5‐Hydroxytryptamine Receptor Assays

Katherine W. Figueroa1, Graeme R. Martin2, M. Teresa Pulido‐Rios3

1 Johnson & Johnson PRD, La Jolla, California, 2 Takeda Research Investment, Palo Alto, California, 3 Theravance, South San Francisco, California
Publication Name:  Current Protocols in Pharmacology
Unit Number:  Unit 4.19
DOI:  10.1002/0471141755.ph0419s46
Online Posting Date:  September, 2009
GO TO THE FULL TEXT: PDF or HTML at Wiley Online Library

Abstract

5‐Hydroxytryptamine (5‐HT) receptors, by virtue of their broad expression pattern in peripheral and central tissues, regulate diverse physiological and behavioral responses through the activation of fourteen molecularly distinct receptor subtypes. The tissue‐specific distribution of these receptors confers specificity for the actions of serotonin and highlights the therapeutic potential of serotonin receptor modulators. To better assess this therapeutic potential, it is useful to characterize serotonergic agonists and antagonists in physiologically relevant organ systems. Provided in this unit are twelve tissue bath assays using vascular and smooth muscle tissues isolated from guinea‐pig, rat, and rabbit. These tests make possible the analyses of compounds at nine serotonin receptor subtypes. Curr. Protoc. Pharmacol. 46:4.19.1‐4.19.45. © 2009 by John Wiley & Sons, Inc.

Keywords: serotonin; 5‐hydroxytriptamine; 5‐HT

     
 
GO TO THE FULL PROTOCOL:
PDF or HTML at Wiley Online Library

Table of Contents

  • Introduction
  • Basic Protocol 1: Inhibition of the 5‐HT1A Receptor–Mediated Twitch Response in Guinea Pig Transmurally Stimulated Ileum
  • Basic Protocol 2: 5‐HT1B Receptor–Mediated Contraction of Rat Caudal Artery
  • 5‐HT1D Receptors
  • Basic Protocol 3: 5‐Hydroxytryptamine 1D Receptor Assays
  • Alternate Protocol 1: 5‐HT1D Receptor–Mediated Contraction of Rabbit Cerebral Arteries
  • Basic Protocol 4: 5‐HT2A Receptor–Mediated Contraction of Rabbit Thoracic Aorta
  • Basic Protocol 5: 5‐HT2B Receptor–Mediated Contraction of the Rat Stomach Fundus
  • Basic Protocol 6: 5‐HT2C Receptor–Mediated Contraction of the Rat Jugular Vein
  • Basic Protocol 7: 5‐HT3 Receptor–Mediated Contraction of Guinea Pig Ileal Smooth Muscle
  • 5‐HT4 Receptors
  • Basic Protocol 8: 5‐HT4 Receptor–Mediated Relaxation of Rat Esophageal Tunica Muscularis Mucosa
  • Alternate Protocol 2: 5‐HT4 Receptor–Mediated Contraction of Guinea Pig Distal Colon
  • Basic Protocol 9: Post‐Junctional 5‐HT7 Receptor–Mediated Relaxation of Guinea Pig Isolated Ileum
  • Alternate Protocol 3: 5‐HT7 Receptor–Mediated Relaxation of the Endothelium‐Denuded, Precontracted Rabbit Jugular Vein
  • Reagents and Solutions
  • Commentary
  • Literature Cited
  • Figures
  • Tables
     
 
GO TO THE FULL PROTOCOL:
PDF or HTML at Wiley Online Library

Materials

Basic Protocol 1: Inhibition of the 5‐HT1A Receptor–Mediated Twitch Response in Guinea Pig Transmurally Stimulated Ileum

