ACAT inhibitor HL-004 accelerates the regression of hypercholesterolemia in stroke-prone spontaneously hypertensive rats (SHRSP): stimulation of bile acid production by HL-004.

The effect of the acyl-CoA:cholesterol acyltransferase (ACAT) inhibitor HL-004 on bile acid production was studied during the regression phase of pre-established hypercholesterolemia in stroke-prone spontaneously hypertensive rats (SHRSP). These rats were fed a hypercholesterolemic diet containing 5% cholesterol, 2% cholic acid, and 20% suet for 30 days to induce hypercholesterolemia. The regression phase was started by switching the diet to normal chow, followed by another 30 days of the diet. The decrease in serum cholesterol level was accelerated by treatment with 0.09% HL-004. At the end of regression, hepatic ACAT activity was significantly lower in the HL-004 treated animals, an event concomitant with the significant decrease in cholesteryl ester content in the liver. In contrast hepatic cholesterol 7 alpha-hydroxylase activity was maintained at a higher level in the HL-004 treated animals. HL-004 increased the secretion of bile acid and biliary lipids in bile duct-cannulated SHRSP. In HepG2:cells, HL-004 at 1-30 microM dose-dependently stimulated bile acid synthesis from [3H]cholesterol. When cholesterol 7 alpha-hydroxylase activity of the liver was compared ex vivo in the presence and in the absence of exogenous cholesterol, it was suggested that the higher 7 alpha-hydroxylase activity of the HL-004 group could be attributed not only to expansion of the endogenous cholesterol pool, which may be the result of hepatic ACAT inhibition by HL-004 but to the direct effect of HL-004 on bile acid production. Thus, HL-004 accelerates the regression of hypercholesterolemia, an event which may be related to the stimulation of bile acid production in the liver.

Up-regulation of low density lipoprotein receptor by a novel isobenzofranone derivative, MD-700.

Stimulatory effects of a novel isobenzofranone, MD-700, on low density lipoprotein (LDL) receptor activity were investigated in vitro and in vivo. MD-700 at 0.03 microg/ml elevated the expression of LDL receptor in HepG2 cells within 4 h. Corresponding to this, uptake of fluorescent labeled-LDL (3,3'-dioctadecylindocarbocyanine-LDL) by the cells increased linearly in time- and dose-dependent manner by MD-700 for up to 12 h. In the experiment using HepG2 cells transiently transfected with promoter-luciferase gene constructs, MD-700 increased luciferase activity in a dose-dependent manner from 0.03 to 0.1 microg/ml. In contrast, luciferase activity was not stimulated by MD-700 in construct with a deleted sterol regulatory element (SRE)-1, suggesting importance of SRE-1 in stimulation of the LDL receptor gene promoter by MD-700. Binding experiments on liver membranes from MD-700-treated hamsters showed about a 60% increase in 125I-labeled LDL binding. A Scatchard plot revealed that MD-700 increased the maximal binding without affecting binding affinity. In contrast to findings with an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, pravastatin, MD-700 had no effect on the sterol synthesis in hamster liver homogenates. These results suggest that MD-700 stimulates the expression of LDL receptor, presumably in a manner independent of change in sterol metabolism, and thereby promotes LDL clearance. Hypocholesterolemic actions of MD-700 in hamsters were then examined. MD-700 lowered serum cholesterol levels in hamsters fed normal chow or a high-fat diet. Fractionation of serum lipoproteins demonstrated that MD-700 selectively decreased LDL and very low density lipoprotein cholesterol. Dose-dependent decrease in serum cholesterol was also seen in hypercholesterolemic rats. Thus, the hypocholesterolemic action of MD-700 may be attributed to up-regulation of the LDL receptor, based on stimulation of the transcription of the LDL receptor gene. Although pravastatin stimulates LDL uptake and lowers serum cholesterol in a manner similar to that seen with MD-700, the mechanism responsible for hypocholesterolemic action appears to differ.

Behavioral evidence for modulation by sigma ligands of (+)MK-801-induced hyperlocomotion in monoamine-depleted mice.

