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Marson L, Piatt R, Cook JB, Thor KB. Neurokinin 2 receptor-mediated bladder and colorectal responses in aged spinal cord injured rats. Spinal Cord 2021; 59:1013-1017. [PMID: 34404911 DOI: 10.1038/s41393-021-00684-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 07/23/2021] [Accepted: 07/26/2021] [Indexed: 11/09/2022]
Abstract
STUDY DESIGN Animal proof of principle study. OBJECTIVES Bladder and bowel dysfunction are common after spinal cord injury (SCI) and in the elderly. Neurokinin 2 receptor agonists are known to produce on-demand urination and defecation in adult SCI rats. This study compared the ability of a neurokinin 2 receptor (NK2R) agonist to produce bladder and colorectal contractions in both young adult and aged SCI rats. SETTING Dignify Therapeutics and Integrated Laboratory Systems, Durham, NC USA. METHODS Bladder and colorectal pressure and voiding efficiency were measured in response to the NK2R agonist, [Lys5,Me,Leu9,Nle10]-NKA(4-10) (LMN-NKA), in anesthetized animals. The potency and efficacy of LMN-NKA was examined in young adult and aged SCI (T3 or T9 transected) rats, with young adult and aged spinal intact rats included as controls. RESULTS LMN-NKA (3-300 μg/kg i.v.) produced dose-dependent increases in bladder and colorectal pressure in all anesthetized rats. No differences in the bladder or colorectal pressure responses or voiding efficiency were observed with age or after SCI. The level of SCI did not change the pharmacodynamic responses to the agonist. CONCLUSIONS An NK2R agonist produced similar responses in young adult and aged SCI rats, suggesting this class of agonists could be used as a potential therapy to induce on-demand urination and defecation in aged populations, with or without SCI.
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Maeda K, Katsuno H, Kono T. The Japanese Extracted Herbal Medicine Daikenchuto Increases the Contractile Activity of the Internal Anal Sphincter Muscle in Conscious Dogs. JOURNAL OF THE ANUS RECTUM AND COLON 2020; 4:193-200. [PMID: 33134601 PMCID: PMC7595681 DOI: 10.23922/jarc.2020-041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 09/01/2020] [Indexed: 11/30/2022]
Abstract
Objectives: This study aimed to elucidate the effect of the extract of daikenchuto (DKT), a Japanese Kampo medicine, on the contractile activity of the internal anal sphincter in conscious dogs. Methods: Force transducers were attached to the serosal surface of the rectum and the internal anal sphincter of male beagle dogs. In addition, the contractile activity of the rectum and the internal anal sphincter was continuously measured until 6 h after DKT administration via telemetry in the conscious state. The DKT dose was 1.5 g/body, and the administration route was intrarectal in the expectation of a direct effect on the rectoanal region. DKT was re-administered to the same animal after drug withdrawal, and the plasma concentrations of hydroxy-α-sanshool (HAS) and hydroxy-β-sanshool (HBS) before and after administration were measured. Results: After DKT administration, the contractile activity of the internal anal sphincter immediately increased, peaked at 10 min, continued for ≥1 h, and had almost disappeared after 4 h. Rectal contraction differed from that of the internal anal sphincter, with no significant contraction observed. HAS and HBS were found in the plasma of animals administered with DKT and persisted up to 2 h after the administration. Conclusions: This is the first report on in vivo telemetry demonstrating that DKT exhibited contractile effects on the dog's internal anal sphincter. The increased anal pressure and improvement of fecal incontinence symptoms observed in previous clinical studies may have been based on this sphincter contraction.
