Characterisation of the selective 5-HT1B receptor antagonist SB-616234-A (1-[6-(cis-3,5-dimethylpiperazin-1-yl)-2,3-dihydro-5-methoxyindol-1-yl]-1-[2'-methyl-4'-(5-methyl-1,2,4-oxadiazol-3-yl)biphenyl-4-yl]methanone hydrochloride): in vivo neurochemical and behavioural evidence of anxiolytic/antidepressant activity

The 5-HT_1B receptor has attracted significant interest as a potential target for the development of therapeutics for the treatment of affective disorders such as anxiety and depression. Here we present the in vivo characterisation of a novel, selective and orally bioavailable 5-HT_1B receptor antagonist, SB-616234-A (1-[6-(cis-3,5-dimethylpiperazin-1-yl)-2,3-dihydro-5-methoxyindol-1-yl]-1-[2′-methyl-4′-(5-methyl-1,2,4-oxadiazol-3-yl)biphenyl-4-yl]methanone hydrochloride). SB-616234-A reversed the 5-HT_1/7 receptor agonist, SKF-99101H-induced hypothermia in guinea pigs in a dose related manner with an ED₅₀ of 2.4 mg/kg p.o. Using in vivo microdialysis in freely moving guinea pigs, SB-616234-A (3–30 mg/kg p.o.) caused a dose-related increase in extracellular 5-HT in the dentate gyrus. Evaluation of antidepressant- and anxiolytic-like effects of this 5-HT_1B receptor antagonist was performed in a variety of models and species. SB-616234-A produced a decrease in immobility time in the mouse forced swim test; an effect suggestive of antidepressant activity. Furthermore, SB-616234-A produced dose-related anxiolytic effects in both rat and guinea pig maternal separation-induced vocalisation models with an ED₅₀ of 1.0 and 3.3 mg/kg i.p., respectively (vs fluoxetine treatment ED₅₀ = 2.2 mg/kg i.p. in both species). Also a significant reduction in posturing behaviours was observed in the human threat test in marmosets; an effect indicative of anxiolytic activity. In summary, SB-616234-A is a novel, potent and orally bioavailable 5-HT_1B receptor antagonist which exhibits a neurochemical and behavioural profile that is consistent with both anxiolytic- and antidepressant-like activity in a variety of species. Taken together these data suggest that SB-616234-A may have therapeutic efficacy in the treatment of affective disorders.     

SB-699551-A (3-cyclopentyl-N-[2-(dimethylamino)ethyl]-N-[(4'-{[(2-phenylethyl)amino]methyl}-4-biphenylyl)methyl]propanamide dihydrochloride), a novel 5-ht5A receptor-selective antagonist, enhances 5-HT neuronal function: Evidence for an autoreceptor role for the 5-ht5A receptor in guinea pig brain

This study utilised the selective 5-ht(5A) receptor antagonist, SB-699551-A (3-cyclopentyl-N-[2-(dimethylamino)ethyl]-N-[(4'-{[(2-phenylethyl)amino]methyl}-4-biphenylyl)methyl]propanamide dihydrochloride), to investigate 5-ht5A receptor function in guinea pig brain. SB-699551-A competitively antagonised 5-HT-stimulated [35S]GTPgammaS binding to membranes from human embryonic kidney (HEK293) cells transiently expressing the guinea pig 5-ht5A receptor (pA2 8.1+/-0.1) and displayed 100-fold selectivity versus the serotonin transporter and those 5-HT receptor subtypes (5-HT(1A/B/D), 5-HT2A/C and 5-HT7) reported to modulate central 5-HT neurotransmission in the guinea pig. In guinea pig dorsal raphe slices, SB-699551-A (1 microM) did not alter neuronal firing per se but attenuated the 5-CT-induced depression in serotonergic neuronal firing in a subpopulation of cells insensitive to the 5-HT1A receptor-selective antagonist WAY-100635 (100 nM). In contrast, SB-699551-A (100 or 300 nM) failed to affect both electrically-evoked 5-HT release and 5-CT-induced inhibition of evoked release measured using fast cyclic voltammetry in vitro. SB-699551-A (0.3, 1 and 3 mg/kg s.c.) did not modulate extracellular levels of 5-HT in the guinea pig frontal cortex in vivo. However, when administered in combination with WAY-100635 (0.3 mg/kg s.c.), SB-699551-A (0.3, 1 or 3 mg/kg s.c.) produced a significant increase in extracellular 5-HT levels. These studies provide evidence for an autoreceptor role for the 5-ht5A receptor in guinea pig brain.     

