Abstract
A range of agonists and antagonists were used to characterize the receptors through which 5-hydroxytryptamine (5-HT) contracts and relaxes the longitudinal muscle of segments of guinea-pig distal colon, in vitro. 5-HT contracted the longitudinal muscle over the concentration range 10−9 to 10−4 mol/l. The 5-HT3 receptor agonist, 2-methyl-5-HT, produced concentration dependent contractions over the range 10−6 to 10−4 mol/l. 5-methoxytryptamine, an agonist at 5-HT4 receptors, caused contractions over a concentration range of 10−8 to 10−4 mol/l. The 5-HT4 antagonist, SDZ 205-557 (5 × 10−7 mol/l) substantially suppressed the responses to low concentrations of 5-HT and to 5-methoxytryptamine, but had no effect on the responses to higher concentrations of 5-HT. In contrast, the 5-HT3 antagonist, granisetron (10−6 mol/l), blocked the effect of 2-methyl-5-HT and substantially depressed responses to high concentrations of 5-HT, but had no effect on lower concentrations of 5-HT. Granisetron produced a small reduction in the response to 5-methoxytryptamine. Tetrodotoxin (TTX) (3 × 10−7 mol/l) almost abolished the response to 5-methoxytryptamine and markedly suppressed the response to 2-methyl-5-HT, but the responses to 5-HT were only partially reduced. The 5-HT, antagonist, methiothepin 10−6 mol/l. depressed the response to 5-HT 10−7 to 10−4 mol/l. and blocked its TTX insensitive component. The 5-HT2 antagonist, ketanserin, in concentrations up to 10−5 mol/l, had no effect on the contractions evoked by 5-HT.
The response to 5-HT was substantially depressed by hyoscine (3 × 10−6 mol/l. The tachykinin antagonist, spantide 10−5 mol/l. depressed the response to 5-HT but to a lesser extent than hyoscine. Spantide and hyoscine combined completely blocked the contractile responses to 5-HT Responses to 2-methyl-5-HT were partially suppressed by hyoscine (3 x 10−6 mol/l. and spantide (10−5 mol/l) and completely blocked when both byoscine and spantide were present. Contractions evoked by 5-methoxytryptamine were partially blocked by hyoscine (3 × 10−6 mol/l) and were unaffected by spantide (10−5 mol/l), but a combination of hyoscine and spantide completely blocked such responses.
When the excitatory transmission was blocked with hyoscine (3 × 10−6 mol/l) and spantide 10−5 mol/l) and the tone of the muscle raised, an inhibitory response to 5-HT was revealed that had a threshold concentration between 10−7 mol/l) and 3 × 10−7 mol/l, and a maximum effect at 10−4 mol/l. It was blocked by TTX (3 × 10−7 mol/l) and granisetron 10−6 mol/l. while N-nitro-l-arginine (NOLA) (10−4 mol/l) and SDZ 205-557 (5 × 10−7 mol/l) had no effect. Apamin A 10−6 mol/l. partially suppressed this response.
It is concluded that 5-HT3, 5-HT4 and 5-HT1-like receptors mediate contraction of the longitudinal muscle of the distal colon. The 5-HT3 and 5-HT4 receptors are located on the excitatory motor neurons innervating the longitudinal muscle and the 5-HT1-like receptor is located on the muscle. 5-HT3 receptors are also found on inhibitory neurons to the muscle.
Similar content being viewed by others
References
Barthó L, Holzer P (1985) Search for a physiological role of substance P in gastrointestinal motility. Neuroscience 16:1–32
Boeckxstaens GE, Pelckmans PA, Rampart M, Bogers JJ, Verbeuren TJ, Herman G, Van Maercke YM (1990) Pharmacological characterization of 5-hydroxytryptamine receptors in the canine terminal ileum and ileocolonic junction. J Pharmacol Exp Ther 254:652–658
Bradley PB, Engel G, Feniuk W, Fozard JR, Humphrey PPA, Middlemiss DN, Mylecharane EJ, Richardson BP, Saxena PR (1986) Proposals for the classification and nomenclature of functional receptors for 5-hydroxytryptamine. Neuropharmacology 25(6): 563–576
Briejer MR, Akkermans LMA, Meulemans AL, Lefebvre RA, Schuurkes JAJ (1992) Nitric oxide is involved in 5-HT-induced relaxations of the guinea-pig colon ascendens in vitro. Br J Pharmacol 107:756–761
Buchheit K-H, Buhl T (1991) Prokinetic benzamides stimulate peristaltic activity in the isolated guinea pig ileum by activation of 5-HT4 receptors. Eur J Pharmacol 205:203–208
Buchheit K-H, Engel G, Mutschler E, Richardson B (1985) Study of the contractile effect of 5-hydroxytryptamine (5-HT) in the isolated longitudinal muscle strip from guinea-pig ileum. Evidence for two distinct release mechanisms. Naunyn Schmiedebergs Arch Pharmacol 329:36–41
