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Category: sex – Page 2

Social disadvantage accelerates aging

As an initial step, we selected ARDs associated with hallmarks of aging. These included a total of 83 diseases linked to one or more hallmarks of aging, based on the taxonomy put forward in ref. 4 (Supplementary Table 2). Support for this taxonomy comes from multiple sources. Analyses of electronic health records from general practice and hospitalizations identified more than 200 diseases with incidence rates increasing with chronological age6,22. Researchers linked a subset of these ARDs to specific hallmarks of aging using several approaches: mining 1.85 million PubMed abstracts on human aging, identifying shared genes in the genome-wide association study catalog, conducting gene set enrichment analysis and analyzing disease co-occurrence networks within each hallmark4.

We confirmed the co-occurrence of ARDs within each hallmark in 492,257 participants from the UK Biobank study23. The presence of one ARD increased the risk of developing another ARD related to the same hallmark, with clustering coefficients ranging from 0.76 for LOP-specific ARDs to 0.92 for SCE-specific ARDs. These findings corroborated the hallmark-specific clustering of ARDs (Extended Data Figs. 3 and 4)23.

In time-to-event analyses of UK Biobank and FPS participants without these ARDs at baseline (n ranging from 477,325 to 492,294 in the UK Biobank and from 278,272 to 286,471 in the FPS, depending on the social disadvantage indicator and ARD), social disadvantage—indicated by education and adult SES (neighborhood deprivation)—was associated with a higher risk of developing ARDs. In the UK Biobank, the age-, sex-and ethnicity-adjusted hazard ratio for developing any ARD was 1.31 (95% confidence interval (CI) 1.29–1.33) for individuals with low compared with high education. For individuals with high versus low adult SES, the hazard ratio was 1.21 (95% CI 1.20–1.23). In the FPS, the corresponding hazard ratios were 1.28 (95% CI 1.25–1.31) and 1.23 (95% CI 1.20–1.27), respectively.

Brain Changes From Early-Life Stress May Be Reversible

Summary: A new study reveals how prenatal infections followed by early-life stress—known as “two-hit stress”—can lead to brain dysfunction and psychiatric-like behaviors. Researchers found that affected mice showed abnormal cerebellar activity, increased microglial turnover, and impaired brain-wide connectivity.

Notably, microglia replacement therapy successfully reversed these effects, offering a potential new approach for mental health treatments. The findings suggest that sex differences may influence stress resilience, highlighting the need for personalized treatments for psychiatric and neurodegenerative disorders.

Sex as a formality: Study shows male stick insects have lost their reproductive function

While most animals reproduce sexually, some species rely solely on females for parthenogenetic reproduction. Even in these species, rare males occasionally appear. Whether these males retain reproductive functions is a key question in understanding the evolution of reproductive strategies.

A new study published in Ecology by a research team led by Assistant Professor Tomonari Nozaki from the National Institute for Basic Biology, Professor Kenji Suetsugu from Kobe University, and Associate Professor Shingo Kaneko from Fukushima University provides insight into this question. The researchers focused on the rare males of Ramulus mikado, a stick insect species in Japan, where parthenogenesis is predominant. Their analysis of male reproductive behavior reveals new findings.

Nicotinamide Riboside Supplementation Alleviates Testicular Aging Induced by Disruption of Qprt‐Dependent NAD+ De Novo Synthesis in Mice

In this study, we have demonstrated the crucial role of NAD+ homeostasis, particularly through the de novo synthesis pathway mediated by Qprt, in maintaining spermatogenesis with age. The deletion of Qprt led to progressive declines in NAD+ levels, particularly after 6 months of age, which were associated with significant defects in germ cell survival and mitochondrial function in spermatocytes. These disruptions manifested as impaired progression through meiosis, defective DNA double-strand break repair, and abnormal meiotic sex chromosome inactivation. Our findings also highlight the therapeutic potential of NAD+ precursor supplementation, as nicotinamide riboside effectively rescued the observed spermatogenic abnormalities in Qprt-deficient mice, emphasizing the importance of NAD+ in reproductive health and aging.