  Materials
  • 200‐ to 450‐g male Hartley guinea pig (Charles River Laboratories)
  • CO 2 (e.g., gas cylinder or dry ice pellets to which a small amount of water has been added)
  • Krebs‐Henseleit solution with and without corticosterone and cocaine (see recipe), 32° ± 1°C
  • Standard 5‐HT receptor antagonists (see recipe and steps 6 and 12)
  • 10 mM pargyline (see recipe)
  • 1 mM phenoxybenzamine hydrochloride (see recipe)
  • Standard 5‐HT agonists (e.g., 5‐CT, 5‐HT; see reciperecipes)
  • Test compound(s)
  • Euthanasia chamber (Harvard Apparatus)
  • Surgical instruments: scalpel, scissors
  • Petri dishes
  • 10‐ml syringes
  • 1.0 surgical silk
  • Fixed tissue holder fitted with two parallel, bipolar, 2 × 0.06–cm platinum electrodes (WPI)
  • Isometric transducer (e.g., Grass FT03, Danish Myo Technology (DMT) Force transducer 750 TOBS) with stainless steel tissue suspension wire
  • 10‐ml tissue bath (also see unit 4.4) including:
    • Electrical stimulator (e.g., Grass S88 plus Grass stimulator isolation units or Digitimer D330)
    • Thermostatically regulated water circulator (WPI)
  • Polygraph/chart recorder/electronic data acquisition system (e.g., Biopac Acknowledge, Notocord, Danish Myo Technology)

Basic Protocol 2: 5‐HT1B Receptor–Mediated Contraction of Rat Caudal Artery

  Materials
  • 250‐ to 350‐g male Wistar rats (Charles River Laboratories)
  • CO 2 (e.g., gas cylinder or dry ice pellets to which a small amount of water has been added)
  • Krebs‐Henseleit solution with and without corticosterone and cocaine (see recipe), 32° ± 1°C
  • 10 mM pargyline (see recipe)
  • 1 mM phenoxybenzamine (see recipe)
  • 1 mM U‐46619 (see recipe)
  • Standard 5‐HT receptor antagonists (e.g., cyanopindolol; see recipe and step 10)
  • Standard 5‐HT receptor agonists (e.g., 1 µM 5‐CT or 5‐HT; see reciperecipes)
  • Test compound(s)
  • Euthanasia chamber (Harvard Apparatus)
  • Dissecting instrument: scalpel, scissors
  • Petri dishes
  • Fixed tissue holder with stainless steel wire mount (WPI)
  • Isometric transducer (e.g., Grass FT03, Danish Myo Technology (DMT) Force transducer 750 TOBS) with stainless steel tissue suspension wire
  • 10‐ml tissue bath (also see unit 4.4) including (WPI):
    • Thermostatically regulated water circulator
    • Polygraph/chart recorder/electronicdata acquisition system (e.g., Biopac Acknowledge, Notocord, Danish Myo Technology)

Basic Protocol 3: 5‐Hydroxytryptamine 1D Receptor Assays

  Materials
  • 200‐ to 450‐g male Dunkin‐Hartley guinea pigs (Charles River Laboratories)
  • CO 2 (gas cylinder or dry ice pellets to which a small amount of water has been added)
  • Krebs‐Henseleit solution with and without corticosterone and cocaine (see recipe), 32° ± 1°C
  • Standard 5‐HT 2 receptor antagonist (e.g., methiothepin; see recipe)
  • 10 mM pargyline (see recipe)
  • 1 mM phenoxybenzamine (see recipe)
  • 1 mM U‐46619 (see recipe)
  • Standard 5‐HT receptor agonist (e.g., 1 µM sumatriptan; see recipe)
  • Test compound(s)
  • Euthanasia chamber (Harvard Apparatus)
  • Dissection instruments: scalpel, scissors
  • Petri dishes
  • Fixed tissue holder with stainless steel wire mount (WPI)
  • Isometric transducer (e.g., Grass FT03, Danish Myo Technology (DMT) Force transducer 750 TOBS) with stainless steel tissue suspension wire
  • 10‐ml tissue bath equipment (WPI)(also see unit 4.4) including:
    • Thermostatically regulated water circulator (WPI)
    • Polygraph/chart recorder/electronic data acquisition system (e.g., Biopac Acknowledge, Notocord, Danish Myo Technology)

