Ontogenetic pattern of gyrification in fetuses of cynomolgus monkeys.

The ontogenetic pattern of gyrification and its relationship with cerebral cortical volume were examined in cynomolgus monkey fetuses. T(1)-weighted coronal magnetic resonance (MR) images at 7 T were acquired from the fixed cerebra of three male fetuses, each at embryonic days (EDs) 70 to 150, and the gyrification index (GI) of each slice was estimated. The mean GI was low (1.1-1.2) during EDs 70 to 90, and then increased dramatically on ED 100. The developmental profiles of the rostrocaudal GI distribution revealed that cortical convolution was more frequent in the parietooccipital region than in other regions during EDs 100 to 150, forming an adult-like pattern by ED 150. The mean GI was closely correlated with the volume of cortical gray matter (r=0.9877), and also with the volume of white matter/intermediate zone (r=0.8961). These findings suggest that cortical convolution is correlated with either the maturation of cortical gray matter or the development of white matter bundles. The characteristic GI distribution pattern of catarrhines was formed by ED 150 in correlation with the progressive sulcal infolding in the parietooccipital region of the cerebrum.

The effects of danaparoid, dalteparin and heparin on tissue factor-induced experimental disseminated intravascular coagulation and bleeding time in the rat.

Danaparoid and heparin, on the basis of anti-activated factor X (anti-FXa) activity, were equipotent in accelerating the rate of interaction of FXa and antithrombin III. In rat tissue factor-induced disseminated intravascular coagulation (DIC) models, an intravenous administration of danaparoid inhibited the decrease in plasma fibrinogen and platelet counts and the increase in serum fibrinogen degradation products. Expressed on the basis of anti-FXa activity, these effects were comparable with those of dalteparin and heparin. In rat mesenteric small artery and vein, less bleeding was observed after intravenous administration of danaparoid than after dalteparin or heparin. Danaparoid did not affect adenosine diphosphate- or collagen-induced platelet aggregation, and showed weaker inhibitory effects on aggregation induced by thrombin, or collagen + thrombin, than did dalteparin or heparin. These findings suggest that danaparoid may be useful for the prevention of DIC and has less tendency to cause bleeding than dalteparin or heparin, probably as a result of its weaker ability to inhibit platelet aggregation.

Selective effects of lomerizine, a novel diphenylmethylpiperazine Ca2+ channel blocker, on cerebral blood flow in rats and dogs.

1. In the present study we examined the effects of a new Ca2+ channel blocker (lomerizine), an antimigraine drug, on cerebral cortical blood flow (CBF) in anaesthetized rats (laser Doppler flowmetry) and on vertebral blood flow in anaesthetized beagle dogs (electromagnetic flowmeter). 2. Lomerizine (1.25-10 mg/kg, p.o.) dose-dependently increased CBF in rats without affecting blood pressure (BP) or heart rate (HR). 3. The plasma concentration of lomerizine (free base) in anaesthetized rats at 30 and 60 min after the initial administration of 5 mg/kg, p.o., time at which there was a significant increase in CBF, was similar to that reported in healthy subjects receiving lomerizine at 10 mg (2 x 5 mg)/day, p.o., a dose that significantly reduces the frequency and mean duration of headache attacks. 4. Flunarizine (10 mg/kg, p.o.) did not increase CBF significantly. Flunarizine (20 mg/kg, p.o.) did not increase CBF, but did decrease BP 30-120 min after its administration. 5. Lomerizine (2.5 and 5 mg/kg, intraduodenally) dose-dependently increased vertebral blood flow in dogs without significantly changing BP or HR. With 10 mg/kg intraduodenal lomerazine, vertebral blood flow remained elevated from 20 to 240 min after administration and BP was decreased from 20 to 120 min. 6. Thus, lomerizine had a greater effect on CBF than on BP and HR and, therefore, it may be clinically effective in conditions associated with circulatory disturbances in the brain, such as migraine, without producing systemic effects (e.g. hypotension) generally seen with other Ca2+ channel blockers.

