Sayak Banerjee, Amity University Kolkata
Hormones vs ageing:
Generally, it is observed that men have a shorter life span than women and it has been found that the reason behind this is hormones, but now this could be altered resulting in an increased lifespan. A research team from the Department of Anatomy of the University of Otago along with some colleagues from the United States has published a study in the journal eLife. In this study, they have demonstrated that castration of male sheep, which involves the removal of the hormone known as androgen, results in the delay of DNA ageing. Androgens are a cluster of hormones that significantly partake in male traits and reproductive activity. Although it is normally considered to be a male hormone, the female body also releases a little number of androgens naturally. This additionally induces the characteristics of a female DNA and the chemical tags it holds, known as DNA methylation.
This is the first time that the DNA has been observed if it is involved in ageing slowly or not. It has been seen by both scientists and farmers that on average, castrated male sheep have a longer lifespan than their intact counterparts. Initially, the scientists produced an ‘epigenetic clock’ from the huge population of sheep for the evaluation of DNA ageing. On comparing the epigenetic clock of intact males and castrated males, it was found that their rate of ticking was different. From this, they concluded that the longer lifespan of castrated sheep, or ‘wethers’ as they are indicated by the farmers, is portrayed in their DNA.
More insight into the study:
This study is supported by the rapid development of the tools used to measure the ageing of DNA. Lately, the probability of estimating the age of humans as well as other mammals has increased by the usage of DNA and epigenetic clocks. One of the researchers said that they had examined at most 200 species and discovered an astonishing resemblance in the ageing of animals. Nevertheless, the sheep study was exclusive as it isolated the effects of male hormones on ageing. Males and female sheep exhibited varying patterns of DNA ageing and despite being male, the castrates or the wethers had characteristics of a female at certain DNA sites. The DNA sites which are influenced due to castration also attach to receptors of male hormones in humans at a higher rate than expected. This serves as a connection between androgen male hormones, castration, and sex-specific differences in DNA ageing.
They stated that most of the researchers use blood for the measurement of biological age but on a contrary, the sex-specific ageing effects are observed in the skin rather than in blood. The finding not only opens the door for the understanding of the mechanism of androgen hormones in accelerating ageing in males but also its extensive implications. This epigenetic clock for sheep could aid the farmers to identify which sheep are going to live longer and thus be more productive.
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Reference:
- Sugrue, V. J., Zoller, J. A., Narayan, P., Lu, A. T., Ortega-Recalde, O. J., Grant, M. J., Bawden, C. S., Rudiger, S. R., Haghani, A., Bond, D. M., Hore, R. R., Garratt, M., Sears, K. E., Wang, N., Yang, X. W., Snell, R. G., Hore, T. A., & Horvath, S. (2021). Castration delays epigenetic aging and feminizes DNA methylation at androgen-regulated loci. ELife, 10, e64932. https://doi.org/10.7554/eLife.64932
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