The selective non-competitive N-methyl-D-aspartate (NMDA) antagonist (+)-5-methyl-10, 11-dihydro-5H-dibenzo(a, d)cyclohepten-5,10-imine maleate ((+)MK-801) led to a dose-dependent increase in locomotor activity in mice pretreated with a combination of reserpine and alpha-methyl-para-tyrosine (alpha-MT). A selective and potent sigma receptor "antagonist" NE-100 (N, N-dipropyl-2- [4-methoxy-3-(2-phenylethoxy)-phenyl]-ethylamine monohydrochloride), which did not per se affect spontaneous locomotor activity, did not prevent the locomotor stimulatory effects of (+)MK-801. Sulpiride, a dopamine D2 receptor antagonist, and clozapine, a dopamine D4 receptor antagonist, which decreased spontaneous locomotor activity, did not prevent the locomotor stimulatory effects of (+)MK-801. The sigma receptor "agonists" (+)N-allynormetazocine [(+)SKF10,047], (+)pentazocine and (+)-3-(3-hydroxyphenyl)-N-(1-propyl) piperidine [(+)3-PPP], which did not per se affect spontaneous locomotor activity, did dose-dependently enhance the hyperlocomotion induced by (+)MK-801. The enhancement of (+)MK-801-induced the hyperlocomotion by (+)SKF10,047, (+)pentazocine and (+)3-PPP was completely blocked by NE-100. The enhancement of (+)MK-801-induced hyperlocomotion by (+)pentazocine was not affected by treatment with sulpiride and clozapine. As sigma ligands can markedly attenuate NMDA antagonist-induced behavior, the major physiological role of sigma receptors in vivo might be to modulate functions of the NMDA receptor ion channel complex.

In vivo receptor occupancy of NRA0045, a putative atypical antipsychotic, in rats.

We have previously reported that (R)-(+)-2-amino-4-(4-fluorophenyl)-5-[1-[4-(4-fluorophenyl)-4-oxobutyl]+ ++pyrrolidin-3-yl]thiazole (NRA0045) is a novel antipsychotic agent with affinities for dopamine D4, 5-hydroxytryptamine 2A (5-HT2A) and alpha1 receptors. In the present study, in vivo receptor occupancy of 5-HT2A, alpha1, dopamine D2 and D3 receptors by NRA0045 was assessed, based on in vivo and ex vivo receptor binding, and findings were compared to reference antipsychotic drugs (haloperidol, risperidone, clozapine). Intraperitoneal administration of haloperidol highly occupied the dopamine D2 receptor in the striatum and nucleus accumbens, and alpha1 adrenoceptors in the frontal cortex. Occupation of the 5-HT2A receptor in the frontal cortex and the dopamine D3 receptor in the nucleus accumbens and islands of Cajella was moderate. By contrast, atypical antipsychotics such as risperidone and clozapine dose-dependently occupied the 5-HT2A receptor in the frontal cortex, with moderate to negligible occupancy of the D2 receptor in the striatum and the nucleus accumbens. Clozapine and risperidone also occupied the alpha1 adrenoceptor in the frontal cortex, and clozapine did not occupy the dopamine D3 receptor. As seen with other atypical antipsychotics, intraperitoneal administration of NRA0045 dose-dependently occupied the 5-HT2A receptor and the alpha1 adrenoceptor in the frontal cortex, while it was without effect on dopamine D2 and D3 receptors in the striatum, nucleus accumbens and islands of Cajella. Thus, the strong occupancy of 5-HT2A and alpha1 receptors is involved in the pharmacological action of NRA0045.

Synthesis and SAR of 1-alkyl-2-phenylethylamine derivatives designed from N,N-dipropyl-4-methoxy-3-(2-phenylethoxy)phenylethylamine to discover sigma(1) ligands.

The synthesis and structure-activity relationships (SAR) of 1-alkyl-2-phenylethylamine derivatives 5-8 designed from N, N-dipropyl-2-[4-methoxy-3-(2-phenylethoxy)phenyl]ethylamine hydrochloride (1, NE-100) are presented. The SAR between compound 1 and 1-alkyl-2-phenylethylamine derivatives suggested that the alkyl group on the 1-position carbon of 2-[4-methoxy-3-(2-phenylethyl)phenyl]ethylamine derivatives played the role of one of the propyl groups on the aminic nitrogen of compound 1. (-)-N-Propyl-1-butyl-2-[4-methoxy-3-(2-phenylethoxy)phenyl]ethylam ine hydrochloride ((-)-6d, NE-537) and (-)-N-propyl-1-(3-methybutyl)-2-[4-methoxy-3-(2-phenylethoxy )phenyl]e thylamine hydrochloride ((-)-6i, NE-535), typical compounds in this series, have potent and selective sigma(1) affinity.

