TY - JOUR T1 - <em>In Vitro</em> and <em>In Vivo</em> Characterization of the Dopamine D<sub>4</sub> Receptor, Serotonin 5-HT<sub>2A</sub>Receptor and <em>Alpha</em>-1 Adrenoceptor Antagonist (R)-(+)-2-Amino-4-(4-Fluorophenyl)- 5-[1-[4-(4-Fluorophenyl)-4-Oxobutyl]Pyrrolidin-3-yl]Thiazole (NRA0045) JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 56 LP - 63 VL - 282 IS - 1 AU - Shigeru Okuyama AU - Shigeyuki Chaki AU - Ryoko Yoshikawa AU - Yoshiko Suzuki AU - Shin-Ichi Ogawa AU - Yasuko Imagawa AU - Naoya Kawashima AU - Yoko Ikeda AU - Toshihito Kumagai AU - Atsuro Nakazato AU - Masashi Nagamine AU - Kazuyuki Tomisawa Y1 - 1997/07/01 UR - http://jpet.aspetjournals.org/content/282/1/56.abstract N2 - (R)-(+)-2-Amino-4-(4-fluorophenyl)-5-[1-[4-(4-fluorophenyl)-4-oxobutyl]pyrrolidin-3-yl]thiazole (NRA0045), a novel thiazole derivative, has high affinities for the human cloned dopamine D4.2, D4.4 and D4.7 receptors, with Ki values of 2.54, 0.55 and 0.54 nM, respectively. NRA0045 is approximately 91-fold more potent at the dopamine D4.2 receptor, compared with human cloned dopamine D2L receptor. NRA0045 also has high affinities for the serotonin (5-HT)2A receptor (Ki = 1.92 nM) and alpha-1 adrenoceptor (Ki = 1.40 nM) but weak affinities (IC50 values are approximately 1 μM) for six other neurotransmitter receptors (adenosine1, 5-HT1A, 5-HT1C, dopamine transporter, α2A and α2A) and negligible affinities (IC50 values are over 10−5 M) for 42 other receptors, including neurotransmitters and hormones, ion channels and second messenger systems. Locomotor hyperactivity induced by methamphetamine (1 mg/kg i.p.) in mice was dose-dependently antagonized by NRA0045 (ED50 = 0.5 mg/kg i.p. and 1.9 mg/kg p.o., respectively). Methamphetamine (10 mg/kg i.p.)-induced stereotyped behavior in mice was dose-dependently antagonized by NRA0045, whereas NRA0045 did not exceed 50% inhibition even at the highest dose given (30 mg/kg i.p.). Catalepsy was dose-dependently and significantly induced by NRA0045 in rats, whereas NRA0045 did not exceed 50% induction even at the highest dose given (30 mg/kg i.p.). Thus NRA0045 blocks behaviors associated with activation of the mesolimbic/mesocortical dopaminergic neurons more selectively than behaviors associated with nigrostriatal dopaminergic neurons. In rats, tryptamine-induced clonic seizure, a 5-HT2 receptor-mediated behavior, was also dose-dependently inhibited by NRA0045 (ED50 = 1.7 mg/kg i.p.). Norepinephrine-induced lethality is regarded as being induced through the alpha-1 adrenoceptor. NRA0045 dose-dependently antagonized norepinephrine-induced lethality in rats (ED50= 0.2 mg/kg i.p.). Thus NRA0045 may have a unique antipsychotic activity with regard to dopamine D4 and 5-HT2Areceptors and alpha-1 adrenoceptor antagonistic activities, without producing the extrapyramidal side effects. The American Society for Pharmacology and Experimental Therapeutics ER -