AF (BPAF) are actively explored as substitutes for BPA and are known as BPA analogues in most manufacturing industries. These analogues may demonstrate the same adverse effects as BPA on the male reproductive system; however, toxicological data explaining the male reproductive hormones' physiological functions are still limited. Hence, this mini-review discusses the effects of BPA and its analogues on the physiological functions of hormones in the male reproductive system, focusing on the hypothalamus-pituitary-gonad (HPG) axis, steroidogenesis, and spermatogenesis outcomes. The BPA analogues mainly show a similar negative effect on the hormones' physiological functions, proven by alterations in the HPG axis and steroidogenesis via activation of the aromatase activity and reduction of spermatogenesis outcomes when compared to BPA in in vitro and in vivo studies. Human biomonitoring studies also provide significant adverse effects on the physiological functions of hormones in the male reproductive system. In conclusion, BPA and its analogues deteriorate the physiological functions of hormones in the male reproductive system as per in vitro, in vivo, and human biomonitoring studies.

Protective Effects of Dietary Supplement Spirulina (Spirulina platensis) against Toxically Impacts of Monosodium Glutamate in Blood and Behavior of Swiss mouse

(1) Background: Well-known monosodium glutamate (E-621, MSG), originally used as a food flavor enhancer, was approved approximately in all countries, but the toxicity versus the safety of (MSG) are still unclear due to variable scientific toxicological reports. Moreover, it was reported to trigger elevated frequencies of nausea and headaches in humans and provide deleterious effects on laboratory animals. The objectives of the present study were to (i) estimate the possible toxic effects of the food additive MSG (ii) and the ameliorating protective effects of the dietary supplement spirulina (Spirulina platensis) on the biochemical parameters of blood and the damage produced in organs of Swiss mice after applying a supplementary daily dose of MSG for 4 weeks. (2) Methods: The present study was conducted on 20 mature Swiss mice, which were randomly organized into four groups of five Swiss mice. The treatments were (I) the control group, in which Swiss mice were fed only animal feed and drinking water; group II MSG1, which received 1 mL of MSG; group III MSG0.5, which was treated with 0.5 mL of MSG; and (IV) the group MSGS, which was treated with 1 mL of monosodium glutamate and 1 mL of spirulina (aiming to reduce the MSG toxicity). (3) Results: At the end of the experiment, Swiss mice treated with MSG demonstrated a passiveness regarding behavioral aspects. As we hypothesized, the parameters of the spirulina group reached similar values to the control group, and no histopathological observations have been found. Altogether, our findings evidenced that monosodium glutamate leads to histopathological changes in Swiss mice kidneys and caused important modifications for all biochemical parameters of the blood serum. Noticeably, the potential protective effect of Spirulina platensis was proved and was described by using the FTIR spectroscopy technique. (4) Conclusions: A diet rich in antioxidants and other plant-derived bioactive compounds may provide healthy nutrition, alleviating the potential side effects of some food additives.

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

Monosodium glutamate (MSG) is one of the most widely spread food additives that might cause male infertility. However, Nigella sativa L. seeds (NSS) could provide a solution. This study was designed to investigate the potential effects of NSS on rats ingesting MSG. To achieve this aim, adult male albino rats were randomly equally assigned into three groups for 21 days: control group received no treatment, MSG group received MSG as 30 g/kg feed, and MSG + NSS group received MSG as 30 g/kg and NSS as 30 g/kg feed. Testis histomorphometry showed marked deterioration by MSG as atrophic seminiferous tubules with degeneration of their lining cells, damaged Leydig cells and decreased germ cells number. Periodic Acid Schiff stain indicated irregular interrupted basement membranes. Glutathione reductase, superoxide dismutase 2 (SOD2), and caspase-3 immuno-expressions increased in testicular cells. Testosterone levels were significantly decreased in MSG challenged rats along with significant increase in luteinizing hormone levels, whereas NSS normalized this hormonal profile. MSG exposure also caused significantly increased lipid peroxides (LPO), glutathione-S-transferase, and total antioxidant capacity (TAC) whereas nitric oxide and SOD2 were significantly decreased. NSS succeeded in rebalance LPO and TAC and ameliorated the histoarchitectural disturbances. NSS mitigated MSG-induced testicular impairment by its antioxidant and cytoprotective activities.

Marsilea crenata ethanol extract prevents monosodium glutamate adverse effects on the serum levels of reproductive hormones, sperm quality, and testis histology in male rats

BACKGROUND AND AIM

Marsilea crenata is an aquatic plant that contains high antioxidants level and could prevent cell damages caused by free radicals. The present study aimed to investigate the effect of M. crenata ethanol extract on luteinizing hormone (LH), testosterone levels, sperm quality, and testis histology of adult male rats induced by monosodium glutamate (MSG).

