This 2016 Chinese rodent study and its accompanying commentary Don’t stress dad — it’s bad for your kids’ health were caught up in an agenda.
The first problem I noticed was that the hyperglycemic effects found only in the male offspring weren’t consistently labelled as sex-specific. Try to find that fact in the paywalled commentary with its intentionally misleading headline, or in the news coverage with headlines such as “Stressed mouse dads give their offspring high blood sugar.”
That the effects were male-only was briefly noted in the study, yet “male” was absent from the “stress-F1 mice” label used after the initial mention. The male and female symbols in the diagrams were likewise applied to the parents but not the offspring in the study, and its misleading graphic was subsequently used by the news coverage.
The researchers provided no mechanisms that plausibly linked the effects to offspring sex. There was plenty of time between the May 3, 2015 submission and the February 18, 2016 publication to clarify this and other items. I wonder what the reviewer noted.
The second problem was that the highest number of male “stress-F1 mice” tested was 6. I didn’t see any disclosures of what led to the scarcity of subjects, or of the likely impact of using so few.
A related limitation was that the male “stress-F1 mice” were killed as young adults. Whether or not the hyperglycemic effects carried through to old age or to another generation wasn’t determined.
I’m leery of studies like this one that didn’t have a Limitations section, and especially so when the news coverage overlooked obvious limitations. It was difficult to place the findings in a context other than promoting that a male’s stress may also adversely affect their offspring.
One of the problems that research caught up in an agenda create is that non-headline findings are overlooked. Other than sex-specific effects, the study found that the putative preconception cause of hyperglycemia didn’t cause other symptoms:
- “No significant growth defects were observed in male offspring from stress-F0 fathers (stress-F1 mice) during their early lives.
- Insulin sensitivity was not changed in stress-F1 mice.
- Serum glucagon, leptin, and pro-inflammatory cytokines (tumor necrosis factor α [TNFα], interleukin-6 [IL-6]) were unaffected.
- Body weight, food intake, locomotor activity, CO2 production, O2 consumption, and respiratory exchange ratios also remained unchanged.
- Liver weight, liver weight/body weight ratios, hepatic triglyceride content, and the histological phenotypes were also comparable.
- The methylation pattern and expression of microRNAs were not affected in the fetal brains of stress-F1 mice.”
The handling of the study reminded me of Transgenerational epigenetic programming with stress and microRNA where most of the news coverage similarly focused on it being a male’s stress, not a female’s, that affected the developing embryo. The important part lost from news coverage of that study was it demonstrated how a damaging influence can begin immediately after conception, but the symptoms didn’t present until adulthood.
http://www.sciencedirect.com/science/article/pii/S1550413116300067 “Paternal Psychological Stress Reprograms Hepatic Gluconeogenesis in Offspring”