Fluoride induced testicular toxicities in adult Wistar rats

Protective effect of platelet-rich plasma against structural and functional changes of the adult rat testis in carbimazole-induced hypothyroidism

OBJECTIVE

Hypothyroidism (HT) influences spermatogenesis and is associated with male infertility. Platelet-rich plasma (PRP), a biological product rich in growth factors, promotes tissue repair. In this study, the likely protective effects of PRP on testicular tissue damage in carbimazole (CBZ)-induced HT were evaluated.

METHODS

Forty male rats were divided into four groups. HT was induced by administering CBZ (1.35 mg/kg orally, for 45 days). Two doses of PRP (40 μL each, locally injected into the testis on days 15 and 30) were also given. After 45 days, blood samples were taken from the heart to measure triiodothyronine (T3), thyroxine (T4), and testosterone levels, and semen analysis was performed. For stereological assessment, the left testis was removed, fixed, embedded, sectioned, and stained with hematoxylin and eosin. The right testis was excised to evaluate antioxidant levels.

RESULTS

CBZ was demonstrated to induce HT, characterized by significant reductions in T3 and T4. HT was associated with decreased testicular weight, impaired sperm parameters, reduced testosterone concentration, diminished antioxidant activity, reduced volumes of testicular components, and lower total numbers of testicular cells of various types. When HT samples were treated with PRP, improvement was observed for all of these changes. This protective effect could be attributed to the growth factors present in PRP.

CONCLUSION

PRP appears to prevent the structural changes in the testes and the deterioration in sperm quality caused by CBZ-induced HT. This protective effect is likely due to mitigation of oxidative damage and elevation of testosterone levels.

Effect of Fluoride on the Expression of 8-Hydroxy-2'-Deoxyguanosine in the Blood, Kidney, Liver, and Brain of Rats

Excessive exposure of fluoride not only leads to damage on bone, but also has an adverse effect on soft tissues. Oxidative DNA damage induced by fluoride is thought to be one of the toxic mechanisms of fluoride effect. However, the dose-response of fluoride on oxidative DNA damage is barely studied in organisms. This study investigated the concentration of fluoride in rat blood, kidney, liver, and brain as well as the dose-time effect of fluoride on the expression of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in the above tissues. Rats were exposed to 0 mg/L, 25 mg/L, 50 mg/L, and 100 mg/L of fluorine ion and treated for one and three months. The results showed that the accumulation of fluoride in soft tissues was very different. At the first month, blood fluoride was increased, liver and brain fluoride showed a U-shaped change, and kidney fluoride was not significant. At the third month, blood fluoride was altered with an inverted U-shaped change, kidney and brain fluoride increased, but liver fluoride decreased. Both the exposure concentration and the time of exposure had a significant effect on the expression of 8-OHdG in the above tissues. However, the effect patterns of fluoride on these tissues were notably different at different times. At the first month of fluoride treatment, blood, kidney, and liver 8-OHdG decreased with the increasing fluoride concentration. At the third month, blood 8-OHdG showed a U-shaped change, but kidney 8-OHdG altered with an inverted U-shaped change. Liver 8-OHdG increased, while brain 8-OHdG decreased at the third month. Correlation analysis showed that only blood 8-OHdG was significantly inversely correlated with blood fluoride and dental fluorosis grade in both the first and third months. Liver 8-OHdG was negatively and significantly correlated with liver fluoride. There was a weak but nonsignificant correlation between kidney and brain 8-OHdG and fluoride in both tissues. Additionally, blood 8-OHdG was positively correlated with kidney and liver 8-OHdG at the first month and positively correlated with brain 8-OHdG at the third month. Taken together, our data suggests that concentration and time of fluoride exposure had a significant effect on 8-OHdG, but the effect patterns of fluoride on 8-OHdG were different in the tissues, which suggests that the impact of fluoride on 8-OHdG may be a tissue-specific, as well as a non-monotonic positive correlation.

