In vitro and in vivo characterization of the dopamine D4 receptor, serotonin 5-HT2A receptor and alpha-1 adrenoceptor antagonist (R)-(+)-2-amino-4-(4-fluorophenyl)-5-[1-[4-(4-fluorophenyl)-4-oxobutyl] pyrrolidin-3-yl]thiazole (NRA0045).
(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 microM) for six other neurotransmitter receptors (adenosine1, 5-HT1A, 5-HT1C, dopamine transporter, alpha2A and alpha2A) 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-HT2A receptors and alpha-1 adrenoceptor antagonistic activities, without producing the extrapyramidal side effects.
Okuyama
S
S
1st Laboratory, Medicinal Research Laboratories, Taisho Pharmaceutical Co., Ltd., Ohmiya, Saitama, Japan.
Chaki
S
S
Yoshikawa
R
R
Suzuki
Y
Y
Ogawa
S
S
Imagawa
Y
Y
Kawashima
N
N
Ikeda
Y
Y
Kumagai
T
T
Nakazato
A
A
Nagamine
M
M
Tomisawa
K
K
D058668:Adrenergic alpha-1 Receptor Antagonists; D000317:Adrenergic alpha-Antagonists / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D019556:COS Cells; D002375:Catalepsy / Q000139:chemically induced; D018492:Dopamine Antagonists / Q000378:metabolism / Q000494:pharmacology*; D065127:Dopamine D2 Receptor Antagonists; D006801:Humans; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009043:Motor Activity / Q000187:drug effects; D009638:Norepinephrine / Q000633:toxicity; D011759:Pyrrolidines / Q000378:metabolism / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D044402:Receptor, Serotonin, 5-HT2A; D050638:Receptors, Dopamine D4; D011985:Receptors, Serotonin / Q000187:drug effects*; D012702:Serotonin Antagonists / Q000378:metabolism / Q000494:pharmacology*; D013239:Stereotyped Behavior / Q000187:drug effects; D013844:Thiazoles / Q000378:metabolism / Q000494:pharmacology*
D058668:Adrenergic alpha-1 Receptor Antagonists; D000317:Adrenergic alpha-Antagonists; C493599:DRD4 protein, human; D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; C493600:Drd4 protein, mouse; C493601:Drd4 protein, rat; C106996:NRA 0045; D011759:Pyrrolidines; D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D013844:Thiazoles; D050638:Receptors, Dopamine D4; D009638:Norepinephrine