Effects of selective h5-HT1B (SB-216641) and h5-HT1D (BRL-15572) receptor ligands on guinea-pig and human 5-HT auto- and heteroreceptors

Human cerebral cortical slices and synaptosomes, guinea-pig cerebral cortical slices and human right atrial appendages were used to study the effects of SB-216641, a preferential h5-HT_1B receptor ligand, and of BRL-15572, a preferential h5-HT_1D receptor ligand, on the presynaptic h5-HT_1B and h5-HT_1B-like autoreceptors in the human and guinea-pig brain preparations, respectively, and on the presynaptic h5-HT_1D heteroreceptors in the human atrium. The brain preparations, preincubated with [³H]serotonin ([³H]5-HT), and the segments of atrial appendages, preincubated with [³H]noradrenaline, were superfused with modified Krebs’ solution and tritium overflow was evoked electrically (human and guinea-pig cerebral cortex slices and human atrial appendages) or by high K⁺ (human cerebral cortex synaptosomes). The electrically evoked tritium overflow from guinea-pig cerebral cortex slices was reduced by the 5-HT receptor agonist 5-carboxamidotryptamine (5-CT). This effect was not modified by BRL-15572 (2μM; concentration 154 times higher than its K_i at h5-HT_1D receptors) but was antagonized by SB-216641 (0.1μM; concentration 100 times higher than its K_i at h5-HT_1B receptors; apparent pA₂ 8.45). SB-216641 (0.1μM) by itself facilitated, whereas BRL-15572 (2μM) did not affect, the evoked overflow. In human cerebral cortex slices SB-216641 (0.1μM) also facilitated, and BRL-15572 (2μM) again failed to affect, the electrically evoked tritium overflow. In human cerebral cortical synaptosomes, 5-CT reduced the K⁺-evoked tritium overflow. This response was unaffected by BRL-15572 (300nM) but antagonized by SB-216641 (15nM; drug concentrations 23 and 15 times higher than their K_i at h5-HT_1D and h5-HT_1B receptors, respectively). Both drugs, given alone, did not modify the K⁺-evoked tritium overflow. In human atrial appendages, the electrically evoked tritium overflow was inhibited by 5-HT in a manner susceptible to antagonism by BRL-15572 (300nM; 23 times K_i at h5-HT_1D receptors) but not by SB-216641 (30nM; 30 times K_i at h5-HT_1B receptors). Both drugs by themselves did not change the electrically evoked tritium overflow. In conclusion, SB-216641 behaves as a preferential antagonist at native human 5-HT_1B receptors and BRL-15572 as a preferential antagonist at native human 5-HT_1D receptors. These compounds are clearly useful tools for the differentiation between human 5-HT_1B and 5-HT_1D receptors in functional studies. Received: 14 March 1997 / Accepted: 18 May 1997     

SB-216641 and BRL-15572 – compounds to pharmacologically discriminate h5-HT1B and h5-HT1D receptors

Despite only modest homology between h5-HT_1B and h5-HT_1D receptor amino acid sequences, these receptors display a remarkably similar pharmacology. To date there are few compounds which discriminate between these receptor subtypes and those with some degree of selectivity, such as ketanserin, have greater affinity for other 5-HT receptor subtypes. We now report on two compounds, SB-216641 (N-[3-(2-dimethylamino) ethoxy-4-methoxyphenyl]-2’-methyl-4’-(5-methyl-1,2,4-oxadiazol-3-yl)-(1,1’-biphenyl)-4-carboxamide) and BRL-15572 3-[4-(3-chlorophenyl) piperazin-1-yl]-1,1-diphenyl-2-propanol), which display high affinity and selectivity for h5-HT_1B and h5-HT_1D receptors, respectively. In receptor binding studies on human receptors expressed in CHO cells, SB-216641 has high affinity (pK_i=9.0) for h5-HT_1B receptors and has 25-fold lower affinity at h5-HT_1D receptors. In contrast, BRL-15572 has 60-fold higher affinity for h5-HT_1D (pK_i=7.9) than 5-HT_1B receptors. Similar affinities for these compounds were determined on native tissue 5-HT_1B receptors in guinea-pig striatum. Functional activities of SB-216641 and BRL-15572 were measured in a [³⁵S]GTPγS binding assay and in a cAMP accumulation assay on recombinant h5-HT_1B and h5-HT_1D receptors. Both compounds were partial agonists in these high receptor expression systems, with potencies and selectivities which correlated with their receptor binding affinities. In the cAMP accumulation assay, results from pK_B measurements on the compounds again correlated with receptor binding affinities (SB-216641, pK _B=9.3 and 7.3; BRL-15572, pK_B=<6 and 7.1, for h5-HT_1B and h5-HT_1D receptors respectively). These compounds will be useful pharmacological agents to characterise 5-HT_1B and 5-HT_1D receptor mediated responses. Received: 14 March 1997 / Accepted: 18 May 1997     

