Histopathological Changes Induced by Monosodium Glutamate and Sodium Nitrite in the Development of Eye in Albino Mice Mus musculus

The present study aimed to discover the histopathological of the Monosodium glutamate (MSG), and Sodium nitrite (NaNO2), on the embryonic development of the eyes of albino mice Mus musculus. On the fourteenth and eighteenth day of pregnancy, the stage of organogenesis in these animals. A concentration of 9 g/kg of MSG, a concentration of 110 mg/kg of NaNO2, and the interaction between them used. The results of the study showed the presence of pathological changes to the eyes of the fetuses. The eye on the 14th day of pregnancy, when 9 g/kg of MSG used, there were retinal duplication, increased vascularization in the retina, condensation of some nuclei of the inner nuclear layer and ganglion cells, and necrosis in the vicinity of the lens. When treating with NaNO2 110 mg/kg, there was an irregularity in the lens, corneal distortion, hyperplasia of the retinal nerve tissue. When the two materials overlapped, the corneal tissue necrosis, the lens fiber, and the inner plexiform layer were observed. On the 18th day of pregnancy, when treated with MSG 9g/kg, the most significant overall and striking damage was retinal duplication and optic nerve necrosis. When treated with NaNO2 110 mg/kg, the corneal stroma and dissociation were seen in the photoreceptor cells. In the case of their overlapping, extensive necrosis and reduction appeared in all layers of the retina. The study concluded that consuming MSG and NaNO2 more than the permissible limit during pregnancy leads to tissue lesions harmful to the eye. Keyword: food additives, fetal development of the eye, MSG, NaNO2. قهملا نارئفلل نيعلا روطت يف مويدوصلا تيرتنو مويدوصلا يداحا تاماتولكب ةثدحملا ةيجسنلا ةيضرملا تاريغتلا Mus musculus نونذلا معنملا دبع لبانس 1 * ، دبع ركشا يلع 2 1 * مولع مسق ةايحلا قارعلا ،لصوملا ،لصوملا ةعماج ،ةفرصلا مولعلل ةيبرتلا ةيلك ، 2 مسق ريدختلا ةيلك ، ةعماجلا رونلا قارعلا ،لصوملا ، Journal of Education and Science (ISSN 1812-125X), Vol: 30, No: 3, 2021 (1-12) Special Issue for Proceeding of 3 National (1 international conference of biology) (ICBSUM 2021) 5, 6 July College of Education for Pure Science, University of Mosul, Mosul, Iraq. Downloaded from https://edusj.mosuljournals.com/ 2 ةصلاخلا : مويدوصلا يداحا تاماتولك يهو ةيئاذغلا تافاضملا ىدحا ريثات ةيلاحلا ةسا ردلا تلوانت MSG يهو ةظفاحلا داوملا ىدحاو، مويدوصلا تيرتن 2 NaNO ةيضرملا تا ريثاتلاو لمحلا نم رشع نماثلاو رشع عبا رلا مويلا يف قهملا نا رئفلا نيعل ينينجلا روطتلا ىلع نيعلا ترهظأ دقف ،ةنجلاا نيعل ةيضرم تا ريغت دوجو يرهجملا صحفلا للاخ نم ةسا ردلا جئاتن تنيب .داوملا هذه اهقحلت يتلا ةيجسنلا مويلا يف 14 ـب ةلماعملا دنعو لمحلل MSG 9 ةجيتن يهو ةلحرملا هذه يف ترهظ يتلا را رضلأا مهأ نم يهو ةيكبشلا ةيجاودزا مغك/مغ ـب ةلماعملا دنع امأ .ةمهمو رظنلل ةتفلم 2 NaNO 110 جيسنلا يف جسنت طرف ةينرقلا هوشت ،ةسدعلا يف ماظتنا مدع ظحول مغك/مغلم يف رخن ظحول نيتداملا لاك لخادتب ةلماعملا دنعو ةيكبشلل يبصعلا .ةيكبشلل ةيلخادلا ةيريفضلا ةقبطلا يفو ةسدعلا فايلاو ةينرقلا جيسن مويلا يف اما 18 ـب ةلماعملا دنعو لمحلل MSG 9 ةيجاودزا يه اًضيأ رظنلل ةتفلملاو ةلماشلا اًضيأ را رضلأا مهأ تناك دقف مغك/مغ ـب ةلماعملا دنع امأ .يرصبلا بصعلا رخن نع لًاضف ةيكبشلا 2 NaNO 110 غك/مغلم ايلاخلا يف ككفتو ةينرقلا ةادس يف ككفت دهوش م ةيكبشلا تاقبط لك يف عساو لا زتخاو رخن رهظ امهلخادت ةلاح يفو ءوضلل ةلبقتسملا . رثكا داوملا هذه كلاهتسا نا ةسا ردلا تجتنتساو .نيعلا يف ةيجسن تافا ثودح ىلا يدؤي حومسملا نم ةيحاتفملا تاملكلا : تافاضملا .مويدوصلا تيرتن ،مويدوصلا يداحا تاماتولك ،ينينجلا ومنلا ،ةيئاذغلا


