Exposure of Fluoride with Streptozotocin-Induced Diabetes Aggravates Testicular Damage and Spermatozoa Parameters in Mice

Exposure to fluoride exacerbates the cognitive deficit of diabetic patients living in areas with endemic fluorosis, as well as of rats with type 2 diabetes induced by streptozotocin via a mechanism that may involve excessive activation of the poly(ADP ribose) polymerase-1/P53 pathway

Epidemiology has shown that fluoride exposure is associated with the occurrence of diabetes. However, whether fluoride affects diabetic encephalopathy is unclear. Elderly diabetic patients in areas with endemic (n = 169) or no fluorosis (108) and controls (85) underwent Montreal Cognitive Assessment. Sprague-Dawley rats receiving streptozotocin and/or different fluoride doses were examined for spatial learning and memory, brain morphology, blood-brain barrier, fasting blood glucose and insulin. Cultured SH-SY5Y cells were treated with 50 mM glucose and/or low- or high-dose fluoride, and P53-knockdown or poly-ADP-ribose polymerase-1 (PARP-1) inhibition. The levels of PARP-1, P53, poly-ADP-ribose (PAR), apoptosis-inducing factor (AIF), and phosphorylated-histone H2A.X (ser139) were measured by Western blotting. Reactive oxygen species (ROS), 8-hydroxydeguanosine (8-OHdG), PARP-1 activity, acetyl-P53, nicotinamide adenine dinucleotide (NAD+), activities of mitochondrial hexokinase1 (HK1) and citrate synthase (CS), mitochondrial membrane potential and apoptosis were assessed biochemically. Cognition of diabetic patients in endemic fluorosis areas was poorer than in other regions. In diabetic rats, fasting blood glucose, insulin resistance and blood-brain barrier permeability were elevated, while spatial learning and memory and Nissl body numbers in neurons declined. In these animals, expression and activity of P53 and PARP-1 and levels of NAD+, PAR, ROS, 8-OHdG, p-histone H2A.X (ser139), AIF and apoptosis content increased; whereas mitochondrial HK1 and CS activities and membrane potential decreased. SH-SY5Y cells exposed to glucose exhibited changes identical to diabetic rats. The changes in diabetic rats and cells treated with glucose were aggravated by fluoride. P53-knockout or PARP-1 inhibition mitigated the effects of glucose with/without low-dose fluoride. Elevation of diabetic encephalopathy was induced by exposure to fluoride and the underlying mechanism may involve overactivation of the PARP-1/P53 pathway.

The fluorosis conundrum: bridging the gap between science and public health

Fluorosis, a chronic condition brought on by excessive fluoride ingestion which, has drawn much scientific attention and public health concern. It is a complex and multifaceted issue that affects millions of people worldwide. Despite decades of scientific research elucidating the causes, mechanisms, and prevention strategies for fluorosis, there remains a significant gap between scientific understanding and public health implementation. While the scientific community has made significant strides in understanding the etiology and prevention of fluorosis, effectively translating this knowledge into public health policies and practices remains challenging. This review explores the gap between scientific research on fluorosis and its practical implementation in public health initiatives. It suggests developing evidence-based guidelines for fluoride exposure and recommends comprehensive educational campaigns targeting the public and healthcare providers. Furthermore, it emphasizes the need for further research to fill the existing knowledge gaps and promote evidence-based decision-making. By fostering collaboration, communication, and evidence-based practices, policymakers, healthcare professionals, and the public can work together to implement preventive measures and mitigate the burden of fluorosis on affected communities. This review highlighted several vital strategies to bridge the gap between science and public health in the context of fluorosis. It emphasizes the importance of translating scientific evidence into actionable guidelines, raising public awareness about fluoride consumption, and promoting preventive measures at individual and community levels.

Pyrroloquinoline quinone inhibits PCSK9-NLRP3 mediated pyroptosis of Leydig cells in obese mice

Abnormal lipid metabolism and chronic low-grade inflammation are the main traits of obesity. Especially, the molecular mechanism of concomitant deficiency in steroidogenesis-associated enzymes related to testosterone (T) synthesis of obesity dominated a decline in male fertility is still poorly understood. Here, we found that in vivo, supplementation of pyrroloquinoline quinone (PQQ) efficaciously ameliorated the abnormal lipid metabolism and testicular spermatogenic function from high-fat-diet (HFD)-induced obese mice. Moreover, the transcriptome analysis of the liver and testicular showed that PQQ supplementation not only inhibited the high expression of proprotein convertase subtilisin/Kexin type 9 (PCSK9) but also weakened the NOD-like receptor family pyrin domain containing 3 (NLRP3)-mediated pyroptosis, which both played a negative role in T synthesis of Leydig Cells (LCs). Eventually, the function and the pyroptosis of LCs cultured with palmitic acid in vitro were simultaneously benefited by suppressing the expression of NLRP3 or PCSK9 respectively, as well the parallel effects of PQQ were affirmed. Collectively, our data revealed that PQQ supplementation is a feasible approach to protect T synthesis from PCSK9-NLRP3 crosstalk-induced LCs' pyroptosis in obese men.

