Exposure of male mice to early life stress alters the levels of specific sperm miRNAs that promote stress-associated behaviors in their offspring. To begin to evaluate whether similar phenomena occur in men, researchers from Tufts University searched for sperm miRNA changes that occur in both mice and men exposed to early life stressors that have long-lasting effects. For men, they used the Adverse Childhood Experience (ACE) questionnaire. It reveals the degree of abusive and/or dysfunctional family experiences when young, which increases risks of developing future psychological and physical disorders. For male mice, they used adolescent chronic social instability (CSI) stress, which not only enhances sociability defects for >1 year, but also anxiety and defective sociability in female offspring for multiple generations through the male lineage.

Using miRNA microarray technology, their study found a statistically significant inverse correlation between levels of multiple miRNAs of the miR-449/34 family and ACE scores of Caucasian males. Remarkably, members of the same sperm miRNA family are also reduced in mice exposed to CSI stress. Thus, future studies should be designed to directly test whether reduced levels of these miRNAs could be used as unbiased indicators of current and/or early life exposure to severe stress. Moreover, after mating stressed male mice, these sperm miRNA reductions persist in both early embryos through at least the morula stage and in sperm of males derived from them, suggesting these miRNA changes contribute to transmission of stress phenotypes across generations. Since offspring of men exposed to early life trauma have elevated risks for psychological disorders, these findings raise the possibility that a portion of this risk may be derived from epigenetic regulation of these sperm miRNAs.

 

a qPCR analysis of miR-449a, miR-449b-5p, miR-34b-3p, miR-34c-5p, miR-152-3p, and miR-375-3p in sperm RNA from low ACE group (score 0–1, n = 5) vs. high ACE group (score >4, n = 5). Wilcoxon rank-sum test *P < 0.05, **P < 0.01. Data represented as mean ± SEM. bc Correlation plot comparing relative expression of miR-449a to miR-449b (b) and miR-34b to miR-34c (c) for individual samples fitted with single-variable linear regression. n = 10, r = Spearman’s coefficient with exact p value listed. Each point represents an individual sample

lc sciences

 

Reference
D. A. Dickson, J. K. Paulus, V. Mensah, J. Lem, L. Saavedra-Rodriguez, A. Gentry, K. Pagidas, L. A. Feig (2018) Reduced levels of miRNAs 449 and 34 in sperm of mice and men exposed to early life stress Translational Psychiatry 8, Article number: 101 [article]

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