The Effect of Carotenoids of Rhodotorula glutinis and Probiotic of Lactobacillus acidophilus on Physiological and Histological Variables of the Kidney in Male Rats Exposed to Ultraviolet Radiation

Ultraviolet rays (UV) are one of the most important types of low-energy non-ionizing rays. The UV range of the spectrum of electromagnetic radiation extends from 10 nm to 400 and a large portion of UV from sun accessing the surface of Earth consists mainly of UVB (90-99%) with a minor UV component (1-10%) nm (Xavier, 2023).

UV radiation can widely induce reactive oxygen species (ROS) by directly impacting on components of cell or by sensitivity mechanisms to light. Indirectly generated reactive oxygen species include a species variety such as OH•, superoxide radical, 1O2, and H2O2 during several processes (Kimeswenger et al., 2016). These radicals can transformed to different species as reactive oxygen species, a low quantity of radicals may result of mutations, the intermediate quantity of ROS can cause of aging, in addition, a elevate quantity from reactive oxygen species may leads to death of cells as necrosis (Wei et al., 2024). To identify a harmful and dangerous effects of ultraviolet rays on the efficiency and functions of the kidney, this study was conducted (Mustafa et al., 2023).

Carotenoids are among the most widespread pigments in nature and are specifically manufactured by plants and microorganisms (Vachali et al., 2012). Adequate intake of carotenoids could be linked to a decreased risk on the heart, eye, skin, and bone diseases, in addition to a variety of malignancies, including breast, ovarian, prostate, colorectal and cervical cancer (Bhatt and Patel, 2020), vegetables and fruits are the major sources of carotenoids in the diets of humans, despite of the carotenoids are found in large quantities in seafood, dairy products, egg yolks, and other foods of animal origin (Meléndez-Martínez et al., 2018). In this study, attention was focused on the carotenoids extracted ability to removal or neutralized free radicals for their potential exploitation in the treatment of damage caused by exposure to ultraviolet radiation to propose the carotenoid molecules as novel, valuable components for nutritional supplements for human health (Mahmoud et al., 2024).

Lactobacillus acidophilus, is a type of gram-positive bacteria that is found in the digestive system. L. acidophilus as a probiotic has a group of benefits to the body, such as improving digestion. It also contributes to maintaining the balance of beneficial bacteria in the digestive system, in addition to promoting health and the immune system (Wen et al., 2023; Karupusamy et al., 2023).

28 male albino rats were used the strain (Sprague Dawely) whose ages ranged between (2-2.5) months and weighed (200-250 g), The animals were given 2 weeks to acclimate to their new surroundings environment of animal-house and verify they were disease-free, then divided into four groups with 7 animals in each group (G1 as healthy control group, G2 refer to UV exposed group, G3 as bacterial probiotic group, and G4 group represent that treated with carotenoids extract). They were given water and food continuously throughout the experiment period, which amounted to 28 days that expanded between February 2023/ April 2023, including a period of 24 hours that represents the time was exposed the animals to UV radiation before receiving therapy. The animals were exposed to ultraviolet radiation at a wavelength of 300 nm by an ultraviolet lamp 30 W and length 90 cm was positioned to the up to the animal cage covers.

An isolate of Rhodotorula glutinis yeast was obtained and previously identified from the laboratories of the College of Agriculture, Kirkuk University. The carotenoid pigment was extracted from the isolate of yeast after growing it on Sabouraud glucose agar (SGA), based on the procedure of (Park et al., 2005) which was modified method (Ali, 2013) for carotenoids extraction. The dye was kept in opaque bottles and in dark conditions at -18 ℃ to avoid oxidation and damage to the dye. 2.39 mg of the prepared carotene was dissolved, and the carotenoids dose was used based on the recommended daily requirement of beta-carotene for rats, which is 2.39 mg/kg of body weight. The animals were dosed orally by using a gavage.

The bacterial suspension of L. acidophilus as a probiotic supplement results from emptying the contents of a ready-made bag (Lacteol fort) containing L. acidophilus in a dried powder form, which was manufactured by a (Rameda Pharma company, Egypt, with permission from Axcan Pharma, France). The contents of the bag were mixed in 10 ml of skimmed milk and then the dose given to the animals 2.5 ml/kg.

Urea, creatinine and uric acid were determined depending on the enzymatic colorimetric method by kits supplied by (Biolabo Company, France).

The animals anesthetized by chloroform, then the blood were taken, and a laparotomy, the chest (sternum) and abdomen were opened in an inverted T shape, then, extirpate the kidneys from each rat, then, completing a steps to the preparation of histological sections (tissue slices) (Suvik and Effendy, 2012; Bancroft and Layton, 2018).

SAS (2001) statistical program executed and examined the results. To compare the variable means, one-way analysis of variance (ANOVA) was utilized. Additionally, Duncan’s Test (1955) was used to assess significant variances, and the significance level (P< 0.05).

According to the data in Tables 1, 2 the concentrations of urea, creatinine, and uric acid in the group exposed to UV radiation were significantly higher (P< 0.05) in comparison to the healthy control group, while, found a significant reduction (P< 0.05) in urea, creatinine and uric acid in the groups were treated with probiotic and the carotenoids that extracted from Rhodotorula glutinis in comparison with ultraviolet radiation exposure group.

UV radiation harm to organisms can happen either directly or indirectly. When water molecules are exposed to UV light, they radiolyze and create free radicals, these radicals then interact with other molecules, changing their structures and functions (Jagetia and Reddy, 2005; Türker, 2015), and thus may lead to damage in kidney cells as in the present study and subsequently, this affects the functions and efficiency of this organ which is the reason for the high concentration of some of the studied parameters, such as urea, creatinine and uric acid.

