Related Experiment Video
Updated: Jun 24, 2026

Gastrointestinal Motility Monitor (GIMM)
Published on: December 1, 2010
Adenosine 2B receptors (A(2B)AR) on enteric neurons regulate murine distal colonic motility
Bindu P Chandrasekharan1, Vasantha L Kolachala, Guillaume Dalmasso
1Division of Digestive Diseases, Emory University, 615 Michael St., Atlanta, GA 30322, USA.
Abstract:
Delayed colonic emptying leading to constipation is a significant health concern. We investigated the role of adenosine 2B receptor (A(2B)AR) in modulating distal colonic motility using wild-type and A(2B)AR-knockout (A(2B)AR(-/-)) mice. Colon motility was assessed using stool characteristics and colonic transit. Distal colonic ganglia, isolated by laser capture microdissection, were tested for A(2B)AR expression by RT-PCR. The distal colon contraction and relaxation responses were assessed by electrical field stimulation (EFS) in presence of A(2B)AR agonists, antagonists or inhibitors of nitric oxide (NO) and guanylate cyclase. Nitrite levels were measured in enteric neuronal cultures exposed to A(2B)AR agonists/antagonists. A(2B)AR(-/-) mice display increased stool retention, decreased stool frequency, delayed colonic emptying, and decreased circular muscle relaxation. RT-PCR identified A(2B)AR expression in distal colonic ganglia. EFS studies revealed that enteric neuronal A(2B)AR is essential for distal colonic relaxation, and A(2B)AR antagonists can inhibit relaxation. Enteric neurons stimulated with A(2B)AR agonists produced more nitrite than cultures treated with antagonists. We demonstrate an essential role of A(2B)AR in regulating distal colon relaxation, as A(2B)AR activation is linked to NO signaling. Hence targeting the colonic A(2B)AR could represent a novel therapeutic strategy to treat constipation.
Related Concept Videos
Adrenergic Receptors: ɑ Subtype
Adrenaline ≥ Noradrenaline >> Isoprenaline
α-adrenoceptors are further divided into α1 and α2-adrenoceptors.
α1-Adrenoceptors: These receptors are located postsynaptically on the effector organs and cause constriction of smooth muscle mediated by activation of phospholipase C—inositol-1,4,5-trisphosphate...
Adrenergic Receptors: β Subtype
Isoprenaline > Adrenaline > Noradrenaline
Neurotransmitter binding to these receptors causes activation of adenylyl cyclase resulting in increased concentrations of cAMP and modulation of calcium ion channels within the cell. They are further classified into β1, β2, and β3 subtypes.
β1-adrenoceptors: β1-adrenoceptors have equal affinities for...
Adrenergic Receptors (Adrenoceptors): Classification
α-Adrenoceptors
α-Adrenoceptors are classified into two main subtypes: α1 and α2. The α1 adrenoceptors, which are found on postsynaptic...
Cholinergic Receptors: Muscarinic
The subtypes M1, M3, and M5 couple with the Gq subunit and activate the phospholipase C (PLC) activity, mobilizing intracellular Ca2+. Activation...
Direct-Acting Cholinergic Agonists: Pharmacological Actions
Parasympathetic Signaling
The effects of...