The atypical antipsychotic profile of NRA0045, a novel dopamine D4 and 5-hydroxytryptamine2A receptor antagonist, in rats.

1. The atypical antipsychotic profile of (R)-(+)-2-amino-4-(4-fluorophenyl)-5-[1-[4-(4-fluorophenyl)-4-oxobutyl] pyrrolidin-3-yl] thiazole (NRA0045), a potent dopamine D4 and 5-hydroxytryptamine (5-HT)2A receptor antagonist, was examined in rats. 2. Spontaneous locomotor activity was decreased dose-dependently with i.p. administration of clozapine (ED50 3.7 mg kg-1), haloperidol (ED50 0.1 mg kg-1) and chlorpromazine (ED50 0.9 mg kg-1), whereas inhibition of this type of behaviour induced by i.p. administration of NRA0045, at doses up to 10 mg kg-1, did not exceed 50%. 3. Locomotor hyperactivity induced by methamphetamine (MAP, 2 mg kg-1, i.p.) in rats (a model of antipsychotic activity) was dose-dependently antagonized by NRA0045 (ED50 0.4 mg kg-1, i.p., and 0.3 mg kg-1, p.o., respectively), clozapine (ED50 0.3 mg kg-1, i.p. and 0.8 mg kg-1, p.o., respectively), haloperidol (ED50 0.02 mg kg-1, i.p. and 0.1 mg kg-1, p.o., respectively), chlorpromazine (ED50 0.3 mg kg-1, i.p. and 3.3 mg kg-1, p.o., respectively). In contrast, the MAP (3 mg kg-1, i.v.)-induced stereotyped behaviour in rats (a model of extrapyramidal symptoms) was not affected by NRA0045 or clozapine, at the highest dose given (30 mg kg-1, i.p.). Haloperidol (ED50 0.3 mg kg-1, i.p.) and chlorpromazine (ED50 4.8 mg kg-1, i.p.) strongly blocked the MAP-induced stereotyped behaviour. NRA0045 and clozapine selectively blocked behaviour associated with activation of the mesolimbic/mesocortical dopamine neurones rather than nigrostriatal dopamine neurones. 4. Extracellular single-unit recording studies demonstrated that MAP (1 mg kg-1, i.v.) decreased the firing rate in the substantia nigra (A9) and ventral tegmental area (A10) dopamine neurones in anaesthetized rats. NRA0045 completely reversed the inhibitory effects of MAP on A10 dopamine neurones (ED50 0.1 mg kg-1, i.v.), whereas the inhibitory effects of MAP on A9 dopamine neurones were not affected by NRA0045, in doses up to 1 mg kg-1 (i.v.). Clozapine completely reversed the inhibitory effects of MAP on A10 dopamine neurones (ED50 1.9 mg kg-1, i.v.) and on A9 dopamine neurones (ED50 2.5 mg kg-1, i.v.). Haloperidol completely reversed the inhibitory effects of MAP on A10 (ED50 0.03 mg kg-1, i.v.) and on A9 dopamine neurones (0.02 mg kg-1, i.v.). NRA0045, like clozapine, was more potent in reversing the effects of MAP on A10 than A9 dopamine neurones. 5. Prepulse inhibition (PPI) is impaired markedly in humans with schizophrenia. The disruption of PPI in rats by apomorphine (0.5 mg kg-1, s.c.) was reversed significantly by NRA0045 (3 mg kg-1, i.p.), clozapine (3 mg kg-1, i.p.) and haloperidol (0.3 mg kg-1, i.p.). 6. Phencyclidine (PCP) elicits predominantly psychotic symptoms in normal humans and in schizophrenics. NRA0045 (0.03-0.3 mg kg-1, i.p.) and clozapine (0.1-1 mg kg-1, i.p.) significantly and dose-dependently shortened the PCP(1.25 mg kg-1, i.p.)-induced prolonged swimming latency in rats in a water maze task, whereas haloperidol (0.01-0.1 mg kg-1, i.p.) did not significantly alter swimming latency. 7. These findings suggest that NRA0045 may have unique antipsychotic activities without the liability of motor side effects typical of classical antipsychotics.