Effects of 16 weeks of treatment with tibolone on bone mass and bone mechanical and histomorphometric indices in mature ovariectomized rats with established osteopenia on a low-calcium diet.

Tibolone is a synthetic steroid with tissue-specific estrogenic, progestogenic, and androgenic properties. The therapeutic effects of tibolone on bone mass and strength, bone metabolic markers, and indices of histomorphometry were investigated in ovariectomized (ovx) rats on a low (0.1%)-calcium diet in comparison with 17alpha-ethynylestradiol (EE) or 1alpha-hydroxyvitamin D3 [1alpha(OH)D3]. Tibolone (0.1-3 mg/kg/day), EE (0.1 mg/kg/day), or 1alpha(OH)D3 (0.5 microg/kg/day) was administered orally once a day for 16 weeks, starting 12 weeks after ovariectomy, when the bone mineral density (BMD) of lumbar vertebrae (L4-5) and femur (global, proximal, and distal regions) had already been decreased by the combination of ovariectomy and low dietary calcium. The BMD of the lumbar vertebrae and the femur were higher in the groups treated with tibolone, EE, or 1alpha(OH)D3 than in the ovx control group. The BMD of the mid-diaphysial regions of femur and tibia, which consist mainly of cortical bone, were decreased 28 weeks after ovariectomy in the ovx control group. The BMD of the mid-diaphysial femur was higher in the groups treated with 1alpha-(OH)D3, and the BMD of mid-diaphysial tibia was higher in the groups treated with tibolone or 1alpha(OH)D3 than in the ovx control group. Like BMD, the compressive strength of the vertebral body of L2, corrected for the volume of each individual vertebra tested, was higher in the groups treated with tibolone, EE, or 1alpha(OH)D3 than in the ovx control group. Trabecular bone volume and trabecular number were reduced 12 and 28 weeks after ovariectomy but there was no change in trabecular thickness. These reduced indices were increased in the groups treated with tibolone, EE, or 1alpha(OH)D3 when compared with the ovx control group. Tibolone or EE decreased serum levels of osteocalcin and bone alkaline phosphatase and urinary levels of deoxypyridinoline and pyridinoline compared with the ovx control group. Furthermore, tibolone or EE decreased the mineralizing surface and bone formation rate as well as the osteoclast surface and osteoclast numbers. 1Alpha(OH)D3, however, did not affect these serum and urinary parameters. These data suggest that tibolone suppresses the accelerated bone turnover induced by a combination of ovariectomy and low dietary calcium, and indicate that tibolone may be a potentially useful drug for the treatment of postmenopausal osteoporosis.

Improvement of cisplatin-induced emesis and delayed gastric emptying by KB-R6933, a novel 5-HT3 receptor antagonist.

The effects of a novel 5-hydroxytryptamine3 (5-HT3) receptor antagonist, KB-R6933, 6-amino-5-chloro-1-isopropyl-2-(4-methyl-1-piperazinyl)-benzimidazole dimaleate, on emesis and delayed gastric emptying induced by cisplatin were assessed in experimental models. Prophylactic intravenous or oral treatment with KB-R6933 prolonged the latent period until the first emetic episode and decreased the number of emetic episodes induced by cisplatin in ferrets. KB-R6933 immediately inhibited the subsequent emesis when administered to the ferrets which exhibited established vomiting after administration of cisplatin. In rats treated with cisplatin, the gastric emptying rate was significantly reduced. KB-R6933 reversed the reduction of gastric emptying induced by cisplatin. These results suggest that KB-R6933 is an antiemetic agent, and could improve the cisplatin-induced delay of gastric emptying.

Selective 5-hydroxytryptamine3 (5-HT3) receptor blocking activity of KB-R6933, a novel benzimidazole derivative.