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Affiliation(s)
- Kotaro Maeda
- International Medical Center, Fujita Health University Hospital, Toyoake, Japan
| | - Hidetoshi Katsuno
- Department of Surgery, Fujita Health University Okazaki Medical Center, Okazaki, Japan
| | - Toru Kono
- Institute of Biomedical Research, Sapporo Higashi Tokushukai Hospital, Sapporo, Japan
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Keef KD, Cobine CA. Control of Motility in the Internal Anal Sphincter. J Neurogastroenterol Motil 2019; 25:189-204. [PMID: 30827084 PMCID: PMC6474703 DOI: 10.5056/jnm18172] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 11/28/2018] [Accepted: 12/09/2018] [Indexed: 12/14/2022] Open
Abstract
The internal anal sphincter (IAS) plays an important role in the maintenance of fecal continence since it generates tone and is responsible for > 70% of resting anal pressure. During normal defecation the IAS relaxes. Historically, tone generation in gastrointestinal muscles was attributed to mechanisms arising directly from smooth muscle cells, ie, myogenic activity. However, slow waves are now known to play a fundamental role in regulating gastrointestinal motility and these electrical events are generated by the interstitial cells of Cajal. Recently, interstitial cells of Cajal, as well as slow waves, have also been identified in the IAS making them viable candidates for tone generation. In this review we discuss four different mechanisms that likely contribute to tone generation in the IAS. Three of these involve membrane potential, L-type Ca2+ channels and electromechanical coupling (ie, summation of asynchronous phasic activity, partial tetanus, and window current), whereas the fourth involves the regulation of myofilament Ca2+ sensitivity. Contractile activity in the IAS is also modulated by sympathetic motor neurons that significantly increase tone and anal pressure, as well as inhibitory motor neurons (particularly nitrergic and vasoactive intestinal peptidergic) that abolish contraction and assist with normal defecation. Alterations in IAS motility are associated with disorders such as fecal incontinence and anal fissures that significantly decrease the quality of life. Understanding in greater detail how tone is regulated in the IAS is important for developing more effective treatment strategies for these debilitating defecation disorders.
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Affiliation(s)
- Kathleen D Keef
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Caroline A Cobine
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
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Cobine CA, McKechnie M, Brookfield RJ, Hannigan KI, Keef KD. Comparison of inhibitory neuromuscular transmission in the Cynomolgus monkey IAS and rectum: special emphasis on differences in purinergic transmission. J Physiol 2018; 596:5319-5341. [PMID: 30198065 DOI: 10.1113/jp275437] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 09/07/2018] [Indexed: 01/04/2023] Open
Abstract
KEY POINTS Inhibitory neuromuscular transmission (NMT) was compared in the internal anal sphincter (IAS) and rectum of the Cynomolgus monkey, an animal with high gene sequence identity to humans. Nitrergic NMT was present in both muscles while purinergic NMT was limited to the rectum and VIPergic NMT to the IAS. The profile for monkey IAS more closely resembles humans than rodents. In both muscles, SK3 channels were localized to PDGFRα+ cells that were closely associated with nNOS+ /VIP+ nerves. Gene expression levels of P2RY subtypes were the same in IAS and rectum while KCNN expression levels were very similar. SK3 channel activation and inhibition caused faster/greater changes in contractile activity in rectum than IAS. P2Y1 receptor activation inhibited contraction in rectum while increasing contraction in IAS. The absence of purinergic NMT in the IAS may be due to poor coupling between P2Y1 receptors and SK3 channels on PDGFRα+ cells. ABSTRACT Inhibitory neuromuscular transmission (NMT) was compared in the internal anal sphincter (IAS) and rectum of the Cynomolgus monkey, an animal with a high gene sequence identity to humans. Electrical field stimulation produced nitric oxide synthase (NOS)-dependent contractile inhibition in both muscles whereas P2Y1-dependent purinergic NMT was restricted to rectum. An additional NOS-independent, α-chymotrypsin-sensitive component was identified in the IAS consistent with vasoactive intestinal peptide-ergic (VIPergic) NMT. Microelectrode recordings revealed slow NOS-dependent inhibitory junction potentials (IJPs) in both muscles and fast P2Y1-dependent IJPs in rectum. The basis for the difference in purinergic NMT was investigated. PDGFRα+ /SK3+ cells were closely aligned with nNOS+ /VIP+ neurons in both muscles. Gene expression of P2RY was the same in IAS and rectum (P2RY1>>P2RY2-14) while KCNN3 expression was 32% greater in rectum. The SK channel inhibitor apamin doubled contractile activity in rectum while having minimal effect in the IAS. Contractile inhibition elicited with the SK channel agonist CyPPA was five times faster in rectum than in the IAS. The P2Y1 receptor agonist MRS2365 inhibited contraction in rectum but increased contraction in the IAS. In conclusion, both the IAS and the rectum have nitrergic NMT whereas purinergic NMT is limited to rectum and VIPergic NMT to the IAS. The profile in monkey IAS more closely resembles that of humans than rodents. The lack of purinergic NMT in the IAS cannot be attributed to the absence of PDGFRα+ cells, P2Y1 receptors or SK3 channels. Rather, it appears to be due to poor coupling between P2Y1 receptors and SK3 channels on PDGFRα+ cells.
