The somatosensory-autonomic reflex and muscarinic M3 receptor are
involved in exacerbating allergic pulmonary inflammation by
electroacupuncture
Abstract
Background and Purpose Emerging evidence has suggested that somatic
stimulation, including electroacupuncture (EA), could produce autonomic
reflexes to modulate visceral functions. However, the efficacy and
underlying mechanisms for EA on allergic pulmonary inflammation (API)
remain elusive. Experimental Approach Papain-induced API mice were
treated with distinct current-intensity EA at the back BL13, hindlimb
ST36, and forelimb LU5 acupoints. The change in API was determined by
whole-body plethysmograph (WBP), immunohistochemistry, flow cytometry,
and HE staining. We employed lung functional testing combined with
pharmacological inhibition and optogenetic activation approaches to
examine the underlying mechanisms for EA effects on API. Key Results EA
at the back BL13 region, but not limb regions, via a
current-intensity-dependent manner, exacerbated the API. Pharmacological
blocking of the local thoracic sensory or the lung-innervated autonomic
nerve eliminates the EA-produced detrimental effects. Chemical pulmonary
sympathectomy was further enhanced, but inhibition of the upregulated
muscarinic M3 acetylcholine receptor within the pulmonary was sufficient
to protect from the inflammation-exacerbation effect of EA. Conclusions
and Implications Our findings suggest that BL13 EA evokes a
somatic-autonomic-pulmonary M3 pathway to enhance API. The revelation of
somatotopic organization and intensity-dependency in driving the
pulmonary autonomic pathways could help optimize stimulation parameters
to improve both efficacy and safety in various forms of physical
therapy, including bioelectronic medicine and traditional as well as
modern forms of moxibustion and EA, to modulate API.