Regulation of NMDA-induced [3H]dopamine release from rat hippocampal slices through sigma-1 binding sites.

To examine the interaction between ionotropic glutamate receptors and sigma binding sites, we made use of [3H]dopamine release from rat hippocampal slices. Agonists for ionotropic glutamate receptors such as N-methyl-D-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) and kainate evoked release of [3H]dopamine from rat hippocampal slices, in a dose-dependent manner. (+)-Pentazocine, a prototype sigma1 agonist, attenuated the NMDA-induced [3H]dopamine release dose-dependently and significantly as did non-competitive NMDA antagonists such as 5-methyl-10,11-dihydro-5H-dibenzo(a,b)cyclohepten-5,10-imine maleate (MK-801) and phencyclidine. In contrast, (+)-pentazocine had no effect on AMPA- or on kainate-induced [3H]dopamine release. Sigma-1 receptor antagonists including N,N-dipropyl-2-[4-methoxy-3-(2-phenylethoxy)phenyl] ethylamine monohydrochloride (NE-100), 1(cyclopropylmethyl)-4-(2'-(4"-fluorophenyl)-2'-oxoethylpiperidine (DuP734) and 1-(cyclopropylmethyl)-4-(2',4"-cianophenyl)-2'-oxoethyl)-pip eridine hydrobromide (XJ448) prevented significantly the inhibitory effect of (+)-pentazocine on NMDA-induced [3H]dopamine release, without affecting the release of [3H]dopamine evoked by NMDA. The inhibitory effect of (+)-pentazocine on [3H]dopamine release was preserved even in the presence of tetrodotoxin. These results suggest that sigma1 binding sites selectively interact with the NMDA receptor channel complex among ionotropic glutamate receptors, and that sigma1 binding sites may be involved in modulating the release of dopamine in the rat hippocampus by interacting with the NMDA receptor on dopaminergic nerve terminal.

Binding characteristics of [3H]DAA1106, a novel and selective ligand for peripheral benzodiazepine receptors.

Here, we investigated the binding characteristics of [3H]N-(2,5-dimethoxybenzyl)-N-(5-fluoro-2-phenoxyphenyl)acetamide ([3H]DAA1106), a potent and selective ligand for peripheral benzodiazepine receptors, in mitochondrial fractions of the rat brain. [3H]DAA1106 bound to the mitochondrial fraction of the rat brain in a saturable manner. The dissociation constant (Kd) and maximal number of binding sites (Bmax) obtained from Scatchard plot analysis of the saturation curve of [3H]DAA1106 binding were 0.12 +/- 0.03 nM and 161.03 +/- 5.80 fmol/mg protein, respectively. [3H]DAA1106 binding to mitochondrial preparations of the rat cerebral cortex was inhibited by several peripheral benzodiapine receptor ligands, and DAA1106 was the most potent inhibitor in inhibiting [3H]DAA1106 binding among the peripheral benzodiazepine receptor ligands we tested. The binding of [3H]DAA1106 was not affected by several neurotransmitter-related compounds, including adrenoceptor, gamma-aminobutyric acid (GABA), dopamine, 5-hydroxytryptamine (5-HT), acetylcholine, histamine, glutamate and central benzodiazepine receptor ligands even at a concentration of 10 microM. In the cerebral cortex of rhesus monkeys, DAA1106 and 1-(2-chlorophenyl)-N-methyl-(1-methylpropyl)-3-isoquinoline carboxamide (PK11195) potently inhibited [3H]DAA1106 binding, while 7-chloro-5-(4-chlorophenyl)-1-methyl-1,3-dihydrobenzo[e][1,4]diazepin -2-one (Ro5-4864) did not. The highest [3H]DAA1106 binding was observed in the olfactory bulb, followed by the cerebellum. In autoradiographic studies, practically the same results were obtained, in that the highest binding of [3H]DAA1106 was in the olfactory bulb. Potent labeling was also noted in ventricular structures such as the choroid plexus. Thus, [3H]DAA1106 is a potent and selective ligand for peripheral benzodiazepine receptors and should prove useful for elucidating the physiological relevance of events mediated through peripheral benzodiazepine receptors.

