Age-related decrease in aromatase and estrogen receptor (ERα and ERβ) expression in rat testes: protective effect of low caloric diets

Icariin alleviates the injury of Sertoli cell junction function by upregulating PKR pathway via ERα/c-fos signaling in aged mice

ETHNOPHARMACOLOGICAL RELEVENACE

Sertoli cells are vital to maintain spermatogenesis and their function decline during aging. Epimedium has the effects of tonifying kidney-yang, strengthening bones and muscles, and expelling wind and dampness, and is commonly used in the treatment of kidney-yang deficiency, impotence and spermatorrhea. Icariin is the main active ingredients from Epimedium exhibiting delaying aging effects and improving male reproductive dysfunction. Whereas, it remains poorly understood how icariin alleviates age-associated decline in testicular function by protecting against the damage of junction function of Sertoli cells.

AIM OF THE STUDY

This study aimed to evaluate the improvement effect of icariin on Sertoli cell junction function damage and explore the underlying mechanisms.

MATERIALS AND METHODS

Male C57BL/6 mice and mouse Sertoli cell line TM4 cells were utilized to assess the improvement effect of icariin on aging-associated Sertoli cell junction function injury. H&E staining, transmission electron microscopy, qPCR, Western blot, molecular docking, siRNA transfection, and immunofluorescence were performed in this study.

RESULTS

Dietary administration of icariin remarkly attenuated age-associated deterioration in spermatogenic function as evidenced by elevated testicular weight and index, sperm concentration and sperm viability. In addition, icariin protected Sertoli cell junction function from age-associated damage as proven by increased Sertoli cell numbers, improved tight junction ultrastructure, and upregulated junction-related proteins (ZO-1, Occludin and β-Catenin). Moreover, icariin significantly upregulated ERα/c-fos signaling and PKR pathway in testicular Sertoli cells. Similarly, in vitro studies revealed that deletion of ERα, c-fos or PKR abolished the improvement effects of icariin on Sertoli cell junction function damage.

CONCLUSIONS

Icariin effectively mitigates age-associated decline in testicular function by diminished Sertoli cell junction function damage through upregulating PKR pathway via ERα/c-fos signaling. Therefore, attenuating Sertoli cell junction function injury by the upregulation of PKR pathway via ERα/c-fos signaling probably indicates an effective target for the prevention and treatment of testicular spermatogenic function with aging.

Intraperitoneal kisspeptin-10 administration ameliorates sodium arsenite-induced reproductive toxicity in adult male mice

The current study investigated the protective ameliorative effect of intraperitoneally administered kisspeptin-10 (50 nmol/day) against reproductive toxicity in adult male mice challenged with 35 days of exposure to sodium arsenite in drinking water. Mice were divided into tap water control, sodium arsenite-alone (4 ppm and 10 ppm), kisspeptin-alone (intermittent and continuous) and combined (sodium arsenite +kisspeptin-10 intermittent and continuous) treatment groups. Results revealed protective effect of both intermittent and continuous kisspeptin doses on reproductive organs against sodium arsenite-induced toxicity. This was indicated by an increase (p < 0.001) in the activity of antioxidant enzymes and a decrease (p < 0.001) in the levels of oxidative stress biomarkers. Concomitant significant increase was noticeable in the relative organ weight (p < 0.01), and serum testosterone and seminal fructose (p < 0.001), and a significant improvement in sperm parameters was also observed. A significant downregulation of lactate dehydrogenase concentration demonstrated further the protective effect of kisspeptin against tissue damage. Histologically, both treatment regimens of kisspeptin combined with sodium arsenite exposure prevented massive germ cell loss and tissue damage, a condition prominent in sodium arsenite-alone-treated mice. The study demonstrates for the first time kisspeptin's potential to mitigate the biochemical and histotoxic effects of arsenic on male reproductive system.