Buchheit K-H, Gamse R, Pfannkuche H-J (1991) SDZ 205–557, a selective antagonist at 5-HT4 receptors in the isolated guinea pig ileum. Eur J Pharmacol 200:373–374
Costall B, Naylor RJ (1990) 5-Hydroxytryptamine: New receptors and novel drugs for gastrointestinal motor disorders. Scand J Gastroenterol 25:769–787
Craig DA, Clarke DE (1990) Pharmacological characterization of a neuronal receptor for 5-hydroxytryptamine in guinea pig ileum with properties similar to the 5-hydroxytryptamine4 receptor. J Pharmacol Exp Therap 252:1378–1386
Craig DA, Clarke DE (1991) Peristalsis evoked by 5-HT and renzapride: evidence for putative 5-HT4 receptor activation. Br J Pharmac 102:563–564
Eglen RM, Swank SR, Walsh LKM, Whiting RL (1990) Characterization of 5-HT3 and “atypical” 5-HT receptors mediating guinea-pig ileal contractions in vitro. Br J Pharmac 101:513–520
Elswood CJ, Bunce KT (1992) Investigation of the 5-HT receptor mediating relaxation in guinea-pig proximal colon. J Pharm Pharmacol 44:264–266
Engel G, Hoyer D, Kalkman HO, Wick MB (1984) Identification of 5-HT2-receptors on longitudinal muscle of the guinea pig ileum. J Receptor Res 4:113–126
Fozard JR (1990) Agonists and antagonists of 5-HT3 receptors. In: Saxena PR, Wallis DI, Wouters W, Bevan P (eds) Cardiovascular Pharmacology of 5-hydroxytryptamine. Kluwer, Dordrecht, pp 101–115
Furness JB, Costa M (1989) Identification of transmitters of functionally defined enteric neurons. In: Schultz SG; Wood JD, Rauner BB (eds) Handbook of physiology - the gastrointestinal system, vol 1. Waverly Press, Baltimore, pp 387–402
Gaddum JH, Picarelli ZP (1957) Two kinds of tryptamine receptor. Br J Pharmac 12:323–328
Galligan JJ, North RA (1991) Opioid, 5HT1A and alpha2 receptors localized to subsets of guinea-pig myenteric neurons. J Anton Nerv Syst 32:1–12
Gershon MD, Wade PR, Kirchgessner AL, Tamir H (1990) 5-HT receptor subtypes outside the central nervous system. Roles of the physiology of the gut. Neuropsychopharmacology 3:385–395
Gunning SJ, Humphrey PPA (1987) Evidence for 5-HT3 receptor mediated release of an inhibitory transmitter in Guinea Pig isolated ileum. tBr J Pharmac 91:359P
Hoyer D (1990) Serotonin 5-HT3, 5-HT4, and 5-HTM receptors. Neuropsychopharmacology 3:371–383
Hoyle CHV, Knight GE, Burnstock G (1990) Suramin antagonizes respones to P2-purinoceptor agonists and purinergic nerve stimulation in the guinea-pig urinary bladder and taenia coli. Br J Pharmac 99:617–621
Humphrey PP (1984) Peripheral 5-hydroxytryptamine receptors and their classification. Neuropharmacology 23:1503–1510
Johnson SM, Katayama Y, North RA (1980) Slow synaptic potentials in neurones of the myenteric plexus. J Physiol (Lond) 301:505–516
Kojima S (1991) Characterization of 5-HT-induced relaxations of guinea-pig proximal colon. Arch Int Pharmacodyn 313:23–32
Mawe GM, Branchek T, Gershon MD (1989) Blockade of a 5-HT-mediated slow EPSPs by BRL 24924: gastrokinetic effects. Am J Physiol 257(20):G386-G396
Sanger GJ (1990) New antiemetic drugs. Can J Physiol Pharmacol 68:314–324
Sanger GJ, Nelson DR (1989) Selective and functional 5-HT3 receptor antagonsim by BRL 43964 (granisetron). Eur J Pharmacol 159: 113–124
Takaki M, Branchek TA, Tamir H, Gershon MD (1985) Specific antagonism of enteric neural serotonin receptors by dipeptides of 5-hydroxytryptophan: Evidence that serotonin is a mediator of slow synaptic excitation in the myenteric plexus. J Neurosci 5:1769–1780
Tonini M, Rizzi CA, Manzo L, Onori L (1991) Novel enteric 5-HT4 receptors and gastrointestinal prokinetic action. Pharmacol Res 24(1):5–14
Wade PR, Wood JD (1988) Synaptic behaviour of myenteric neurones in guinea-pig distal colon. Am J Physiol 255:G184-G190
Wardle KA, Sanger GJ (1994) The guinea-pig distal colon - a sensitive preparation for the investigation of 5-HT4 receptor-mediated contractions. Br J Pharmacol 110:1593–1599
Wood JD, Mayer CJ (1978) Slow synaptic excitation mediated by serotonin in Auerbach's plexus. Nature 276:836–837
Author information
Authors and Affiliations
Additional information
Correspondence to: D. J. Woollard at the above address
Rights and permissions
About this article
Cite this article
Woollard, D.J., Bornstein, J.C. & Furness, J.B. Characterization of 5-HT receptors mediating contraction and relaxation of the longitudinal muscle of guinea-pig distal colon in vitro. Naunyn-Schmiedeberg's Arch Pharmacol 349, 455–462 (1994). https://doi.org/10.1007/BF00169133
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00169133