In vitro pharmacological profile of nonpeptide CRF1 receptor antagonists, CRA1000 and CRA1001.

We investigated pharmacological properties of CRA1000 (2-(N-(2-methylthio-4-isopropylphenyl)-N-ethylamino-4-(4-(3-fluoro phenyl)-1,2,3,6-tetrahydropyridin-1-yl)-6-methylpyrimidine) and CRA1001 (2-( N-(2-bromo-4-isopropylphenyl)-N-ethylamino-4-(4-(3-fluorophenyl)-1 ,2,3,6-tetrahydropyridin-1-yl)-6-methylpyrimidine), novel and selective antagonists for the corticotropin-releasing factor1 (CRF1) receptor. Both CRA1000 and CRA1001 inhibited [125I]ovine CRF binding to membranes of COS-7 cells expressing the rat CRF1 receptor with IC50 values of 30 and 38 nM, respectively, without affecting [125I]sauvagine binding to membranes of COS-7 cells expressing the rat CRF2alpha receptor. CRF elicited intracellular cyclic AMP (cAMP) accumulation in AtT-20 cells which express the CRF1 receptor but not the CRF2 receptor, and COS-7 cells expressing CRF1 or CRF2alpha receptors. The CRF-induced cAMP accumulation was inhibited by both CRA1000 and CRA1001, concentration-dependently, in AtT-20 cells and COS-7 cells expressing the CRF1 receptor, while these compounds did not attenuate the CRF response in COS-7 cells expressing the CRF2alpha receptor. CRF increased adrenocorticotropin (ACTH) secretion from AtT-20 cells, and CRA1000 and CRA1001 inhibited CRF-induced ACTH secretion, concentration-dependently, as did other CRF1 receptor antagonists. These results show that both CRA1000 and CRA1001 are potent and selective CRF1 receptor antagonists.

Improvement in cholesterol metabolism in mice given chronic treatment of taurine and fed a high-fat diet.

The effects of chronic treatment of taurine on hypercholesterolemia and atherosclerosis were examined in C57BL/6J mice fed a high-fat diet containing 15% fat and 1.25% cholesterol. Taurine was dissolved in drinking water at 1% (w/v) and was given to mice ad libitum during 6 months-feeding of a high-fat diet. Hypercholesterolemia occurred and lipid accumulation on the aortic valve was evident. Taurine treatment lowered serum LDL + VLDL cholesterol by 44% in mice fed a high-fat diet, while it elevated serum HDL cholesterol by 25%. As a result, the atherogenic index, the ratio of HDL to LDL + VLDL was markedly improved. Cholesterol content in the liver also decreased by 19% with taurine. Similar tendencies were seen in mice fed regular chow, but the changes were not significant. The area of aortic lipid accumulation, which served as an index of atherosclerosis, was reduced by 20% with taurine. In the liver, taurine doubled the activity of cholesterol 7alpha-hydroxylase. These observations, together with prior findings, suggest that the cholesterol-lowering action of taurine may relate to the increased conversion of cholesterol to bile acids via stimulation of cholesterol 7a-hydroxylase activity. Thus, chronic treatment of high-fat mice with taurine improves the abnormal profile of the serum lipoproteins, and thereby retards the progression of atherosclerosis.

Effects of selective dopamine D4 receptor blockers, NRA0160 and L-745,870, on A9 and A10 dopamine neurons in rats.

Extracellular single-unit activities of dopamine neurons were recorded using chloral hydrate anaesthetized rats. We examined the reversal effects of the selective dopamine D4 receptor blockers, NRA0160 (2-Carbamoyl-4-(4-fluorophenyl)-5-[2-[4-(3-fluorobenzylidene) piperidin-1-yl] ethyl] thiazole) and L-745,870 (3-[[4-(4-chlorophenyl) piperazin-1-yl] methyl]-1H-pyrrolo [2,3-b] pyridine), on dopamine agonists induced inhibition of dopamine neural activity. The firing rates of the substantia nigra pars compacta (A9) and the ventral tegmental area (A10) dopamine neurons were inhibited by methamphetamine (MAP: 1 mg/kg, i.v.) and apomorphine (APO: 40 microg/kg, i.v). NRA0160 dose-dependently reversed the inhibitory effects of MAP and APO on both A9 and A10 dopamine neurons. NRA0160 was more potent in reversing the inhibitory effects of both MAP and APO on A10 than A9 dopamine neurons. L-745,870 failed to reverse the inhibition produced by MAP on A9 and A10 dopamine neurons, whereas L-745,870, at the highest dose used, significantly reversed APO-induced inhibition of A10 but not A9 dopamine neurons. These results suggest that NRA0160 has different electrophysiological profiles on dopaminergic neural activity compared to L-745,870 and may have atypical antipsychotic effects.

