1985 — 1986 |
Galligan, James J. |
F32Activity Code Description: To provide postdoctoral research training to individuals to broaden their scientific background and extend their potential for research in specified health-related areas. |
Intrinsic Neural Control of Intestinal Motility @ Flinders University of South Australia |
0.936 |
1986 |
Galligan, James J. |
F32Activity Code Description: To provide postdoctoral research training to individuals to broaden their scientific background and extend their potential for research in specified health-related areas. |
Opioid Actions On Single Enteric Neurons @ Massachusetts Institute of Technology |
0.909 |
1990 — 1994 |
Galligan, James J. |
R29Activity Code Description: Undocumented code - click on the grant title for more information. |
Intestinal Motility--Mechanisms of Regulation @ Michigan State University
There are a large number of transmitters and receptors contained in enteric nerves. The interaction of nerves, and the substances they release, with other nerves and with intestinal smooth muscle is poorly understood. The principal aims of this proposal are to determine some of the specific neural connections in the myenteric plexus which coordinate propulsive contractions in the small intestine. This will be accomplished in 3 projects. The first project will use intracellular electrophysiological techniques to study drug receptors on neuronal cell bodies by measuring changes in membrane potential following drug application, and on nerve terminals by measuring drug-induced changes in synaptic potentials. Preliminary data indicate that groups of drug receptors may be co-localized on the soma and nerve terminals of specific subsets of neurons and receptor neurons. These studies will focus on opioid, 5-HT, and alpha2 adrenergic receptors. The electrophysiologically and pharmacologically identified neurons will be marked with an intracellular dye and the tissues processed for immunohistochemical localization of the neuropeptides substance P and vasoactive intestinal peptide in neurons. The second project will use pharmacological and microsurgical techniques to determine the transmitters and pathways involved in the peristaltic reflex. The third project will use intracellular electrophysiological techniques to record from myenteric neurons during peristalsis. The results of these three projects would describe, in detail, the neural circuitry underlying reflex contractions of the small intestine. Specific functions would be assigned to identified neurons and the actions of drugs could be attributed to an effect on specific neurons. These data would have applications to basic neurobiology in describing the functions of a complete nerve network. Additional benefits could be derived from the development of therapies for disorders of gastrointestinal motility involving enteric nerves. These disorders include Hirshprung's disease, colitis and ileitis, the irritable bowel syndrome and neuropathies associated with diabetes.
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1994 — 1999 |
Galligan, James J. |
K04Activity Code Description: Undocumented code - click on the grant title for more information. R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Mechanisms of Slow Synaptic Excitation in Enteric Nerves @ Michigan State University |
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2000 — 2010 |
Galligan, James J. |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. R56Activity Code Description: To provide limited interim research support based on the merit of a pending R01 application while applicant gathers additional data to revise a new or competing renewal application. This grant will underwrite highly meritorious applications that if given the opportunity to revise their application could meet IC recommended standards and would be missed opportunities if not funded. Interim funded ends when the applicant succeeds in obtaining an R01 or other competing award built on the R56 grant. These awards are not renewable. |
Presynaptic Mechanisms in the Intestine @ Michigan State University
Presynaptic mechanisms are an important means for neurotransmitters, hormones, paracrine substances and drugs to modulate the activity of myenteric nerves and gut motility. Despite the clear importance of presynaptic mechanisms in regulating neurotransmission in the myenteric plexus, little is known about the details of these mechanisms. The proposed studies are designed to characterize these mechanisms. Electrophysiological methods will be used to study excitatory synaptic transmission between myenteric neurons in acutely isolated preparations of guinea pig intestine and between guinea pig myenteric neurons maintained under tissue culture conditions. These studies will investigate the contributions of acetylcholine (ACh) acting at nicotinic cholinergic receptors and ATP acting at P2X purine receptors, to fast excitatory synaptic potentials (fEPSPs) during long trains of stimulation. As nicotinic receptors desensitize quickly, it is anticipated that ACh will be the predominate transmitter early while ATP will predominate later in the train of activity. Presynaptic mechanisms controlling the release of these two important transmitters will also be investigated. These studies will focus on channels which provide the calcium needed for transmitter release and the presynaptic receptors which facilitate their release. The facilitatory effects of 5-HT4 receptor activation on fEPSPs mediated by ACh and ATP will be investigated. In addition, these studies will investigate the contribution of 5-HT3 and 5-HT4 receptors to excitation of enteric sensory nerve terminals. The role of presynaptic nicotinic acetylcholine receptors (nAChRs) in controlling the release of the slow synaptic transmitters, substance P/neurokinin A will also be investigated. These latter studies will attempt to establish that there are presynaptic nAChRs on the terminals of sensory neurons and that ACh released from sensory neurons facilitates SP/NKA release and enhances slow excitatory synaptic transmission. There are many disorders of gut motility which have their basis either directly or indirectly in alterations in enteric neurotransmission. These disorders include gastroesophageal reflux disease, the irritable bowel syndrome and chronic intestinal pseudo-obstruction. It is anticipated that these studies will provide new insights into mechanisms of synaptic transmission in the gut which could lead to the development of new and effect drug treatments for motility disorders.