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Affiliation(s)
- C A Cobine
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - M McKechnie
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - R J Brookfield
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - K I Hannigan
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - K D Keef
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
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Marson L, Thor KB, Katofiasc M, Burgard EC, Rupniak NMJ. Prokinetic effects of neurokinin-2 receptor agonists on the bladder and rectum of rats with acute spinal cord transection. Eur J Pharmacol 2017; 819:261-269. [PMID: 29237540 DOI: 10.1016/j.ejphar.2017.12.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 11/29/2017] [Accepted: 12/08/2017] [Indexed: 11/18/2022]
Abstract
The suitability of various neurokinin-2 (NK2) receptor agonists and routes of administration to elicit on-demand voiding of the bladder and bowel, as future therapy for individuals with spinal cord injury, was examined using a rat model. The current study examined the feasibility of alternative routes of administration, which are more practical for clinical use than intravenous (IV) administration. Voiding and isovolumetric cystometry were recorded in anesthetized, acutely spinalized, female rats after IV, subcutaneous (SC), intramuscular (IM), intranasal (IN), or sublingual (SL) administration of [Lys5,MeLeu9,Nle10]-NKA(4-10) (LMN-NKA). Administration of LMN-NKA (1-10μg/kg IV; 10-300μg/kg SC or IM; 15-1000μg/kg IN or 300-1500μg/kg SL) elicited rapid-onset, short-duration, dose-related increases in bladder pressure and voiding with the rank order for time of both onset and duration being IV < IN < SC = IM < SL. The incidence of voiding was dependent on the dose and route, with all routes resulting in a high voiding efficiency (~ 70%). Like LMN-NKA, neurokinin A (NKA 1-100μg/kg IV) and GR 64349 (0.1-30μg/kg IV or 1-300μg/kg SC) produced rapid-onset, short-duration increases in bladder pressure, as well as colorectal pressure. Administration of vehicle never produced bladder or rectal contractions or voiding. Transient hypotension was observed after IV injection of LMN-NKA, which was less pronounced after SC injection. Hypotension was not apparent with GR 64349. In conclusion, selective NK2 receptor agonists, administered through various non-IV routes of administration, may provide a safe, convenient, and efficacious method for inducing voiding.
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Affiliation(s)
- Lesley Marson
- Dignify Therapeutics LLC, 2 Davis Drive, P.O. Box 13169, Research Triangle Park, NC 27709, USA.