Solubilization and characterization of binding sites for [3H]NE-100, a novel and potent sigma 1 ligand, from guinea pig brain.

The binding sites for [3H]NE-100, a newly defined sigma 1 ligand, was solubilized from guinea pig brain, using zwitterionic detergent 3-[(3-c holamidopropyl) dimethylamino]-1-propanesulfonate (CHAPS), and the properties of the solubilized binding sites were compared to those for [3H](+)-pentazocine, a selective sigma 1 ligand. The pharmacological selectivity of solubilized sites for both [3H]NE-100 and [3H](+)-pentazocine was identical to that obtained from membrane preparations. Stereoselectivity of benzomorphan such as pentazocine and SKF10,047 was preserved in displacing [3H]NE-100 binding in solubilized preparations as observed in membrane preparations. The inhibitory potencies of several sigma ligands on [3H]NE-100 binding were similar to those on [3H](+)-pentazocine binding, indicating that the pharmacological characteristics of the binding sites for [3H]NE-100 are retained after solubilization. Phenytoin augmented the binding of [3H](+)-3-(3-hydroxyphenyl)-N-(1-propyl) piperidine hydrochloride (3-PPP) to solubilized sigma binding sites while it had no effect on the binding of [3H]NE-100. Furthermore, the inhibitory effect of putative sigma receptor agonists such as (+)-3-PPP and dextromethorphan were enhanced by phenytoin; the effects of haloperidol, a putative sigma receptor antagonist, were unaltered. Molecular weight of [3H]NE-100 binding protein was estimated to be 440KDa by Sepharose CL-6B gel filtration chromatography, and the value was identical to that of [3H](+)-pentazocine binding protein, a putative sigma 1 binding protein. These findings indicate that [3H]NE-100 binding sites are putative sigma 1 binding sites, and that NE-100 may act as an antagonist at sigma 1 binding sites.

Neuropharmacological profile of peripheral benzodiazepine receptor agonists, DAA1097 and DAA1106.

Receptor binding and behavioral profiles of N-(4-chloro-2-phenoxyphenyl)-N-(2-isopropoxybenzyl)acetamide (DAA1097) and N-(2,5-dimethoxybenzyl)-N-(5-fluoro-2-phenoxyphenyl)acetamide (DAA1106), novel, selective agonists for the peripheral benzodiazepine receptor (PBR) were examined. DAA1097 and DAA1106 inhibited [3H]PK 11195 binding to crude mitochondrial preparations of rat whole brain, with IC50 values of 0.92 and 0.28 nM. Likewise, DAA1097 and DAA1106 inhibited [3H]Ro 5-4864 binding to the same mitochondrial preparation, with IC50 values of 0.64 and 0.21 nM. In contrast, DAA1097 and DAA1106 did not inhibit [3H]-flunitrazepam, the central benzodiazepine receptor (CBR) ligand, binding to membranes of rat whole brain (IC50>10,000nM). Oral administration of DAA1097 and DAA1106 had anxiolytic effects in the mouse light/dark exploration test and in the rat elevated plus- maze test. Oral administration of DAA1106, diazepam and buspirone but not DAA1097 significantly increased sleeping time in hexobarbital-induced anesthesia in mice. The order of potency of potentiation of hexobarbital anesthesia was diazepam> buspirone> DAA1106> DAA1097. Oral administration of DAA1097 and DAA1106 but not diazepam and buspirone did not affect spontaneous locomotor activity in mice. These findings indicate that DAA1097 and DAA1106 are PBR selective ligands with potent anxiolytic-like properties, in laboratory animals.