5-Hydroxytryptamine3 (5-HT3)-receptor blocking activities of KB-R6933 (6-amino-5-chloro-1-isopropyl-2-(4-methyl-1-piperazinyl)-benzimidazole dimaleate) were assessed in vivo and in vitro. Intravenous administration of KB-R6933, granisetron, ondansetron and azasetron inhibited 5-HT-induced bradycardia (von Bezold-Jarisch reflex) in anesthetized rats, with ED50 values of 0.071, 0.71, 4.0 and 0.82 microg/kg, respectively. The inhibitory effect of KB-R6933 at a dose of 0.3 microg/kg lasted for at least 8 hr, whereas those of granisetron at 30 microg/kg, ondansetron at 100 microg/kg and azasetron at 30 microg/kg nearly disappeared within 2-4 hr. Oral administration of KB-R6933 and granisetron also inhibited the bradycardia, with ED50 values of 0.41 and 76.3 microg/kg, respectively. In guinea pig ileum, KB-R6933 concentration-dependently antagonized 5-HT-evoked contraction and reduced the maximal contraction (pK(B)=8.75). Granisetron, ondansetron and azasetron shifted the dose-response curve for 5-HT to higher concentrations with no reduction of maximal contraction, and their pK(B)s were 7.65, 7.00 and 6.29, respectively. In a radioligand receptor binding study, KB-R6933, granisetron, ondansetron and azasetron displaced [3H]GR65630 binding to rat entorhinal cortex membrane, with Ki values of 0.066, 0.99, 2.70 and 2.5 nM, respectively. On the other hand, KB-R6933 exhibited negligible affinities for other receptors or binding sites tested, except for a weak affinity for the cholinergic M1-receptor, even at concentrations up to 10 microM. These results suggest that KB-R6933 is a potent and selective 5-HT3-receptor antagonist with a longer duration of action than those of existing 5-HT3-receptor antagonists.

Effect of the 5-hydroxytryptamine3 (5-HT3)-receptor antagonist KB-R6933 on experimental diarrhea models.

The effects of a 5-hydroxytryptamine3 (5-HT3)-receptor antagonist KB-R6933 (6-amino-5-chloro-1-isopropyl-2-(4-methyl-1-piperazinyl)-benzimidazole dimaleate) on experimental diarrhea and on intestinal fluid secretion stimulated by cholera toxin were examined and compared with those of ramosetron and loperamide. KB-R6933 and ramosetron (0.03-1 mg/kg, p.o.) inhibited the diarrhea induced by 5-HT, but not that by castor oil or prostaglandin E2 (PGE2), in mice. Loperamide significantly inhibited the diarrhea induced by 5-HT, castor oil and PGE2. All drugs tested inhibited the diarrhea induced by restraint stress and the intestinal fluid secretion stimulated by cholera toxin in rats. The results suggest the possibility that KB-R6933 may have clinical efficacy in the treatment of diarrhea.

The effect of danaparoid sodium (danaparoid) on endotoxin-induced experimental disseminated intravascular coagulation (DIC) in rats.

Danaparoid sodium (danaparoid) is a low molecular weight heparinoid with anticoagulation properties, which mainly consists of heparan sulfate. Compared with heparin sodium (heparin), danaparoid has a much higher anti-Xa/anti-thrombin ratio. We compared the effect of danaparoid on endotoxin-induced experimental disseminated intravascular coagulation (DIC) in rats with heparin. A bolus injection of endotoxin (10 mg/kg) induced gradual decreases in the platelet count, and the plasma fibrinogen, antithrombin III (AT-III) and heparin cofactor II levels, as well as an increase in the fibrinogen/fibrin degradation products level from 1 to 6 hours after the injection, indicating that both coagulation and fibrinolysis were activated. The intravenous administration of danaparoid or heparin 3 hours after the endotoxin injection inhibited the endotoxin-induced decreases in the platelet count and plasma fibrinogen level and also inhibited the endotoxin-induced increase in glomerular fibrin deposition in the kidney. Differences between danaparoid and heparin were observed in their effects on the plasma AT-III level and clotting time. Danaparoid significantly inhibited both the decrease in the plasma AT-III level and the prolongation of the prothrombin time induced by endotoxin, where as heparin showed no effect on those responses. Moreover, danaparoid enhanced the prolongation of the activated partial thromboplast in time induced by endotoxin to a lesser degree than heparin. These findings suggest that the effects of danaparoid on the endotoxin-induced decrease of the plasma AT-III level and the prolongation of the clotting time are more advantageous than those of heparin. The results may have been due to a higher anti-Xa/anti-thrombin ratio of danaparoid than that of heparin, indicating that danaparoid may be useful in the treatment of DIC.

