Scientists believe they have identified the way curcumin – the natural phenol compounds found in turmeric – reduces inflammation.
Curcumin-containing turmeric is given to some horses by their owners because of its perceived anti-inflammatory properties. Indeed, researchers have shown the ability of curcuminoids to reduce inflammation in aging horses.
Yue Dai and his colleagues, writing in the Journal of Neuroinflammation, described their work with rats with collagen-induced arthritis to learn more about the performance of curcumin.
The research team from the China Pharmaceutical University in Nanjing said many studies in recent years had shown that taking curcumin by mouth eased collagen-induced arthritis.
A clinical trial, they noted, had shown that curcumin was safe and effective for patients with rheumatoid arthritis.
However, studies had shown that its bioavailability was poor, which raised questions about how it produced its anti-inflammatory effect.
They set out to explore whether the gut-brain axis was involved in its therapeutic action.
The researchers found that curcumin did indeed reduce collagen-induced arthritis through the gut-brain axis by regulating the function of the cholinergic system.
The cholinergic system is composed of organized nerve cells that use the neurotransmitter acetylcholine. It is associated with several cognitive functions, including memory, selective attention, and emotional processing.
The study team said their findings suggested that targeting the gut cholinergic anti-inflammatory pathway could be a promising approach for patients with rheumatoid arthritis and with other inflammatory disorders, such as irritable bowel disorder, characterized by an imbalanced autonomic nervous system.
The researchers said previous studies in their lab suggested that curcumin exerted its effects in a gut-dependent way.
The gut, they said, was a sensory organ, with signals from the lumen sent to the central nervous system, which in turn sent signals to peripheral tissues or organs.
Interestingly, recent studies had shown that curcumin showed regulatory effects on the gut microbiota in some situations, and that the gut microbiota was involved in the development of arthritis.
“It is possible,” they said, “that curcumin affects the cholinergic anti-inflammatory pathway through the gut-brain axis via modulation of gut microbiota.”
Curcumin attenuates collagen-induced inflammatory response through the “gut-brain axis”
Yannong Dou, Jinque Luo, Xin Wu, Zhifeng Wei, Bei Tong, Juntao Yu, Ting Wang, Xinyu Zhang, Yan Yang, Xusheng Yuan, Peng Zhao, Yufeng Xia, Huijuan Hu and Yue Dai.
Journal of Neuroinflammation 2018 15:6 https://doi.org/10.1186/s12974-017-1047-7