Molecular and pharmacological characterization of serotonin 5-HT2A and 5-HT2B receptor subtypes in dog.
We report the cloning, molecular characterization, and pharmacological characterization of the canine 5-HT2A and 5-HT2B receptors. The canine and human 5-HT2A receptors share 93% amino acid homology. The canine and human 5-HT2B receptors are also highly conserved (87% homology) with the exception of the carboxyl termini where the canine protein is 62 amino acids shorter. Both the canine 5-HT2A and 5-HT2B receptors have high affinity for [3H]5-HT (KD=4.50+/-0.89 nM and 3.10+/-0.82 nM, respectively) and, in general, the pharmacology of these two receptors matches closely the pharmacology of their human homologs for the 19 serotonergic ligands tested. However, the functional response (Ca2+ mobilization) of the canine 5-HT2B receptor to several agonists was weaker compared to the human 5-HT2B receptor. Using quantitative reverse transcriptase polymerase chain reaction, a high expression level of canine 5-HT2A receptor mRNA was detected in the brain and lower levels in peripheral tissues, whereas the highest levels of canine 5-HT2B receptor mRNA were observed in lungs and smooth muscles. A significant level of canine 5-HT2B receptor mRNA was detected in brain tissue. The availability of the full sequence and pharmacology of the canine 5-HT2A and canine 5-HT2B receptors provides useful information for the interpretation of previous and future pharmacological studies of 5-HT2A/2B ligands in dog.
Bonaventure
Pascal
P
Johnson & Johnson Pharmaceutical Research and Development, L.L.C., 3210 Merryfield Row, San Diego, CA 92121, USA. pbonave1@prdus.jnj.com
Nepomuceno
Diane
D
Miller
Kirsten
K
Chen
Jingcai
J
Kuei
Chester
C
Kamme
Fredrik
F
Tran
Da-Thao
DT
Lovenberg
Timothy W
TW
Liu
Changlu
C
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D004285:Dogs; D006801:Humans; D008969:Molecular Sequence Data; D009928:Organ Specificity; D012333:RNA, Messenger / Q000096:biosynthesis; D011869:Radioligand Assay; D044402:Receptor, Serotonin, 5-HT2A / Q000096:biosynthesis / Q000187:drug effects* / Q000235:genetics*; D044403:Receptor, Serotonin, 5-HT2B / Q000096:biosynthesis / Q000187:drug effects* / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013045:Species Specificity; D014162:Transfection
D012333:RNA, Messenger; D044402:Receptor, Serotonin, 5-HT2A; D044403:Receptor, Serotonin, 5-HT2B; D002118:Calcium