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Overweight does not decrease sperm production

A new study by The Endocrine Society found that overweight men are not more likely to be infertile, contradicting previous research on obese women. Greater body weight was linked to lower testosterone levels in some participants, but impaired sperm production remains the primary cause of infertility in men.

SourceThe Endocrine Society·JournalThe Journal of Clinical Endocrinology & Metabolism·DateJun 15, 2008

New barn swallow study reveals image makes the bird

A new study by Arizona State University researchers found that artificially coloring the breast feathers of male barn swallows increased their testosterone levels, challenging the traditional view that internal processes determine external features. The study suggests a dynamic system where physical appearance affects physiology.

SourceArizona State University·JournalCurrent Biology·DateJun 2, 2008

Biology of Reproduction highlights

Recent studies in Biology of Reproduction suggest that maternal follicular testosterone influences the sex of bovine embryos, while research on maternal cell microchimerism reveals its presence in major organs of healthy newborn mice. These findings highlight the importance of understanding the mechanisms behind these phenomena.

SourceSociety for the Study of Reproduction·JournalBiology of Reproduction·DateApr 21, 2008

Low testosterone levels associated with depression in older men

A study of 3,987 older men found that those with low free testosterone levels had a higher prevalence of depression, with men in the lowest quintile having three times the odds of depression compared to those in the highest quintile. Researchers suggest that hormone imbalances may contribute to this link.

SourceJAMA Network·JournalArchives of General Psychiatry·DateMar 3, 2008

Cell death in sparrow brains may provide clues in age-related human diseases

A study on Gambel's white-crowned sparrows reveals that the brain regions controlling singing behavior shrink rapidly after testosterone withdrawal, leading to neuron loss and apoptosis. This natural phenomenon may hold potential medical implications for understanding age-related degenerative diseases such as Parkinson's and dementia.

SourceUniversity of Washington·JournalProceedings of the National Academy of Sciences·DateSep 17, 2007

Researchers find gene that spurs development of the epididymis

A team of researchers at the University of Illinois has discovered a key gene involved in the development of the epididymis, a critical structure for sperm fertility. The gene, inhibin beta A, plays a vital role in stimulating cell growth and differentiation, leading to the formation of the epididymal tube.

SourceUniversity of Illinois at Urbana-Champaign, News Bureau·JournalProceedings of the National Academy of Sciences·DateJun 27, 2007

Finger length helps predict elementary exam results, study shows

A new study found that a child's finger length can predict their performance in numeracy and literacy tests. The researchers discovered that a higher digit ratio, indicating greater prenatal testosterone exposure, is associated with stronger numeracy skills. In contrast, a lower digit ratio is linked to higher literacy scores for girls.

SourceUniversity of Bath·JournalBritish Journal of Psychology·DateMay 22, 2007

Testosterone may help men with multiple sclerosis

A small pilot study suggests that testosterone treatment is safe and well-tolerated and may reduce symptoms, slow brain degeneration, and increase muscle mass in men with relapsing-remitting multiple sclerosis. Testosterone treatment showed a possible neuroprotective effect on the brain.

SourceJAMA Network·JournalArchives of Neurology·DateMay 14, 2007

A key to male fertility

Scientists at IGBMC have identified SHP protein as a major player in controlling testosterone synthesis and differentiation of germ cells in mouse testes. Mice without SHP protein reproduced earlier than controls, suggesting its role in regulating sexual maturity.

SourceCNRS·JournalGenes & Development·DateMar 2, 2007

Timing is everything

Researchers found that mice deficient for SHP exhibited an earlier onset of fertility due to reduced repression on testosterone production and germ cell differentiation. This discovery may lead to exploration of SHP in human subjects with fertility issues.

SourceCold Spring Harbor Laboratory·JournalGenes & Development·DateJan 31, 2007

Benefits of testosterone treatment unknown, research shows

Two Mayo Clinic studies found no strong evidence supporting testosterone's safety from cardiovascular harm and inconsistent results regarding its impact on sexual dysfunction. The research highlights the need for large-scale trials to inform clinicians' decisions about prescribing testosterone.

SourceMayo Clinic·JournalMayo Clinic Proceedings·DateJan 9, 2007

Elevated testosterone kills nerve cells

A Yale University study reveals that high levels of testosterone can lead to programmed cell death in nerve cells, associated with conditions like Alzheimer's disease. Elevated testosterone also triggers behavioral changes such as hyperexcitability and suicidal tendencies.

SourceYale University·JournalJournal of Biological Chemistry·DateSep 26, 2006