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2004 — 2007 |
Galligan, James J. |
P01Activity Code Description: For the support of a broadly based, multidisciplinary, often long-term research program which has a specific major objective or a basic theme. A program project generally involves the organized efforts of relatively large groups, members of which are conducting research projects designed to elucidate the various aspects or components of this objective. Each research project is usually under the leadership of an established investigator. The grant can provide support for certain basic resources used by these groups in the program, including clinical components, the sharing of which facilitates the total research effort. A program project is directed toward a range of problems having a central research focus, in contrast to the usually narrower thrust of the traditional research project. Each project supported through this mechanism should contribute or be directly related to the common theme of the total research effort. These scientifically meritorious projects should demonstrate an essential element of unity and interdependence, i.e., a system of research activities and projects directed toward a well-defined research program goal. |
Neurotransmission in Arteries and Veins in Hypertension @ Michigan State University |
1 |
2006 |
Galligan, James J. |
R13Activity Code Description: To support recipient sponsored and directed international, national or regional meetings, conferences and workshops. |
Experimental Approaches to Understanding the Ens and Its Disorders @ Michigan State University
[unreadable] DESCRIPTION (provided by applicant): [unreadable] The American Motility Society (AMS) in collaboration with the European Society for Neurogastroenterology and Motility, the Functional Brain-Gut Research Group and the International Motility Group has organized the first Joint International Neurogastroenterology and Motility meeting. This meeting will bring together an international group of senior and junior scientists and trainees who share a common interest in neural control of gastrointestinal motility in health and disease. The AMS would like to capitalize on this rare opportunity to request partial support for a Young Investigator workshop that would immediately precede the joint international meeting. The workshop will be held on September 14, 2006 (1-5:30 PM) at the Boston Seaport Hotel and World Trade Center in downtown Boston, MA. The title of the workshop will be "Experimental approaches to understanding the enteric nervous system and its disorders". Workshop speakers will be drawn from the roster of international experts that will be attending the joint meeting. Eight talks will cover topics that range from analysis of gene expression in single cells through integrative control of motility and visceral sensation in intact animals and human subjects. The presentations will focus on state of the art techniques in molecular, cellular and systems biology and advanced imaging methods. Workshop attendance will be limited to 25 participants to maintain a low attendee to faculty ratio. The workshop is targeted at young investigators who have recently made the transition from a training position to independent investigator and do not yet have substantial funding or who are currently in a training position but anticipate moving on to an independent faculty position within one year of the workshop date. The goal of the workshop is to provide participants with an objective critique of modern research methods in neurogastroenterology. Presenters will provide an overview of the technical details of the approaches, their appropriate use and also the major shortcomings or limitations of individual methods. Workshop attendees will be provided with a course syllabus which will contain the text and slides of each presentation. There will also be a post-workshop reception where attendees will have the opportunity to meet the speakers in an informal setting. This will help the attendees develop a network of professional contacts who can help the young investigator in the career development process. [unreadable] [unreadable]
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2009 — 2011 |
Galligan, James J |
F31Activity Code Description: To provide predoctoral individuals with supervised research training in specified health and health-related areas leading toward the research degree (e.g., Ph.D.). |
Modification of Pdi by 4-Hne and 4-One and Its Role in Ethanol-Induced Er Stress @ University of Colorado Denver
DESCRIPTION (provided by applicant): The build-up of misfolded and/or unfolded proteins in the endoplasmic reticulum (ER) is characterized as the unfolded protein response (UPR). The pathological consequence of this response is known as endoplasmic reticulum (ER) stress and has recently emerged as a possible mechanism for the initiation and progression of numerous disease states, including the alcoholic liver. The ER-resident molecular chaperone, protein disulfide isomerase (PDI), is a key enzyme in both oxidative folding and isomerization reactions. Published data has shown modification of the active-site of PDI by the reactive aldehyde 4-hydroxynonenal (4-HNE). 