The antiaggressive potency of (-)-penbutolol involves both 5-HT1A and 5-HT1B receptors and beta-adrenoceptors.

The relative importance of 5-HT1A and beta-adrenergic activities in the antiaggressive effects of (-)-penbutolol was studied in male mice. (-)-Penbutolol had high affinity for 5-HT1A receptors and beta-adrenoceptors, and antagonized the 5-methoxy-N,N-dimethyltryptamine (5-MeODMT)-induced 5-HT syndrome and the 8-hydroxy-2-(di-n-propylamin)tetralin (8-OH-DPAT)-induced discriminatory stimulus in rats. (-)-Penbutolol abolished aggressive behaviour (ED50 = 56 mumol/kg), and reversed the antiaggressive effects of 8-OH-DPAT and 1-(3-trifluoromethylphenyl)piperazine (TFMPP) (ED50 = 8.1 and 2.1 mumol/kg, respectively). (N-[2-[4-(2-Methoxyphenyl)-1-piperazinyl]ethyl-N-(2-pyridinyl) cyclohexanecarboxamide (WAY 100635) reversed the antiaggressive effects of 8-OH-DPAT (ED50 = 0.012 mumol/kg), but did not affect the antiaggressive effects of TFMPP. The antiaggressive effect of a submaximal dose of 8-OH-DPAT was markedly potentiated by beta-adrenoceptor antagonists without 5-HT1A receptor affinity, whereas (-)-penbutolol was effective at only one dose (4.5 mumol/kg). In conclusion, the 5-HT1A receptor antagonistic potency of (-)-penbutolol in aggressive mice is attenuated by beta-adrenoceptor-induced facilitation of serotonergic neurotransmission.

Metabolism of sertindole: identification of the metabolites in the rat and dog, and species comparison of liver microsomal metabolism.

1. The main exretion pathways of a novel antipsychotic drug, sertindole, in the rat and dog are faecal excretion via intestinal secretion and biliary excretion respectively. 2. Similar liver microsomal metabolic patterns were observed in the rat, monkey, and man, and Lu 30-131 (5-hydroxy-serindole) and Lu 30-148 (4-hydroxy-serindole) were the major metabolites, and Lu 25-073 (nor-sertindole) and Lu 28-092 (dehydro-sertindole) were minor ones. In the dog, however, Lu 31-096 (3'-fluoro-4'-hydroxy-sertindole) and Lu 30-148 (4-hydroxy-sertindole) were the major metabolites, and Lu 25-073 (nor-sertindole), Lu 28-092 (dehydro-sertindole), and Lu 30-131 (5-hydroxy-sertindole) were minor ones. These findings suggest that the metabolism of sertindole in man resembles those in the rat and monkey and is different from that in the dog. 3. Rat in vitro and in vivo liver metabolites, dog liver microsomal metabolites, and dog biliary metabolites were isolated and identified by liquid chromatography/mass spectrometry and/or 1H-nmr. 4. Two metabolites, Lu 31-096 (3'-fluoro-4'-hydroxy-sertindole) and Lu 31-154 (3'-fluoro-4'-hydroxy-dehydro-sertindole), were formed via the 'NIH shift' mechanism. 5. Sertindole is metabolized by hydroxylation at the 4- and 5-positions on the imidazolidinone ring, N-dealkylation, and an NIH shift at the fluorophenyl group. Further metabolism (dehydration, oxidation, hydroxylation, glucuronidation and sulphation) was also observed. 6. In the rat, oxidation at the imidazolidinone ring and N-dealkylation are the main metabolic reactions. On the other hand, in the dog, the NIH shift at the fluorophenyl group, followed by conjugation is the main metabolic pathway.

Sigma ligands with subnanomolar affinity and preference for the sigma 2 binding site. 1. 3-(omega-aminoalkyl)-1H-indoles.