Alternate Protocol 1: 5‐HT1D Receptor–Mediated Contraction of Rabbit Cerebral Arteries

  • 2.5‐ to 3.5‐kg male New Zealand white rabbits (Charles River Laboratories)
  • Pentobarbitone/sodium heparin (Henry Schein)
  • 1 mM indomethacin (see recipe)
  • 4 M KCl
  • 10 mM acetylcholine (see recipe)
  • Small animal guillotine (Harvard Apparatus)
  • Binocular microscope
  • 0.04 × ∼3–in. long stainless steel wire roughened by rubbing with steel wool

Basic Protocol 4: 5‐HT2A Receptor–Mediated Contraction of Rabbit Thoracic Aorta

  Materials
  • 2.5‐ to 3.0‐kg male New Zealand white rabbits (Froxfield, Hampshire, UK)
  • Pentobarbitone/sodium heparin (Henry Schein)
  • Krebs‐Henseleit solution with and without corticosterone and cocaine (see recipe), 32° ± 1°C
  • 10 mM pargyline (see recipe)
  • 1 mM benextramine tetrahydrochloride (see recipe)
  • Standard 5‐HT agonists (i.e., 5‐HT; see recipe)
  • Standard 5‐HT 2A receptor antagonists (agonist‐dependent, e.g., Ketanserin; see recipe and step 8)
  • Test compound(s)
  • Surgical instruments
  • Petri dishes
  • 0.04 × ∼3–in. long stainless steel wire roughened by rubbing with steel wool
  • Fixed tissue holder with stainless steel wire mount (WPI)
  • Isometric transducer (e.g., Grass FT03, Danish Myo Technology (DMT) Force transducer 750 TOBS) with stainless steel tissue‐suspension wire
  • 10‐ml tissue bath (WPI) (also see unit 4.4) including:
    • Thermostatically regulated water circulator (WPI)
    • Polygraph/chart recorder/electronic data acquisition system (e.g., Biopac Acknowledge, Notocord, Danish Myo Technology)

Basic Protocol 5: 5‐HT2B Receptor–Mediated Contraction of the Rat Stomach Fundus

  Materials
  • 250‐ to 350‐g male Sprague Dawley rats (Charles River Laboratories)
  • CO 2 (gas cylinder or dry ice pellets to which a small amount of water has been added)
  • Tyrode's solution with and without corticosterone, cocaine, and ketanserin (see recipe), 37° ± 1°C
  • Standard 5‐HT antagonists (e.g., SB204741; see recipe and step 9)
  • 10 mM pargyline (see recipe)
  • 10 mM benextramine tetrahydrochloride (see recipe)
  • Standard 5‐HT receptor agonist (e.g., 5‐HT, α‐methyl‐5‐HT, 5‐CT; see recipe)
  • Test compound(s)
  • 4 M KCl
  • Airtight euthanasia chamber (Harvard Apparatus)
  • 23‐G hypodermic needle and 5‐ml syringe
  • Surgical instruments: scalpel, scissors, fine scissors with sharp pointed edges, curved forceps
  • Petri dishes
  • Blade (razor blade)
  • 1.0 surgical silk threads
  • Fixed tissue holder with stainless steel wire mount (WPI)
  • Isometric transducer (e.g., Grass FT03, Danish Myo Technology (DMT) Force transducer 750 TOBS) with stainless steel tissue suspension wire
  • 10‐ml tissue bath (WPI) (also see unit 4.4) including:
    • Thermostatically regulated water circulator (WPI)
    • Polygraph/chart recorder/electronic data acquisition system (e.g., Biopac Acknowledge, Notocord, Danish Myo Technology)