4-HNE, as well as 4-oxononenal (4-ONE), are products of lipid peroxidation and have been implicated to have a role in the progression of the alcoholic liver. Through the adduction of active site cysteines, these aldehydes have been shown to cause alterations in the enzymatic activity of numerous proteins. The experiments outlined in this proposal are designed to test the general working hypothesis that covalent adduction of PDI by 4-HNE and 4-ONE increase the erred protein burden in the ER and subsequently induces the ER stress response. The first phase of this proposal is designed to elucidate the role of PDI in the ER stress response in vitro, as well as in a chronic ethanol rodent feeding model. Secondly, the alterations in the redox status of PDI will be examined following chronic ethanol feeding. Finally, alterations in the enzymatic activities of PDI will be examined in vivo following ethanol feeding, as well as in vitro, following treatment with the aforementioned aldehydes. Upon completion, the data provided by this proposal will further elucidate the role of PDI in an ethanol-induced ER stress response. With alcoholic liver disease affecting nearly 2 million people in the United States alone, the mechanisms behind its progression remain far from elucidated. The four-year survival rate for end-stage liver disease remains a staggeringly low 35%, stressing an urgency for unraveling the mechanisms behind its pathogenesis. It is most conceivable that the progression of the alcoholic liver is multi-factorial;however, current research suggests a role for both the ER stress response and lipid peroxidation products.
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0.936 |
2010 — 2013 |
Galligan, James J. |
P01Activity Code Description: For the support of a broadly based, multidisciplinary, often long-term research program which has a specific major objective or a basic theme. A program project generally involves the organized efforts of relatively large groups, members of which are conducting research projects designed to elucidate the various aspects or components of this objective. Each research project is usually under the leadership of an established investigator. The grant can provide support for certain basic resources used by these groups in the program, including clinical components, the sharing of which facilitates the total research effort. A program project is directed toward a range of problems having a central research focus, in contrast to the usually narrower thrust of the traditional research project. Each project supported through this mechanism should contribute or be directly related to the common theme of the total research effort. These scientifically meritorious projects should demonstrate an essential element of unity and interdependence, i.e., a system of research activities and projects directed toward a well-defined research program goal. |
Neurotransmission to Arteries and Veins in Hypertension @ Michigan State University
The main theme of this theme is that there is differential control of mesenteric arteries (MA) and veins (MV) by sympathetic nerves. We will identify these differences in detail and we will also identify the molecular mechanisms mediating deoxycorticosterone acetate (DOCA)-salt hypertension associated changes in sympathetic transmission to MA and MV in rats. Specific aim 1 will test the hypothesis that sympathetic transmission to MA and MV is different and these mechanisms are differentially altered in hypertension. These studies will use intracellular electrophysiological techniques to record purinergic excitatory junction potentials (EJPs) caused by ATP released from sympathetic nerves supplying MA in vitro. We show that oxidative stress is responsible for impairment of purinergic signaling to MA in hypertension. We will also use continuous amperometry and fast scan cyclic voltametry (FSCV) to make electrochemical measurements of neurotransmitter release profiles from sympathetic nerves associated with MA and MV in vitro. Finally, these studies will use FSCV to study neurotransmitter release profiles from adrenal chromaffin cells in primary culture. The studies in this aim will show that sympathetic nerves supplying MA and MV use different neurotransmitters, release and clearance mechanisms and that sympathetic transmission to MA but not MV is altered in DOCA-salt hypertension. Adrenal chromaffin cells will used as a model of periarterial sympathetic nerves. Specific aim 2 will test the hypothesis that B2-adrenergic receptor (AR)-mediated vasodilation is reduced in DOCA-salt rats. We propose that increased vascular tone in DOCA-salt hypertension is partly due to impairment of the link between the B2-AR-cAMP-protein kinase A signaling pathway and large conductance Ca[2+] activated K[+] (BK) channels in MA and MV. These studies will measure: B2-AR agonist-induced relaxations of MA and MV in vitro, BK channel currents using patch clamp methods and heterologous receptor and ion channel expression to study molecular mechanisms linking B2- ARs to BK channels. Specific aim 3 will test the hypothesis that MV reverse remodel in DOCA-salt rats. Reverse remodeling is caused by activation of endothelin-B and a1-adrenergic receptor activation on venous smooth muscle cells which couple to activation of matrix metalloproteinase-2 and tenascin-C. Reverse remodeling is an adaptive response of veins to the decreased venous volume caused by volume shifts from the capacitance to the resistance side of the circulation in hypertension. These studies will provide new information about differential neurohumoral control of arteries and veins. We will also identify specific changes in neural control of arteries and veins in hypertension and this information will facilitate the development of new treatments for high blood pressure.