Table 1: Concentrations of urea and creatinine in serum of all study groups.

Table 2: Concentration of uric acid in serum of all study groups.

The therapeutic effect of carotenoids on the above parameters and organ in current research may be due to that carotenoids can regulate oxidative stress through peroxisome proliferator-activated receptors (PPAR) and nuclear factor erythroid 2 (Nrf2) or cause upregulation of antioxidants and enzymes of cytoprotective phase II. Carotenoid-mediated Nrf2 signaling’s main function is to reduce reactive oxygen species and responses of inflammation (Bohn, 2019; Kohandel et al., 2021). It has been shown through research that carotenoids, which act as antioxidants, can prevent the formation of tumors or damage by reducing the levels of free radicals that can cause damage to DNA (Dawson, 2000; Vardi et al., 2010), also, oxidative stress and the inflammatory process can be considered as a part of the pathogenesis of renal diseases, so, carotenoids are the most fat-soluble chemicals have anti-inflammatory, antioxidant and anti-apoptotic activities, which are associated with the regulation of signaling pathways related to oxidative damage and inflammation, on the other hand, carotenoids can removal or neutralized reactive oxygen species and improve the ability of cells to prevent free radicals (Kaulmann and Bohn, 2014).

Also, the causes of improved functions and health of kidneys may be due to the use of L. acidophilus probiotic to increase normal flora in the gut, which in return improves digestion and increases absorption of food and supplements. Furthermore, probiotic help activate the immune system and improve and support overall function in the body (Vemuri et al., 2022; Mani-López et al., 2022). Moreover, found that the carotenoids were associated with activity and efficiency of GFR, both in older persons and renal patients (Hirahatake et al., 2019; Alsalame and Laylani, 2024). In addition, the effects of L. acidophilus probiotic on renal tissue not only improve intestinal homeostasis but also decrease uremic toxins production or retention, and probiotic of L. acidophilus may lowering urinary protein excretion and urea nitrogen in the blood and decreased oxidative stress and fibrosis in the renal tissues by transforming of intestinal microflora composition toward homeostasis (Yoshifuji et al., 2016; Tsai et al., 2024), subsequently, that may lead to decrease of creatinine, urea, and uric acid concentrations. Furthermore, exposure to UV effect may lead to an increased risk of constipation, which may promote the fermentation of unprocessed peptides and amino acids in the colon, as well as the production and uptake of additional precursors to uremic toxins which effects on the efficiency of the kidney (Huang et al., 2021), and thus, administrated probiotic can be a new pathway to give prospective benefits to improve quality of life and renal functions.

On the other hand, the specimens were within the histological section (Figure 1), which shows a section in renal tissue from the ultraviolet-exposed group that illustrates the damage of glomeruli, thickening walls of blood vessels and infiltration of lymphocytes with present fibrocytes. Whereas the current histological study for the carotenoids extract group in (Figure 2), explains the effect of giving carotenoids to male rats daily for (28) days when compared with the kidney sections of the control group clearly showed the treatment effect of the extract on the effect of radiation and observed the renal glomeruli, the proximal urinary tubules and distal urinary tubules naturally. Also, the histological section for the group treated with bacterial probiotic of L. acidophilus in (Figure 3), explains the effect of giving probiotic to male rats daily for (28) days when compared with the kidney sections of the control group clearly showed the effect of treatment on the UV effect and observed the healing effect to probiotic on the damage and only closed tubules remains in the renal tissue, in addition to the glomeruli and kupffer cells.

The causes of this physiological and histological injury might result from an increase in the lipid peroxidation process and a reduction in the body’s antioxidant enzyme activity accompanied by the cellular membranes damage (Saada and Azab, 2001; Singh et al., 2022). Furthermore, high concentrations of reactive oxygen species may result in endothelial dysfunction, inflammation, and renal fibrosis (Gwozdzinski et al., 2021). While the improvement in the health and recovery of the renal tissues may be due to the carotenoids that are important as the antioxidant level and activity, in addition, have anti-inflammatory and anti-apoptotic activities, and associated with the regulation of signaling pathways related to oxidative damage and inflammation (Kaulmann and Bohn, 2014). In addition, the carotenoids have a role in lipid peroxidation inhibition, and participating in apoptosis (Do Nascimento et al., 2020). Furthermore, Supplementation of L. acidophilus probiotic may due to reducing fibrotic-related proteins and kidney damage lowered pro-inflammatory processes and oxidative stress, and enhanced immunological reactions in the kidney (Huang et al., 2021), thus, that maybe lead to a decrease and treatment of the effect of oxidative stress that resulting from exposure to ultraviolet radiation (Abd-AlWahab et al., 2024).

The current study concludes that exposure to UV rays leads to damage to kidneys, and their functions are impaired, while administration of probiotics and carotenoids leads to an improvement in the functions of the kidney and restoration of potential renal tissue injury that resulting from the effect of ultraviolet rays.

The authors sincerely acknowledge the staff of the Department of Biology, College of Education and University of Samarra for their general and technical support.

This study presents a novel approach to mitigating the harmful effects of ultraviolet (UV) radiation on kidney health by investigating the protective potential of carotenoids extracted from Rhodotorula glutinis yeast and L. acidophilus as a probiotic. This study uniquely combines carotenoids and probiotics as therapeutic agents. The findings provide evidence for the significant therapeutic effects of these compounds in reducing UV-induced renal damage, providing new insights into alternative, non-pharmacological interventions for kidney health.

LSL and WIAA-A designed the experiment. HSA and MAM conducted the laboratory work and the data was analyzed. Editing, revision, and proofreading were done by all researchers to improve the language of writing. All authors contributed to the article and approved the submitted version.

The authors declare no interest conflicts associate with this manuscript.