Basic Protocol 6: 5‐HT2C Receptor–Mediated Contraction of the Rat Jugular Vein

  Materials
  • 250‐ to 350‐g male Sprague‐Dawley rats (Charles River Laboratories)
  • CO 2 (gas cylinder or dry ice pellets to which a small amount of water has been added)
  • Krebs‐Henseleit solution with and without corticosterone and cocaine (see recipe), 37° ± 1°C
  • 10 µM ketanserin (see recipe)
  • 10 mM pargyline (see recipe)
  • 1 mM phenoxybenzamine (see recipe)
  • Test compound(s)
  • Standard 5‐HT agonist (see recipe)
  • Standard 5‐HT antagonists (e.g., RS102221 or mesulergine; see recipe and step 9)
  • Euthanasia chamber (Harvard Apparatus)
  • Surgical instruments: scalpel, scissors
  • Polypropylene tubing (1‐mm o.d.)
  • Petri dishes
  • Fixed tissue holder with stainless steel wire mount (WPI)
  • Isometric transducer (e.g., Grass FT03, Danish Myo Technology (DMT) Force transducer 750 TOBS) with stainless steel tissue‐suspension wire
  • 10‐ml tissue bath (WPI) (also see unit 4.4) including:
    • Thermostatically regulated water circulator (WPI)
    • Polygraph/chart recorder/electronic data acquisition system (e.g., Biopac Acknowledge, Notocord, Danish Myo Technology)

Basic Protocol 7: 5‐HT3 Receptor–Mediated Contraction of Guinea Pig Ileal Smooth Muscle

  Materials
  • 200‐ to 450‐g male Hartley guinea pig (Charles River Laboratories)
  • CO 2 (i.e., gas cylinder or dry ice pellets to which a small amount of water has been added)
  • Krebs‐Henseleit solution with and without corticosterone and cocaine (see recipe), 37° ± 1°C
  • Standard 5‐HT receptor antagonists (e.g., granisetron; see recipe)
  • 1 mM methacholine bromide (see recipe)
  • 10 mM pargyline (see recipe)
  • Test compound(s)
  • Standard 5‐HT receptor agonist (e.g., 5‐HT; see recipe)
  • Euthanasia chamber (Harvard Apparatus)
  • Surgical instruments: scalpel, scissors
  • 10‐ml syringes
  • Petri dishes
  • 13.8‐cm Pasteur pipets (0.65‐cm o.d.)
  • Cotton wool
  • 1.0 surgical silk threads
  • Fixed tissue holder (WPI)
  • Isotonic transducer (Hugo Sachs Elektronik, type 373)
  • 10‐ml tissue bath (WPI) (also see unit 4.4) including:
    • Thermostatically regulated water circulator (WPI)
    • Polygraph/chart recorder/electronic data acquisition system (e.g., Biopac Acknowledge, Notocord, Danish Myo Technology)

Basic Protocol 8: 5‐HT4 Receptor–Mediated Relaxation of Rat Esophageal Tunica Muscularis Mucosa

  Materials
  • 250‐ to 350‐g male Sprague‐Dawley rat (Charles River Laboratories)
  • CO 2 (gas cylinder or dry ice pellets to which a small amount of water has been added)
  • Krebs‐Henseleit solution with and without corticosterone and cocaine (see recipe), 32° ± 1°C
  • Standard 5‐HT receptor antagonists (e.g., GR 113808; see recipe)
  • 10 mM pargyline (see recipe)
  • 1 mM carbachol (see recipe)
  • Standard 5‐HT agonist (e.g., 5‐HT; see recipe)
  • Test compound(s)
  • Euthanasia chamber (Harvard Apparatus)
  • Surgical instruments: scalpel, fine forceps, scissors
  • Petri dishes
  • 1.0 surgical silk threads
  • Fixed tissue holder with stainless steel wire mount (WPI)
  • Isometric transducer (e.g., Grass FT03, Danish Myo Technology (DMT) Force transducer 750 TOBS) with stainless steel tissue suspension wire
  • 10‐ml tissue bath (WPI) (also see unit 4.4) including:
    • Thermostatically regulated water circulator (WPI)
    • Polygraph/chart recorder/electronic data acquisition system (e.g., Biopac Acknowledge, Notocord, Danish Myo Technology)

