Frederik Christian Gronvald

A comparison between dopamine-stimulated adenylate cyclase and 3H-SCH 23390 binding in rat striatum

Methods for measuring 3H-SCH 23390 binding and dopamine (DA) stimulated adenylate cyclase (AC) were established in identical tissue preparations and under similar experimental conditions. Pharmacological characterization revealed that both assays involved interaction with the D1 receptor or closely associated sites. In order to investigate whether the binding sites for 3H-SCH 23390 and DA in fact are identical, the antagonistic effects of a variety of pharmacologically active compounds were examined. Surprisingly, the Ki-values obtained from Schild-plot analysis of the antagonism of DA-stimulated AC, were 80-240 times higher than the Ki-values obtained from competition curves of 3H-SCH 23390 binding. Since both assays were performed under identical conditions, the differences in Ki-values indicate the possibility of different binding sites for DA and 3H-SCH 23390 or, that DA and 3H-SCH 23390 label different states of the same receptor.

NNC-112, NNC-687 and NNC-756, new selective and highly potent dopamine D1 receptor antagonists

The neurochemical properties of three novel benzazepine derivatives NNC-112, NNC-687 and NNC-756 were assessed. These compounds inhibited dopamine D1 receptor binding in vitro with low nanomolar to picomolar dissociation constants whereas those for the D2 receptor were in the micromolar range. Contrary to classical neuroleptics, but similar to the atypical neuroleptics, clozapine and fluperlapine, NNC-112, NNC-687 and NNC-756 were relatively more potent in inhibiting dopamine-stimulated adenylyl cyclase than [3H]SCH 23390 binding. Both NNC-112 and NNC-756 had high affinity for the 5-HT2 receptor whereas NNC-687 had low affinity for this receptor. The affinity for other receptors or neurotransmitter transporters was very low. In vivo, the dopamine D1 receptor selective profile of NNC-112, NNC-687 and NNC-756 was evident from the potent inhibition of D1 receptor binding whereas no effect on D2 receptor binding was apparent. In addition, the compounds blocked D1 receptor-mediated rotation in unilaterally 6-hydroxydopamine-lesioned rats, but had no effect on D2-induced rotation. Thus, NNC-112, NNC-687 and NNC-756 are potent and selective dopamine D1 receptor antagonists that may be useful in the treatment of schizophrenia.

Specific binding of 3H-SCH 23390 to dopamine D1 receptors in vivo

The binding of 3H-SCH 23390 was studied in vivo in the mouse brain. The binding was saturable, reversible and stereospecific. The level of nonspecific binding was 5-15% of total binding. Pharmacological characterization revealed binding of 3H-SCH 23390 to D1 receptors. Thus, dopaminergic antagonists known to possess D1 affinity, e.g., SCH 23390 itself, cis-flupentixol and (+)-butaclamol, were potent inhibitors of the 3H-SCH 23390 binding. On the other hand, high doses of D2 selective compounds were required to inhibit the 3H-SCH 23390 binding. These results indicate that 3H-SCH 23390 is a ligand of choice for in vivo studies of D1 receptors.

[11C]NNC 687 and [11C]NNC 756, dopamine D-1 receptor ligands. Preparation, autoradiography and PET investigation in monkey.

NNC 687 and NNC 756 [(+)-5-(2,3-dihydrobenzofuran-7-yl)-7-hydroxy-3-methyl- 8-nitro-2,3,4,5-tetrahydro-1H-3-benzazepine and (+)-8-chloro-5-(2,3-dihydrobenzofuran-7-yl)-7-hydroxy-3-methyl-2,3,4,5- tetrahydro-1H-3-benzazepine] are two new potent dopamine D-1 receptor antagonists. [11C]NNC 687 and [11C]NNC 756 were both prepared by N-methylation of the corresponding desmethyl compounds with [11C]methyl iodide. The reactions were performed in acetone with subsequent normal-phase semi-preparative HPLC and resulting in 50-60% radiochemical yield (from EOB and decay-corrected) with a total synthesis time of 30-35 min and a radiochemical purity higher than 99%. The specific radioactivity obtained at time of injection was about 1500 Ci/mmol (55 GBq/mumol). Autoradiographic examination of [11C]NNC 687 and [11C]NNC 756 binding in post-mortem human brain sections showed specific binding in the striatum, a region with high density of dopamine D-1 receptors. PET examination of the radioligands in a Cynomolgus monkey demonstrated accumulation of radioactivity predominantly in the striatum. The ratio between radioactivities in the striatum and the cerebellum was about 2 and 8 for [11C]NNC 687 and [11C]NNC 756 after 60 min. [11C]NNC 756 should have potential as PET ligand for examination of central dopamine D-1 receptors in man.

Synthesis of FF-MAS from lithocholic acid

An effective synthesis of 4,4 dimethyl-cholest-8,14,24-trien-3beta-ol (FF-MAS) from lithocholic acid is described, utilising a double oxidation and regioselective Wittig reaction as key steps.

NNC 19-1228 and NNC 22-0031, novel neuroleptics with a “mesolimbic-selective” behavioral profile

Abstract NNC 19-1228 [1-(3(6-benzothiazolylcarbamoyloxy)propyl)-4-(6-flouro-1,2-benzisoxazol-3-yl)piperidine] and NNC 22-0031 [4-(6-flouro-1,2-benzisoxazol-3-yl)-1-(3-(3,4-methylenedioxyphenylcarbamoyloxy)propyl)piperidine] are newly developed compounds with an in vitro pharmacologic profile similar to that of clozapine, i.e., mixed dopamine (DA), 5-hydroxytryptamine (5-HT)2 and α1-adrenergic antagonist action. In pharmacological experiments in mice, the compounds inhibited DA D2 receptor binding in vivo at doses that produced only moderate antagonism of methylphenidate (MPD)-induced stereotyped gnawing. However, the compounds were markedly more potent in blocking MPD-induced motility, a model which showed a high degree of sensitivity to α1-adrenergic antagonism, but not 5-HT2 antagonism. In rats, the NNC-compounds blocked conditioned avoidance responding and attenuated the discriminative stimulus effects of amphetamine, but failed to induce catalepsy. These results are discussed in terms of adrenergic, serotonergic and dopaminergic interactions which suggest that the NNC compounds may act as DA antagonists with mesolimbic selectivity, and thus may have efficacy as antipsychotics without coincident extrapyramidal side effects.