Discriminative stimulus properties of indorenate, a serotonin agonist. To determine whether indorenate, a serotonin-receptor agonist, can exert discriminative control over operant responses, to establish the temporal course of discriminative control and to compare its stimulus properties to a (5-HT)IA receptor agonist. [3H]-8-hydroxy-2-(di-N-propylamino) tetralin (8-OH-DPAT). Prospective animal study. Ten male Wistar rats. Rats were trained to press either of 2 levers for sucrose solution according to a fixed ratio schedule, which was gradually increased. Rats were given injections of either indorenate or saline solution during discrimination training. Once they had achieved an 83% accuracy rate, rats underwent generalization tests after having received a different dose of indorenate
of 8-OH-DPAT, N,N-di-n-propyl-5-carboxamidotryptamine (DP-5-CT) and 5-carboxamidotryptamine (5-CT, 2.5-40 nmol kg-1), sumatriptan (10-160 nmol kg-1), indorenate (100-800 nmol kg-1), 5-hydroxytryptamine (5-HT, 20-640 nmol kg-1) both alone and in the presence of cinanserin (0.1 mg kg-1) were given into the IVth ventricle of cats which were anaesthetized with a mixture of alpha-chloralose a differential inhibition of sympathetic nerve activities, with renal nerve activity being the most sensitive and cardiac nerve activity the least sensitive. In the dose-ranges used, administration of sumatriptan evoked reductions only in renal and splanchnic nerve activities whilst indorenate reduced activity in all three sympathetic nerves to a similar extent. 4. The effect of the agonists on heart rate
-trifluoromethylphenyl)-piperazine (PAPP or LY 165163, 20), 5-methoxy-3-(1,2,3,6-tetrahydro-4-pyridinyl)-1H indole (RU 24969, 20), buspirone (65) and ipsapirone (56). Emax amounted to 18-20% inhibition for all but the latter two agonists (14%). 3. The following hypotensive agents with high affinity for 5-HT1A sites were potent agonists in this system (mean EC50 value, nM): flesinoxan (24), indorenate (99), erythro-1