| | - Karl B Thor
- Dignify Therapeutics LLC, 2 Davis Drive, P.O. Box 13169, Research Triangle Park, NC 27709, USA
| | - Mary Katofiasc
- Dignify Therapeutics LLC, 2 Davis Drive, P.O. Box 13169, Research Triangle Park, NC 27709, USA
| | - Edward C Burgard
- Dignify Therapeutics LLC, 2 Davis Drive, P.O. Box 13169, Research Triangle Park, NC 27709, USA
| | - Nadia M J Rupniak
- Dignify Therapeutics LLC, 2 Davis Drive, P.O. Box 13169, Research Triangle Park, NC 27709, USA
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Kullmann FA, Katofiasc M, Thor KB, Marson L. Pharmacodynamic evaluation of Lys 5, MeLeu 9, Nle 10-NKA (4-10) prokinetic effects on bladder and colon activity in acute spinal cord transected and spinally intact rats. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2017; 390:163-173. [PMID: 27889808 PMCID: PMC5512890 DOI: 10.1007/s00210-016-1317-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Accepted: 11/14/2016] [Indexed: 11/24/2022]
Abstract
The purpose of this study was to determine feasibility of a novel therapeutic approach to drug-induced voiding after spinal cord injury (SCI) using a well-characterized, peptide, neurokinin 2 receptor (NK2 receptor) agonist, Lys5, MeLeu9, Nle10-NKA(4-10) (LMN-NKA). Cystometry and colorectal pressure measurements were performed in urethane-anesthetized, intact, and acutely spinalized female rats. Bladder pressure and voiding were monitored in response to intravenous LMN-NKA given with the bladder filled to 70% capacity. LMN-NKA (0.1-300 μg/kg) produced dose-dependent, rapid (<60 s), short-duration (<15 min) increases in bladder pressure. In intact rats, doses above 0.3-1 μg/kg induced urine release (voiding efficiency of ~70% at ≥1 μg/kg). In spinalized rats, urine release required higher doses (≥10 μg/kg) and was less efficient (30-50%). LMN-NKA (0.1-100 μg/kg) also produced dose-dependent increases in colorectal pressure. No tachyphylaxis was observed, and the responses were blocked by an NK2 receptor antagonist (GR159897, 1 mg/kg i.v.). No obvious cardiorespiratory effects were noted. These results suggest that rapid-onset, short-duration, drug-induced voiding is possible in acute spinal and intact rats with intravenous administration of an NK2 receptor agonist. Future challenges remain in regard to finding alternative routes of administration that produce clinically significant voiding, multiple times per day, in animal models of chronic SCI.
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Affiliation(s)
- F Aura Kullmann
- Department of Medicine, Renal Division, University of Pittsburgh, 3500 Terrace St, Scaife A1220, Pittsburgh, PA, 15261, USA
| | - M Katofiasc
- Dignify Therapeutics LLC, 2 Davis Drive, PO Box 13169, Research Triangle Park, NC, 27709, USA
| | - K B Thor
- Dignify Therapeutics LLC, 2 Davis Drive, PO Box 13169, Research Triangle Park, NC, 27709, USA
| | - Lesley Marson
- Dignify Therapeutics LLC, 2 Davis Drive, PO Box 13169, Research Triangle Park, NC, 27709, USA.
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Keef KD, Saxton SN, McDowall RA, Kaminski RE, Duffy AM, Cobine CA. Functional role of vasoactive intestinal polypeptide in inhibitory motor innervation in the mouse internal anal sphincter. J Physiol 2013; 591:1489-506. [PMID: 23339175 DOI: 10.1113/jphysiol.2012.247684] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
There is evidence that vasoactive intestinal polypeptide (VIP) participates in inhibitory neuromuscular transmission (NMT) in the internal anal sphincter (IAS). However, specific details concerning VIP-ergic NMT are limited, largely because of difficulties in selectively blocking other inhibitory neural pathways. The present study used the selective P2Y1 receptor antagonist MRS2500 (1 μm) and the nitric oxide synthase inhibitor N(G)-nitro-l-arginine (l-NNA; 100 μm) to block purinergic and nitrergic NMT to characterize non-purinergic, non-nitrergic (NNNP) inhibitory NMT and the role of VIP in this response. Nerves were stimulated with electrical field stimulation (0.1-20 Hz, 4-60 s) and the associated changes in contractile and electrical activity measured in non-adrenergic, non-cholinergic conditions in the IAS of wild-type and VIP(-/-) mice. Electrical field stimulation gave rise to frequency-dependent relaxation and hyperpolarization that was blocked by tetrodotoxin. Responses during brief trains of stimuli (4 s) were mediated by purinergic and nitrergic NMT. During longer stimulus trains, an NNNP relaxation and hyperpolarization developed slowly and persisted for several minutes beyond the end of the stimulus train. The NNNP NMT was abolished by VIP6-28 (30 μm), absent in the VIP(-/-) mouse and mimicked by exogenous VIP (1-100 nm). Immunoreactivity for VIP was co-localized with neuronal nitric oxide synthase in varicose intramuscular fibres but was not detected in the VIP(-/-) mouse IAS. In conclusion, this study identified an ultraslow component of inhibitory NMT in the IAS mediated by VIP. In vivo, this pathway may be activated with larger rectal distensions, leading to a more prolonged period of anal relaxation.