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2011 — 2015 |
Galligan, James J. |
T32Activity Code Description: To enable institutions to make National Research Service Awards to individuals selected by them for predoctoral and postdoctoral research training in specified shortage areas. |
Integrative Training in the Pharmacological Sciences @ Michigan State University
DESCRIPTION (provided by applicant): This Integrative Pharmacological Sciences Training Program (IPSTP) is designed for 2nd and 3rd year Ph.D. students pursuing dissertation research projects in the pharmacological sciences. Trainees and training faculty (n=36) are drawn from 4 Ph.D. programs (Biochemistry & Molecular Biology, Cell & Molecular Biology, Neuroscience and Pharmacology & Toxicology). The unique focus of the IPSTP is training with in vivo pharmacological approaches and concepts. The research expertise of IPSTP training faculty is clustered into three overlapping themes: 1) cell growth, differentiation, injury and repair; 2) intra and intercellular signaling and, 3) integrative pharmacology and physiology. Funds are requested to support 3 students in year 1 and 6 students in years 2-5 (each student receives 2 years of support). The training program will be administered by a Program Director (Galligan) and an Executive Committee composed of a representative of each program and a student trainee. The program is also guided by an Internal Advisory Committee composed of the Chairs or Directors of the participating Ph.D. programs. There are 7 core elements to the training plan: 1) a research project whose results lead to a Ph.D. dissertation and a contribution to knowledge in the pharmacological sciences; 2) a two week short course in pharmacological methods (Boot camp); 3) a three course curriculum in pharmacology and biostatistics; 4) a weekly Communications Skills and Professional Development Workshop (trainee participation is required during the two years of program support and for two years after support has ended); 5) a mentored teaching experience; 6) participation in a quantitative systems biology workshop and; 7) participation in an annual program retreat. Trainees are also required to attend the Responsible Conduct of Research (RCR) workshop series provided by the Graduate School and program specific RCR activities. Supplemental activities that are available to trainees include: 1) opportunities to participate in development and delivery of online classes; 2) participation in an internship (4-6 week) in an on-campus In Vivo Pharmacology facility which functions as a contract research organization. Trainees would be exposed to issues related to contract work (Good Laboratory Practice protocols, budget and contract development, data security, delivering outcomes on schedule). The IPSTP has developed a comprehensive plan to recruit highly qualified students including under-represented minority students. The IPSTP will provide trainees with excellent research and professional training and will prepare them for research careers in academia, industry and government.