Functional behavioral homology between rat 5-HT1B and guinea pig 5-HT1D receptors in the modulation of prepulse inhibition of startle

The serotonin (5-HT) 1B receptor in rats and mice appears to be homologous to the 5-HT_1D receptor found in other mammals, such as guinea pigs and humans. The present series of experiments explored the functional similarity between the rat 5-HT_1B receptor and the guinea pig 5-HT_1D receptor on two behavioral measures known to be influenced by 5-HT_1B receptor manipulations in rats: prepulse inhibition of the startle response (PPI) and locomotor activity. Because the 5-HT_1B agonist RU 24969 disrupts PPI and stimulates locomotor behavior in rats, it was predicted that the 5-HT_1D agonist, SDZ 219–964, would demonstrate a similar behavioral profile in guinea pigs. In support of this hypothesis, SDZ 219–964 was found to disrupt PPI dose-dependently (1.0 and 2.0 mg/kg) without significantly affecting startle amplitude and to increase locomotor activity (0.5–2.0 mg/kg) in guinea pigs. In guinea pigs, RU 24969 failed to affect PPI, although it did increase locomotor activity, indicating that RU 24969 may have activity at the 5-HT_1D receptor. As expected, RU 24969 in rats disrupted PPI (2.5 and 5.0 mg/kg) and significantly increased locomotor activity (1.25–5.0 mg/kg). In rats, however, SDZ 219–964 had generalized, stimulatory effects on startle reactivity, without independent effects on PPI or locomotor activity. The spatial patterns of locomotion exhibited by guinea pigs treated with SDZ 219–964 versus those of rats treated with RU 24969 demonstrate important qualitative differences in structure, indicating that the neural substrates subserving these effects may be different. It is concluded that a functional similarity exists between 5-HT_1D and 5-HT_1B receptors with regard to the modulation of sensorimotor inhibition and, to a lesser extent, locomotor activity.     

A Search for New 5-HT1A/5-HT2A Receptor Ligands. In Vitro and in vivo Studies of 1-[ω-(4-Aryl-1-piperazinyl)alkyl]indolin-2(1H)-ones

A series of 1-[ω-(4-aryl-1-piperazinyl)alkyl]indolin-2(1H)-one derivatives 2–14 was synthesized in order to obtain ligands with a dual 5-HT_1A/5-HT_2A activity. The majority of those compounds ( 2–5, 7, 10–13 ) exhibited a high 5-HT_1A (K_i = 2 – 44 nM) and/or 5-HT_2A affinity (K_i = 51 and 39 for 5 and 7 , respectively). Induction of lower lip retraction (LLR) and behavioral syndrome and inhibition of these efects evoked by 8-hydroxy-2-(di-n-propyl-amino)tetralin (8-OH-DPAT) were used for determination the agonistic and antagonistic activity, respectively, at 5-HT_1A receptors. The 5-HT_2A antagonistic activity was assessed by the blocking effect on the head twitches induced by (±)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) in mice. Two of the tested compounds, 1-{3-[4-(3-chlorophenyl)-1-piperazinyl]propyl}-6-fluoroindolin-2(1H)-one ( 5 ) and 1-{3-[4-(2-methoxyphenyl)-1-piperazinyl]propyl}indolin-2(1H)-one ( 7 ), demonstrated a high 5-HT_1A/5-HT_2A affinity and an in vivo antagonistic activity towards both receptor subtypes.     