Alternate Protocol 2: 5‐HT4 Receptor–Mediated Contraction of Guinea Pig Distal Colon

  • 200‐ to 450‐g male Dunkin Hartley guinea‐pig (Charles River Laboratories)
  • 10‐ml pipets
  • Squirt bottle
  • Glass rod (5‐mm diameter)
  • Q‐tips

Basic Protocol 9: Post‐Junctional 5‐HT7 Receptor–Mediated Relaxation of Guinea Pig Isolated Ileum

  Materials
  • 200‐ to 450‐g male Dunkin‐Hartley guinea pigs (Charles River Laboratories)
  • CO 2 (i.e., gas cylinder or dry ice pellets to which a small amount of water has been added)
  • Krebs‐Henseleit solution with and without corticosterone, cocaine, indomethacin, and atropine (see recipe), 37°C
  • 10 mM pargyline (see recipe)
  • Histamine or substance P
  • Standard 5‐HT agonists (e.g., 5‐CT, 5‐HT; see recipe)
  • Test compound(s)
  • Standard 5‐HT receptor antagonists (see recipe)
  • Euthanasia chamber (Harvard Apparatus)
  • Surgical instruments: scalpel, scissors
  • 10‐ml syringes
  • 1.0 surgical silk threads
  • Petri dishes
  • Fixed tissue holder with stainless steel wire mount (WPI)
  • Isometric transducer (e.g., Grass FT03, Danish Myo Technology (DMT) Force transducer 750 TOBS) with stainless steel tissue suspension wire
  • 10‐ml tissue bath (WPI) (also see unit 4.4) including:
    • Thermostatically regulated water circulator (WPI)
    • Polygraph/chart recorder/electronic data acquisition system (e.g., Biopac Acknowledge, Notocord, Danish Myo Technology)

Alternate Protocol 3: 5‐HT7 Receptor–Mediated Relaxation of the Endothelium‐Denuded, Precontracted Rabbit Jugular Vein

  • 2.4‐ to 3.0‐kg male New Zealand white rabbit (Froxfield, Hampshire, UK)
  • Pentobarbitone/sodium heparin (Henry Schein)
  • Krebs‐Henseleit solution with and without corticosterone and cocaine (see recipe), 37° +/– 1°C
  • 1 mM phenoxybenzamine (see recipe)
  • Standard 5‐HT receptor agonist (i.e., 0.1 mM α‐methyl‐5‐HT; see recipe)
  • Standard 5‐HT receptor antagonists (e.g., SB‐269970; see recipe)
  • Test compound(s)
  • 1 mM U‐46619 (see recipe)
  • Standard 5‐HT receptor agonists (e.g., 5‐CT, 5‐HT; see recipe)
  • 0.04 × ∼3–in. long stainless steel wire roughened by rubbing with steel wool
GO TO THE FULL PROTOCOL:
PDF or HTML at Wiley Online Library