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2012 — 2016 |
Galligan, James J. |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Purinergic Neurotransmission in the Gut @ Michigan State University
DESCRIPTION (provided by applicant): The enteric nervous system (ENS) is the division of the autonomic nervous system that resides within the gut wall. The ENS controls gastrointestinal (GI) motility, secretion and local blood flow. The ENS can perform these complex functions because it contains all the neuronal elements (sensory neurons, interneurons and motorneurons) required for GI reflexes and integration. The ENS contains 14 different types of neurons that release different neurotransmitters. There are also multiple receptors for each neurotransmitter. In addition, synapses in the ENS may be coded by the neurotransmitters released from presynaptic nerve terminals and by receptors expressed by postsynaptic cells. The proposed studies will use intracellular electrophysiological, immunohistochemical and molecular biological methods to study enteric neuromuscular transmission. There are 3 specific aims in this proposal. Specific aim 1 will test the hypothesis that there are two separate populations of inhibitory nerves supplying the muscle layers. One subset uses nitric oxide (NO) as the primary neurotransmitter while the second population is purinergic (ATP and/or b-nicotinamide adenine dinucleotide are the neurotransmitters). These studies will show that release of ATP/b-NAD and NO from nerve terminals is controlled by different Ca2+ channel types. An antibody against the vesicular nucleotide (VNUT) antibody will be used to localize purinergic nerves. These studies will also make use of P/Q type and R-type Ca2+ channel mutant mice. Specific aim 2 will focus on Ca2+ channels expressed by interneurons in the myenteric plexus. Interneurons which project in an oral-anal direction release acetylcholine (ACh) and ATP as fast synaptic transmitters, while neurons that project in an anal-oral direction release ACh. These studies will test the hypothesis that R-, N- and P/Q type Ca2+ channels are expressed by neurons in the orally-projecting pathway while only N- and P/Q type Ca2+ channels are expressed by nerve terminals in the anally-projecting pathway. These studies will also use wild type and P/Q-type and R-type Ca2+ channel mutant mice. Specific aim 3 will focus on K+ channels as regulators of gut smooth muscle tone and neuromuscular transmission in the colon. These studies will make use of a b1 subunit of the large conductance Ca2+-activated K+ (BK) channel knockout mouse. Significance: Disturbances in enteric synaptic mechanisms contribute to GI motility disorders. Changes in the function of enteric neurons and their synapses might also contribute to visceral pain. Therefore, a more complete understanding of enteric neural circuits and synaptic transmission would provide insights into the pathophysiology of GI motility disorders. This information would help to develop new drug treatments for common motility disorders.
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1 |
2012 — 2013 |
Galligan, James J. |
R21Activity Code Description: To encourage the development of new research activities in categorical program areas. (Support generally is restricted in level of support and in time.) |
Sert Ko Rats Are a Model of Sex Specific Visceral Pain @ Michigan State University
DESCRIPTION (provided by applicant): This project will test the hypothesis that 5-hydroxytryptamine (5-HT, serotonin) and estrogen signaling interact to increase excitability of primary afferent neurons supplying the colon. Increased excitability is caused by changes in ion channel expression that result in visceral hypersensitivity in female rats. This hypothesis will be tested using male and female serotonin transporter (SERT) knockout (KO) rats, which we propose is a unique animal model of gender specific visceral hypersensitivity. The underlying pathophysiology of visceral pain is unclear and this is partly due to a lack of animal models where mechanistic and interventional studies can be conducted. However, published data indicate that alterations in 5-HT signaling may play a role in humans. In addition, visceral pain i more common in women than in men, suggesting that there are interactions between 5-HT and gender in the genesis of visceral pain. The overall hypothesis will be tested in 3 specific aims. Specific aim 1 will test the hypothesis that there is increased extracellular availability of 5-HT n vitro in the colon of wild type (WT) and SERT KO rats and that 5-HT release from enterochromaffin (EC) cells is unaffected by the SERT KO. Amperometry will measure 5-HT near the mucosa in response to mechanical and chemical mucosal stimulation. Immunohistochemical (IHC) and Western blot techniques will be used to verify SERT deletion and to assess 5-HT-containing EC cells in the gut of WT and SERT KO rats. IHC localization of the dopamine and norepinephrine transporters and organic cation transporters will be assessed to determine if their expression increases in SERT KO rats. Specific aim 2 will test the hypothesis that estrogen interacts with 5-HT to cause visceral hypersensitivity in female SERT KO rats. The visceromotor response to colorectal balloon distention will be used to measure visceral sensitivity in intact and ovariectomized female WT and SERT KO rats with and without estrogen replacement. In Specific Aim 3, the functional properties of colon projecting sensory neurons maintained in short term primary culture will be studied. These studies will test the hypothesis that colon projecting sensory nerves from female but not male SERT KO rats exhibit increased excitability when studied using whole cell patch clamp methods in vitro. The increased excitability is proposed to be due to interactions between 5-HT and estrogen on sensory neurons that lead to upregulation of tetrodotoxin-resistant sodium channels. These studies will show that increased 5-HT availability in female SERT KO rats alters visceral sensitivity as occurs in female human irritable bowel syndrome patients. The data would indicate that the SERT KO rat is a model for studying changes in the sensory nerve supply of the gut that leads to visceral hypersensitivity.