Icariin Improves Age-Related Testicular Dysfunction by Alleviating Sertoli Cell Injury via Upregulation of the ERα/Nrf2-Signaling Pathway

Sertoli cells play crucial roles in spermatogenesis and are impaired by aging. Icariin, a flavonoid from Epimedium, has been reported to exhibit anti-aging effects and improve testicular dysfunction in the clinical setting. However, whether icariin improves age-related degeneration of testicular function via protection from Sertoli cell injury remains unclear. In the present study, we evaluated the protective effect of icariin on Sertoli cell injury and explored the possible mechanism(s) in vivo and in vitro. Dietary administration of icariin for 4 months significantly ameliorated the age-related decline in testicular function by increasing testicular and epididymal weights and indices, sperm count and sperm viability, testicular testosterone and estradiol concentrations, and seminiferous tubule diameters and heights. In addition, icariin protected age-related Sertoli cells from injury as evidenced by an analysis of Sertoli cell number, ultrastructure, and function. Such changes were accompanied by upregulation of ERα and Nrf2 signaling in Sertoli cells. Parallel in vitro studies also demonstrated that icariin inhibited untoward effects on the TM4 mouse Sertoli cell line with concomitant upregulation of ERα and Nrf2 signaling. Conversely, ERα siRNA reversed icariin-mediated protection of Sertoli cell injury. Our data suggest that icariin effectively ameliorates age-related degeneration of testicular function by alleviating Sertoli cell injury via the ERα/Nrf2 signal-transduction pathway. Thus, mitigating Sertoli cell damage via the ERα/Nrf2 signaling pathway likely represents a promising strategy for the prevention of age-related testicular dysfunction.

Daidzein upregulates anti-aging protein Klotho and NaPi 2a cotransporter in a rat model of the andropause

In a rat model of the andropause we aimed to examine the influence of daidzein, soy isoflavone, on the structure and function of parathyroid glands (PTG) and the expression levels of some of the crucial regulators of Ca²⁺ and Pi homeostasis in the kidney, and to compare these effects with the effects of estradiol, serving as a positive control. Middle-aged (16-month-old) male Wistar rats were divided into the following groups: sham-operated (SO), orchidectomized (Orx), orchidectomized and estradiol-treated (Orx+E; 0.625mg/kg b.w./day, s.c.) as well as orchidectomized and daidzein-treated (Orx+D; 30mg/kg b.w./day, s.c.) group. Every treated group had a corresponding control group. PTH serum concentration was decreased in Orx+E and Orx+D groups by 10% and 21% (p<0.05) respectively, in comparison with the Orx. PTG volume was decreased in Orx+E group by 16% (p<0.05), when compared to the Orx. In Orx+E group expression of NaPi 2a was lower (p<0.05), while NaPi 2a abundance in Orx+D animals was increased (p<0.05), when compared to Orx. Expression of PTH1R was increased (p<0.05) in Orx+E group, while in Orx+D animals the same parameter was decreased (p<0.05), in comparison with Orx. Klotho expression was elevated (p<0.05) in Orx+D rats, in regard to Orx. Orx+D induced reduction in Ca²⁺/creatinine and Pi/creatinine ratio in urine by 32% and 16% (p<0.05) respectively, in comparison with Orx. In conclusion, presented results indicate the more coherent beneficial effects of daidzein compared to estradiol, on disturbed Ca²⁺ and Pi homeostasis, and presumably on bone health, in the aging male rats.

