Wednesday 31 May 2017

Penicillin changes behaviour

Research published in Nature Communications reveals that even a low dose of penicillin in mice can result in a change in behaviour in the long term. Following administration, the mice were found to be less anxious, but also more aggressive than usual.


In 2014, a study was published which revealed that low doses of penicillin in the late pregnancy and early life of mice makes them more susceptible to weight gain. The recent study builds on that and reveals that low doses of penicillin in mice disrupt the gut flora and influence the behaviour.  


Results of the study

The mice that were given penicillin scored higher for aggression and lower for anxiety in comparison to those mice given a placebo. Characteristic changes were found in the brain and in the nature and the level of the microbes in the intestines. Simultaneous treatment with beneficial lactobacilli prevented the behavioural change.


"Antibiotics are not only prescribed, but can also be found in meat and dairy products. If mothers pass on the effects of this to their children, that raises questions about the long-term effects of our society’s antibiotic consumption", say the researchers.


Effect of penicillin on offspring

Evidence is mounting that high doses of broad-spectrum antibiotics can change the behaviour of animals. But this is the first study that has been conducted into the effects of commonly used low doses of penicillin on intestinal bacteria and behaviour, say the researchers.


At a later stage, the research team will study the effects of penicillin on offspring, where only the pregnant mother will be given penicillin. In addition, they will study the protective effect of different types of potentially beneficial bacteria in relation to behavioural changes as a result of taking antibiotics.


Further research in humans

In the last decade, it has mainly been proven in mice that bacteria in the intestines determines the level of resilience to stress, the functioning of the immune system and even learning performance and memory. This could therefore possibly be favourably influenced by probiotics, but have these results also been found in humans? Read Psychobiotics: the current state.
Read the Dutch article.
Read the German article.
Read the Spanish article.



Sophie Leclercq, Firoz M. Mian, Andrew M. Stanisz, Laure B. Bindels, Emmanuel Cambier, Hila Ben-Amram, Omry Koren, Paul Forsythe & John Bienenstock, Low-dose penicillin in early life induces long-term changes in murine gut microbiota, brain cytokines and behavior, Nature Communications 8, Article number: 15062 (2017)