[Effects of an antidiarrhoeica containing an extract from geranium herb on astringent action and short-circuit current across jejunal mucosa].

A consists of berberine chloride and an extract from geranium herb. To clarify mechanisms of the antidiarrheal effect of Phelloberin-A, we investigated the astringent action by determining its binding activity to rabbit hemoglobin and effects on active transport, which was indicated by short-circuit current (Isc), in rat jejunum by the Ussing chamber technique. The effects of berberine chloride and geranium herb on both the binding activity to hemoglobin and the electrophysiological parameters such as Isc were compared with those of the antidiarrhoeicas, tannic acid, albumin tannate and bismuth subnitrate. Geranium herb, tannic acid and bismuth subnitrate increased significantly the binding activity to hemoglobin at concentrations of > 1 mg/ml, > 0.3 mg/ml and 10 mg/ml, respectively, but berberine or albumin tannate did not. Geranium herb and tannic acid dose-dependently and moderately increased Isc in rat jejunal mucosa and the increase became significant at a concentration of 10 mg/ml. Neither berberine chloride, albumin tannate nor bismuth subnitrate affected Isc. In contrast, cholera toxin, which increases the secretion from intestinal mucosa to the lumen and induces diarrhea, decreased Isc at a concentration of 0.1 mg/ml. The decrease of Isc induced by cholera toxin was antagonized by pretreatment with geranium herb (10 mg/ml), indicating that geranium herb inhibited the toxin-induced increase in secretion. These results suggest that geranium herb possesses an astringent action and moderately increases Isc across the intestinal mucosa. Therefore, the effects may support an antidiarrheal effect of both geranium herb and Phelloberin-A.

Effects of tibolone (Org OD14) treatment for 3 months on ovariectomy-induced osteopenia in 8-month-old rats on a low-calcium diet: preventive testing for 3 months.

Tibolone (Org OD14), (7alpha, 17alpha)-17-hydroxy-7-methyl-19-norpregn-5(10)-en-20-yn++ +-3-one, is a synthetic steroid with weak estrogenic, progestational, and androgenic properties. We investigated the prophylactic effects of tibolone on bone loss, bone strength, and plasma and urinary parameters in 8-month-old ovariectomized rats on a low-Ca diet. Oral administration of tibolone (0.03-3 mg/kg/day) was started immediately after ovariectomy (ovx) and continued for 3 months. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry. Oral administration of tibolone (1 or 3 mg/kg/day) significantly prevented a decrease in BMD and bone ash density (bone ash weight/volume) of the global femur, and BMDs in the femoral distal and proximal regions. Also in the lumbar vertebrae, the ovx-induced reduction in BMD was prevented by tibolone (1 and 3 mg/kg/ day) treatment, resulting in a significantly higher lumbar vertebral (L-2) bone compression strength compared to the ovx control group. Neither ovx alone nor supplemented with tibolone affected the BMD or bending strength of the femoral mid-diaphysial region. Tibolone (0.03-3 mg/kg/day) significantly reduced the ovx-induced increases in serum osteocalcin level. Furthermore, tibolone inhibited an increase in the urinary hydroxyproline/creatinine, pyridinoline/creatinine, and deoxypyridinoline/creatinine ratios induced by ovx. Tibolone also reduced body weight gain and serum cholesterol level, as has been reported for estrogen. These findings indicate that tibolone prevents reduction in bone mass associated with osteopenia by reducing increased trabecular bone resorption induced by a combination of ovx and a low-Ca diet.

[Anti-migraine effects of lomerizine].

