Mechanisms of damage to sperm structure in mice on the zinc-deficient diet

Zinc Deficiency Leads to Reproductive Impairment in Male Mice Through Imbalance of Zinc Homeostasis and Inflammatory Response

Zinc is an essential trace element crucial for growth and development and plays a significant role in male reproductive function. The aim of this study was explore the mechanism of male reproductive damage caused by different degrees of zinc deficiency. Thirty male ICR mice were randomly assigned to three groups: zinc-normal diet group (ZN, n = 10, Zn content = 30 mg/kg), low zinc-deficiency diet group (LZD, n = 10, Zn content = 15 mg/kg), and high zinc-deficiency diet group (HZD, n = 10, Zn content = 7.5 mg/kg). The mice were maintained for 8 weeks. At the end of the experiment, they were sacrificed, and their blood, testicular, and epididymal tissues were collected for further study. Zinc-deficient diet led to weight loss, testicular structural disorder, decreased semen quality, imbalance of zinc homeostasis, and inflammatory damage in mice. Semen quality, testosterone, serum Zn, testicular tissue Zn, testicular free Zn ions, Zrt-, Irt-like protein8 (ZIP8), Zrt-, Irt-like protein5 (ZIP5), and interleukin-10 (IL-10) were significantly decreased; zinc transporter 4(ZnT4), NF-κB p65, P-NF-κB p65, NLRP3, Caspase-8, and Caspase-3 were significantly increased in both LZD and HZD group mice. While compared with the LZD group, Zrt-, Irt-like protein13 (ZIP13), TNF-α, NF-κB p65, P-NF-κB p65, NLRP3, Caspase-1, and GSDMD were significantly increased in the HZD group. Both low and high zinc-deficiency diets can disrupt zinc homeostasis in mice, leading to heightened inflammatory responses, the activation of the NF-κB pathway, and increased apoptosis in testicular cells. Notably, a high zinc-deficiency diet led to an up-regulation of ZIP13 expression, exacerbated inflammation, and induced testicular pyroptosis, resulting in more severe reproductive damage in male mice.

Zinc as a Modulator of Male Fertility: Interplay Between Lipid Metabolism, Oxidative Stress, and Sperm Function

Infertility is a multifaceted and pressing global health challenge, with male reproductive impairment playing a significant role in its overall burden. Zinc (Zn), a biologically indispensable trace element, is fundamental to spermatogenesis and overall male reproductive function. This narrative review explores the following aspects: (1) the mechanistic function of Zn in spermatogenesis, (2) the impact of oxidative stress on Zn status and male infertility, (3) the interplay between Zn and lipid metabolism in male reproductive physiology, (4) the relationship between Zn concentrations and semen parameters, and (5) the effects of Zn supplementation on sperm quality, alongside relevant institutional recommendations. The molecular pathways underlying Zn deficiency-induced enzymatic dysfunction, oxidative stress, and lipid homeostasis disruption remain partially elucidated, warranting further investigation into their interdependent effects on male infertility. While accumulating evidence suggests that Zn supplementation may have therapeutic potential in male infertility management, guidelines for its clinical application vary considerably across institutions and regions. To establish a clear and evidence-based framework for the function of Zn in male reproductive health, future research should prioritize determining of optimal Zn levels, the mechanistic links between Zn and lipid metabolism, and the long-term clinical outcomes of Zn supplementation in infertile populations.

Effects of short term dietary zinc deficiency and zinc supplementation on nitro-oxidative stress in testes of Wistar rats

Zinc is crucial for several cellular functions in the biological system. Zinc insufficiency is one of the most prevalent types of micronutrient malnutrition in the world. Present study was conducted to detect testicular free radical levels i.e. lipid peroxidation (LPO), hydroperoxides, hydroxyl radical (OH.), nitric oxide (NO) and peroxynitrite (ONOO-) after short term dietary zinc deficiency and zinc supplementation. Pre-pubertal rats (n = 144) were divided into two groups with 6 sub-groups viz. zinc control (ZC, 100 µg/g zinc diet), pair-fed (PF, 100 µg/g zinc diet), zinc deficient (ZD, < 1.00 µg/g), zinc control supplementation (ZCS, 100 µg/g zinc diet), pair-fed supplementation (PFS, 100 µg/g zinc diet) and zinc deficient supplementation (ZDS, 100 µg/g zinc diet). Experiments were set for 2- and 4-weeks followed by 4 weeks of dietary zinc supplementation. Zinc deficient groups (2- and 4-weeks) exhibited significant (p < 0.05) increase in testicular LPO (TBARS), hydroperoxides, OH·, NO and ONOO- levels as compared to their respective control and pair-fed groups. Zinc deficient supplementation group (2ZDS) revealed a non-significant increase in OH·, NO and ONOO- levels while a significant increase in LPO and hydroperoxides levels. 4ZDS group showed a significant increase in the free radical levels, however the increase was less as compared to 4ZD group. Dietary zinc deficiency results in induction of cellular lipoperoxidation as well as causes stimulation of nitro-oxidative stress. Zinc supplementation (although for short duration signifying zinc redistribution in the testicular tissue) indicated positive response accounting for reduced free radical generation and also implicating its requirement in optimum level for sustentation of reproductive functions.

