Isolated Enteric Ganglion
Cultured Enteric Ganglion (stained for BDNF)
Cultured Gastric Smooth Muscle
DRG Neuron Transfected with GFP
Gastrointestinal Research Group
The Gastrointestinal Tract (GI) is one of the largest and most diverse of all organ systems. Its function and regulation are critical to providing adequate nutrition and elimination of wastes from the body. The physiology GI group provides an integrated approach to the examination of gut function that ranges from the molecular and cellular biology of autonomic, sensory and enteric neurons, and smooth muscle cells to whole organ reflexes such as peristalsis, to understanding visceral hyperalgesia associated with inflammatory bowel diseases in intact animal models.
Isolated Human Intestinal Smooth Muscle Cell
Our three main areas of study are (1) characterization of the role the enteric nervous system in regulating gut motility, (2) identification of the signal transduction pathways mediating contraction and relaxation of smooth muscle cells, and (3) understanding the sensory neural pathways that mediate the response to inflammatory bowel disease and which produce hyperalgesia and cross-sensitization of pain fibers from other viscera.
The physiology GI group maintains strong ties to and interacts with a larger group of gastrointestinal scientists in the Departments of Pharmacology/Toxicology and the Department of Medicine/Division of Gastroenterology through membership in the VCU Program for Enteric Neuromuscular Sciences (VPENS).
Dr. John Grider
The group led by Dr. John Grider focuses on the examination of the enteric nervous system in human and animal models with the goal of identifying the neural circuit which regulates intestinal smooth muscle motility, and the changes in neuronal phenotype and circuitry that occur during development and in response to inflammation. The intimate relationships between nerve and muscle are evaluated by a variety of histochemical, molecular, and biochemical techniques. Intact preparations that retain the in situ interconnections are used to examine circuits; isolated and cultured enteric neurons are used to examine cellular and molecular regulation of neurotransmitter release. Recent focus is on the role of neurotrophins in the regulation of normal function and in the remodeling of the enteric nervous system in inflammatory bowel disease.
Dr. S. Murthy Karnam
The group led by Dr. S Murthy Karnam focuses on understanding the molecular basis of signaling mechanisms mediated by G proteins in smooth muscle contraction and relaxation. The research is aimed at understanding what G proteins become activated by receptors coupled to different neurotransmitters, what signaling cascades the G proteins in turn coupled to, and how the signal is turned off. A variety of cell biochemical, molecular, and genetic approaches are used to identify these pathways in isolated and cultured smooth muscle from human and animal models. Recent focus has been on identifying the detailed regulation of the contractile and relaxant proteins that differentially mediate the phasic and tonic contraction of smooth muscle, as well as identifying changes in the signal transduction pathways leading to altered motility during inflammation.
Dr. Liya Qiao
The group led by Dr. Liya Qiao focuses on understanding the mechanisms by which the sensory information from the GI tract and urinary bladder is processed at the levels of the enteric nervous system, the dorsal root ganglion (DRG), and the spinal cord. The complex interaction at these levels of sensory processing are examined by applying anatomical, histological, and molecular techniques to isolated neurons, and cultures of spinal cord slices and DRGs from each spinal level. Physiological measurements of gut and bladder function are made in in vivo animal models and correlated with cellular and molecular data. Recent focus has been on identifying the role of neurotrophins in mediating the viscero-visceral cross-hypersensitivity between bladder and colonic afferent nerve fibers following colonic inflammation.