Absence of preference for social novelty and increased grooming in integrin β3 knockout mice: initial studies and future directions.
Deleting the integrin β3 gene makes mice lose interest in new friends and groom too much, hinting that this pathway feeds autism-like social and repetitive traits.
01Research in Context
What this study did
Scientists deleted one gene, integrin β3, in newborn mice.
They then watched how the grown mice acted around other mice.
The team tracked two things: time spent with new versus familiar mice, and how much the mice groomed themselves.
What they found
The knockout mice did not care about meeting new mice.
Normal mice sniff and stay longer with strangers; these mice did not.
They also groomed themselves far more, a repetitive behavior like hand-flapping.
How this fits with other research
Smith et al. (2010) looked at the same gene in Irish children and found no autism link.
Species gap: human DNA markers did not predict diagnosis, yet mouse behavior still changed.
Ey et al. (2011) and Minshew et al. (2011) both list this mouse in their 2011 reviews.
They note adult mice can still improve with treatment, so the brain change is not final.
Together, the papers say: the gene pathway matters for behavior, but human studies need bigger samples.
Why it matters
You will not use gene therapy in clinic, but you can watch for similar social and repetitive signs in your clients.
If a child ignores new peers and shows intense self-stimming, note it as a red flag.
Share this biology nugget with parents: genes shape motivation circuits, yet practice can still re-wire them.
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02At a glance
03Original abstract
Elevated whole blood serotonin 5-HT, or hyperserotonemia, is a common biomarker in autism spectrum disorder (ASD). The integrin β3 receptor subunit gene (ITGB3) is a quantitative trait locus for whole blood 5-HT levels. Recent work shows that integrin β3 interacts with the serotonin transporter (SERT) in both platelets and in the midbrain. Furthermore, multiple studies have now reported gene-gene interaction between the integrin β3 and SERT genes in association with ASD. Given the lack of previous data on the impact of integrin β3 on brain or behavioral phenotypes, we sought to compare mice with decreased or absent expression of the integrin β3 receptor subunit (Itgb3 +/- and -/-) with wildtype littermate controls in behavioral tasks relevant to ASD. These mice did not show deficits in activity level in the open field or anxiety-like behavior on the elevated plus maze, two potential confounds in the evaluation of mouse social behavior. In the three-chamber social test, mice lacking integrin β3 were shown to have normal sociability but did not show a preference for social novelty. Importantly, the absence of integrin β3 did not impair olfaction or the ability to recall familiar social odors. Additionally, mice lacking integrin β3 showed increased grooming behavior in novel environments. These preliminary studies reveal altered social and repetitive behavior in these mice, which suggests that the integrin β3 subunit may be involved in brain systems relevant to ASD. Further work is needed to fully characterize these behavioral changes and the underlying brain mechanisms.
Autism research : official journal of the International Society for Autism Research, 2011 · doi:10.1002/aur.180