Figures

Videos

Literature Cited

   Alexander, S.P.H., Mathie, A., and Peters, J.A. 2008. Guide to Receptors and Channels (GRAC), 3rd ed. Br. J. Pharmacol. 153:S1‐S209.
   Baxter, G.S., Craig, D.A., and Clarke, D.E. 1991. 5‐HT4 receptors mediate relaxation of the rat esophageal tunica muscularis mucosae. N.‐S. Arch. Pharmacol. 343:439.
   Baxter, G.S., Murphy, O.E., and Blackburn, T.P. 1994. Further characterization of 5‐hydroxytryptamine receptors (putative 5‐HT2B) in rat stomach fundus longitudinal muscle. Br. J. Pharmacol. 112:323‐331.
   Black, J.W. and Shankley, N.P. 1989. Interpretation of agonist affinity estimations: The question of distributed receptor states. Proc. R. Soc. Lond. 240:503‐518.
   Bonhaus, D., Flippin, L., Greenhouse, R., Jaime, S., Rocha, C., Dawson, M., Van Natta, K., Chang, L.K., Pulido‐Rios, T., Webber, A., Leung, E., Eglen, R., and Martin, G. 1999. RS‐127445: A selective, high affinity, orally bioavailable 5‐HT2B receptor antagonist. Br. J. Pharmacol. 127:1075‐1082.
   Butler, A., Elswood, C.J., Burridge, J., Ireland, S.J., Bunce, K.T., Kilpatrick, G.J., and Tyers, M.B. 1990. The pharmacological characterization of 5‐HT3 receptors in three isolated preparations derived from guinea‐pig tissues. Br. J. Pharmacol. 101:591‐598.
   Carter, D., Champney, M., Hwang, B., and Eglen, R.M. 1995. Characterization of a postjunctional 5‐HT receptor mediating relaxation of guinea‐pig isolated ileum. Eur. J. Pharmacol. 280:243‐250.
   Cohen, M.L., Schenck, K.W., Mabry, T.H.E., Nelson, D.L., and Audio, J.E. 1996. LY272015, a potent, selective and orally active 5‐HT2B receptor antagonist. J. Serotonin Res. 3:131‐144.
   Craig, D.A. and Martin, G.R. 1993. 5‐HT1B receptors mediate potent contractile responses to 5‐HT in rat caudal artery. Br. J. Pharmacol. 109:609‐611.
   Deckert, V., Pruneau, D., and Elghozi, J.‐L. 1994. Mediation by 5‐HT1D receptors of 5‐hydroxytryptamine‐induced contractions of rabbit middle and posterior cerebral arteries. Br. J. Pharmacol. 112:939‐945.
   Derkach, V., Surprenant, A., and North, R.A. 1989. 5‐HT3 receptors are membrane ion channels. Nature 339:706‐709.
   Eglen, R.M., Lee, C., Smith, W.L., Johnson, L.G., Whiting, R.L., and Hedge, S.S. 1993. RS 42358‐197, a novel and potent 5‐HT3 receptor antagonist, in vitro and in vivo. J. Pharmacol. Exp. Therap. 266:535‐543.
   Fletcher, A., Bill, D.J., Bill, S.J., Cliffe, I.A., Dover, G.M., Forster, E.A., Haskins, J.T., Jones, D., Mansell, H.L., and Reilly, Y. 1993. WAY100135: A novel, selective antagonist at presynaptic and postsynaptic 5‐HT1A receptors. Eur. J. Pharmacol. 237:283‐291.
   Forster, E.A., Cliffe, I.A., Bill, D.J., Dover, G.M., Jones, D., Reilly, Y., and Fletcher, A. 1995. A pharmacological profile of the selective silent 5‐HT1A receptor antagonist, WAY‐100635. Eur. J. Pharmacol. 281:81‐88.
   Fozard, J.R. and Kilbinger, H. 1985. 8‐OH‐DPAT inhibits transmitter release from guinea‐pig enteric cholinergic neurons by activating 5‐HT1A receptors. Br. J. Pharmacol. 86:601P.
   Gaddum, J.H. and Picarelli, Z.P. 1957. Two kinds of tryptamine receptor. Br. J. Pharmacol. 12:23‐28.