Molecular characterisation of oestrogen receptor ERα and the effects of bisphenol A on its expression during sexual development in the Chinese giant salamander (Andrias davidianus)

The aim of this study was to characterise the molecular structure of the oestrogen receptor ERα and to evaluate the effect of bisphenol A (BPA) on ERα expression during sexual development of the Chinese giant salamander (Andrias davidianus). The ERα cDNA of A. davidianus includes an open reading frame of 1755bp (encoding 584 amino acids), a 219-bp 5' untranslated region (UTR) and a 611-bp 3'UTR. A polyadenylation signal was not found in the 3'UTR. Amino acid sequence analysis showed high homology between ERα of A. davidianus and that of other amphibians, such as Andrias japonicas (99.66% identity) and Rana rugose (81.06% identity). In 3-year-old A. davidianus, highest ERα expression was observed in the liver and gonads. During different developmental stages in A. davidianus (from 1 to 3 years of age), ERα expression in the testes increased gradually. ERα was localised in the epithelial cells of seminiferous lobules and in interstitial cells. ERα-positive cells were more abundant in the interstitial tissue during testicular development. ERα was located in the nucleus of oocytes during ovary development. We found that the sex of 6-month-old A. davidianus larvae could not be distinguished anatomically. The sex ratio did not change after larvae were treated with 10μM BPA for 1 month. However, BPA treatment reduced bodyweight and ERα expression in the gonads in male larvae.

Calorie restriction with a high-fat diet effectively attenuated inflammatory response and oxidative stress-related markers in obese tissues of the high diet fed rats

Obesity characterized by increased mass of adipose tissue leads to systemic inflammation. Calorie restriction (CR) improves parameters associated with immune response and antioxidant defense. We hypothesized that CR with a high fat diet (HFCR) regulates local and systemic inflammation and oxidative stress damage in a high fat diet induced obesity (HF group). We investigated effect of HFCR on inflammation and oxidative stress-related markers in liver and adipose tissues as well as adipokines in plasma. HFCR lowered liver triglyceride levels, total cholesterol levels, and the plasma leptin/adiponectin ratio to normal levels and improved glucose tolerance. HFCR also improved fatty liver and normalized adipocyte size and morphology. HFCR reduced lipid peroxidation and decreased the expression levels of inducible nitric oxide synthetase, cyclooxygenase-2, NF-E2-related factor, and heme oxygenase-1 in the liver. Moreover, HFCR suppressed the expression levels of C- reactive protein and manganese superoxide dismutase in the adipose tissue in the HF group. These results suggest that HFCR may have beneficial effects on inflammation and oxidative stress as well as lipid profiles in the HF diet induced obesity. Moreover, HFCR may be a good way to increase compliance in obese patients and to prevent obesity induced complications without changes in dietary pattern.

Potential protective effect on key steroidogenesis and metabolic enzymes and sperm abnormalities by fenugreek steroids in testis and epididymis of surviving diabetic rats

The current study showed that the daily oral treatment of fenugreek steroids, designated F(steroids), to diabetic rats during 30 days demonstrated a significant (p < 0.05) decrease of blood glucose level and a considerable increase of the area of insulin-immunoreactive beta-cells in diabetic rats. Interestingly, this study showed that F(steroids) potentially unregulated the key steroidogenesis enzymes such as 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMG-CoA reductase), malic enzyme, 3beta-hydroxysteroid dehydrogenase (3beta-HSD) and glucose-6-phosphate dehydrogenase (G6P-DH) activities as cholesterol rate in testis, which considerably enhanced testosterone and estradiol levels in the plasma of surviving diabetic rats. More interestingly, F(steroids) obviously prevented the alteration of the key carbohydrate enzymes such as hexokinase and pyruvate kinase activities as well as testicular glycogen and seminal fructose contents in surviving diabetic rats. Furthermore, F(steroids) administration to surviving diabetic rats significantly decreased the sperm shape abnormality and improved the sperm count. Above all, the potential protective action of reproductive systems was approved by the histological study of testis and epididymis.

Inhibitory effect of estrogens, phytoestrogens, and caloric restriction on oxidative stress and hepato-toxicity in aged rats

OBJECTIVE

To investigate the protective effect of 17beta-estradiol (E2), peganum harmala extract (PHE) administration and calorie restriction (CR) treatment (60%) on oxidative stress and hepato-toxicity in aged rats.