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2015 — 2019 |
Galligan, James J. |
P01Activity Code Description: For the support of a broadly based, multidisciplinary, often long-term research program which has a specific major objective or a basic theme. A program project generally involves the organized efforts of relatively large groups, members of which are conducting research projects designed to elucidate the various aspects or components of this objective. Each research project is usually under the leadership of an established investigator. The grant can provide support for certain basic resources used by these groups in the program, including clinical components, the sharing of which facilitates the total research effort. A program project is directed toward a range of problems having a central research focus, in contrast to the usually narrower thrust of the traditional research project. Each project supported through this mechanism should contribute or be directly related to the common theme of the total research effort. These scientifically meritorious projects should demonstrate an essential element of unity and interdependence, i.e., a system of research activities and projects directed toward a well-defined research program goal. |
Neuroeffector Transmission to Arteries and Veins in Health and Disease @ Michigan State University
Project Summary/Abstract - Project 2 The splanchnic circulation is supplied by sympathetic nerves which control resistance and capacitance. Elevated sympathetic nerve activity (SNA) increases resistance and decreases capacitance causing increased blood pressure. Dysregulation of SNA and dilator mechanisms contribute to obesity-related hypertension. We will study how obesity disrupts molecular control of norepinephrine (NE) and ATP release at the arterial and venous sympathetic neuroeffector junction. A novel concept guiding these studies is that mesenteric perivascular fat (mPVAT) is a source of inflammatory mediators and norepinephrine (NE) that can alter sympathetic function. Specific aim 1: Prejunctional alpha2 adrenergic receptors (alpha2ARs) regulate NE and ATP release from sympathetic nerves and alpha2AR function is impaired in obesity-associated hypertension. The mechanisms responsible for impairment are linked to inflammation. We will test the hypothesis that alpha2AR function is impaired due to the action of mPVAT-derived inflammatory mediators. Specific aim 2: NE and ATP constrict and NE and endothelial derived nitric oxide (NO) relax vascular smooth muscle. Pannexin-1 is a smooth muscle ATP permeable channel and ATP contributes to arterial constriction caused by NE. This conclusion is based only on studies of exogenously applied NE; pannexin-1 contributions to neurogenic arterial or venous constriction have not been established. These studies will test the hypothesis that pannexin-1 contributes to neurogenic constriction in mesenteric arteries and veins and that pannexin-1 expression and function and NE and NO dilator mechanisms are impaired in obesity-associated hypertension. Specific aim 3: This aim will focus on neurogenic constrictions and dilator mechanisms of human mesenteric arteries and veins obtained from obese patients undergoing gastric by-pass surgery and from non-obese patients undergoing intestinal or colonic resection. In addition to studies of basic mechanisms of sympathetic constriction of arteries and veins in the human splanchnic circulation, we will identify the mechanisms responsible for disruption of vascular tone and sympathetic neuroeffector transmission in obesity.
