Electroacupuncture in the treatment of IBS in rats: investigation of the mechanisms of CRH⁺ neurons in the paraventricular nucleus

Abstract

Electroacupuncture (EA) is well documented to treat irritable bowel syndrome (IBS). However, the mechanism of the central nervous system related to IBS and acupuncture stimulation is still not well known. In this study, a rat model of IBS was established by cold-restraint comprehensive stresses for 15 days, and it was found that the levels of corticotropin-releasing hormone (CRH), corticosterone (CORT), and adrenocorticotropic hormone (ACTH) in the peripheral serum were increased; the visceral sensitivity was enhanced; and the intestinal motility was accelerated, specifically, there was an enhancement in the discharge frequency of neurons in the paraventricular nucleus (PVN). EA treatment for 3 days, 20 min/day, alleviated the increase in the levels of CRH, CORT, and ACTH in the peripheral serum of rats, reduced the visceral sensitivity of IBS rats, and inhibited colon movement and discharge frequency of the neurons in the PVN. Additionally, EA could reduce the excitability of CRH neurons and the expression of CRHR1 and CRHR2 in PVN. At the same time, the expression of CRH, CRHR1, and CRHR2 in the peripheral colon was decreased. Taken together, EA appears to regulate intestinal functional activity through the central CRH nervous system, revealing the central regulation mechanism of EA in IBS rats, and providing a scientific research basis for the correlation among the meridians, viscera, and brain.

Neural circuits regulating visceral pain

“…Previous evidence has shown that the expression of PVN c-Fos, pituitary and plasma CRH, ACTH and cortisol increase in rodents with visceral hypersensitivity, indicating that the HPA axis is activated 114 , 150 – 153 . Additionally, stress-induced activation or enhancement of the CRH and HPA axis systems is associated with visceral hypersensitivity, which is an important feature of IBS.…”