A solution to the problem of antipsychotic-provoked weight gain may lie in the bacteria that make their home in the gut, some researchers believe.
Animal research has suggested that bacteria that reside in the gut play a key role in energy regulation and obesity. A link between obesity and gut bacteria has also been found in humans. Moreover, John Cryan, Ph.D., chair of anatomy and neuroscience at University College Cork in Cork, Ireland, and his colleagues recently found, in rats, that chronic olanzapine treatment altered the composition of bacteria living in the gut.
Cryan and colleagues thus reasoned that if they were able to find a way of reversing olanzapine-induced alterations in gut bacteria in rats, it might counter olanzapine-induced weight gain in the animals.
John Cryan, Ph.D.: “What we have shown is a proof-of-concept that the gut microbiome will attenuate antipsychotic-induced weight gain.”
John Cryan, Ph.D..
First they gave rats olanzapine and found that it led not only to rapid weight gain and an increase in visceral fat, but to a shift in the abundance of the major types of bacteria inhabiting the animals’ guts. Specifically, it increased the phyla Firmicutes and decreased the phyla Bacteriodetes. This same shift had been found in obese animals and humans in the past.
They then gave the rats a cocktail of broad-spectrum antibiotics. They found that the antibiotics not only caused the bacteria in the guts of the rats to shift back toward their original state, but attenuated the rats’ olanzapine-induced weight gain and visceral fat accumulation by some 20 percent. Thus it looked as if antibiotics might be a way of countering antipsychotic-induced weight gain in humans.
A problem with this strategy, though, is that it could increase antibiotic resistance, which is of broad public-health concern, the researchers pointed out in their report, which was published online October 1, 2013, in Translational Psychiatry.
Nonetheless, they believe that gut bacteria might constitute a new target for finding a way of countering antipsychotic-induced weight gain in humans. And as Cryan told Psychiatric News, “We are currently investigating whether other strategies for manipulating the gut microbiota may be useful in animal models and then [tested] in humans.”
Meanwhile, other research groups are using gut bacteria to counter obesity due to causes other than antipsychotics, Cryan noted. “This is a really exciting area, probably the best developed in microbiome research.” ■