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2015 — 2018 |
Galligan, James J. |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Sex, Serotonin and Visceral Hypersensitivity @ Michigan State University
DESCRIPTION (provided by applicant): Irritable bowel syndrome (IBS) is a gastrointestinal motility and visceral sensation disorder that affects 30 million people in the United States. IBS is twice as common in women as men and IBS symptom severity is related to fluctuations in circulating female sex hormones and to episodes of stress. In addition, drugs which act at some 5-hydroxytryptamine (5- HT serotonin) receptors relieve IBS symptoms, including visceral pain, in some patients. Finally, many IBS patients have a polymorphism in the promoter region of the gene that encodes the serotonin transporter (SERT). This polymorphism leads to low SERT expression. These data indicate that there is an interaction between serotonin and female sex hormone signaling that leads to IBS symptoms especially visceral pain. The underlying pathophysiology of visceral pain is unclear and this is partly due to a lack of animal models where mechanistic and interventional studies can be conducted. We will use This hypothesis will be tested using male and female serotonin transporter (SERT) knockout (KO) rats, which we propose is an animal model of sex specific visceral hypersensitivity. This project will test th hypothesis that 5-hydroxytryptamine (5-HT, serotonin) corticotropin releasing hormone (CRH) and estrogen signaling interact to increase neurotransmission of primary afferent neurons supplying the colon to second order spinal sensory neurons and that probiotic bacteria L. reuteri (Lactobacillus reuteri 6475) can be used as a safe and effective treatment for visceral pain in IBS. The overall hypothesis will be tested in 3 specific aims. Specific aim 1 will tes the hypothesis that 5-HT3 and CRH1 antagonists can reduce visceral hypersensitivity as measured by the visceromotor response (VMR) to colorectal balloon distention (CRD). Specific aim 2 will test the hypothesis that the probiotic bacteria L. retueri can reduce visceral hypersensitivity in female SERT KO rats and this this probiotic may be a safe and effective treatment for visceral pain in IBS. Specific aim 3 will test the hypothesis that serotonin, 17-beta estradiol and CRH interaction to alter the excitability of colon projecting sensory neurons and that colon projecting neurons from female SERT KO rats will show reduced excitability. The data would indicate that the SERT KO rat is a model for studying changes in the sensory nerve supply of the gut that leads to visceral hypersensitivity.
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2019 — 2021 |
Galligan, James J. |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Identification of Enteric Nerve Circuits Controlling Gut Motility @ Michigan State University
Project Summary The enteric nervous system (ENS) is a semi-autonomous division of the autonomic nervous system. The ENS controls gastrointestinal motor function, absorption and secretion of nutrients and water and gut sensation. The nerve circuits controlling these important functions are incompletely mapped. In specific aim 1, we will use an antibody against the vesicular nucleotide transporter (VNUT), a protein marker for purinergic nerves to identify these pathways. Purinergic neurotransmission is important in the ENS but there are no data describing the purinergic neurons or pathways in the ENS. These will be important new data that will broaden our knowledge of enteric synaptic connectivity. In specific aim 2 we will use cre-lox technology and adeno-associated virus (AAV9) transduction of myenteric neurons to express the light-activated ion channel, channel rhodopsin-2 (ChR2) in specific neuronal subtypes. This will allow selective activation of specific functional classes of neurons (interneurons, motorneurons, sensory neurons) to determine their specific synaptic connections and the neurotransmitters that these neurons release. These studies will be done in mice and guinea pigs. We will use cre driver mice where cre is driven by neuron-subtype specific promoter (choline acetyltransferase, purines, nitric oxide synthase, 5-HT, for example) crossed with mice containing the floxed gene encoding ChR2. We will measure excitatory and inhibitory junction potentials (EJPs, IJPs) using microelectrode electrophysiology techniques to determine the neurochemical phenotype of neurons synapsing with excitatory and inhibitory motorneurons supplying the longitudinal and circular muscle layers. In specific aim 3, we will also use the cre- lox approach to study synaptic connections in myenteric ganglia. We will also use electrochemical methods to measure local release of ATP and nitric oxide (NO) from myenteric neurons. We will optically stimulate individual ganglia and make intracellular recordings from myenteric neurons on the oral and anal sides of the site of stimulation. We will use microelectrodes filled with neurobiotin so the recorded neurons can be identified in subsequent immunohistochemical studies to identify the neurochemical phenotype of neurons receiving synaptic input from the optically stimulated neurons. These studies will identify synaptic connections responsible for periodic propulsive colonic contractions. Successful completion of these studies will identify synaptic connections between neurochemically identified subsets of myenteric neurons. These connections control coordinated contractions and relaxation of gut smooth muscle leading to propulsion of gut content. A more complete understanding of these pathways will aid in identifying deficits in neural control of gut motility and identification of new drug or genetic treatments of gut motility disorders.
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