Anti-Aging Effect of Urolithin A on Bovine Oocytes In Vitro

Exposure to chlorpyrifos interferes with intercellular communication in cumulus-oocyte complexes during porcine oocyte maturation

Chlorpyrifos (CPF), a widely used organophosphorus pesticide (OP) to control pests has been verified reproductive toxicity on mammalian oocytes. However, limited information exists on its correlation with the dysfunction of the intercellular communication in cumulus-oocyte complexes (COCs). Herein, our study utilized porcine COCs as models to directly address the latent impact of CPF on the communication between cumulus cells (CCs) and oocytes during in vitro maturation. The results demonstrated that CPF exposure decreased the rate of the first polar body (PB1) extrusion and blocked meiosis progression. Notably, the cumulus expansion of CPF-exposed COCs was suppressed significantly, accompanied by the down-regulated mRNA levels of cumulus expansion-related genes. Furthermore, the early apoptotic level was raised and the expression of BAX/BCL2 and cleaved caspase 3 was up-regulated in the CCs of CPF-exposed COCs (p < 0.05). Moreover, CPF exposure impaired mRNA levels of antioxidant enzyme-related genes, induced higher levels of reactive oxygen species (ROS) and reduced the levels of mitochondrial membrane potential (MMP) in CCs (p < 0.05). Additionally, the integrated optical density (IOD) rate (cumulus/oocyte) of calcein and the expression of connexin 43 (CX43) was increased in CPF treatment groups (p < 0.05). As well, CPF exposure reduced the expression levels of FSCN1, DAAM1 and MYO10, which resulted in a significant decrease in the number and fluorescence intensity of transzonal projections (TZPs). In conclusion, CPF inhibited the expansion of cumulus and caused oxidative stress and apoptosis as well as disturbed the function of gap junctions (GJs) and TZPs, which eventually resulted in the failure of oocyte maturation.

Gut microbiota-generated metabolites: missing puzzles to hosts' health, diseases, and aging

The gut microbiota, an intricate community of bacteria residing in the gastrointestinal system, assumes a pivotal role in various physiological processes. Beyond its function in food breakdown and nutrient absorption, gut microbiota exerts a profound influence on immune and metabolic modulation by producing diverse gut microbiota-generated metabolites (GMGMs). These small molecules hold potential to impact host health via multiple pathways, which exhibit remarkable diversity, and have gained increasing attention in recent studies. Here, we elucidate the intricate implications and significant impacts of four specific metabolites, Urolithin A (UA), equol, Trimethylamine N-oxide (TMAO), and imidazole propionate, in shaping human health. Meanwhile, we also look into the advanced research on GMGMs, which demonstrate promising curative effects and hold great potential for further clinical therapies. Notably, the emergence of positive outcomes from clinical trials involving GMGMs, typified by UA, emphasizes their promising prospects in the pursuit of improved health and longevity. Collectively, the multifaceted impacts of GMGMs present intriguing avenues for future research and therapeutic interventions. [BMB Reports 2024; 57(5): 207-215].

Urolithins: A Prospective Alternative against Brain Aging

The impact of host-microbiome interactions on cognitive health and disease has received increasing attention. Microbial-derived metabolites produced in the gut are one of crucial mechanisms of the gut-brain axis interaction, showing attractive perspectives. Urolithins (Uros) are gut microbial-derived metabolites of ellagitannins and ellagic acid, whose biotransformation varies considerably between individuals and decreases greatly with age. Recently, accumulating evidence has suggested that Uros may have specific advantages in preventing brain aging including favorable blood-brain barrier permeability, selective brain distribution, and increasingly supporting data from preclinical and clinical studies. However, the usability of Uros in diagnosis, prevention, and treatment of neurodegenerative diseases remains elusive. In this review, we aim to present the comprehensive achievements of Uros in age-related brain dysfunctions and neurodegenerative diseases and discuss their prospects and knowledge gaps as functional food, drugs, or biomarkers against brain aging.

