The effect of different types of exercise training on diet-induced obesity in rats, cross-talk between cell cycle proteins and apoptosis in testis

The Effect of Different Exercise Modalities on Sertoli-germ Cells Metabolic Interactions in High-fat Diet-induced Obesity Rat Models: Implication on Glucose and Lactate Transport, Igf1, and Igf1R-dependent Pathways

The study aimed to uncover a unique aspect of obesity-related metabolic disorders in the testicles induced by a high-fat diet (HFD) and explored the potential mitigating effects of exercise modalities on male fertility. Thirty mature male Wistar rats were randomly assigned to control, HFD-sole, moderate-intensity exercise with HFD (HFD+MICT), high-intensity continuous exercise with HFD (HFD+HICT), and high-intensity interval exercise with HFD (HFD+HIIT) groups (n=6/group). Intracytoplasmic carbohydrate (ICC) storage, expression levels of GLUT-1, GLUT-3, MCT-4, Igf1, and Igf1R, and testicular lactate and lactate dehydrogenase (LDH) levels were assessed. ICC storage significantly decreased in HFD-sole rats, along with decreased mRNA and protein levels of GLUT-1, GLUT-3, MCT-4, Igf1, and Igf1R. The HFD-sole group exhibited a notable reduction in testicular lactate and LDH levels (p<0.05). Conversely, exercise, particularly HIIT, upregulated ICC storage, expression levels of GLUT-1, GLUT-3, MCT-4, Igf1, and Igf1R, and enhanced testicular lactate and LDH levels. These results confirm that exercise, especially HIIT, has the potential to mitigate the adverse effects of HFD-induced obesity on testicular metabolism and male fertility. The upregulation of metabolite transporters, LDH, lactate levels, Igf1, and Igf1R expression may contribute to maintaining metabolic interactions and improving the glucose/lactate conversion process. These findings underscore the potential benefits of exercise in preventing and managing obesity-related male fertility issues.

Effects of high-fat diet and treadmill running on the hypothalamic Kiss-1-GPR54 signaling pathway in male growing rats

BACKGROUND

Kiss-1 neuron, one of the metabolic sensors in the hypothalamus, is necessary for puberty initiation. It acts through G protein-coupled receptor, known as GPR54. In this study, the mechanism of the hypothalamic Kiss-1-GPR54 signaling pathway in a high-fat diet and exercise was investigated in growing male rats.

METHODS

A total of 135 3-week-old male weaned rats were kept on a high-fat diet (HFD) and exercise (60-70% [Formula: see text], 1 h/day, 5 days/week). They were randomly divided, as follows: control group (C); normal diet + exercise group (CE); HFD group (H); and HFD + exercise group (HE). Hypothalamus, testis, and serum samples of each group were collected on postnatal day (PND) 21 (early childhood), 43 (puberty), and 56 (maturity). Immunofluorescence, quantitative real-time PCR, hematoxylin and eosin staining, and chemiluminescent immunoassays were used in the study. ANOVA was used to analyze the effects of age (PNDs 21, 43, and 56), exercise (exercise and sedentariness), and diet (high-fat and normal) on the biological indices of rats.

RESULTS

mRNA and protein expression of Kiss-1 and GPR54 in the hypothalamus gradually increased along with growth and peaked at PND 43, while those in serum testosterone increased and peaked at PND 56. The high-fat diet increased the expression of the Kiss-1-GPR54 system in the hypothalamus, whereas the serum testosterone decreased during different stages of growth. Exercise decreased the expression of Kiss-1 at PND 56 and increased it at PND 43. Meanwhile, it decreased testosterone and the deposition of lipid droplets in the testis at all ages of development.

CONCLUSIONS

The expression of Kiss-1-GPR54 in male rats showed fluctuating changes during growth and development. The high-fat diet was able to upregulate the expression of the Kiss-1-GPR54 system in the hypothalamus. The exercise was able to correct the adverse effect of the high-fat diet on the Kiss-1-GPR54 signaling pathway in the hypothalamus and the function of the hypothalamic-pituitary-gonadal (HPG) axis, but had age-specific effects on the male rats' development.