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Affiliation(s)
- K D Keef
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA.
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Cobine CA, Hennig GW, Bayguinov YR, Hatton WJ, Ward SM, Keef KD. Interstitial cells of Cajal in the cynomolgus monkey rectoanal region and their relationship to sympathetic and nitrergic nerves. Am J Physiol Gastrointest Liver Physiol 2010; 298:G643-56. [PMID: 20150245 PMCID: PMC2867417 DOI: 10.1152/ajpgi.00260.2009] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The morphology of interstitial cells of Cajal (ICC) in the circular muscle layer of the cynomolgus monkey internal anal sphincter (IAS) and rectum and their relationship to sympathetic and nitrergic nerves were compared by dual-labeling immunohistochemistry. Contractile studies confirmed that nitrergic nerves participate in neural inhibition in both regions whereas sympathetic nerves serve as excitatory motor nerves only in the IAS. Muscle bundles extended from myenteric to submucosal edge in rectum but in the IAS bundles were further divided into "minibundles" each surrounded by connective tissue. Dual labeling of KIT and smooth muscle myosin revealed KIT-positive stellate-shaped ICC (ICC-IAS) within each minibundle. In the rectum intramuscular ICC (ICC-IM) were spindle shaped whereas stellate-shaped ICC were located at the myenteric surface (ICC-MY). ICC were absent from both the myenteric and submucosal surfaces of the IAS. Nitrergic nerves (identified with anti-neuronal nitric oxide synthase antibodies or NADPH diaphorase activity) and sympathetic nerves (identified with anti-tyrosine hydroxylase antibody) each formed a plexus at the myenteric surface of the rectum but not the IAS. Intramuscular neuronal nitric oxide synthase- and tyrosine hydroxylase-positive fibers were present in both regions but were only closely associated with ICC-IM in rectum. Minimal association was also noted between ICC-IAS and cells expressing the nonspecific neuronal marker PGP9.5. In conclusion, the morphology of rectal ICC-IM and ICC-MY is similar to that described elsewhere in the gastrointestinal tract whereas ICC-IAS are unique. The distribution of stellate-shaped ICC-IAS throughout the musculature and their absence from both the myenteric and submucosal surfaces suggest that ICC-IAS may serve as pacemaker cells in this muscle whereas their limited relationship to nerves suggests that they are not involved in neuromuscular transmission. Additionally, the presence of numerous minibundles, each containing both ICC-IAS and nerves, suggests that this muscle functions as a multiunit type muscle.