[3H]Rauwolscine: an antagonist radioligand for the cloned human 5-hydroxytryptamine2B (5-HT2B) receptor

In previous reports, [³H]5-HT has been used to characterize the pharmacology of the rat and human 5-HT_2B receptors. 5-HT, the native agonist for the 5-HT_2B receptor, has a limitation in its usefulness as a radioligand since it is difficult to study the agonist low-affinity state of a G protein-coupled receptor using an agonist radioligand. When using [³H]5-HT as a radioligand, rauwolscine was determined to have relatively high affinity for the human receptor (K_i human = 14.3 ± 1.2 nM, compared to K_i rat = 35.8 ± 3.8 nM). Since no known high affinity antagonist was available as a radioligand, these studies were performed to characterize [³H]rauwolscine as a radioligand for the cloned human 5-HT_2B receptor expressed in AV12 cells. When [³H]rauwolscine was initially tested for its usefulness as a radioligand, complex competition curves were obtained. After testing several α₂-adrenergic ligands, it was determined that there was a component of [³H]rauwolscine binding in the AV12 cell that was due to the presence of an endogenous α₂-adrenergic receptor. The α₂-adrenergic ligand efaroxan was found to block [³H]rauwolscine binding to the α₂-adrenergic receptor without significantly affecting binding to the 5-HT_2B receptor and was therefore included in all subsequent studies. In saturation studies at 37° C, [³H]rauwolscine labeled a single population of binding sites, K_d = 3.75 ± 0.23 nM. In simultaneous experiments using identical tissue samples, [³H]rauwolscine labeled 783 ± 10 fmol of 5-HT_2B receptors/mg of protein, as compared to 733 ± 14 fmol of 5-HT_2B receptors/mg of protein for [³H]5-HT binding. At 0° C, where the conditions for [³H]5-HT binding should label mostly the agonist high affinity state of the human 5-HT_2B receptor, [³H]rauwolscine (B_max = 951 ± 136 fmol/ mg), again labeled significantly more receptors than [³H]5-HT (B_max = 615 ± 34 fmol/mg). The affinity of [³H]rauwolscine for the human 5-HT_2B receptor at 0° C did not change, K_d = 4.93 ± 1.27 nM, while that for [³H]5-HT increased greatly (K_d at 37° C = 7.76 ± 1.06 nM; K_d at 0° C = 0.0735 ± 0.0081 nM). When using [³H]rauwolscine as the radioligand, competition curves for antagonist structures modeled to a single binding site, while agonist competition typically resulted in curves that best fit a two site binding model. In addition, many of the compounds with antagonist structures displayed higher affinity for the 5-HT_2B receptor when [³H]rauwolscine was the radioligand. Typically, ∼ 85% of [³H]rauwolscine binding was specific binding. These studies display the usefulness of [³H]rauwolscine as an antagonist radioligand for the cloned human 5-HT_2B receptor. This should provide a good tool for the study of both the agonist high- and low-affinity states of the human cloned 5-HT_2B receptor. Received: 26 June 1997 / Accepted: 30 August 1997     

咪苯嗪酮对花生四烯酸诱导的大鼠脑血栓形成的影响

花生四烯酸(AA)0.25～1 mg·kg~(-1)经颈内动脉注射能诱发大鼠同侧大脑半球脑内血栓形成,明显增加伊文思蓝通过血脑屏障渗入脑实质的量,峰值为205±s 50 mg·kg~1脑组织,相应对照组为10±s 5mg·kg~1,咪苯嗪酮0.25～0.5mg·kg~1 iv能对抗AA引起的大鼠脑血栓形成,显著降低脑实质内伊文思蓝的含量,作用呈剂量依赖性,且强于哒唑氧苯     

Synthesis and pharmacological evaluation of 4-[2-hydroxy-3-(4-phenyl-piperazin-1-yl)-propoxy]-4-azatricyclo[5.2.1.02,6]dec-8-ene-3,5-dione

The synthesis and pharmacological activity of 4-[2-hydroxy-3-(4-phenyl-piperazin-1-yl)-propoxy]-4-aza-tricyclo[5.2.1.0^2,6]dec-8-ene-3,5-dione is described. The structure of the compound was confirmed by elemental analysis, ¹H nuclear magnetic resonance (NMR), ¹³C NMR, mass spectra, and X-ray crystallography. The compound exhibited significant affinity to both 5-HT_1A and 5-HT_2A receptors, similarly to aripiprazole, which is an atypical antipsychotic drug.     

