The experimental design was deliberately rigorous. Forty male Sprague Dawley rats were divided into four groups: a control group on a standard diet, an obesity group, a Kisspeptin-10 group, and a group that was both obese and treated with the peptide. Obesity was induced by feeding the animals a high-fat diet in which 60 percent of calories came from fat for twelve weeks, a demanding regimen designed to mimic the metabolic burden of chronic dietary excess in humans. At the end of that period, rats with a Lee index of 300 or above, a standard anthropometric measure of adiposity in rodents, were classified as obese. Treatment then ran for a further four weeks, during which the obese groups continued on the high-fat diet while Kisspeptin-10 was administered intraperitoneally at a dose of 50 nanomoles per kilogram to the two designated groups.

The damage that obesity inflicted on the reproductive system was clear and multifaceted. In the untreated obese rats, the researchers measured a decline in antioxidant capacity within the testes, alongside an increase in malondialdehyde, or MDA, a well-established marker of lipid peroxidation. Lipid peroxidation is essentially the oxidative degradation of the fatty membranes that surround cells and organelles, and spermatozoa are particularly vulnerable because their membranes are unusually rich in polyunsaturated fatty acids. When those membranes are attacked by reactive oxygen species, sperm motility, membrane integrity, and fertilizing capacity all suffer. The obese animals also showed reduced sperm concentration and motility, a higher proportion of sperm with tail abnormalities, impaired mitochondrial function, reduced reproductive organ weights, and evidence of sperm DNA damage.

Against that bleak backdrop, the effects of Kisspeptin-10 were striking in several domains. Treated animals showed significantly lower MDA levels and higher levels of glutathione, or GSH, one of the cell’s most important endogenous antioxidants. Glutathione acts as the cell’s primary redox buffer, neutralizing peroxides and detoxifying electrophilic compounds through conjugation reactions, so its restoration signals a meaningful rebalancing of the testicular redox environment. The peptide also improved sperm motility and concentration, reduced the ratio of tail-abnormal sperm, and decreased sperm DNA damage. Additionally, the researchers observed an increase in prostate weight in treated animals, suggesting a broader trophic effect on the male reproductive tract.

Perhaps the most intriguing part of the study concerned mitochondria, the energy-producing organelles that sperm depend on almost entirely for the power needed to swim. Sperm mitochondria sit in the midpiece of the cell and generate the ATP that drives flagellar beating, and their membrane potential, known as MMP, is a widely used proxy for mitochondrial health. In the present study, obesity impaired sperm MMP, and while Kisspeptin-10 treatment showed only a non-significant tendency toward partial restoration of mitochondrial function, the molecular data hinted at a deeper story. The researchers measured the expression of proteins involved in mitophagy, the specialized form of autophagy that selectively identifies and removes damaged mitochondria before they can leak reactive oxygen species and trigger cell death.

That story centered on two proteins in particular. PTEN-induced putative kinase 1, or PINK1, accumulates on the surface of damaged mitochondria and recruits the ubiquitin ligase Parkin to tag those organelles for degradation. Prohibitin 2, or PHB2, is an inner mitochondrial membrane protein that serves as a receptor for the autophagy machinery, linking damaged mitochondria to the engulfing autophagosome. In the Kisspeptin-10-treated rats, expression of both PINK1 and PHB2 was increased, suggesting that the peptide may enhance the cell’s ability to recognize and clear dysfunctional mitochondria. The researchers also observed increased expression of Beclin-1, a core component of the class III phosphatidylinositol 3-kinase complex that initiates autophagosome formation, indicating broader engagement of the autophagy pathway.

Not every measured parameter responded, and the authors are candid about those limits. Expression of Parkin itself, the downstream ubiquitin ligase in the canonical PINK1-Parkin pathway, did not change significantly, nor did LC3-II, the lipidated form of the microtubule-associated protein light chain 3 that marks mature autophagosomes. Apoptosis-related proteins were likewise unaffected. This pattern suggests that Kisspeptin-10’s influence on mitochondrial quality control may operate primarily at the level of damage recognition and initiation rather than at the downstream execution steps of autophagic degradation or programmed cell death. Whether longer treatment durations, higher doses, or different disease models would recruit those downstream arms of the pathway remains an open question for future work.

The biological plausibility of these effects rests on kisspeptin’s expanding résumé. Encoded by the KiSS-1 gene and acting through the GPR54 receptor, kisspeptin is the critical upstream regulator of gonadotropin-releasing hormone neurons, and its administration potently stimulates luteinizing hormone release in both men and women. But a growing body of evidence suggests the peptide has direct protective actions in peripheral tissues as well. Previous studies have shown that Kisspeptin-10 ameliorates methotrexate-induced sperm damage and testicular oxidative stress in rats, reduces lipid peroxidation in testicular tissue, protects against amyloid-beta neurotoxicity in vitro, and improves testicular redox status in hypothyroid animals. The new findings extend that protective profile into the context of metabolic disease, where the interplay between obesity, leptin signaling, and reproductive function has long implicated kisspeptin as a potential mediator.

The clinical implications are considerable. Meta-analyses have consistently shown that elevated body mass index is associated with reduced sperm count and altered semen parameters in men, and obesity now affects hundreds of millions of adults worldwide. Because sperm mitochondrial membrane potential is a recognized predictor of sperm motility, and because mitochondrial dysfunction is increasingly recognized as a central mechanism linking metabolic disease to reproductive failure, interventions that restore mitochondrial quality control could address a root cause rather than a symptom. The authors suggest that Kisspeptin-10 may alleviate obesity-induced testicular dysfunction through modulation of redox balance and mitochondrial quality-control mechanisms, and they describe the peptide as a promising candidate for treating obesity-related male infertility, while acknowledging that its effects on downstream autophagy signaling and apoptosis appear limited.

As with all rodent studies, the path from a 50-nanomole-per-kilogram intraperitoneal injection in Sprague Dawley rats to a safe and effective human therapy will require careful translation. Dose optimization, route of administration, treatment duration, and safety profiling all remain to be established, and the non-significant mitochondrial membrane potential findings underscore that the functional benefits may lag behind the molecular signals. Still, the study offers a compelling proof of concept: a hormone that nature already placed at the top of the reproductive control hierarchy may also possess the cellular janitorial powers needed to keep sperm factories running cleanly under the chronic stress of obesity. For a field in which treatment options for obese men with impaired fertility remain limited largely to weight loss and antioxidant supplementation, that combination of endocrine authority and mitochondrial housekeeping makes kisspeptin a name worth watching closely.

Subject of Research: Effects of Kisspeptin-10 on obesity-induced testicular oxidative stress, sperm dysfunction, and mitochondrial quality control in rats

Article Title: Kisspeptin-10 Alleviates Obesity-induced Testicular Oxidative Stress and Mitochondrial Dysfunction via Modulation of Mitophagy and Autophagy Signaling

Article References: Arkalı, G., Çay, M., Güler Ekmen, E., Acısu, T. C., Fi̇ri̇k, M., Toz, A., Yüce, A., & Aksakal, M. (2026). Kisspeptin-10 Alleviates Obesity-induced Testicular Oxidative Stress and Mitochondrial Dysfunction via Modulation of Mitophagy and Autophagy Signaling. Reproductive Sciences. https://doi.org/10.1007/s43032-026-02211-7

Image Credits: AI Generated

DOI: 10.1007/s43032-026-02211-7

Keywords: Kisspeptin-10, obesity, male infertility, oxidative stress, mitophagy, autophagy, mitochondria, sperm quality, testis, PINK1, glutathione, reproductive sciences