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Affiliation(s)
- C. A. Cobine
- Department of Physiology and Cell Biology University of Nevada, Reno, Nevada
| | - G. W. Hennig
- Department of Physiology and Cell Biology University of Nevada, Reno, Nevada
| | - Y. R. Bayguinov
- Department of Physiology and Cell Biology University of Nevada, Reno, Nevada
| | - W. J. Hatton
- Department of Physiology and Cell Biology University of Nevada, Reno, Nevada
| | - S. M. Ward
- Department of Physiology and Cell Biology University of Nevada, Reno, Nevada
| | - K. D. Keef
- Department of Physiology and Cell Biology University of Nevada, Reno, Nevada
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Cobine CA, Fong M, Hamilton R, Keef KD. Species dependent differences in the actions of sympathetic nerves and noradrenaline in the internal anal sphincter. Neurogastroenterol Motil 2007; 19:937-45. [PMID: 17973631 DOI: 10.1111/j.1365-2982.2007.00982.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Excitatory motor innervation to the internal anal sphincter (IAS) of the monkey, the rabbit and mouse were compared. Contractile responses to electrical field stimulation of nerves (EFS, atropine 1 micromol L(-1) and N(omega)-nitro-L-arginine 100 micromol L(-1) present throughout) were examined in isolated strips of IAS. In the monkey IAS, EFS caused frequency dependent (1-30 Hz) contractions which were abolished by guanethidine (10 micromol L(-1)) or phentolamine (3 micromol L(-1)). The sympathetic neurotransmitter noradrenaline (NA) also caused concentration-dependent (10 nmol L(-1)-100 micromol L(-1)) contractions which were abolished by phentolamine revealing a small relaxation that was abolished by propranolol (3 micromol L(-1)). In contrast, EFS caused only relaxation of the mouse and rabbit IAS which was not affected by guanethidine. Furthermore, NA relaxed these muscles and relaxation was nearly abolished by combined addition of phentolamine and propranolol. In conclusion, the monkey IAS is functionally innervated by sympathetic nerves that contract the muscle via excitatory alpha-adrenergic receptors. In contrast, no significant motor function could be identified for sympathetic nerves in the rabbit or mouse IAS although adrenergic receptors linked to muscle inhibition are present. These data reveal species dependent differences in sympathetic motor innervation and suggest that some species are more appropriate than others as models for motor innervation to the human IAS.
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Affiliation(s)
- C A Cobine
- Department of Physiology and Cell Biology, University of Nevada, Reno, NV 89557, USA
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Nie Y, Chen JDZ. Effects and mechanisms of anal electrical stimulation on anorectal compliance and tone in dogs. Dis Colon Rectum 2006; 49:1414-21. [PMID: 16826335 DOI: 10.1007/s10350-006-0599-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
PURPOSE This study was designed to investigate the changes in rectal compliance and tone during anal electric stimulation and the involvement of the alpha-adrenergic pathway in conscious dogs. METHODS Eight healthy dogs were studied in five randomized sessions. Anal sphincter pressure was quantified by using the area under the contractile curve. Rectal compliance and tone were measured in a pressure-controlled phasic and isobaric distention by using an electronic barostat. Anal electric stimulation was performed via a pair of ring electrodes attached to the catheter. RESULTS The electric stimulation-induced increase in sphincter pressure was lowered by the presence of an alpha(1)-adrenergic receptor antagonist, prazosin (18.6 +/- 7.4 vs. 45.4 +/- 9.7, P < 0.05), or alpha(2)-adrenergic receptor antagonist, yohimbine (10.2 +/- 8.2 vs. 38.3 +/- 7.6, P < 0.05), compared with the control. The threshold volume in rectoanal inhibitory reflex during electric stimulation was significantly higher than during baseline (27.5 +/- 0.9 vs. 22.5 +/- 1.9 ml, P < 0.05). There were no significant differences between the percentage drops in sphincter pressure with and without stimulation at a rectal distention level of 45 ml of air. Anal electric stimulation significantly increased rectal compliance reflected as reduced P(1/2) (11.1 +/- 1.5 vs. 16.7 +/- 1.1, P = 0.027) and reduced kappa (11.6 +/- 2.5 vs. 20.5 +/- 2.6, P = 0.0095), compared with the control session, but did not significantly alter rectal tone. CONCLUSIONS Anal electric stimulation increases anal sphincter pressure, mediated at least partially by the alpha-adrenergic pathway. It also increases rectal compliance but does not alter rectal anal inhibitory reflexes.