In vitro and in vivo pharmacological characterisation of the potent and selective vasopressin V(1A) receptor antagonist 4-[4-(4-Chloro-phenyl)-5-[1,2,3]triazol-2-ylmethyl-4H-[1,2,4]triazol-3-yl]-piperidin-1-yl-(3,5-difluoro-phenyl) methanone (PF-00738245)

The dysregulation of arginine vasopressin (AVP) release and activation of vasopressin receptors plays an important role in disease conditions including polycystic kidney disease, congestive heart failure and dysmenorrhoea. The development of potent and selective vasopressin receptor ligands is needed to help dissect the function of the specific subtypes in disease pathogenesis. Here we report the pharmacological characterisation of PF-00738245 in in vitro binding and functional assays using cells expressing vasopressin V(?A), V(?B) or V? receptors. PF-00738245 inhibited AVP binding to the recombinant human vasopressin V(?A) receptor (K(i)=2.85 nM) and blocked AVP-induced rat aortic ring and human myometrial contraction (pK(B)=7.35 and 8.62 respectively). PF-00738245 was selective for the vasopressin V(1A) receptor by demonstrating minimal binding to vasopressin V(?B) (3.6% inhibition at 10 μM) or functional activity at vasopressin V? receptors (8.1% agonist and -8.4% antagonist activity at 10 μM) as well as the oxytocin receptor (46.3% antagonist activity at 10 μM). The in vivo pharmacological properties were tested orally in the rat and PF-00738245 dose dependently blocked the effect of AVP on a capsaicin-induced cutaneous flare response. Taken together the data support the use of PF-00738245 as a potent and selective vasopressin V(?A) receptor antagonist which may have utility in the treatment of disease conditions which are propagated by elevation in vasopressin V(?A) receptor signalling.     

Mixed Dopaminergic/Serotonergic Properties of Several 2-Substituted 4-[2-(5-Benzimidazole)ethyl]-1-arylpiperazines

A series of substituted 4-[2-(5-benzimidazole)ethyl]-arylpiperazines was synthesized by introducing different substituents into position 2 of benzimidazole ring of 4-[2-(N,N-di-n-propyl-amino)ethyl]-1,2-diaminobenzenes. They were evaluated for in vitro binding affinity at the D₁ and D₂ dopamine and 5-HT_1A serotonin receptors using synaptosomal membranes of the bovine caudate nuclei and hippocampi, respectively. Tritiated SCH 23390 (D₁ receptor-selective), spiperone (D₂ receptor selective) and 8-OH-DPAT (5-HAT_1A receptor selective) were employed as the radioligands. Only compound 6 expressed a moderate binding affinity at the dopamine D₁ receptor, while the remaining ligands were inefficient or weak competitors of [³H]SCH 23390. Compound 12 was an absolutely inactive competitor of all three radioligands. Also, compound 7 was an inefficient displacer of [³H]-8-OH-DPAT. Compound 19 with a K_i value of 3.5 nM was the most potent competitor of [³H]spiperone and compound 13 (K_i = 3.3 nM) was the most efficient in displacing [³H]-8-OH-DPAT from the 5-HAT_1A serotonin receptor. Ligands 5, 6, 8–11 , and 13–20 expressed mixed dopaminergic/serotonergic activity in nanomolar range of concentrations with varying affinity ratios which strongly depended on the properties of the substituents introduced into position 2 of benzimidazole ring of the parent compounds.     