The Antioxidant Auraptene Improves Aged Oocyte Quality and Embryo Development in Mice

Decrease in quality of postovulatory aged oocytes occurs due to oxidative stress and leads to low fertilization and development competence. It is one of the main causes that exerting detrimental effect on the success rate in assisted reproductive technology (ART). Auraptene (AUR), a citrus coumarin, has been reported to possess an antioxidant effects in other tissues. In this study, we aimed to confirm the potential of AUR to delay the oocyte aging process by alleviating oxidative stress. Superovulated mouse oocytes in metaphase of second meiosis (MII) were exposed to 0, 1 or 10 μM AUR for 12 h of in vitro aging. AUR addition to the culture medium recovered abnormal spindle and chromosome morphology and mitigated mitochondrial distribution and mitochondrial membrane potential (ΔΨ) in aged oocytes. AUR-treated aged oocytes also showed suppressed oxidative stress, with lower reactive oxygen species (ROS) levels, higher glutathione (GSH) levels and increased expression of several genes involved in antioxidation. Furthermore, AUR significantly elevated the fertilization and embryo developmental rates. Oocytes aged with 1 μM AUR exhibited morphokinetics that were very similar to those of the control group. Altogether, these data allowed us to conclude that AUR improved the quality of aged oocytes and suggest AUR as an effective clinical supplement candidate to prevent postovulatory aging.

Oocyte mitophagy is critical for extended reproductive longevity

Women’s reproductive cessation is the earliest sign of human aging and is caused by decreasing oocyte quality. Similarly, C. elegans’ reproduction declines in mid-adulthood and is caused by oocyte quality decline. Aberrant mitochondrial morphology is a hallmark of age-related dysfunction, but the role of mitochondrial morphology and dynamics in reproductive aging is unclear. We examined the requirements for mitochondrial fusion and fission in oocytes of both wild-type worms and the long-lived, long-reproducing insulin-like receptor mutant daf-2. We find that normal reproduction requires both fusion and fission, but that daf-2 mutants utilize a shift towards fission, but not fusion, to extend their reproductive span and oocyte health. daf-2 mutant oocytes’ mitochondria are punctate (fissioned) and this morphology is primed for mitophagy, as loss of the mitophagy regulator PINK-1 shortens daf-2’s reproductive span. daf-2 mutants maintain oocyte mitochondria quality with age at least in part through a shift toward punctate mitochondrial morphology and subsequent mitophagy. Supporting this model, Urolithin A, a metabolite that promotes mitophagy, extends reproductive span in wild-type mothers–even in mid-reproduction—by maintaining youthful oocytes with age. Our data suggest that promotion of mitophagy may be an effective strategy to maintain oocyte health with age.

Female reproductive decline begins in a woman’s 30’s, and has become an increasingly important area of research as more women delay child bearing. Like women, the nematode C. elegans undergoes reproductive senescence starting in mid-life, and its reproductive span is determined by oocyte quality decline with age. One of the hallmarks of aging is an increase in mitochondrial dysfunction that can be driven by aberrant mitochondrial fission and fusion, the main regulators of metabolic function and mitochondrial dynamics. In this study we identified a mechanism that promotes reproductive longevity using mitochondrial fission and mitophagy, the trash compactor of dysfunctional mitochondria. This mechanism led us to test Urolithin A, a common metabolite that promotes mitophagy and extends lifespan in C. elegans, as a possible therapeutic to delay reproductive decline. We suggest promotion of mitophagy in oocytes as a new target to extend reproductive longevity through Urolithin A supplementation.

Urolithin A attenuates auditory cell senescence by activating mitophagy

Aging of sensory organs is associated with a decline in mitochondrial function and the accumulation of dysfunctional mitochondria. Impaired mitophagy blocks the turnover of dysfunctional mitochondria and leads to their accumulation. Urolithin A (UA) induces mitophagy in various mammalian cells. This study was aimed at investigating the effect of the mitophagy activator, UA, on premature senescent auditory cells. The levels of cellular senescence-associated p53 and p21 significantly increased in H₂O₂-induced senescent House Ear Institute-Organ of Corti 1 (HEI-OC1) cells and cochlear explants. However, the levels of mitophagy-related molecules significantly decreased. UA significantly decreased the expression of senescence-associated p53 and p21, and increased the expression of mitophagy-related proteins, in H₂O₂-induced senescent cells and cochlear explants. The percentage of β-galactosidase-stained senescent cells also reduced in H₂O₂-treated cells and cochlear explants upon UA pre-treatment. The formation of mitophagosomes and mitophagolysosomes was restored upon UA pre-treatment of H₂O₂-induced senescent cells. The knockdown of mitophagy-related genes (Parkin and Bnip3) resulted in annulment of UA-induced anti-senescent activity. UA significantly increased the ATP content, mitochondrial DNA (mtDNA) integrity, and mitochondrial membrane potential in senescent HEI-OC1 cells. These findings indicate that UA counteracted mitophagy decline and prevented premature senescence in auditory cells. Hence, UA administration might be a promising strategy for preventing mitochondrial dysfunction in patients with age-related hearing loss.