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Michael B Stout

Publications and source records attributed to Michael B Stout.

2 recordsLinked to original sources
PubMed2026

17α-Estradiol: A mildly feminizing estrogen with sex-specific metabolic and lifespan benefits.

Estrogens are pleiotropic hormones that regulate reproductive and non-reproductive physiological processes in both sexes. Among these, 17α-estradiol (17α-E2), a C17 epimer of the canonical estrogen 17β-estradiol (17β-E2), has emerged as a promising modulator of aging and metabolism with sexual dimorphism. Unlike 17β-E2, which exerts broad estrogenic effects in both sexes, 17α-E2 extends lifespan and preferentially improves metabolic homeostasis in male mice while inducing only mild feminizing effects. Many of these benefits are mediated through estrogen receptor alpha (ERα). However, it remains unknown if its biological actions are mediated through genomic or nongenomic pathways and what the molecular basis is for male-biased efficacy. This review outlines evidence from preclinical models and translational studies, demonstrating that 17α-E2 mitigates age-related metabolic declines in males by reducing adiposity, enhancing insulin sensitivity, and preserving hepatic metabolic plasticity. Elucidating the sexually divergent actions of 17α-E2 can advance our understanding of sex-biased endocrine signaling and how these pathways modulate aging in a sex-specific manner.

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PubMed2026

Mitochondrial Haplotype Shapes the Trajectory of Ovarian Aging in Genetically Heterogeneous Rats.

Ovarian aging leads to permanent reproductive senescence and systemic hormonal changes that predispose women to age-associated comorbidities. Despite these observations, the intrinsic mechanisms driving age-related ovarian decline are poorly defined. Mitochondrial DNA (mtDNA) mutations and instability are strongly associated with aging; however, it remains unknown if naturally occurring mitochondrial genetic variation influences the trajectory of ovarian aging. To address this, we compared two genetically heterogeneous rat cohorts (OKC-HETB and OKC-HETW) that differ in mitochondrial haplotype on a randomized but equivalently distributed nuclear background. The OKC-HETW haplotype was associated with accelerated loss of primordial follicles and pathological remodeling marked by fibrosis, macrophage infiltration, and multinucleated giant cells. These tissue-level pathologies were paralleled by mitochondrial dysfunction, characterized by decreased respiratory complex activity, ATP production, and mtDNA copy number. Mechanistically, we identified a haplotype-specific defect in mitochondrial genome maintenance. Although TFAM expression was normal, and total TFAM protein was elevated, OKC-HETW ovaries showed reduced mitochondrial TFAM abundance, TFAM-mtDNA binding, and TOMM20, suggesting that impaired TOMM20-mediated import is associated with compromised mitochondrial genomic stability. Longitudinal transcriptomic and proteomic analyses further indicate that mitochondrial haplotype influences the rate of ovarian aging, with OKC-HETW ovaries showing accelerated activation of inflammatory and fibrotic pathways alongside suppressed proteostasis and mitochondrial function. These defects corresponded to impairments in ovulation and a trend toward worsening oocyte quality. Collectively, our findings identify mitochondrial haplotype as a heritable modifier of ovarian aging rate that acts in concert with the nuclear genome, and a putative target for preserving ovarian function and female healthspan.

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