Characterization of 4-(2-hydroxyphenyl)-1-[2'-[N-(2'-pyridinyl)-p-fluorobenzamido]ethyl]piperazine (p-DMPPF) as a new potent 5-HT1A antagonist

BACKGROUND AND PURPOSE: The identification of potent and selective radioligands for the mapping of 5-HT receptors is interesting both for clinical and experimental research. The aim of this study was to compare the potency of a new putative 5-HT(1A) receptor antagonist, p-DMPPF, (4-(2-hydroxyphenyl)-1-[2'-[N-(2'-pyridinyl)-p-fluorobenzamido]ethyl]piperazine) with that of the well-known 5-HT(1A) antagonists, WAY-100635 (N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]-ethyl]-N-(2-pyridinyl) cyclohexanecarboxamide) and its fluorobenzoyl analogue, p-MPPF (4-(2-methoxyphenyl)-1-[2'-[N-(2'-pyridinyl)-p-fluorobenzamido]ethyl]piperazine). EXPERIMENTAL APPROACH: Single cell extracellular recordings of dorsal raphe (DR) neurones were performed in rat brain slices. The potency of each compound at antagonizing the effect of the 5-HT(1A) agonist, 8-OH-DPAT [8-hydroxy-2-(di-n-propylamino)-tetraline], was quantified using the Schild equation. The pharmacological profile of p-DMPPF was defined using competition binding assays. KEY RESULTS: Consistently with a 5-HT(1A) receptor antagonist profile, incubation of slices with an equimolar (10 nM) concentration of each compound markedly reduced the inhibitory effect of 8-OH-DPAT on the firing rate of DR neurones, causing a significant rightward shift in its concentration-response curve. The rank order of potency of the antagonists was WAY-100635>p-DMPPF>or=p-MPPF. The sensitivity of DR neurones to the inhibitory effect of 8-OH-DPAT was found to be heterogeneous. The binding experiments demonstrated that p-DMPPF is highly selective for 5-HT(1A) receptors, with a K(i) value of 7 nM on these receptors. CONCLUSIONS AND IMPLICATIONS: The potency of the new compound, p-DMPPF, as a 5-HT(1A) antagonist is similar to that of p-MPPF in our electrophysiological assay. Its selectivity towards 5-HT(1A) receptors makes it a good candidate for clinical development.     

1-pentanoyl-N-{[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl}-pyrrolidine-2-carboxamide: investigation of structural variations

We recently reported a series of 1-acyl-N-(biphenyl-4-ylmethyl)pyrrolidine-2-carboxamides as AT(1) receptor ligands. The most potent compound of the series, 1-pentanoyl-N-{[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl}-pyrrolidine-2-carboxamide, showed an interesting affinity for the receptor. To investigate the influence of structure variations on affinity, the synthesis of additional compounds belonging to this series has been performed. Biological tests run on the newly synthesized compounds on CHO-hAT(1) cells stably expressing the human AT(1) receptor confirm our previous hypothesis, i.e. that, within this series, the length of the acyl chain, the substitution of the amidic group and the nature of the acidic one are crucial for the receptor interaction, being a valeric chain, a secondary amidic function and the tetrazole moiety, respectively, the optimal ones.     

3-(ω-Aminoalkyl)-5,5-dialkyl(or spirocycloalkyl-1′,5-)hydantoins as New 5-HT1A and 5-HT2A Receptor Ligands

A series of new 3-(ω-aminoalkyl)-5,5-disubstituted hydantoins, containing 1-phenylpiperazine, 1-(o-methoxyphenyl)piperazine or 1,2,3,4-tetrahydroisoquinoline fragments, were synthesized by standard alkylation procedures and their 5-HT_1A and 5-HT_2A receptor affinities were determined. It has been shown that the investigated derivatives are recognized by 5-HT_1A and 5-HT_2A receptors due to the presence of a 1-arylpiperazine fragment; however, the terminal hydantoin moiety plays an important role in stabilization of the receptor-ligand complex. It has also been found that the two 1-phenylpiperazine derivatives 32 and 36 are new, selective 5-HT_2A receptor ligands (K_i = 34 and 37 nM, respectively), whereas the derivative of 1-(o-methoxyphenyl)piperazine ( 38 ) is a new, highly potent 5-HT_1A receptor ligand (K_i = 0.51 nM) with a moderate affinity for 5-HT_2A receptors (K_i = 213 nM).     