Running exercise training-induced impact on oxidative stress and mitochondria-related apoptosis in rat's testicles

The current study has been designed to explore the effects of running exercise training protocols (ETPs), with different intensities, on testicular redox and antioxidant capacities. Moreover, the crosstalk between oxidative stress (OS) and mitochondria-related apoptosis was analysed. To this end, 24 Wistar rats were subdivided into sedentary control, low- (LICT), moderate- (MICT), and high (HICT)-intensity continuous running ETP groups. Following 8 weeks, the Johnsen score, sperm count, testicular malondialdehyde (MDA) content, total oxidant status (TOS), and redox biomarkers, including glutathione peroxidase (GPX), superoxide dismutase (SOD), and catalase (CAT) levels were evaluated. Additionally, the expression levels of Bcl-2, Bax, caspase-3, proteins involving in the mitochondria-related apoptosis, and the apoptotic index were analysed. The LICT and MICT running ETPs did not affect the spermatogenesis development, sperm count, and antioxidant and redox capacities. Accordingly, no significant changes were revealed in Bcl-2, Bax, and caspase-3 expression levels and apoptosis index compared to sedentary rats. In contrast, the HICT-induced rats showed a significant (p < 0.05) reduction in spermatogenesis development, sperm count, antioxidant and redox capacities versus control, LICT, and MICT groups. Moreover, the expression of Bcl-2 was decreased, while the Bax and caspase-3 expression levels were increased in the HICT-induced group. Finally, the apoptosis index was increased in the HICT group. In conclusion, the suppressed redox system after HICT can trigger the mitochondria-mediated ROS overload, result in OS condition in the testicular tissue, and reversely target the mitochondrial membrane permeability. All of these molecular alterations are suspected to initiate progressive mitochondria-related apoptosis after HICT.

Influence of physical activity on male fertility

Infertility is a worldwide issue impacting 15% of couples' population. Male-related infertility results in almost 50% of these cases. Considering lifestyle factors associated with infertility, here in this literature review article, we aimed to discuss training/sport effects on male-related infertility. Regarding this issue, human and animal model studies related to the subject were gathered and analysed. Exercise is well known as a general improving factor, however, excessive exercise can result in male infertility due to reduced hypothalamus-pituitary-gonadal axis (HPT) function, increased oxidative stress and chronic inflammation. Consequently, these underlying impacts result in a low testosterone production, and reduced semen quality, and can lead to infertility. In contrast, it has been revealed that exercise can improve male fertility status in lifestyle-induced infertility condition such as obesity and diabetes. Indeed, exercise, by increasing testicular antioxidant defence, reducing pro-inflammatory cytokines level and enhancing the steroidogenesis process, leads to improved spermatogenesis and semen quality in lifestyle-induced infertility. In fact, it seems that individual health status as well as exercise volume, intensity and duration are effective-involved co-factors that influence the impact that exercise will promote on male fertility. Regarding these findings, it is important to study exercise different impacts in further clinical trials in order to generate preservative guidelines for exercise and also considering exercise as a treatment option in lifestyle-induced disease management.

Influence of sperm DNA fragmentation on the clinical outcome of in vitro fertilization-embryo transfer (IVF-ET)

PURPOSE

To evaluate the effect of elevated sperm DNA fragmentation index (DFI) on fresh and frozen embryo transfer cycles.

METHODS

A retrospective study was performed with 549 fresh embryo transfer cycles and 1340 frozen embryo transfer cycles after in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) from 2016 to 2021.

RESULTS

The statistical results of 549 fresh embryo transfer cycles showed that the delivery rate in the normal sperm DFI group (43.9% vs. 27.1%, P = 0.014) was significantly higher than that in the abnormal sperm DFI group, and there were no significant differences in the biochemical pregnancy rate (59.0% vs. 50.8%, P = 0.232), clinical pregnancy rate (53.1% vs. 40.7%, P = 0.072), or miscarriage rate (17.3% vs. 33.3%, P = 0.098) between the two groups. The results of 1340 frozen embryo transfer cycles showed that the biochemical pregnancy rate (57.9% vs. 45.6%, P = 0.006) and clinical pregnancy rate (50.3% vs. 40.7%, P = 0.027) in the normal sperm DFI group were significantly higher than those in the abnormal sperm DFI group. The delivery rate (40.9% vs. 33.3%, P = 0.074) and miscarriage rate (18.6% vs. 18.0%, P = 0.919) were not significantly different between the two groups.

CONCLUSION

The increase of sperm DFI significantly reduced the delivery rate of fresh embryo transfer cycles and the biochemical pregnancy rate and clinical pregnancy rate of frozen embryo transfer cycles.

Different continuous exercise training intensities induced effect on sertoli-germ cells metabolic interaction; implication on GLUT-1, GLUT-3 and MCT-4 transporting proteins expression level