The possible protective and therapeutic effects of ginger and cinnamon on the testis and coda epididymis of streptozotocin-induced-diabetic rats: Histological and biochemical studies

Diabetes mellitus (DM) is a metabolic condition characterized by high blood sugar levels with serious system complications. Ginger (Zingiber officinale) and Cinnamon (Cinnamomum zeylanicum) have anti-diabetic activities. The goal of this study is to evaluate the possible protective and therapeutic effects of ginger and Cinnamon against histological, Ki67 Immunohistochemistry (IHC) and biochemical studies in testis and coda epididymis of Streptozotocin (STZ) induced diabetic rats. The experimental rats were divided into six groups: G1 was the control, G2 induced diabetic without treatment, G3 was treated with ginger before induction of DM (ginger protective), G4 were given ginger after DM induction (ginger therapeutic), G5 were given cinnamon before induction of DM (cinnamon protective) and G6 were given cinnamon after DM induction (cinnamon therapeutic). In diabetic rats' significant increases in fasting blood sugar and body weight were observed after three weeks. Ginger and cinnamon effectively decreased serum glucose levels. Histopathological evaluations of seminiferous tubules and coda epididymis sections from diabetic rats showed severe damage to them. Furthermore, the sections of seminiferous tubules and coda epididymis rats administered ginger and cinnamon extract showed normal structure, healthy lining epithelium and sperm contents compared to diabetic rats. The results of the study show that both Ginger and Cinnamon aqueous extracts are effective as both hypoglycemic natural supplements that can protect against diabetic-induced testicular damage as well as share in the reservation of the cauda epididymal structure and sperm contents.

Effect of Fluoride on Cytotoxicity Involved in Mitochondrial Dysfunction: A Review of Mechanism

Fluoride is commonly found in the soil and water environment and may act as chronic poison. A large amount of fluoride deposition causes serious harm to the ecological environment and human health. Mitochondrial dysfunction is a shared feature of fluorosis, and numerous studies reported this phenomenon in different model systems. More and more evidence shows that the functions of mitochondria play an extremely influential role in the organs and tissues after fluorosis. Fluoride invades into cells and mainly damages mitochondria, resulting in decreased activity of mitochondrial related enzymes, weakening of protein expression, damage of respiratory chain, excessive fission, disturbance of fusion, disorder of calcium regulation, resulting in the decrease of intracellular ATP and the accumulation of Reactive oxygen species. At the same time, the decrease of mitochondrial membrane potential leads to the release of Cyt c, causing a series of caspase cascade reactions and resulting in apoptosis. This article mainly reviews the mechanism of cytotoxicity related to mitochondrial dysfunction after fluorosis. A series of mitochondrial dysfunction caused by fluorosis, such as mitochondrial dynamics, mitochondrial Reactive oxygen species, mitochondrial fission, mitochondrial respiratory chain, mitochondrial autophagy apoptosis, mitochondrial fusion disturbance, mitochondrial calcium regulation are emphasized, and the mechanism of the effect of fluoride on cytotoxicity related to mitochondrial dysfunction are further explored.

miR-378d is Involved in the Regulation of Apoptosis and Autophagy of and E2 Secretion from Cultured Ovarian Granular Cells Treated by Sodium Fluoride

Taking excessive sodium fluoride may cause female reproductive dysfunction, but underlying molecular mechanism is unclear. The ovarian granulosa cells are the key endocrine cells releasing reproductive hormones. The miRNAs in the granulosa cells play an important function in regulating reproduction. The aim of this study is to explore the role of miRNAs in granulosa cell apoptosis and autophagy, as well as estradiol (E₂) release in response to excessive sodium fluoride. The ovarian granulosa cells (KGN cells) were treated in vitro by different concentrations of sodium fluoride (NaF) for 24 h. The level of estradiol (E₂) in the incubation medium was measured by ELISA kits. The total RNA and protein were collected and purified from KGN cells. The expression of miRNAs was detected by the real-time PCR. The signal molecules involved in cell apoptosis and autophagy were detected by the real-time PCR and Western blotting. Six miRNAs in granulosa cells were significantly up- or downregulated by NaF and selected for real-time PCR analysis. The miR-378d was the most significantly upregulated one dose dependently by NaF. It was positively correlated to the extent of apoptosis but negatively correlated to the level of autophagy in KGN cells in response to NaF. In addition, miR-378d promoted E₂ release in response to 1 and 2 mM NaF but reduced E₂ release in response to 4 and 8 mM NaF treatments. It is concluded that expression of miR-378d in ovarian granulosa cells is negatively correlated to the autophagy and E₂ release and positively correlated to cell apoptosis under the influence of NaF.