A series of 4-(1H-indol-3-yl)-1-butyl-substituted 4-phenylpiperidines, 4-phenyl-1,2,3,6-tetrahydropyridines, and 4-phenylpiperazines was synthesized. The phenyl group was optionally substituted with 4-fluoro or 2-methoxy substituents. High affinity for both sigma 1 and sigma 2 binding sites was achieved with these compounds. Additionally, these compounds had relatively high affinity for serotonin 5-HT1A and 5-HT2A, dopamine D2, and adrenergic alpha 1 receptors. Introduction of a 4-fluorophenyl substituent at the indole nitrogen atom rendered very selective sigma 2 ligands with subnanomolar affinity for the sigma 2 binding site. The prototype of such a compound was 1-(4-fluorophenyl)-3-[4-[4-(4-fluorophenyl)-1-piperidinyl]-1-butyl]-1H- indole, 11a (code no. Lu 29-253). This compound had the following binding affinities: IC50 (sigma 1) = 16 nM, IC50 (sigma 2) = 0.27 nM, IC50 (5-HT1A) = 22,000 nM, IC50 (5-HT2A) = 270 nM, IC50 (D2) = 4200 nM, IC50 (alpha 1) = 220 nM. Spiro-joining of the phenyl and the piperidine rings into a spiro[isobenzofuran-1(3H),4'-piperdine] ring system resulted in even more selective compounds. Variations of the 1-substituent at the indole and of the chain length of the alkylene spacer group were studied. The optimal compound was the spiro analogue of compound 11a. This compound is 1'-[4-[1-(4-fluorophenyl)-1H-indol-3-yl]-1-butyl]spiro[isobenzofuran- 1(3H),4'-piperidine], 14f (code no. Lu 28-179), with the binding affinities: IC50 (sigma 1) = 17 nM, IC50 (sigma 2) = 0.12 nM, IC50 (5-HT1A) = 21,000 nM, IC50 (5-HT2A) = 2000 nM, IC50 (D2) = 800 nM, IC50 (alpha 1) = 330 nM. However, the most selective sigma 2 versus sigma 1 ligand was the tropane derivative 1-(4-fluorophenyl)-3-[4-[3-(4-fluorophenyl)-8-azabicyclo[3.2.1]oct-2- en-8-yl]-1-butyl]-1H-indole, 15a. This compound had the following binding affinities: IC50 (sigma 1) = 1200 nM, IC50 (sigma 2) = 2.5 nM. Potent anxiolytic activity in the black/white box exploration test in rats was found with the two most prominent sigma 2 ligands Lu 29-253 and Lu 28-179. Good penetration into the CNS was documented both after subcutaneous and peroral administration of Lu 28-179 by ex vivo binding studies. Long duration of action was demonstrated both in ex vivo binding (T1/2 approximately 20 h) and in the black/white box exploration test.

Sigma ligands with subnanomolar affinity and preference for the sigma 2 binding site. 2. Spiro-joined benzofuran, isobenzofuran, and benzopyran piperidines.

Spiro[isobenzofuran-1(3H),4'-piperidines] and the corresponding benzofuran and benzopyran derivatives have been synthesized and evaluated as sigma ligands. The compounds are related to Lu 28-179 (1'-[4-[1-(4-fluorophenyl)-1H-indol-3-yl]-1- butyl]spiro[isobenzofuran-1(3H),4'-piperidine]) that has been demonstrated to be a selective sigma 2 ligand with affinity in the subnanomolar range. The object of the study was to determine the structural factors governing sigma 1/sigma 2 affinity and selectivity within this class of compounds. The N-substituent in spiro[isobenzofuran-1(3H),4'-piperidines] is highly important, both for affinity and selectivity. Spiropiperidines with no or small N-substituents (H, Me, Et) exert very low affinity for both sigma 1 and sigma 2 binding sites (IC50(sigma 1, sigma 2) > 100 nM), whereas medium-sized substituents (e.g., Pr, Bu, Ph(CH2)2) result in potent, but unselective compounds (IC50(sigma 1, sigma 2) = 2-5 nM). Increasing the chain length and the lipophilicity of the N-substituent result in compounds in which high affinity for sigma 2 binding sites is retained and with selectivity for sigma 2 vs sigma 1 binding sites (e.g., 4-cyclohexyl-1-butyl: IC50-(sigma 1) = 1.5 nM, IC50(sigma 2) = 0.07 nM). Introduction of substituents in the benzene ring of the spiro[isobenzofuran-1(3H),4'-piperidine] ring system of Lu 28-179 mainly affects affinity for sigma 1 binding sites. Compounds with substituents (F, CF3) in the 4- or 7-position of the isobenzofuran display high affinity for sigma 2 binding sites (IC50(sigma 2) = 0.5-2 nM) and very low affinity for sigma 1 binding sites (IC50(sigma 1) > 100 nM). Compounds with substituents (F, CF3, Me) in the 5- or 6-position of the isobenzofuran exert increased affinity for sigma 1 binding sites (IC50(sigma 1) = 5-30 nM, IC50(sigma 2) = 0.3-7 nM), thus rendering unselective compounds. Exchanging the isobenzofuran moiety of Lu 28-179 with thioisobenzofuran, benzofuran, or benzopyran also has a pronounced effect on both affinity and selectivity for sigma binding sites. The position of the oxygen atom and the position of the spiroconnection with the 4-position of the piperidine ring were varied, and only compounds in which both the benzene ring and the heteroatom are attached directly to the piperidine ring retain high affinity and selectivity for sigma 2 binding sites (e.g., 3,4-dihydro-1'-[4-[1-(4-fluorophenyl)-1H-indol-3-yl]-1- butyl]spiro[1H-2-benzopyran-1,4'-piperidine]: IC50(sigma 1) = 53 nM, IC50(sigma 2) = 0.9 nM).(ABSTRACT TRUNCATED AT 400 WORDS)

Bioisosteres of arecoline: 1,2,3,6-tetrahydro-5-pyridyl-substituted and 3-piperidyl-substituted derivatives of tetrazoles and 1,2,3-triazoles. Synthesis and muscarinic activity.