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Affiliation(s)
- Yuqiang Nie
- Division of Gastroenterology, University of Texas Medical Branch, Galveston, TX 77555-0632, USA
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Nie Y, Pasricha JP, Chen JDZ. Anal electrical stimulation with long pulses increases anal sphincter pressure in conscious dogs. Dis Colon Rectum 2006; 49:383-91. [PMID: 16474988 DOI: 10.1007/s10350-005-0272-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
PURPOSE This study was designed to investigate the effects and mechanisms of anal electric stimulation with long pulses on anal sphincter pressure in conscious dogs. METHODS The study was performed after enema in nine healthy female hound dogs and composed of four randomized sessions ("dose"-response, anal electric stimulation only, or with atropine or phentolamine). The anal sphincter pressure was measured by using manometry and quantified by using the area under the contractile curve (mmHg/sec). Anal electric stimulation was performed via a pair of ring electrodes attached to a manometric catheter. The stimulation parameters in all but dose-response sessions included a frequency of 20 ppm, pulse width of 200 ms, and amplitude of 3 mA. RESULTS The anal sphincter pressure was 55.7 +/- 6 at baseline and increased by 37 percent to 76.4 +/- 6.5 during electric stimulation (P = 0.009). The increase of anal pressure during stimulation was positively correlated with the stimulation energy (r = 0.395; P < 0.01). The excitatory effect of electric stimulation was sustained for at least 20 minutes. Atropine did not alter anal pressure and did not abolish the excitatory effect of anal electric stimulation on the sphincter. Phentolamine reduced anal pressure from the baseline value of 50.5 +/- 4.7 to 33.1 +/- 5.4 (P = 0.019). The electric stimulation induced increase in anal pressure was dropped from 19 +/- 2.6 to 9.9 +/- 2.8 (P = 0.029) at the presence of phentolamine. CONCLUSIONS Anal electric stimulation with long pulses increases anal sphincter pressure in an energy-dependent manner. The alpha-adrenergic but not the cholinergic pathway at least partially mediates the excitatory effect of anal electric stimulation.
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Affiliation(s)
- Yuqiang Nie
- Division of Gastroenterology, University of Texas Medical Branch, Galveston, Texas 77555-0632, USA
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Kojima Y, Nakagawa T, Katsui R, Fujii H, Nakajima Y, Takaki M. A 5-HT4 agonist, mosapride, enhances intrinsic rectorectal and rectoanal reflexes after removal of extrinsic nerves in guinea pigs. Am J Physiol Gastrointest Liver Physiol 2005; 289:G351-60. [PMID: 15817810 DOI: 10.1152/ajpgi.00532.2004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Distension-evoked reflex of rectorectal (R-R) contractions and rectointernal anal sphincter (R-IAS) relaxations can be generated in guinea pigs through an extrinsic sacral excitatory neural pathway (pelvic nerves) as well as intrinsic cholinergic excitatory and nitrergic inhibitory pathways. The aim of the present study was to create intrinsic R-R and R-IAS reflex models by pithing (destruction of the lumbar and sacral cords; PITH) and to evaluate whether the prokinetic benzamide mosapride, a 5-HT(4) receptor agonist, enhances these reflexes. The mechanical activities of the R-R and R-IAS were recorded in the anesthetized guinea pig on days 2-9 after PITH. Although the basal rectal pressure at distension after PITH was significantly lower than control, the reflex indexes of R-R contractions and synchronous R-IAS relaxations were unchanged between days 4 and 9 after PITH. The frequency of spontaneous rectal and IAS motility were also unchanged. Immunohistochemical studies revealed that the distribution of myenteric and intramuscular interstitial cells of Cajal (ICC) were not altered after PITH. Mosapride (0.1-1.0 mg/kg iv) dose-dependently increased both intrinsic R-R (maximum: 1.82) and R-IAS reflex indexes (maximum: 2.76) from control (1.0) 6-9 days after PITH. The 5-HT(4) receptor antagonist, GR-113808 (1.0 mg/kg iv) decreased the R-R and R-IAS reflex indexes by approximately 50% and antagonized the effect of mosapride (1.0 mg/kg iv). The present results indicate that mosapride moderately enhanced intrinsic R-R and R-IAS reflexes functionally compensated after deprivation of extrinsic nerves, mediated through endogenously active intrinsic 5-HT(4) receptors.