Exposure to Fluoride From in Utero to Puberty Alters Gonadal Structure and Steroid Hormone Expression in Offspring Rats

The reproductive toxicity of fluoride has been proven by a large number of studies. While the underlying mechanism of reproductive toxicity during pregnancy is still unclear. Hence, in this study, we investigated the effects of fluoride exposure on ovarian and testicular steroid hormone synthesis in young and adult rat offspring. We established a model of fluoride-exposed rat pups from in utero to puberty to explore the mechanisms of fluoride impacts on reproductive toxicity in the offspring. The results showed that NaF exposure did not affect the 3 weeks of age offspring. Whereas the body weight in both sexes significantly decreased, and the ovarian and testicular tissue structures were damaged at 11 weeks of age. In females, the total number of secondary follicles and mature follicles were significantly reduced after NaF exposure. Moreover, estradiol (E2) and follicle-stimulating hormone (FSH) levels in the females were significantly reduced in the 100 mg/L NaF exposure group. In males, the sperm viability and testosterone (T) were significantly decreased in the NaF exposure groups. Additionally, during steroidogenesis in ovaries and testes, fluoride remarkably decreased the expression levels of genes and proteins, including acute regulatory protein (StAR), 3β-hydroxysteroid dehydrogenase (3β-HSD), cytochrome P450 17a-hydroxylase (CYP17A1), and cholesterol side-chain cleavage enzyme (CYP11A1), while the mRNA levels of 17β-hydroxysteroid dehydrogenase (17β-HSD) decreased only in the testes. These results indicated that fluoride exposure disrupted the steroid hormone balance by changing several important steroidogenic-related genes associated with the development of the gonads, and damage the normal structure of the gonads in rat offspring.

Contribution of Oxidative Stress, Apoptosis, Endoplasmic Reticulum Stress and Autophagy Pathways to the Ameliorative Effects of Hesperidin in NaF-Induced Testicular Toxicity

The ameliorative effects of hesperidin (HES) on the toxicities created by sodium fluoride (NaF) in the testes tissue of rats were studied via oxidative stress, apoptosis and endoplasmic reticulum (ER) stress pathways. The animals were divided into five distinct groups (7 rats in each group). Group 1 was control group, group 2 received NaF-only (600 ppm), group 3 received HES-only (200 mg/kg bw); group 4 received NaF (600 ppm)+HES (100 mg/kg bw) and group 5 received NaF (600 ppm)+HES (200 mg/kg bw) for 14 days. NaF-induced testes tissue damage by reducing activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) and levels of glutathione (GSH), and increasing lipid peroxidation levels. NaF treatment significantly downregulated the mRNA levels of SOD1, CAT and GPx. NaF supplementation caused apoptosis in the testes by upregulating p53, NFkB, caspase-3, caspase-6, caspase-9, and Bax and downregulating Bcl-2. Furthermore, NaF caused ER stress via increasing mRNA transcript levels of PERK, IRE1, ATF-6 and GRP78. NaF treatment led to autophagy via upregulation of Beclin1, LC3A, LC3B and AKT2. In testes tissue, however, co-treatment with HES at doses of 100 and 200 mg/kg significantly reduced oxidative stress, apoptosis, autophagy and ER stress. Overall, the findings of this study suggest that HES may help to reduce testes damage caused by NaF toxicity.

Fluoride subacute testicular toxicity in Wistar rats: Benchmark dose analysis for the redox parameters, essential elements and DNA damage

Excessive fluoride (F^-) levels in the environment could induce different pathological changes, including comorbidities in reproductive functions. Hence, the aim of the present in vivo study was to explore F^- subacute toxicity mechanisms via Benchmark dose (BMD) methodology on rat's testicles. The experiment was conducted on thirty male Wistar rats for 28 days, divided into six groups (n = 5): 1) Control (tap water); 2) 10 mg/L F^-; 3) 25 mg/L F^-; 4) 50 mg/L F^-; 5) 100 mg/L F^-; 6) 150 mg/L F^-. Testicles were dissected out and processed for the determination of F^- tissue concentrations, redox status parameters, essential elements level, and DNA damage. PROASTweb 70.1 software was used for determination of external and internal dose-response relationship. The results confirmed a significant increase in superoxide anion (O₂^.-), total oxidative status (TOS), copper (Cu), zinc (Zn), iron (Fe), DNA damage levels, and decrease in superoxide dismutase activity (SOD1) and total thiol (SH) groups. The dose-dependent changes were confirmed for SOD1 activity and DNA damage. The most sensitive parameters were SOD1 activity and DNA damage with the lowest BMDLs 0.1 μg F^-/kg b. w. Since human and animal populations are daily and frequently unconsciously exposed to F^-, this dose-response study is valuable for further research regarding the F^- health risk assessment.

