caa a22 4500 469078685 CHVBK 20180323132943.0 cr unu---uuuuu 170328e19920801xx s 000 0 eng 10.1007/BF00165296 doi (NATIONALLICENCE)springer-10.1007/BF00165296 Effects of N -ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline on the prolactin suppression induced by a series of full and partial dopamine D2 receptor agonists in male rats [Elektronische Daten] [Agneta Ekman, Elias Eriksson] Summary: The effect of pretreatment with a high dose of the alkylating agent N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) (20 mg/kg, 24 h) on the intrinsic activity displayed by a series of full and partial dopamine D2 receptor agonists on prolactin regulating pituitary D2 receptors in male rats was studied. To increase baseline prolactin levels, gamma-butyrolactone in a dose inhibiting brain dopamine neurotransmission was given to all animals. In controls, i. e. rats not given EEDQ, supramaximal doses of all full and partial D2 receptor agonists tested decreased serum prolactin levels with > 80%. While the intrinsic activities of the dopamine precursor 1-DOPA and of the full agonists (+)-3-PPP, 5-OH-DPAT, B-HT 920 (talipexole), apomorphine, and NPA (R-(−)-N-n-propylnorapomorphine) were not affected by pretreatment with EEDQ, the effects of supramaximal doses of the partial agonists (−)-HW-165, TDHL (terguride), SDZ 208-911, (−)-3-PPP (preclamol), and SDZ 208-912 were reduced to 66%, 74%, 59%, 100%, and 100%, respectively. The effect of EEDQ on the intrinsic activity displayed by the various agonists corresponds inversely to the intrinsic efficacy displayed by the drugs in other models of D2 receptor function with one exception only; thus, the prolactin suppressive effect of (−)-3-PPP was more effectively antagonized by EEDQ than would have been predicted from the intrinsic efficacy usually attributed to the drug. Since the dose of EEDQ used in the present study has previously been shown not to decrease D2 receptor density in the pituitary as measured using in vivo radioligand binding, it is suggested that alkylation of D2 receptors may change the conformation of the individual receptor complexes in a way that decreases the responsiveness to partial but not full agonists. Springer-Verlag, 1992 Dopamine D2 receptors nationallicence Partial agonists nationallicence Intrinsic activity nationallicence N -ethoxycarbonyl-2-ethoxy-1,2-di-hydroquinoline (EEDQ) nationallicence Prolactin nationallicence Ekman Agneta Department of Pharmacology, University of Göteborg, P.O. Box 33031, S-400 33, Göteborg, Sweden aut Eriksson Elias Department of Pharmacology, University of Göteborg, P.O. Box 33031, S-400 33, Göteborg, Sweden aut Naunyn-Schmiedeberg's Archives of Pharmacology Springer-Verlag 346/2(1992-08-01), 152-157 0028-1298 346:2<152 1992 346 210 https://doi.org/10.1007/BF00165296 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00165296 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Ekman Agneta Department of Pharmacology, University of Göteborg, P.O. Box 33031, S-400 33, Göteborg, Sweden aut NATIONALLICENCE 700 1- Eriksson Elias Department of Pharmacology, University of Göteborg, P.O. Box 33031, S-400 33, Göteborg, Sweden aut NATIONALLICENCE 773 0- Naunyn-Schmiedeberg's Archives of Pharmacology Springer-Verlag 346/2(1992-08-01), 152-157 0028-1298 346:2<152 1992 346 210 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer