Janusz Jozef Kulagowski

Genetic knockout and pharmacological blockade studies of the 5-HT7 receptor suggest therapeutic potential in depression

The affinity of several antidepressant and antipsychotic drugs for the 5-HT7 receptor and its CNS distribution suggest potential in the treatment of psychiatric diseases. However, there is little direct evidence of receptor function in vivo to support this. We therefore evaluated 5-HT7 receptors as a potential drug target by generating and assessing a 5-HT7 receptor knockout mouse. No difference in assays sensitive to potential psychotic or anxiety states was observed between the 5-HT7 receptor knockout mice and wild type controls. However, in the Porsolt swim test, 5-HT7 receptor knockout mice showed a significant decrease in immobility compared to controls, a phenotype similar to antidepressant treated mice. Intriguingly, treatment of wild types with SB-258719, a selective 5-HT7 receptor antagonist, did not produce a significant decrease in immobility unless animals were tested in the dark (or active) cycle, rather than the light, adding to the body of evidence suggesting a circadian influence on receptor function. Extracellular recordings from hypothalamic slices showed that circadian rhythm phase shifts to 8-OH-DPAT are attenuated in the 5-HT7 receptor KO mice also indicating a role for the receptor in the regulation of circadian rhythms. These pharmacological and genetic knockout studies provide the first direct evidence that 5-HT7 receptor antagonists should be investigated for efficacy in the treatment of depression.

Schizophrenia and L-745, 870, a novel dopamine D4 receptor antagonist

The discovery of a novel high-affinity and selective dopamine D4 receptor antagonist, L-745,870, and the results of clinical trials with this compound are reviewed. Despite several lines of evidence which suggest that a selective D4 receptor antagonist may be an effective antipsychotic agent with a lower propensity to induce extrapyramidal side-effects, L-745,870 was ineffective as an antipsychotic in humans.

The hypothermic effect of 5-CT in mice is mediated through the 5-HT7 receptor

The 5-HT(7) receptor is a recent addition to the 5-HT receptor family and to date there is no clear idea as to its potential role in the CNS. The receptor has been mapped by in situ hybridization and 5-HT(7)-like immunoreactivity and has been detected in discrete areas of the brain including the hypothalamus (Oliver et al., 1999). This suggests the receptor may be involved in temperature regulation and have shown that a selective 5-HT(7) receptor antagonist reverses the hypothermic effect of 5-CT in guinea-pigs. The current study confirmed that the 5-HT(7) receptor antagonists, SB-269970 (1-30 mg/kg, i.p.) and SB-258719 (5-20 mg/kg, i.p.), but not the 5-HT(1A) receptor antagonist, WAY 100635(0.1-1 mg/kg, s.c.), or the 5-HT(1B/D) antagonist, GR127935 (1.25-5 mg/kg, i.p.), reversed the hypothermic effect of 5-CT in mice. In addition the effect of 5-CT on body temperature was examined on 5-HT(7) receptor null mutant mice. 5-CT (0.1-1 mg/kg, i.p.) significantly reduced rectal temperature in wildtype but not 5-HT(7) receptor knockout mice. This suggests that the hypothermic effects of 5-CT are mediated through the 5-HT(7) receptor. All procedures were carried out in accordance with the UK Animals (Scientific Procedures) Act (1986).

The total synthesis of myo-inositol polyphosphates

Abstract Total synthesis of the individual enantiomers of myo-inositol 4-phosphate ( 15 ), myo-inositol 1,4-bisphosphate ( 2 ) and myo-inositol 1,4,5-trisphosphate ( 1 ), together with syntheses of racemic myo-inositol 1,3,4-trisphosphate ( 4 ) and myo-inositol 2,4,5-trisphosphate ( 5 ) are reported. The syntheses feature the use of camphanic acid esters for resolution of protected inositols, and the use of tetrabenzylpyrophosphate as an efficient phosphorylating agent for polyhydroxy alcohols.

Identification of Imidazo-Pyrrolopyridines as Novel and Potent JAK1 Inhibitors.

A therapeutic rationale is proposed for the treatment of inflammatory diseases, such as rheumatoid arthritis (RA), by specific targeting of the JAK1 pathway. Examination of the preferred binding conformation of clinically effective, pan-JAK inhibitor 1 led to identification of a novel, tricyclic hinge binding scaffold 3. Exploration of SAR through a series of cycloamino and cycloalkylamino analogues demonstrated this template to be highly tolerant of substitution, with a predisposition to moderate selectivity for the JAK1 isoform over JAK2. This study culminated in the identification of subnanomolar JAK1 inhibitors such as 22 and 49, having excellent cell potency, good rat pharmacokinetic characteristics, and excellent kinase selectivity. Determination of the binding modes of the series in JAK1 and JAK2 by X-ray crystallography supported the design of analogues to enhance affinity and selectivity.

In vitro and in vivo inhibition of prolyl endopeptidase

Four derivatives of a known prolyl endopeptidase (PEP) inhibitor (N-[N-(phenyl)butyryl-L-propyl]pyrrolidine; SUAM-1221) were synthesized along with the parent compound. All five compounds were relatively potent, competitive inhibitors of rat brain and mouse brain and kidney PEP, with IC50S in the range of 3-27 nM. Ex vivo experiments showed that all compounds penetrated into the CNS and produced inhibition of brain PEP, although inhibition was not as great as in the periphery (kidney PEP). Each compound had a similar time course of duration, with maximum inhibition of brain PEP being achieved within 5-10 min after i.p. administration, with inhibition of brain PEP (up to 20%) still present 6 h after dosing. However, two of the compounds, SUAM-1221 and its amine derivative, had ED50S versus mouse brain PEP (1-3 mg/kg) an order of magnitude less than the other compounds (25-40 mg/kg). Administration of the amine compound resulted in a significant partial reversal of the deficit in memory performance produced by scopolamine.

Rhodium-carbenoid mediated O-H insertion reactions. O-H insertion vs. H-abstraction and effect of catalyst

Abstract The synthesis and rhodium mediated O-H insertion reactions of a wide range of diazo compounds are described. The rate at which the diazo compounds decompose in the presence of 2-propanol and the rhodium catalyst is strongly dependent on the electron withdrawing group(s) attached to the diazo carbon, with diazophosphonates being the least reactive. Insertion into the O-H bond of methanol, t-butanol and phenols was also investigated, as well as the effect of catalyst. In some cases ‘reduction’ of the diazo group to the corresponding CH 2 group competes with O-H insertion, although this is highly catalyst and substrate dependent. Of the catalysts used, rhodium(II) trifluoroacetamide is the most effective for O-H insertion reactions.

Orally Efficacious NR2B-Selective NMDA Receptor Antagonists

A novel series of benzamidines was synthesized and shown to exhibit NR2B-subtype selective NMDA antagonist activity. Compound 31 is orally active in a carrageenan-induced rat hyperalgesia model of pain and shows no motor coordination side effects.

Discriminative stimulus properties of the putative dopamine D3 receptor agonist, (+)-PD 128907: role of presynaptic dopamine D2 autoreceptors.

The putative D3 receptor agonist, (+)-PD 128907, is widely used to study the functional relevance of D3 receptors in vivo. Given that non-selective D2/3/4 receptor agonists serve as effective discriminative stimuli in rats we have trained animals to discriminate (+)-PD 128907 (30 microg kg(-1), s.c.) from saline and examined the pharmacological specificity of the response. Consistent with a D3 receptor mediated response, the non-selective D2/3 receptor agonist apomorphine and the D3 preferring agonists 7-OH-DPAT and (-) quinpirole generalised to the cue whilst the D2/3 receptor antagonists haloperidol, raclopride, spiperone and (+)-butaclamol antagonised drug lever responding. In contrast, the D1 selective agonist (+/-)-SKF 81297 and D1/5 selective antagonist, R-(+)-SCH 23390 had no effect. Results also suggest that presynaptic dopamine receptors are involved. Thus the dopamine depleting agent alpha-methyl-p-tyrosine potentiated the effects of a submaximal dose of (+)-PD 128907 whereas amphetamine failed to generalise per se and blocked (+)-PD 128907 lever selection. However, studies using subtype selective antagonists argue against a role for the D3 receptor. Thus the 10-fold selective D2 receptor antagonist L-741,626 blocked the (+)-PD 128907 discriminative stimulus whereas L-745,829 and GR 103,691, antagonists > 40 and > 100-fold selective for D3 receptors, failed to modify the response. These results suggest that presynaptic D2 receptors mediate the discriminative stimulus properties of (+)-PD 128907 and highlight the lack of selectivity of (+)-PD 128907 for D3 receptors in vivo.

Antagonism of the effects of (+)-PD 128907 on midbrain dopamine neurones in rat brain slices by a selective D2 receptor antagonist L-741,626.

1 The ability of PD 128907 to activate dopamine receptors in the ventral tegmental area, substantia nigra pars compacta, and striatum was investigated by use of in vitro electrophysiological recording and fast cyclic voltammetry. The affinity of a novel D2 selective antagonist L‐741,626 for receptors activated by this agonist was measured to determine if its effects were mediated by D2 or D3 receptors. 2 The active (+) enantiomer of PD 128907 bound with high affinity and selectivity to rat D3 dopamine receptors. The Ki values for (+)‐PD 128907 were 620 nM at D2, 1 nM at D3 and 720 nM at D4 receptors. 3 (+)‐PD 128907 inhibited cell firing in both the ventral tegmental area and substantia nigra pars compacta with EC50 values of 33 nM (pEC50 = 7.48 ± 0.10, n= 10) and 38 nM (pEC50 = 7.42 ± 0.15, n = 5), respectively. No effects of (+)‐PD 128907 (100 nM) were observed on glutamate or GABA‐mediated synaptic potentials elicited by focal bipolar stimulation. 4 L‐741,626 antagonized these effects of (+)‐PD 128907 in a concentration‐dependent and surmountable manner with an affinity, determined from Schild analysis, of 20 nM (pKB = 7.71 ± 0.14) in the ventral tegmental area and 11 nM (pKB = 7.95 ± 0.18) in the substantia nigra pars compacta. 5 (+)‐PD 128907 also inhibited dopamine release in the caudate‐putamen with an EC50 of 66 nM (n = 5). The affinity of L‐741,626 for these nerve terminal autoreceptors (pKB = 7.71 ± 0.06; =20 nM) was identical to that observed on midbrain dopamine neurones. 6 These data demonstrate that the D3 receptor ligand (+)‐PD 128907 is a potent agonist on rat midbrain dopamine neurones. However, its lack of regional selectivity, and the high affinity of the selective D2 receptor antagonist L‐741,626 for receptors activated by (+)‐PD 128907, was more consistent with an action on D2 autoreceptors rather than upon a D3 dopamine receptor subtype.