MATERIALS AND METHODS

This study randomly divided 48 male rats into eight groups (n=6): control group; MSG group (4 mg/g body weight [b.w.] for 30 days); MS1, MS2, and MS3 groups (4 mg/g b.w. MSG and M. crenata ethanol extract at dose 0.216, 0.432, and 0.648 mg/g b.w., respectively, for 30 days); and S1, S2, and S3 groups (M. crenata ethanol extract at dose of 0.216, 0.432, and 0.648 mg/g b.w., respectively, for 30 days). The blood sample was collected on days 0 and 30 to determine the LH and testosterone levels. The animals were dissected on day 30, and the testes were isolated for morphometric, histology (spermatogenic cell number), and malondialdehyde (MDA) examination. Moreover, semen was collected to determine the sperm quality parameter.

RESULTS

The LH and testosterone levels significantly increased (p<0.05) after M. crenata administration at all doses. The higher dose of M. crenata ethanol extract demonstrated a high decrease in MDA level in MSG-treated rat testis; increase of spermatogonia, spermatocytes, spermatids, and Leydig cells number; and increase of seminiferous tubular diameter and germinal epithelium thickness.

CONCLUSION

The ethanol extract of M. crenata can improve the levels of LH, testosterone, sperm quality, number of testis morphometric, spermatogenic, and Leydig cells in MSG-treated male rats.

Effects of monosodium glutamate on testicular structural and functional alterations induced by quinine therapy in rat: An experimental study

Background

Quinine (QU) as an anti-malarial drug induces alterations in testicular tissue. Toxic effects of monosodium glutamate (MSG) on the male reproductive system have been recognized.

Objective

To investigate the impact of MSG administration on the intensity of gonadotoxicity of QU.

Materials and Methods

Sixty eight-wk old Wistar rats weighing 180-200 gr were divided into six groups (n = 10/each): the first group as a control; the second and third groups received low and high doses of MSG (2 & 4 gr/kg i.p.), respectively, for 28 days; the fourth group received QU for seven days (25 mg/kg); and in the fifth and sixth groups, QU was gavaged following the MSG administration (MSG + QU) from day 22 to day 28. Serum testosterone and malondialdehyde (MDA) levels were measured. Testes samples were prepared for tissue MDA levels, histomorphometry, and immunohistochemistry of p53. Sperm analysis was performed on cauda epididymis.

Results

Serum and tissue MDA levels were increased in treated groups compared to the control group. This increment was higher in the MSG + QU groups. The testosterone levels were reduced significantly (p < 0.0001) in all treated groups. In addition, histomorphometric indices and tubular epithelium population were reduced significantly (p < 0.0001) in QU, MSG + QU, and consequently in high-dose MSG, QU, MSG + QU groups. All spermatogenic indices were reduced in the treated groups, particularly in the MSG + QU groups. Sperm motility and viability indices were reduced significantly (p = 0.003) in the MSG + QU groups. Finally, the overexpression of p53 was observed in the MSG + QU groups.

Conclusion

The administration of MSG before and during QU therapy may intensify testicular tissue alterations.

Admissible daily intake for glutamate

PURPOSE OF REVIEW

Total glutamate (Glu) intake is 5-20 g/day in adults and about 40 mg/kg in breast-fed infant. Glu intake is constituted by Glu from protein and free Glu from certain foods and flavor-enhancing additive. The admissible intake of free Glu additive is addressed.

RECENT FINDING

In the gut, Glu is actively metabolized by enterocytes and because of this metabolism, the systemic availability of ingested Glu remains relatively low. Human studies are preferred to assess the transfer in blood of dietary free Glu salts and their possible risks. When human data are not available, experimental animal models provide the basis to assess the risks to humans but toxicity studies in rodents remain for a part controversial. A No Observable Adverse Effect Level (NOAEL) in rodent of 3200 mg/kg/day and an uncertainty factor of 100 lead to an acceptable daily intake (ADI) of 30 mg/kg/day for free Glu salts used as additives, whereas a NOAEL higher than 6000 mg/kg/day and an uncertainty factor of 25 leads to an ADI of 240 mg/kg/day for free Glu salts.

SUMMARY

Current discussions indicate an ADI from 30 to 240 mg/kg/day depending on the chosen NOAEL in animal model and compound-specific uncertainty factor (from 25 to 100).