Despite other tissues, the effect of different exercise training protocols (ETPs) on the expression levels of metabolic substrates transmembrane transporters in the testicular tissue, remains completely unexplored. Thus, the effects of low, moderate and high-intensity ETPs on the SCs and germ cells potentials in GLUT-1, GLUT-3 and MCT-4 expression levels was investigated in this study. The animals were assigned into 4 groups, including sedentary control, low-intensity continuous (LICT), moderate-intensity (MICT) and high-intensity (HICT) ETPs-induced groups (n = 6/group). The GLUT-1, GLUT-3 and MCT-4 expressions, cytoplasmic carbohydrate storages of SCs and germ cells, the SCs survival and the spermatogenesis and spermiogenesis rates were assessed. The LICT and MICT did not significantly alter the protein expression levels of GLUT-3 and MCT-4 in the SCs and germ cells, while decreased the GLUT-1 protein content versus the sedentary control animals. In contrast, the HICT remarkably suppressed the GLUT-1 and MCT-4 in both SCs, and germ cells and diminished GLUT-3 in SCs and increased in the germ cells. No significant changes were revealed in the cytoplasmic carbohydrate storage in the LICT and MICT groups, while significantly diminished in the HICT group. The HICT group showed a failed spermatogenesis and spermiogenesis, which were not demonstrated in the sedentary control, LICT and MICT groups. In conclusion, the HICT, by reducing the GLUT-1, GLUT-3 and MCT-4 protein contents in the SCs and reducing the SCs survival, can suppress the glucose transmembrane transport and inhibit the lactate export from SCs, which in turn, ends with failed spermatogenesis and spermiogenesis.

High-fat diet-induced obesity amplifies HSP70-2a and HSP90 expression in testicular tissue; correlation with proliferating cell nuclear antigen (PCNA)

AIMS

Current study was conducted to uncover the effect of high-fat diet (HFD)-induced obesity on heat shock proteins 70-2a and 90 expression levels and to investigate the network between these proteins with PCNA expression, endocrine status of testicular tissue and nucleotide backbone damages.

MAIN METHODS

For this purpose, 20 mature male Wistar rats were divided into two groups of control and HFD-received obese animals (n = 10/group). After 8 weeks from obesity approval, the animals were euthanized. The expression levels of Hsp70-2a, Hsp90 and PCNA were analyzed by qRT-PCR and immunohistochemical staining techniques. The Leydig cell distribution/mm² of interstitial tissue, serum level of testosterone, testicular total antioxidant capacity (TAC), and mRNA and DNA damage were investigated.

KEY FINDINGS

The obese (HFD-received) animals represented a remarkable (p < 0.05) increment in the mRNA levels of hsp70-2a and Hsp90, and the percentages of Hsp70-2a⁺ and Hsp90⁺ cells/seminiferous tubules with the same criteria. The PCNA mRNA level and the percentage of PCNA⁺ cells were decreased in the obese (HFD-received) group. The obesity, significantly decreased testicular TAC and with no effect on the Leydig cell distribution, but by reducing their steroidogenic activity resulted in a remarkable (p < 0.05) reduction in serum testosterone level. Finally, severe mRNA and DNA damage were revealed in the obese (HFD-received) group.

SIGNIFICANCE

Therefore, considering massive testicular DNA damage in the obese (HFD-received) animals, we can conclude that an increased expression of Hsp70-2a and Hsp90 with no harmony with PCNA could not properly maintain the cellular DNA integrity and/or appropriately finalize the DNA repair process.

ROS and metabolomics-mediated autophagy in rat's testicular tissue alter after exercise training; Evidence for exercise intensity and outcomes

AIMS

Oxidative damage and altered metabolic reactions are suspected to initiate the autophagy. The exercise training significantly impacts testicular antioxidant and metabolic potentials. However, the underlying mechanism(s) that the exercise-induced alterations can affect the autophagy markers remained unknown. This study explored the effect of exercise training on antioxidant and metabolic statuses of testicular tissue and uncovered the possible cross-link between these statuses and autophagy-inducers expression.

MAIN METHODS

Wistar rats were divided into sedentary control, low (LICT), moderate (MICT), and high (HICT) intensity continuous training groups. Following 8 weeks of training, the testicular total antioxidant capacity (TAC), total oxidant status (TOS), glutathione (GSH), and NADP⁺/NADPH as oxidative biomarkers along with intracytoplasmic carbohydrate and lipid droplet patterns, lactate dehydrogenase (LDH) activity, and lactate as metabolic elements were assessed. Finally, the autophagy-inducers expression and sperm count were examined.

KEY FINDINGS

With no significant impact on the oxidative biomarkers and metabolic elements, the LICT and MICT groups exhibited statistically unremarkable (p < 0.05) impacts on spermatogenesis differentiation, spermiogenesis ratio, and sperm count while increased the autophagy-inducers expression. Reversely, the HICT group, simultaneous with suppressing the antioxidant biomarkers (TAC↓, GSH↓, TOS↑, NADP⁺/NADPH↑), significantly (p < 0.05) reduced the testicular LDH activity and lactate level, changed the intracytoplasmic carbohydrate and lipid droplet's pattern, and amplified the classical autophagy-inducers p62, Beclin-1, autophagy-related gene (ATG)-7, and light chain 3 (LC3)-II/I expression.

SIGNIFICANCE

The autophagy-inducers overexpression has occurred after HICT induction, most probably to eliminate the oxidative damage cargoes, while increased to maintain the metabolic homeostasis in the LICT and MICT groups.