   Gale, J.D., Grossman, C.J., Whitehead, J.W.F., Oxford, A.W., Bunce, K.T., and Humphrey, P.P.A. 1994. GR113808: A novel, selective antagonist with high affinity at the 5‐HT4 receptor. Br. J. Pharmacol. 111:332‐338.
   Girdlestone, D. (ed.) 2000. The IUPHAR compendium of receptor characterization and classification. IUPHAR Media, London.
   Glusa, E. and Richter, M. 1993. Endothelium‐dependent relaxation of porcine pulmonary arteries via 5‐HT1C‐like receptors. N.‐S. Arch. Pharmacol. 347:471‐477.
   Gupta, P. 1992. An endothelial 5‐HT receptor that mediates relaxation in guinea‐pig isolated jugular vein resembles the 5‐HT1D subtype. Br. J. Pharmacol. 106:703‐709.
   Hooker, C.S., Calkins, P.J., and Fleisch, J.H. 1977. On the measurement of vascular and respiratory smooth muscle response in vitro. Blood Vessels 14:1‐11.
   Hoyer, D., Clarke, D.E., Fozard, J.R., Hartig, P.R., Martin, G.R., Mylecharane, E.J., Saxena, P.R., and Humphrey, P.A. 1994. VII. International Union of Pharmacology classification of receptors for 5‐hydroxytryptamine (serotonin). Pharmacol. Rev. 46:157‐203.
   Humphrey, P.P.A., Hartig, P., and Hoyer, D. 1993. A reappraisal of 5‐HT receptor classification. Med. Sci. Symp. Ser. 5:41‐47.
   Kosterlitz, H.W. and Watt, A.J. 1968. Kinetic parameters of narcotic agonists and antagonists, with particular reference to N‐allylnoroxymorphone (naloxone). Br. J. Pharmacol. Chemother. 33:266‐276.
   Leff, P. and Morse, J.M. 1987. Resultant pharmacological actions of Verapamil: Quantification of competitive 5‐hydroxytryptamine antagonism in combination with calcium antagonism. J. Pharmacol. Exp. Therap. 240:284‐287.
   Leff, P., Martin, G.R., and Morse, J.M. 1986. The classification of peripheral 5‐HT2‐like receptors using tryptamine agonist and antagonist analogs. Br. J. Pharmacol. 89:493‐499.
   Leung, E., Pulido‐Rios, M.T., Bonhous, D.W., Perkins, L.A., Zeitung, K.D., Hsu, S.A.O., Clark, R.D., Wong, E.H.F., and Eglen, R.M. 1996a. Comparison of 5‐HT4 receptors in guinea‐pig colon and rat oesophagus: Effects of novel agonist and antagonists. N.‐S. Arch. Pharmacol. 354:145‐156.
   Leung, E., Walsh, L.K., Pulido‐Rios, M.T., and Eglen, R.M. 1996b. Characterization of putative 5‐HT7 receptors mediating direct relaxation in Cynomolgus monkey isolated jugular vein. Br. J. Pharmacol. 117:926‐930.
   Martin, G.R., Leff, P., Cambridge, D., and Barrett, V.J. 1987. Comparative analysis of two types of 5‐hydroxytryptamine receptor mediating vasorelaxation: Differential classification using tryptamines. N.‐S. Arch. Pharmacol. 336:365‐373.
   McLean, P.G. and Coupar I.M. 1995. 5‐HT4 receptor antagonist affinities of SB207710, SB205008, and SB203186 in the human colon, rat oesophagus, and guinea‐pig ileum peristaltic reflex. Naunyn Schmiedebergs Arch. Pharmacol. 352:132‐140.
   Mize, A.L., Poisner, A.M., and Alper, R.H. 2001. Estrogens act in rat hippocampus and frontal cortex to produce rapid, receptor‐mediated decreases in serotonin 5‐HT1A receptor function. Neuroendocrinology 73:166‐174.
   Oksenberg, D., Marsters, S.A., O'Dowd, B.F., Jin, H., Havlik, S., Peroutka, S.J., and Ashkenazi, A. 1992. A single amino‐acid difference confers major pharmacological variation between human and rodent 5‐HT1B receptors. Nature 360:161‐163.