A series of arecoline bioisosteres, where the ester group is replaced by a 1,2,3-triazole-4-yl or a tetrazole-5-yl group, was synthesized and evaluated in vitro for affinity and efficacy at muscarinic receptors and in vivo for cholinergic side effects. The corresponding piperidine derivatives were also studied. In the 1,2,3,6-tetrahydropyridyl-1,2,3-triazole series, only derivatives with 2-substituents in the 1,2,3-triazole ring exert muscarinic agonist activity. The same trend is seen in the corresponding tetrazole series, where only 2-substituted derivatives display muscarinic agonist activity. The methyl derivatives in both series are full agonists, whereas the derivatives with longer side chains are partial agonists. Introduction of methyl substituents in the 1,2,3,6-tetrahydropyridine ring generally lowers affinity considerably except for the 3-substituted derivatives, where some activity is retained. In both the 1,2,3-triazole and tetrazole series, derivatives without substituents at the basic nitrogen in the 1,2,3,6-tetrahydropyridine ring are unselective full agonists, whereas the methyl-substituted derivatives generally are more M1 selective compared to M2. Larger substituents than methyl abolish activity. The 4-(3-piperidyl)-1,2,3-triazole and 5-(3-piperidyl)-2H-tetrazole derivatives are generally less active than the corresponding 1,2,3,6-tetrahydropyridine derivatives, and only the 2-allyl- and 2-propargyl-1,2,3-triazole derivatives display activities comparable to the most active compounds in the 1,2,3,6-tetrahydropyridine series. The propargyl derivative is an unselective full agonist, and resolution did not reveal any stereoselectivity The allyl derivative is a partial agonist with some selectivity for the M1 receptor, and testing of the enantiomers showed that the (+)-enantiomer is an unselective partial agonist, whereas the (-)-enantiomer is a partial agonist with preference for the M1 receptor. Generally, the structure-activity relationships of the 1,2,3-triazole and tetrazole series are very similar, and two compounds, 2-ethyl-4-(1-methyl-1,2,3,6-tetrahydro-5-pyridyl)-1,2,3-triazole and 2-ethyl-5-(1-methyl-1,2,3,6-tetrahydro-5-pyridyl)-2H-tetrazole, are M1 agonists/M2 antagonists. Muscarinic compounds with this profile are of particular interest as drugs for the treatment of Alzheimer's disease.

The role of serotonergic mechanisms in inhibition of isolation-induced aggression in male mice.

The role of serotonergic (5-HT) receptor subtypes in mediation of aggressive behaviour in isolated male mice has been studied. Increase of attack latency was used as a simple measure of antiaggressive behaviour. 5-HT1A agonists (BAY R 1531, 8-OHDPAT, flesinoxan, gepirone, 5MeO DMT, buspirone, ipsapirone, BMY 14802) completely inhibit the aggressive behaviour irrespective of their intrinsic activities. Also the putative antagonists spiroxatrine and NAN 190 as well as the non-selective 5-HT1 agonists RU 24969, TFMPP, mCPP and eltoprazine have an antiaggressive effect. The mixed 5-HT1A and beta-adrenoceptor antagonists (-)-alprenolol and pindolol are ineffective and do not inhibit the effect of 8-OHDPAT. Neither does the non-selective 5-HT antagonist metergoline. The antiaggressive effect correlates with 5-HT1A receptor affinity in vitro and with generalization to the 8-OHDPAT-induced discriminative stimulus. The selective 5-HT uptake inhibitor citalopram does not inhibit aggressive behaviour. The 5-HT2 agonist DOI has an antiaggressive effect only at high doses, whereas the 5-HT2 antagonist ritanserin and the 5-HT3 antagonist ondansetron are ineffective. Prazosin (alpha 1-adrenoceptor antagonist), clonidine (alpha 2-adrenoceptor agonist), clenbuterol (beta-adrenoceptor agonist), ketanserin (5-HT2 receptor and alpha 1-adrenoceptor antagonist), clozapine and (-)-octoclothepin (dopamine (DA), 5-HT2 receptor and alpha 1-adrenoceptor antagonist) all show an antiaggressive effect. SCH 23390 (DA D1 receptor antagonist) and emonapride (DA D2 receptor antagonist) are ineffective. In conclusion, 5-HT1A receptors are involved in mediation of isolation-induced aggressive behaviour in mice. The involvement of other 5-HT receptor subtypes needs further clarification. The adrenergic system may also be involved.(ABSTRACT TRUNCATED AT 250 WORDS)