Introduction
Food additives can be defined as industrial or natural compounds added to food and are widely used in the food industries to increase the shelf life of the product and improve certain qualities in food, including coloring, preservation, and sweetening. Still, nevertheless, they have negative aspects, and some of them have been prohibited for their toxicity [1].
One of these substances widely used in the world is Monosodium glutamate (MSG), a substance that improves food flavor. It is a white crystalline powder [2]. It is the sodium salt of the non-essential amino acid Glutamic acid [3], symbolized as E621. It is used in the preparation of dried foods, canned soups, as well as in preserving frozen vegetables and fruits. It increases appetite and consumes large amounts of food, leading to obesity [4]. Also, glutamate and glutamate receptors contribute to an important role in many neurological diseases and pathological conditions of the eye, such as Ischemia and Trauma and Diabetic retinopathy, and Glaucoma [5]. The name of MSG is covered in foods under various names, including Umami or Ajinomoto. The US Food and Drug Administration considered it a safe and usable compound. The European Union classified it as a food additive that can be used in some foods, but according to specific conditions [6]. However, many studies recorded an increase in liver weight in rats given a diet containing MSG, which led to an increase in the activity of inflammatory tissue factors and led to hepatitis [7].
Sodium nitrite (NaNO2) is also a food additive. It is a yellowish-white crystalline powder with unique pharmacological and industrial properties. It has been used in human and veterinary medicines as a vasodilator, antimicrobial agent, protection against hypoxia, and Preservative against bacterial contamination. [8]. NaNO2 added to food as a preservative may interact in the stomach with amino compounds in food and form nitrosamine compounds that can cause cancer [9]. It may also contribute to the emergence of compounds and free radicals that accelerate fat oxidation, which causes dangerous 3 effects to various tissues and organs of the body. Therefore, NaNO2 is a toxic chemical, and it is harmful when exposed to it, as it irritates the eyes, skin, and lungs [10].
The vertebrate eye is one of the most important and sensory organs in the body, so it has a complex structure and function, as it receives incoming light and turns it into images through which we can see the world around us [11]. The mammals' eyes are similar in structure to the rest of vertebrate eyes, as they consist of three main layers. The external is the sclera which contains the cornea. The middle layer is the Uvea, and the inner is the retina, which is the most important layer, and it is the eye photoreceptor layer because it contains photoreceptors. There are differences in vertebrates' eyes in terms of numbers and types of cells and their organization and arrangement [12].
The eyes are sensitive to teratogenic effects and infectious factors, as visual defects may result from an infection of tissues and organs with some microorganisms during the fetal period, such as rubella virus and syphilis, as well as the physical and chemical factors that a pregnant mother may be exposed to, which may lead to a defect in Eye formation and some defects that may affect the visual process after birth. Most ophthalmic defects result from damaged closure of retinal fissures such as coloboma of the iris, cataracts, and glaucoma may result from intrauterine infections [13]. As a result of the previous, and to investigate the effect of MSG and NaNO2 on developing all parts of the eye in mice, this study was conducted.

