Table 2.
Agonist profiles of 5-HT2β and 5-HT1α from Panulirus and Procambarus are very similar
| Drug | Potency (EC50, μmol l−1)
|
Efficacy (%5-HT effect)
|
||||||
|---|---|---|---|---|---|---|---|---|
| 5-HT2βPan | 5-HT2βPro | 5-HT1αPan | 5-HT1αPro | 5-HT2βPan | 5-HT2βPro | 5-HT1αPan | 5-HT1αPro | |
| 5-HT | 0.052 | 0.27 | 0.0084 | 0.031 | 100 | 100 | 100 | 100 |
| Dopamine | 310 | 362 | IA | IA | 54 | 19 | IA | IA |
| Octopamine | IA | IA | IA | IA | IA | IA | IA | IA |
| Tyramine | 283 | IA | IA | 30 | 32 | IA | IA | 67 |
| Histamine | IA | IA | IA | IA | IA | IA | IA | IA |
| DOI | 4.5 | IA | Bkd | NS | 32 | IA | Bkd | NS |
| 5-CT | 6.1 | 4.6 | 2.2 | NS | 79 | 50 | 100 | NS |
| 2-Me-5-HT | 0.78 | 5.2 | Bkd | 0.043 | 96 | 104 | Bkd | 73 |
| MeOTryp | 1.0 | 1.5 | 4.2 | NS | 80 | 29 | 94 | NS |
| N-acetyl-5-HT | IA | IA | IA | NS | IA | IA | IA | NS |
| Quipazine | IA | IA | Bkd | 111 | IA | IA | Bkd | 92 |
| α-Me-HT | 1.5 | 7.3 | 1.1 | 0.22 | 79 | 76 | 120 | 67 |
| 8-OH-DPAT | 0.27 | 1.1 | 7.6 | 65 | 77 | 64 | 105 | 68 |
| mCPP | IA | IA | 139 | 109 | IA | IA | 97 | 70 |
| Methysergide | 0.11 | 0.11 | 0.089 | 0.42 | 48 | 19 | 81 | 109 |
EC50 values (potency) and relative efficacy were calculated from dose–response curves for each drug. Efficacy is presented as a given drug’s ability to activate the receptor compared to the maximum activation obtained from 5-HT (100%). Drugs that activate one and not the other of 5-HT2β and 5-HT1α for each species are indicated in bold.
IA, inactive; Bkd, drug has background activity on non-induced cells and was not tested; NS, curve could not be fit because of complex effects of the drug. N≥3 separate experiments for each drug.
DOI, 2,5-dimethoxy-4-iodoamphetamine; 5-CT, 5-carboxamidotryptamine; 2-Me-5-HT, 2-methyl-serotonin; MeOTryp, 5-methoxytryptamine; α-Me-5-HT, α-methyl-serotonin; 8-OH-DPAT, (±)-8-hydroxy-2-(di-n-dipropylamino) tetralin; mCPP, 1-(m-chlorophenyl)-piperazine.