Neuroprotective effect of 4'-(4-methylphenyl)-2,2':6',2-terpyridine trihydrochloride, a novel inducer of nerve growth factor.

We have identified 4'-(4-methylphenyl)-2,2':6',2-terpyridine: trihydrochloride (SS701), which belongs to a family of a small unique neuroprotective agents. SS701 accelerated the production of nerve growth factor (NGF) in cultured astroglial cells, dose- and time-dependently. In in vivo studies, SS701, when administered 30 min after induced cerebral ischemia, neuroprotective effects on delayed neuronal death in Mongolian gerbils were evident. The neuroprotective effects of SS701 against ischemia-induced delayed neuronal death are attributed to stimulation of the production of NGF.

A selective dopamine D4 receptor antagonist, NRA0160: a preclinical neuropharmacological profile.

NRA0160, 5 - [2- ( 4- ( 3 - fluorobenzylidene) piperidin-1-yl) ethyl] - 4 -(4-fluorophenyl) thiazole-2-carboxamide, has a high affinity for human cloned dopamine D4.2, D4.4 and D4.7 receptors, with Ki values of 0.5, 0.9 and 2.7 nM, respectively. NRA0160 is over 20,000fold more potent at the dopamine D4.2 receptor compared with the human cloned dopamine D2L receptor. NRA0160 has negligible affinity for the human cloned dopamine D3 receptor (Ki=39 nM), rat serotonin (5-HT)2A receptors (Ki=180 nM) and rat alpha1 adrenoceptor (Ki=237 nM). NRA0160 and clozapine antagonized locomotor hyperactivity induced by methamphetamine (MAP) in mice. NRA0160 and clozapine antagonized MAP-induced stereotyped behavior in mice, although their effects did not exceed 50% inhibition, even at the highest dose given. NRA0160 and clozapine significantly induced catalepsy in rats, although their effects did not exceed 50% induction even at the highest dose given. NRA0160 and clozapine significantly reversed the disruption of prepulse inhibition (PPI) in rats produced by apomorphine. NRA0160 and clozapine significantly shortened the phencyclidine (PCP)-induced prolonged swimming latency in rats in a water maze task. These findings suggest that NRA0160 may have unique antipsychotic activities without the liability of motor side effects typical of classical antipsychotics.

Effect of VA-045, a novel apovincaminic acid derivative, on closed head injury-induced neurological dysfunction in aged rats.

Effects of VA-045, a novel apovincaminic acid derivative, on behavioral outcome following closed head injury (CHI) were examined in aged (21-28 months) rats. CHI was induced by dropping a 400 g weight through a tube from 150 cm above a steel helmet placed on the vertex. Beam balancing latency, neurological deficits and body weight were recorded before CHI and for up to 14 days after CHI. When compared with the sham group, all measurements of parameters of behavioral outcome in the CHI group were significantly worsened after CHI. Intraperitoneal administration of VA-045 (1 and 3 mg kg-1) or thyrotropin-releasing hormone (TRH, 10 mg kg-1) and vehicle was started 24 h after CHI, and continued once daily for 13 days. VA-045 but not TRH significantly overcame the CHI-induced neurological deficits, shortened the latency of beam balancing and decreased body weight loss. VA-045 may prove useful for treating aged patients with disturbances of consciousness or motor deficits after CHI.

Prevention of atherosclerotic lesion development in mice by taurine.

The antiatherosclerotic effects of taurine were evaluated in two murine models. In C57BL/6J mice fed a high-fat diet, 6-month treatment with taurine decreased serum atherogenic low-density lipoprotein (LDL) and very low-density lipoprotein (VLDL) cholesterol by 44%. The same treatment increased antiatherogenic high-density lipoprotein (HDL) cholesterol by 25%. Hepatic cholesterol content was also decreased by taurine. Taurine improved the area of oil red O positive arterial lipid accumulation by 20%. Hepatic cholesterol 7 alpha-hydroxylase activity, a rate-limiting enzyme of bile acid synthesis from cholesterol, was doubled in taurine-treated mice, suggesting stimulation of cholesterol catabolism to bile acid as the cholesterol-lowering mechanism seen with taurine. Thus, taurine prevented the progression of atherosclerotic lesions, and concomitantly improved the serum lipoprotein profile. In another murine model, in apolipoprotein-E-deficient mice fed regular chow, a 3-month treatment with taurine prevented accumulation of arterial lipids by 31%, despite a significant increase in serum LDL and VLDL cholesterol levels. Serum thiobarbituric acid reactive substances (TBARS) in apolipoprotein-E-deficient mice were significantly higher than those in wild type mice and treatment with taurine lowered serum TBARS level by 26%. Thus, taurine prevents the development of atherosclerotic lesions and this antioxidative effect may play an important role in the antiatherosclerotic effect that is unrelated to serum cholesterol levels.