NAD+ can be synthesized through three pathways: the Preiss-Handler pathway, the salvage pathway, and the de novo pathway (Liu et al. 2018 ; Harjes 2019). In the de novo pathway, the essential amino acid tryptophan serves as a substrate, with Qprt catalyzing the formation of nicotinic acid mononucleotide, which is subsequently converted into NAD+ via a series of enzymatic reactions in the Preiss-Handler pathway. Coordinated regulation of these three pathways is crucial for maintaining intracellular NAD+ levels, which are essential for cellular function, a decline in NAD+ levels can lead to various pathological and physiological conditions (Minhas et al. 2019 ; Zhang et al. 2019a). In this study, we identified that Qprt, the rate-limiting enzyme in the NAD+ de novo synthesis pathway, is predominantly expressed in spermatocytes within the testes.

Technology for lab-grown eggs or sperm on brink of viability, UK fertility watchdog finds

Bolstered by Silicon Valley investment, scientists are making such rapid progress that lab-grown human eggs and sperm could be a reality within a decade, a meeting of the Human Fertilisation and Embryology Authority board heard last week.

In-vitro gametes (IVGs), eggs or sperm that are created in the lab from genetically reprogrammed skin or stem cells, are viewed as the holy grail of fertility research.

The technology promises to remove age barriers to conception and could pave the way for same-sex couples to have biological children together. It also poses unprecedented medical and ethical risks, which the HFEA now believes need to be considered in a proposed overhaul of fertility laws.

Brain Regions that Relieve Effects of Chronic Stress in Mice Differ based on Sex

Subtle activation of a small subset of neurons in one region of the brain can make male mice resilient to, and even reverse, the detrimental effects of chronic stress. The same is true for female mice, but in a totally different region of the brain.

Researchers at Penn State reported these findings in two studies published in the journal Molecular Psychiatry and said the results could help explain the efficacy, or lack thereof, of certain antidepressant drugs and inform the development of new drugs and therapies.

The team developed a protocol to continuously activate neurons that produce the signaling molecule somatostatin, which helps regulate several biological processes, in specific brain regions in mice. The researchers found that doing so in a region of the brain called the prelimbic cortex made male mice resilient to stress, but failed to do so in female mice.

Sex differences in brain structure are present from birth, research shows

Gray matter is made up of neuron cell bodies and dendrites and is responsible for processing and interpreting information, such as sensation, perception, learning, speech, and cognition. White matter is made up of axons, which are long nerve fibers that connect neurons together from different parts of the brain.

In the study, male brains tended to be greater in volume than female brains. When adjusted for total brain volume, female infants on average had significantly more , while on average had significantly more in their brains.

Yumnah Khan, a Ph.D. student at the Autism Research Center at the University of Cambridge, who led the study, said, Our study settles an age-old question of whether male and female brains differ at birth. We know there are differences in the brains of older children and adults, but our findings show that they are already present in the earliest days of life.

Four Clinical Trials We’re Watching That Could Change Medicine in 2025

Meanwhile, scientists dug into how psychedelics and MDMA fight off depression and post-traumatic stress disorders. The year was a relative setback for the psychedelic renaissance, with the FDA rejecting MDMA therapy. But the field is still gaining recognition for its therapeutic potential.

Then there’s lenacapavir, a shot that protects people from HIV. Named “breakthrough of the year” by Science, the shot completely protected African teenage girls and women against HIV infection. Another trial supported the results, showing the drug protected people who have sex with men at nearly 100 percent efficacy. The success stems from a new understanding of the protein “capsule” guarding the virus’ genetic material. Many other viruses have a similar makeup—meaning the strategy could help researchers design new drugs to fight them off too.

So, what’s poised to take the leap from breakthrough to clinical approval in 2025? Here’s what to expect in the year ahead.