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Affiliation(s)
- Yu Kojima
- Dept. of Physiology II, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8521, Japan
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Lecci A, Capriati A, Maggi CA. Tachykinin NK2 receptor antagonists for the treatment of irritable bowel syndrome. Br J Pharmacol 2004; 141:1249-63. [PMID: 15037522 PMCID: PMC1574903 DOI: 10.1038/sj.bjp.0705751] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2003] [Revised: 02/12/2004] [Accepted: 02/19/2004] [Indexed: 01/15/2023] Open
Abstract
Tachykinin NK2 receptors are expressed in the gastrointestinal tract of both laboratory animals and humans. Experimental data indicate a role for these receptors in the regulation of intestinal motor functions (both excitatory and inhibitory), secretions, inflammation and visceral sensitivity. In particular, NK2 receptor stimulation inhibits intestinal motility by activating sympathetic extrinsic pathways or NANC intramural inhibitory components, whereas a modulatory effect on cholinergic nerves or a direct effect on smooth muscle account for the NK2 receptor-mediated increase in intestinal motility. Accordingly, selective NK2 receptor antagonists can reactivate inhibited motility or decrease inflammation- or stress-associated hypermotility. Intraluminal secretion of water is increased by NK2 receptor agonists via a direct effect on epithelial cells, and this mechanism is active in models of diarrhoea since selective antagonists reverse the increase in faecal water content in these models. Hyperalgesia in response to intraluminal volume signals is possibly mediated through the stimulation of NK2 receptors located on peripheral branches of primary afferent neurones. NK2 receptor antagonists reduce the hyper-responsiveness that occurs following intestinal inflammation or application of stressful stimuli to animals. Likewise, NK2 receptor antagonists reduce intestinal tissue damage induced by chemical irritation of the intestinal wall or lumen. In healthy volunteers, the selective NK2 antagonist nepadutant reduced the motility-stimulating effects and irritable bowel syndrome-like symptoms triggered by intravenous infusion of neurokinin A, and displayed other characteristics that could support its use in patients. It is concluded that blockade of peripheral tachykinin NK2 receptors should be considered as a viable mechanism for decreasing the painful symptoms and altered bowel habits of irritable bowel syndrome patients.
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Affiliation(s)
- Alessandro Lecci
- Clinical Research Department, Menarini Ricerche via Sette Santi 1, 50131 Florence, Italy.
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Mutafova-Yambolieva VN, O'Driscoll K, Farrelly A, Ward SM, Keef KD. Spatial localization and properties of pacemaker potentials in the canine rectoanal region. Am J Physiol Gastrointest Liver Physiol 2003; 284:G748-55. [PMID: 12540368 DOI: 10.1152/ajpgi.00295.2002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The present study investigated the spatial organization of electrical activity in the canine rectoanal region and its relationship to motility patterns. Contraction and resting membrane potential (E(m)) were measured from strips of circular muscle isolated 0.5-8 cm from the anal verge. Rapid frequency [25 cycles/min (cpm)] E(m) oscillations (MPOs, 12 mV amplitude) were present across the thickness of the internal anal sphincter (IAS; 0.5 cm) and E(m) was constant (-52 mV). Between the IAS and the proximal rectum an 18 mV gradient in E(m) developed across the muscle thickness with the submucosal edge at -70 mV and MPOs were replaced with slow waves (20 mV amplitude, 6 cpm). Slow waves were of greatest amplitude at the submucosal edge. Nifedipine (1 micro M) abolished MPOs but not slow waves. Contractile frequency changes were commensurate with the changes in pacemaker frequency. Our results suggest that changing motility patterns in the rectoanal region are associated with differences in the characteristics of pacemaker potentials as well as differences in the sites from which these potentials emanate.
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