Serotonin induces four pharmacologically separable contractile responses in the pharynx of the leech Hirudo medicinalis.
Stimulation of the serotoninergic innervation of the leech pharynx or application of serotonin to the isolated pharynx induced four distinct types of contractile activity: an increase in basal tonus, large phasic contractions of 10-15 s in duration, smaller phasic contractions occurring at approximately 1 Hz, and a relaxation after washout of serotonin. Application to the isolated pharynx of the selective serotonin agonists (+/-)-8-hydroxy-2-(di-n-propylamino)tetralin, N-(3-trifluoromethylphenyl)piperazine, 1-(m-chlorophenyl)-piperazine, (+/-)-2,5-dimethoxy-4-iodoamphetamine, 2-methyl-5-hydroxytrypamine, alpha-methyl-5-hydroxytryptamine, and 5-methoxytryptamine induced distinct types of pharyngeal contractile activity. The results of this study suggest that the leech pharynx possesses more than one type of serotonin receptor.
O'Gara
B A
BA
Department of Biological Sciences, Barnard College of Columbia University, New York, NY 10027-6598, USA. bogara@barnard.columbia.edu
Illuzzi
F A
FA
Chung
M
M
Portnoy
A D
AD
Fraga
K
K
Frieman
V B
VB
D008735:5-Methoxytryptamine / Q000494:pharmacology; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000662:Amphetamines / Q000494:pharmacology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D066298:In Vitro Techniques; D007865:Leeches / Q000187:drug effects* / Q000502:physiology; D009119:Muscle Contraction / Q000187:drug effects*; D010614:Pharynx / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D010879:Piperazines / Q000494:pharmacology; D012701:Serotonin / Q000031:analogs & derivatives / Q000494:pharmacology*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology
D000662:Amphetamines; D010879:Piperazines; D017366:Serotonin Receptor Agonists; C042390:alpha-methylserotonin; C018406:1-(3-trifluoromethylphenyl)piperazine; D012701:Serotonin; D008735:5-Methoxytryptamine; C045918:2-methyl-5-HT; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; C015952:4-iodo-2,5-dimethoxyphenylisopropylamine; C015068:1-(3-chlorophenyl)piperazine