Materials and Methods
• Laboratory animals This study was conducted on Swiss white mice Mus musculus, and they were selected at an age ranging from (8)(9)(10)(11)(12) weeks, their average weight ranged (2 ± 23)g. They were placed in special laboratory conditions in terms of ventilation, temperature (2 ± 24) ° C and photoperiod (12 hours of light / 12 hours of darkness) [14]. The mice were fed continuously with their food [15].
• Choosing of doses Concentration used in the study The dose concentrations were selected in light of the median lethal dose 50 (LD50) for MSG ranging from 15-18 g/kg B.W. [16] and for NaNO2 ranging from 85-150 mg/kg B.W. [17]. The doses that were used in this study were as following: (9 g / kg) MSG, the dose was administered in 0.5 ml D.W. orally by the Gavage needle, and (110 mg/kg) for NaNO2 in 0.1 ml D.W. was given as intraperitoneal (I.P.) injection.
• Experimental Design (24) pregnant mice were used, which were divided into four subgroups, as follows:

• Histological sections preparation
The histopathological sections were attended by anesthetizing and dissecting the pregnant mice on the 14th day and the 18th day of pregnancy for the control group and experimental groups mediated by 6 In the case of the two substances being treated together, necrosis of the inner plexiform layer of the retina was observed, deformation of the lens with condensation of part of it, infiltration of inflammatory cells in a part of it, and the lining of the retina (Figure 6). also observed necrosis of the inner plexiform layer of the retina and increased awareness of the corneal tissue (Figure 7).
• Histopathological changes in the eye of the fetuses aged of 18 th days In the eye of 18 th day old fetuses, several histopathological lesions were observed compared to the control group (Figure 8,9). When treated with MSG, the most striking damage was retinal duplication. Also appeared necrosis of the optic nerve and condensation of part of it ( Figure 10) and in another part, in addition to retinal duplication, necrosis of the inner plexiform layer, reduction of the nervous tissue of a part of the retina, condensation of the lens (Figure 11). There was also a deformation of the lens, thickening of the epithelial tissue and its capsule, thickening of the cornea's inner lining, necrosis of the cornea's stroma, and deformation in another area of the cornea (Figure 12). When treated with NaNO2, the retina showed necrosis on the outer and inner nuclear layer, the inner plexiform layer, the dissolution of the photoreceptor cells, and the infiltration of inflammatory cells the edge of the inner plexiform layer ( Figure 13). In another part of the eye, dissociation of the cornea's stroma fibers was observed, reducing the cornea's superficial epithelial layer, condensation of the periphery of the lens (the capsular), and hyperplasia of its epithelium ( Figure 14). When the treatment with both MSG and NaNO2, extensive necrosis and reductions were observed in all retina layers (Figure 15). In the cornea, dissociation and necrosis of the stroma, reduction of the surface epithelium, and endothelial condensation were observed. Condensation of the lens's epithelium, hyperplasia, and necrosis of the fibers appeared ( Figure 16).

Discussion
• Histopathological changes in the eye of fetuses aged 14 th days When pregnant were treated with MSG, many histopathological changes was observed, they included increased vascularization, condensation of some nuclei, necrosis in the vicinity of the lens, duplication of the retina, and necrosis in the photoreceptor cells and the lens. The duplication of the retina is one of the most important damages that appeared. It did not appear in previous studies and is considered a first-time result to the best of our knowledge. Some of these results are also consistent with the results that were performed on birds, as it was observed when treating chicken embryos during an incubation period with MSG causing them to have both morphological and retinal deformations, as the eyes were damaged, especially retinal tissues [22,23] In a study on pregnant mice, they were treated with MSG, as they were dosed from day 17 of pregnancy at different concentrations 2, 4, 8 g / kg of body weight and studied the newborn's embryonic development mice`s cornea. The histopathological changes were observed during different periods, including the stroma fibers puncture, necrosis and reduction of the corneal epithelial layer, hyperplasia of the peripheral corneal epithelium, and part of it deformed, corrugation of the basement membrane of the central corneal epithelium, distortion of the fibers of the central corneal stroma, corrugation of the anterior surface of the cornea, reduction layering and irregularity, hyperplasia of fibroblasts, significant breakdown of stroma fibers, damage on the peripheral of the corneal epithelial tissue, hyperplasia of the central cornea, a reduction in the peripheral cornea of the generative cells for fibers, the separation of the endothelial epithelial tissue and the appearance of the condensed layer on the epithelial tissue [24].
When pregnant mice were treated with NaNO2, there was an irregularity of the lens, deformation of the cornea, hyperplasia of the retinal nerve tissue, and necrosis of the inner plexiform layer. This tissue damage may lead to a defect in the eye's fetal development process, which may ultimately cause a defect in the visual process after birth.

7
In the case of the two substances being treated together, necrosis of the inner plexiform layer of the