Mice whiskers may offer clues on autism treatment, Chinese study suggests

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Mice that had their whiskers trimmed at an early stage in life could exhibit social dysfunction later on, Chinese researchers have found, in a study they say could shed light on the treatment of autism in humans.

“Whiskers are one of the most important sensory systems for mice, they help them explore their surroundings,” Wang Hao, corresponding author of the study and a professor of neuroscience at Zhejiang University, said.

“Our brain develops by the interaction of neurons and the changing environment. The input of sensory signals is critical for the establishment of the precise neural circuits in our brain,” he said.

“So we wanted to know if the mice would have behavioural disorders in adulthood if their whiskers were trimmed in early life.”

To explore the role of early life sensory experience on the adult brain and behaviour, Wang and his university team trimmed the whiskers of the experimental mice group when they were 12 to 16 days old. The team then returned to observe the rodents’ social behaviour when they were two months old and their whiskers had grown back.

The researchers carried out a three-chamber sociability test – a set-up often used to analyse social deficits and social recognition in rodents – with one empty chamber and one chamber containing a mouse. The whisker-trimmed group and a control group of mice both showed similar interest in the chamber containing a mouse, the team found.

However, the control group exhibited significantly increased interaction time with the new mouse, compared with the previously shaved group which showed no preference between a familiar mouse and a new one.

The results indicated the mice that had their whiskers trimmed during day 12-16 of their lives showed impaired social interaction in adulthood, the authors said.

The study, published in the peer-reviewed journal Molecular Psychiatry last month, may shed light on the treatment of autism, Wang said.

Further experiments using different time windows revealed adult social behaviour would be impacted only if the trimming was carried out within 16 days of birth.

“It means that there is a critical period in which the sensory experience will have a big impact on the brain’s function,” Wang said.

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“Because social dysfunction is the key symptom of autism, our result indicates that there may be such a critical period for human beings in the treatment of autism,” he said.

The social interaction deficit in the whisker-trimmed mice was caused by the over-activation of a region in the brain’s hippocampus called CA3.

The hippocampus is a part of the brain associated with study, memory and social activities, and shown to regulate spatial learning and location. However, the new study is the first to identify the relationship between over-activation of CA3 and social impairment, according to the researchers.

The team also observed a significant reduction in levels of the bonding or “love hormone” oxytocin in the CA3 region of whisker-trimmed mice.

Wang and his colleagues found that early administration of oxytocin in the study group mice could reverse the social interaction deficit in adulthood.

Oxytocin has previously been suggested as a potential therapy to reduce social impairment in autism, but this study finds that the time period of administering the hormone matters.

The compensatory effect of oxytocin would be permanent if administered during the early stages of development for the mice, but only temporary if given in adulthood, the researchers found in their study.

Wang said: “Our study reveals the importance of early intervention with oxytocin. The mechanisms we found in mice brains probably work in human beings.”

This article was first published in South China Morning Post.