5-HT1B receptors modulate release of [3H]dopamine from rat striatal synaptosomes

The effect of the selective r5-HT_1B agonist 3-(1,2,5,6-tetrahydro)-4-pyridil-5-pyrrolo [3,2-b] pyril-5-one (CP93,129) on the K⁺-evoked overflow of [³H]dopamine was studied in rat striatal synaptosomes loaded with [³H]dopamine. The aim of the study was to investigate the participation of 5-HT_1B receptors in the serotonergic modulation of striatal dopaminergic transmission. The Ca²⁺-dependent, tetrodotoxin-resistant K⁺-evoked overflow of [³H]dopamine was inhibited by CP93,129 (0.01–100 μM) in a concentration-dependent manner (IC₅₀=1.8 μM; maximal inhibition by 35.5% of control). [±]8-OH-DPAT, a 5-HT_1A receptor agonist, [+/–]DOI, a 5-HT₂ receptor agonist, and 2-methyl-5-hydroxytryptamine, a 5-HT₃ receptor agonist, at concentrations ranging from 0.01 μM to 100 μM did not show any significant effect. Neither ketanserin (1 μM and 5 μM), a selective 5-HT₂/5-HT_1D receptor antagonist, nor ondansetron (1 μM), a 5-HT₃ receptor antagonist, changed the inhibitory effect of CP93,129. SB224289, GR55562, GR127935, isamoltane and metergoline, selective and non-selective 5-HT_1B receptor antagonists, in contrast, used at a concentration of 1 μM, antagonized the inhibitory effect of CP93,129 (3 μM and 10 μM). SB224289, a selective 5-HT_1B receptor antagonist, inhibited the effect of CP93,129 in a concentration-dependent manner; the calculated K _i value was 1.8 nM. Our results indicate that in rat striatal axon terminals the K⁺-evoked release of dopamine is regulated by the presynaptic 5-HT_1B heteroreceptors. Received: 7 September 1998 / Accepted: 2 November 1998     

4-[1-烷基-5-氧代-1H-1,2,4-三唑-4(5H)-基]-苯甲酸的合成

目的制备用于全合成卡泊芬净类环六脂肽抗真菌剂的关键脂肪酸侧链4-[1-烷基5-氧代-1H-1,2,4-三唑4（5H）-基]-苯甲酸（5）。方法以对氨基苯甲酸（1）为起始原料,经氨基苯氧羰酰化、肼解、甲脒环合及N-烃化4步反应制备目标化合物。结果以42．9％～46．2％的总收率成功合成了目标化合物5a～5n,其结构经电喷雾质谱（ESI—MS）和氢谱（^1HNMR）确证;所有目标化合物均为首次报道。结论该合成路线具有操作简便及收率高等优点,适合工业化生产。     

Partial postsynaptic 5-HT1A agonist properties of the novel stereoselective 8-OH-DPAT analogue (+)cis-8-hydroxy-1-methyl-2-(di-n-propylamino)tetralin, (+)ALK-3

The present study assessed the pharmacological activity of the stereoisomers of the novel 8-OH-DPAT analogue cis-8-hydroxy-1-methyl-2-(di-n-propylamino)tetralin, ALK-3, at postsynaptic 5-HT_1A receptors involved in 5-HT-mediated behaviour. Reserpine-pretreated rats were injected with (+)8-OH-DPAT (0.03–1.0 mg/kg s.c), (+)ALK-3 (0.3–10.0 mg/kg s.c.) or (-)ALK-3 (3.0–10.0 mg/kg s.c.), and components of the ‘5-HT behavioural syndrome’ were scored. (+8-OH-DPAT dose dependently elicited forepaw treading, flattened body posture and hindlimb abduction. In this respect, (+)ALK-3 was significantly less efficacious although its beahvioural action was prevented by pindolol (8 mg/kg s.c.), indicating that it was 5-HT_1A receptor mediated. Following pretreatment, (+)ALK-3 dose dependently, but partially, attenuated the effect of (+)8-OH-DPAT. (-)ALK-3 did not elicit 5-HT behaviours per se, and only very weakly antagonized the behavioural actions of (+)8-OH-DPAT at the highest dose tried. Our data indicate that the (+) enantiomer of ALK-3 is a partial but stereoselective agonist at postsynaptic 5-HT_1A receptors.     

In vitro metabolism of R(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrrolo [1,2,3-de]1,4-benzoxazinyl]-(1-naphthalenyl) methanone mesylate, a cannabinoid receptor agonist.