Role of oxidative stress-mediated cell death and signaling pathways in experimental fluorosis

Free radicals and other oxidants have enticed the interest of researchers in the fields of biology and medicine, owing to their role in several pathophysiological conditions, including fluorosis (Fluoride toxicity). Radical species affect cellular biomolecules such as nucleic acids, proteins, and lipids, resulting in oxidative stress. Reactive oxygen species-mediated oxidative stress is a common denominator in fluoride toxicity. Fluorosis is a global health concern caused by excessive fluoride consumption over time. Fluoride alters the cellular redox homeostasis, and its toxicity leads to the activation of cell death mechanisms like apoptosis, autophagy, and necroptosis. Even though a surfeit of signaling pathways is involved in fluorosis, their toxicity mechanisms are not fully understood. Thus, this review aims to understand the role of reactive species in fluoride toxicity with an outlook on the effects of fluoride in vitro and in vivo models. Also, we emphasized the signal transduction pathways and the mechanism of cell death implicated in fluoride-induced oxidative stress.

Hesperidin Attenuates Oxidative Stress, Inflammation, Apoptosis, and Cardiac Dysfunction in Sodium Fluoride-Induced Cardiotoxicity in Rats

Excessive fluoride intake has been reported to cause toxicities to brain, thyroid, kidney, liver and testis tissues. Hesperidin (HSP) is an antioxidant that possesses anti-allergenic, anti-carcinogenic, anti-oxidant and anti-inflammatory activities. Presently, the studies focusing on the toxic effects of sodium fluoride (NaF) on heart tissue at biochemical and molecular level are limited. This study was designed to evaluate the ameliorative effects of HSP on toxicity of NaF on the heart of rats in vivo by observing the alterations in oxidative injury markers (MDA, SOD, CAT, GPX and GSH), pro-inflammatory markers (NF-κB, IL-1β, TNF-α), expressions of apoptotic genes (caspase-3, -6, -9, Bax, Bcl-2, p53, cytochrome c), levels of autophagic markers (Beclin 1, LC3A, LC3B), expression levels of PI3K/Akt/mTOR and cardiac markers. HSP treatment attenuated the NaF-induced heart tissue injury by increasing activities of SOD, CAT and GPx and levels of GSH, and suppressing lipid peroxidation. In addition, HSP reversed the changes in expression of apoptotic (caspase-3, -6, -9, Bax, Bcl-2, p53, cytochrome c), levels of autophagic and inflammatory parameters (Beclin 1, LC3A, LC3B, NF-κB, IL-1β, TNF-α), in the NaF-induced cardiotoxicity. HSP also modulated the gene expression levels of PI3K/Akt/mTOR signaling pathway and levels of cardiac markers (LDH, CK-MB). Overall, these findings reveal that HSP treatment can be used for the treatment of NaF-induced cardiotoxicity.

Vitamin C and E supplementation can ameliorate NaF mediated testicular and spermatozoal DNA damages in adult Wistar rats

OBJECTIVE

Present study was designed to explore the efficacy of vitamin C and E (VC&VE) against fluoride mediated testicular, epididymal and spermatozoal anomalies.

MATERIALS AND METHODS

Thirty two adult Wistar rats were divided into four groups. Group-I was control; Group-II received sodium fluoride (NaF) at 15 mg/kg/day dose; Group-III was provided with VC (200 mg/kg/day) and VE (400 mg/kg/day) plus NaF; Group-IV received only VC&VE. Structural integrity and oxidative stress markers (superoxide dismutase, catalase, malondialdehyde and protein carbonyl) of testis and epididymis were assessed. Spermatozoal parameters (count, motility, viability and hypo-osmotic swelling) were evaluated. Testicular functional maker enzymes (acid phosphatase, alkaline phosphatase and lactate dehydrogenase) were also assessed. Integrity of testicular and spermatozoal DNA were evaluated. Testicular fluoride content was measured.

RESULT

Fluoride induced structural changes and alterations of oxidative stress markers were observed in testis and epididymis. Spermatozoal potentials were altered and reduced activities of testicular functional marker enzymes were observed. Fluoride caused testicular and spermatozoal DNA damages. VC&VE supplementation resulted in protectionfrom all fluoride mediated alterations and helped in attenuating testicular fluoride accumulation.

CONCLUSION

Antioxidant properties of VC&VE ameliorated fluoride mediated reproductive damages but only supplementation did not exhibit any notable effect compared to control rats.