Sulforaphane acts through the NFE2L2/AMPK signaling pathway to protect boar spermatozoa from cryoinjury by activating antioxidant defenses

During cryopreservation, a substantial portion of spermatozoa undergoes apoptosis due to cryoinjury, resulting in decreased fertility. Boar spermatozoa are highly sensitive to temperature, with low temperature triggering reactive oxygen species (ROS) generation, leading to oxidative stress and apoptosis. Sulforaphane (SFN), a potent natural compound found in cruciferous vegetables, is efficacious in mitigating oxidative stress. We here supplemented different SFN concentrations (0, 1.25, 2.5, 5, 10, and 20 μM) into the freezing extender to explore its effect on boar sperm during cryopreservation and determine the optimal SFN concentration. Supplementation of 5 μM SFN exhibited the highest sperm motility, motion performance, plasma membrane integrity, acrosome integrity, and antioxidant properties (total antioxidant capacity (T-AOC) and antioxidant enzyme activity) after freezing and thawing. Then, RT group, C group and C + SFN group were established to explore the effect of SFN on the cryopreservation-induced sperm apoptosis level and fertilizing capacity of post-thawed sperms. SFN effectively rescued the apoptosis and fertilizing capacity of post-thawed sperms. Mechanistically, SFN activated the redox-sensitive nuclear factor erythroid 2-related factor 2 (NRF2/NFE2L2) by promoting adenosine monophosphate-activated protein kinase (AMPK) phosphorylation. This activation improved antioxidant defenses, ultimately improving cryoinjury in boar spermatozoa. In summary, SFN suppressed cryopreservation-induced apoptosis of spermatozoa by activating antioxidant defenses and the AMPK/NFE2L2 signaling pathway. These findings suggest a novel approach for augmenting the cryoprotective efficiency and spermatozoa fertility after cryopreservation.

A Dietary Supplement Jinghuosu Ameliorates Reproductive Damage Induced by Tripterygium Glycosides

OBJECTIVE

To determine the possible protective effects of Jinghuosu, a dietary supplement (DS), on tripterygium glycosides (TG)-induced reproductive system injury in rats and its underlying mechanisms.

METHODS

A reproductive damage model was established in rats by feeding of TGs. Twenty-eight male Sprague Dawley rats were randomly divided into 4 groups using a random number table (n=7 in each): control (C) group, model (M) group, DS group and L-carnitine (LC) group. Rats in M, DS and LC groups received 40 mg/kg TGs orally. Starting from the 5th week, after administration of TGs for 4 h every day, rats in DS and LC groups were administered with 2.7 g/kg DS and 0.21 g/kg LC, respectively, for protective treatment over the next 4 weeks. Rats in Group C continued to receive the control treatment. Hematoxylin-eosin staining was used for histopathological analysis of rat testicular tissues. Enzyme-linked immunosorbent assay was performed to measure alkaline phosphatase (ALP), lactate dehydrogenase, alcohol dehydrogenase, total antioxidant capacity (T-AOC), superoxide dismutase, glutathione peroxidase (GSH-Px), and malondialdehyde (MDA) concentrations. Chemiluminescence assay was used to determine the serum testosterone content. Quantitative real-time PCR and Western blotting were conducted to analyze the expression of genes and proteins related to the testosterone synthesis pathway and the nuclear factor erythroid 2-related factor 2/heme oxygenase 1 antioxidant pathway.

RESULTS

Oral administration of TGs induced significant increases in the testicular levels of zinc transporter 1 and MDA (P<0.05). On the other hand, sperm concentration, sperm motility, and serum testosterone, serum zinc, testicular zinc, Zrt-, Irt-like protein 1, ALP, luteinizing hormone (LH) receptor, steroidogenic acute regulatory protein, Cytochrome P450 family 11 subfamily A member 1, 3 β -hydroxysteroid dehydrogenase 1 T-AOC, GSH-Px, nuclear factor erythroid 2-related factor 2, heme oxygenase-1 and NAD (P)H: quinone oxidoreductase 1 levels decreased following TGs exposure (P<0.05). All of these phenotypes were evidently reversed by DS (P<0.05).

CONCLUSION

DS Jinghuosu protects against TG-induced reproductive system injury in rats, probably by improving zinc homeostasis, enhancing the testosterone synthesis and attenuating oxidative stress.