METHODS

Eighteen months old animals that were treated at the age of 12 months were divided into 4 groups: normal control group with free access to food, E2 treatment group, PHE treatment group and CR treatment group of the food given to control group. Six male rats at the age of 4 months were used as a reference group.

RESULTS

Aging significantly decreased superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), and increased lactate deshydrogenase (LDH), gamma-glytamyl transferase (GGT), phosphatase alkalines (PAL), aspartate and lactate transaminase (AST and ALT) activities in the liver. Aging also induced an increased lipid peroxidation level, histological changes and a decreased E2 level. However, treatment with E2, PHE, and CR increased 17beta-estradiol, and decreased hepatic dysfunction parameters and lipid peroxidation as well as histological changes in the liver of aged rats.

CONCLUSION

The antioxidant and hepatoprotective activity of PHE and CR is possibly attributed to its ability to increase E2 level, which as an antioxidant, acts as a scavenger of ROS. Further studies on the pharmaceutical functions of E2 in males may contribute to its clinical application.

Pathological changes induced by rancid feed in rats and effects on growth and protein utilisation

The objective of this trial was to study the effect of rancid feeds on the health status and growth of rats and to determine the pathological changes induced by dietary rancidity. Forty-two weaned male rats (body weight: 69.3 +/- 1.0 g) were divided into seven experimental groups (n = 6 each). Rats in the different groups were fed diets containing meat-and-bone meal at an inclusion rate of 19 to 22%, low or high in peroxides and high in organic acids, with or without antioxidant. The diets were isoproteic (10%) and isolipidic (6%). During the 26-day-long trial (5 days for adjustment and 21 days for the main period) the body weight gain and the feed consumption were recorded. At the end of the trial detailed gross and histopathological examinations were performed. Feeding high-peroxide feed mixtures for 21 days significantly (P < 0.05) decreased feed intake and liveweight gain, while high organic acid concentration had only slight negative effects. Antioxidant supplementation alleviated the harmful effects, especially in the high-peroxide group. The ingestion of rancid feed mixtures and the subsequent decreased feed intake caused a decrease of glycogen content in the hepatocytes, accompanied by a slight centrolobular fatty infiltration. Peroxides caused lymphocyte depletion in the spleen, decreased the size of Malpighian bodies and the number of lymphoblasts, and altered the spermatogenesis. The protective effect of the antioxidant mixture seemed to be negligible in this respect.

Protective effects of estrogens and caloric restriction during aging on various rat testis parameters

AIM

To investigate the effects of 17beta-estradiol (E2), Peganum harmala extract (PHE) and caloric restriction (CR) on various testis parameters during aging.

METHODS

Twelve month-old male rats were treated for 6 months with either E2 or PHE, or submitted to CR (40%).

RESULTS

Our results show that estrogens and CR are able to protect the male gonad by preventing the decrease of testosterone and E2 levels as well as the decrease of aromatase and estrogen receptor gene expressions. Indeed, E2, PHE and CR treatments induced an increase in the superoxide dismutase activities and decreased the activity of testicular enzymes: gamma-glutamyl transferase, alkaline phosphatase, lactate deshydrogenase as well as the aspartate and lactate transaminases in aged animals. In addition, the testicular catalase and gluthatione peroxidase activities were enhanced in E2, PHE and CR-treated rats compared to untreated animals at 18 months of age. Moreover, the positive effects of estradiol, PHE and CR were further supported by a lower level of lipid peroxidation. Recovery of spermatogenesis was recorded in treated rats.

CONCLUSION

Besides a low caloric diet which is beneficial for spermatogenesis, a protective antioxydant role of estrogens is suggested. Estrogens delay testicular cell damage, which leads to functional senescence and, therefore, estrogens are helpful in protecting the reproductive functions from the adverse effects exerted by reactive oxygen species (ROS) produced in large quantities in the aged testis.