R(+)-[2,3-Dihydro-5-methyl-3-[(morpholinyl)methyl]pyrrolo[1,2, 3-de]1,4-benzoxa zinyl]-(1-naphthalenyl methanone mesylate (WIN55212-2) is a potent cannabinoid receptor agonist that has been found to exhibit antinociceptive activity and to inhibit brain cyclooxygenase. The metabolism of WIN55212-2 has not been reported, and it is unknown whether its metabolites retain any agonist properties. In this study, in vitro metabolism of WIN55212-2 in rat liver microsome was investigated. The metabolic profile was obtained using high-performance liquid chromatography (HPLC) with UV and mass spectrometry detectors. The HPLC chromatogram revealed two major and at least six minor metabolites derived from the parent compound ([M + H](+) = m/z 427). The two major metabolites (structural isomers at m/z 461), constituting 60 to 75% of the total metabolites, were each identified as dihydrodiol metabolites resulting from the arene oxide pathway. The minor metabolites were all detected as protonated molecules, three of which appeared at m/z 477, corresponding to structural isomers of trihydroxylated parent compound; another two appeared at m/z 443, representing monohydroxylated isomers; and another was observed at m/z 425, and was assigned as a dehydrogenation product. These structural assignments are based on HPLC/tandem mass spectrometry and NMR analysis. Metabolic pathways have been proposed to account for the various metabolites observed. Two major metabolites have been isolated in pure form, allowing future receptor binding studies to be conducted.     

Pharmacological properties and discriminative stimulus effects of a novel and selective 5-HT2 receptor agonist AL-38022A [(S)-2-(8,9-dihydro-7H-pyrano[2,3-g]indazol-1-yl)-1-methylethylamine

AL-38022A is a novel synthetic serotonergic (5-HT) ligand that exhibited high affinity for each of the 5-HT₂ receptor subtypes (K_i ≤ 2.2 nM), but a significantly lower (> 100-fold less) affinity for other 5-HT receptors. In addition, AL-38022A displayed a very low affinity for a broad array of other receptors, neurotransmitter transport sites, ion channels, and second messenger elements, making it a relatively selective agent. AL-38022A potently stimulated functional responses via native and cloned rat (EC₅₀ range: 1.9-22.5 nM) and human (EC₅₀ range: 0.5-2.2 nM) 5-HT₂ receptor subtypes including [Ca²⁺]_i mobilization and tissue contractions with apparently similar potencies and intrinsic activities and was a full agonist at all 5-HT₂ receptor subtypes. The CNS activity of AL-38022A was assessed by evaluating its discriminative stimulus effects in both a rat and a monkey drug discrimination paradigm using DOM as the training drug. AL-38022A fully generalized to the DOM stimulus in each of these studies; in monkeys MDL 100907 antagonized both DOM and AL-38022A. The pharmacological profile of AL-38022A suggests that it could be a useful tool in defining 5-HT₂ receptor signaling and receptor characterization where 5-HT may function as a neurotransmitter.     

Antibacterial, antifungal and anticonvulsant evaluation of novel newly synthesized 1-[2-(1H-tetrazol-5-yl)ethyl]-1H-benzo[d][1,2,3]triazoles

Several novel 1-[2-(1H-tetrazol-5-yl) ethyl]-1H-benzo[d][1,2,3]triazoles (3a-h) have been synthesized by the condensation of 1-[2-(1H-tetrazol-5-yl)-ethyl]-1H-benzotriazole (2) and appropriate acid chlorides. 1-[2-(1H-tetrazol-5-yl)-ethyl]-1H-benzotriazole (2) was synthesized by reacting 3-(1H-benzo[d][1,2,3]triazol-1-yl)propanenitrile with sodium azide and ammonium chloride in the presence of dimethylformamide. The synthesized compounds were characterized by IR and PMR analysis. The titled compounds were evaluated for their in-vitro antibacterial and antifungal activity by the cup plate method and anticonvulsant activity evaluated by the maximal electroshock induced convulsion method in mice. All synthesized compounds exhibited moderate antibacterial activity against Bacillus subtilis and moderate antifungal activity against Candida albicans. Compounds 5-(2-(1H-benzo[d][1,2,3]triazo-1-yl)ethyl)-1H-tetrazol-1-yl)(4-aminophenyl)methanone 3d and 5-(2-(1 H-benzo[d][1,2,3]triazo-1-yl)ethyl)-1H-tetrazol-1-yl)(2-aminophenyl)methanone 3e elicited excellent anticonvulsant activity.