   Peroutka, S.J. and Snyder, S.H. 1979. Multiple serotonin receptors: Differential binding of [3H]5‐hydroxytryptamine, [3H]lysergic acid diethylamide and [3H]spiroperidol. Mol. Pharmacol. 16:687‐699.
   Prins, N.H., Briejer, M.R., Van Bergen, P.J., Akkermans, L.M., and Schuurkes, J.A. 1999. Evidence for 5‐HT7 receptors mediating relaxation of human colonic circular smooth muscle. Br. J. Pharmacol. 128:849‐852.
   Rapport, M.M., Green, A.A., and Page, I.H. 1948. Serum vasconstrictor (serotonin) IV isolation and characterization. J. Biol. Chem. 176:1243‐1251.
   Ruat, M., Traiffort, E., Leurs, R., Tardivel‐Lacombe, J., Diaz, J., Arrang, J., and Schwartz, J. 1993. Molecular cloning, characterization and localization of a high‐affinity serotonin receptor (5‐HT7) activating camp formation. Proc. Natl. Acad. Sci. U.S.A. 90:8547‐8551.
   Shen, Y., Monsma, F.J., Metcalf, M.A., Jose, P.A., Hamblin, M.W., and Sibley, D.R. 1993. Molecular cloning and expression of a 5‐hydroxytryptamine 7 serotonin receptor subtype. J. Biol. Chem. 268:18200‐18204.
   Stollack, J.S. and Furchgott, R.F. 1983. Use of selective antagonists for determining the types of receptors mediating the actions of 5‐hydroxytryptamine and tryptamine in the isolated rabbit aorta. J. Pharmacol. Exp. Therap. 224:215‐221.
   Terrón, J.A. and Falcón‐Neri, A. 1999. Pharmacological evidence for the 5‐HT7 receptor mediating smooth muscle relaxation in canine cerebral arteries. Br. J. Pharmacol. 127:609‐616.
   Tonini, M., Vicini, R., Cervio, E., De Ponti, F., De Giorgio, R., Barbara, G., Stanghellini, V., Dellabianca, A., and Sternini, C. 2005. 5‐HT7 receptors modulate peristalsis and accomodation in the guinea pig ileum. Gastroenterology 129:1557‐1566.
   Wardle, K.A. and Sanger, G.J. 1993. The guinea‐pig distal colon—A sensitive preparation for the investigation of 5‐HT4 receptor‐mediated contractions. Br. J. Pharmacol. 13:1593‐1599.
Key References
   Alexander et al., 2008. See above.
  The above references are recommended for tracing the development of the current 5‐HT receptor classification scheme and its associated nomenclature.
   Bradley, P.B., Engel, G., Feniuk, W., Fozard, J.R., Humphrey, P.P.A., Middlemiss, D.N., Mylecharane, E.J., Richardson, B.P., and Saxena, P.R. 1986. Proposals for the classification and nomenclature of functional receptors for 5‐hydroxytryptamine. Neuropharmacology 25:563‐576.
   Gaddum and Picarelli, 1957. See above.
   Hoyer, D., Hannon, J.P., and Martin, G.R. 2002. Molecular, pharmacological and functional diversity of 5‐HT receptors. Pharmacol. Biochem. Behav. 71:533‐554.
   Humphrey et al., 1993. See above.
   Peroutka and Snyder, 1979. See above.
   Saxena, P.R., De Vries, P., and Villalon, C.M. 1998. 5‐HT‐like receptors: A time to bid goodbye. Trends Pharmacol. Sci. 19:311‐316.
Internet Resources
  http://www.iuphar‐db.org/GPCR/ReceptorListForward
  The above Web site is recommended for obtaining a comprehensive list of 5‐HT receptor ligands and references.
GO TO THE FULL PROTOCOL:
PDF or HTML at Wiley Online Library