Structural manipulation on the catecholic fragment of dopamine D(1) receptor agonist 1-phenyl-N-methyl-benzazepines.

A series of new benzazepines with modification on the catecholic fragment were designed. The 8-hydroxyl group, other than the 7-hydroxyl was confirmed crucial to the interaction with the dopamine D1 receptor. Subsequent replacement of the 7-hydroxyl with benzylamino groups was found tolerable. 7-(m-Chlorophenyl)methylamino- and 7-(m- or o-tolyl)methylamino-substituted benzazepines 13b-d displayed Ki values of 270-370 nM at the D1 receptor, which were slightly more potent than that of parent compound 1. In addition, 7-(arylmethyl)amino-benzazepines 13a-c were found possessing high binding affinities less than 10 nM at the 5-HT2A receptor. Among them, the non-substituted 7-benzylamino analogue 13a was the most potent showing a Ki values of 4.5 nM at the 5-HT2A receptor and a 5-HT2A/D1 selectivity of 147.

Evaluation of the antipsychotic effect of bi-acetylated l-stepholidine (l-SPD-A), a novel dopamine and serotonin receptor dual ligand.

Bi-acetylated l-stepholidine (l-SPD-A), a novel derivate of l-stepholidine (l-SPD), possesses a pharmacological profile of D(1)/5-HT(1A) agonism and D(2) antagonism. In the present study, we examined the potential antipsychotic effect of l-SPD-A in a phencyclidine (PCP)-induced rat model of schizophrenia. Pretreatment with l-SPD-A blocked acute PCP-induced hyperlocomotion and reversed prepulse inhibition (PPI) deficits. Chronic l-SPD-A administration (i.p., 10mg/kg/day for 14 days) improved social interaction and novel object recognition impairments in rats that were pretreated with PCP (i.p., 5mg/kg/day for 14 days). Moreover, in a conditioned avoidance response (CAR) test, l-SPD-A, with either i.p. or oral administration, significantly decreased active avoidance without affecting the escape response of rats. Importantly, compared to that of the parent compound l-SPD, l-SPD-A showed stronger suppression of CARs. Lastly, using a [(35)S]GTPgammaS binding assay, we demonstrated that l-SPD-A improved impaired dopamine D(1) receptor function in the prefrontal cortex (PFC) in chronic PCP-treated rats. Taken together, these results indicate that l-SPD-A was not only effective against the hyperactivity, but also improved the sensorimotor gating deficit, social withdrawal and cognitive impairment in an animal model of schizophrenia. The present data suggest that l-SPD-A, a potential neurotransmitter stabilizer, is a promising novel candidate drug for the treatment of schizophrenia.

'Click' D(1) receptor agonists with a 5-HT(1A) receptor pharmacophore producing D(2) receptor activity.

A series of new 1-aryl-3-benzazepine derivatives containing an arylpiperazinyl function as the N3 substituent were synthesized by combining a D(1) receptor agonistic pharmacophore and a 5-HT(1A) receptor pharmacophore through Click reaction. Interestingly, these compounds generally do not have good binding affinity at the D(1) receptor, but most compounds are potent at both D(2) and 5-HT(1A) receptors. Compound 8h, containing 1-m-tolyl-benzazepine scaffold and 2-methoxyphenylpiperazine core, displayed good affinity at all tested receptors, with K(i) values of 144, 80, and 133nM, for the D(1), D(2), and 5-HT(1A) receptors, respectively. Compound 13 with the triazole moiety formed differently from that in 8h showed the highest affinity at the D(2) receptor with K(i) value of 19nM. This compound also showed moderate affinity at the 5-HT(1A) (K(i), 105nM), and D(1) (K(i), 551nM) receptors. Functional assays indicated that both compounds 13 and 8h are antagonists at D(1) and D(2) receptors, whereas full agonistic activity at the 5-HT(1A) receptor was observed. In agreement with the binding affinity, compound 13 is a high efficacy D(2) antagonist and 5-HT(1A) agonist.