Immunopharmacological studies of new 3-benzoyl-4-mercaptobutyric acid derivatives. II. Immunosuppressive effects.

A number of D-penicillamine (PA) derivatives (3-benzoyl-4-mercaptobutyric acids) with an acetylthio group on the gamma-position of the carboxylic acid were synthesized. Their immunological effects were examined and compared with PA and other immunosuppressors. PA derivatives suppressed adjuvant-induced arthritis in SD and Lewis rats, suppressed delayed-type hypersensitivity and IgE antibody response in mice, and prolonged the survival time of NZBXNZW F1 hybrid (BWF1) mice, as did immunosuppressors. In vitro, PA derivatives suppressed lymphocyte transformation and the proliferation of KB cells. 4-Acetylthio-3-[-4-(4-chlorophenyl)benzoyl]butyric acid was the most effective of the PA derivatives. Thus, these PA derivatives with an acetylthio group on the gamma-position of the carboxylic acid showed immunosuppressive effects and, furthermore, substitution of the halogen atom on the phenyl group increased immunosuppressive activities.

Inhibition of gastric H+, K(+)-ATPase by flavonoids: a structure-activity study.

Gastric H+, K(+)-ATPase plays a pivotal role in the final step of gastric acid secretion. Over 80 flavonoids, including flavones, flavanones, isoflavones and anthocyanidins were examined for their in vitro effect on gastric H+, K(+)-ATPase and some were found to be inhibitors of this enzyme. Kinetic studies showed that the inhibition of H+, K(+)-ATPase by flavonoids was competitive with respect to ATP, and non-competitive with respect to K+. Structure-activity analysis revealed the following: (1) The inhibitory potency of flavonoids depends on the number of hydroxyl groups up to four per molecule and that above this, no marked enhancement is seen; (2) The hydroxylation pattern is an important determinant of inhibitory potency. Two adjacent hydroxyl groups (catechol-type), three adjacent hydroxyl groups (pyrogallol-type) or hydroxyl groups at C-3, C-5 and C-7 are a minimum requirement for high potency inhibition; (3) Protection of the hydroxyl group(s) by glycosylation or methylation decreases potency; (4) Saturation of the C-2-C-3 double bond results in a decrease in potency; and (5) A ketone at C-4 is not essential for inhibition.

Immunopharmacological studies of new 3-benzoyl-4-mercaptobutyric acids. Immunomodulating effects.

A number of D-penicillamine (PA) derivatives (3-benzoyl-4-mercaptobutyric acids) having acetylthio groups on an alpha or beta position of a carboxylic acid, were synthesized and examined for their immunological effects compared with PA. New PA derivatives suppressed adjuvant-induced arthritis (AA) in SD rats and enhanced AA in Lewis rats like PA. Suppressive effects of 2-acetylthiomethyl-3-(4-methyl-benzoyl)propionic acid (compound II-3) on AA in SD rats was most potent among PA derivatives and PA. II-3 enhanced type II collagen-induced arthritis in rats more effectively than PA, and it slightly prolonged the survival time of NZBXNZW hybrid (BWF1) mice. Hemolytic plaque forming cells in the spleen cells of BDF1 and aged Balb/c mice were potentiated but those of BWF1 were suppressed by both compounds. In in vitro experiments, both compounds enhanced lymphocyte transformation. On the contrary, II-3 had no effect on the acute inflammatory response, delayed type hypersensitivity and IgE antibody response. The abnormal release of lysosomal enzymes from the peritoneal macrophages of aged MRL/l mice were suppressed by both compounds. These results suggest that II-3 is an immunomodulator like PA but more effective than PA. II-3 may be clinically effective for rheumatoid arthritis.