Lomerizine, a novel Ca2+ channel blocker, is under development as an anti-migraine drug. We examined the effects on spreading depression (SD) induced by a brief period of hypoxia (40 to 60 sec) in rat hippocampal slices, the cortical hypoperfusion and cortical c-Fos-like immunoreactivity that follow KCl-induced SD in anesthetized rats as compared with those of flunarizine. Extracellular recording was made from the CA1 subfield. The latency of initiated SD was examined. Lomerizine (1 and 10 nM) and flunarizine (1 microM) significantly prolonged the latency in a concentration-dependent manner. After KCl application to the cortex, cerebral blood flow monitored by the laser Doppler flowmetry was approximately 20 to 30% below baseline for at least 60 min. Lomerizine (0.3 and 1 mg/kg, i.v.) and flunarizine (1 and 3 mg/kg, i.v.) administered 5 min before KCl application inhibited the cortical hypoperfusion that followed KCl application. c-Fos-like immunoreactivity, an indicator of neuronal activation, was detected in the ipsilateral, but not in the contralateral frontoparietal cortex 2 hr after KCl application. Lomerizine (3-30 mg/kg, p.o.) and flunarizine (30 mg/kg, p.o.) significantly attenuated the expression of c-Fos-like immunoreactivity in the ipsilateral frontoparietal cortex. Lomerizine was 3 to 1000 times more potent than flunarizine in the above SD models. These findings suggest that the inhibitory effects of lomerizine and flunarizine on the interval between the initiated and subsequent spontaneous SDs, the cortical hypoperfusion and expression of c-Fos-like immunoreactivity induced by SD are mediated via the effects of Ca2+ entry blockade, which may include an increase in cerebral blood flow and the prevention of excessive Ca2+ influx into brain cells.

Inhibitory effect of lomerizine, a diphenylpiperazine Ca2+-channel blocker, on Ba2+ current through voltage-gated Ca2+ channels in PC12 cells.

We investigated the effect of lomerizine, an anti-migraine drug, on the Ba2+ current through voltage-gated Ca2+ channels in rat pheochromocytoma (PC12) cells using a whole-cell voltage-clamp technique. Lomerizine inhibited the Ba2+ current with an IC50 value of 1.9 microM. Lomerizine and nicardipine were >4 times more potent than flunarizine, diltiazem, verapamil and dimetotiazine. The time course of inactivation induced by lomerizine was similar to that induced by nicardipine and flunarizine. These data indicate that lomerizine may inhibit the Ca2+ channel in a similar manner to nicardipine and flunarizine, and its potency is almost equal to that of nicardipine.

Synthesis and structure-activity relationships of novel phenylcyanoguanidine derivatives as potassium channel openers.

3,5-Di-substituted phenylcyanoguanidine derivatives with halogen, cyano and/or nitro groups at the 3- and 5-positions of the benzene ring exhibited very strong smooth muscle relaxation activity in vitro, as compared to pinacidil. Among them, N-(3-chloro-5-cyanophenyl)-N'-cyano-N" -tert-pentylguanidine (5s) showed 27-fold more potent activity than pinacidil, and exhibited a stronger and more lasting antihypertensive effect than pinacidil by oral administration to spontaneously hypertensive rats. We propose a new pharmacophore model in which the essential factors for binding to the potassium channel are an NH and a bulky alkyl group.

[Antinociceptive effects of Kami-kihi-to in mice].

Oral administration of Kami-kihi-to (KMK) dose-dependently inhibited the response to acetic acid-induced writhing in mice. The KMK-induced antinociceptive action was reduced by pretreatment with yohimbine, an alpha 2-adrenergic antagonist, or cyproheptadine, a serotonergic antagonist, but not naloxone, an opiate antagonist. The antinociceptive action of KMK was clearly reduced by pretreatment with alpha-methyl-DL-p-tyrosine, reserpine or p-chlorophenylalanine or by simultaneous treatment with diethyldithiocarbamate, all of which are monoamine synthetic inhibitors or monoamine depletors. After spinal transection, the antinociceptive effect of KMK was markedly reduced. These findings suggest that the antinociceptive action of KMK may be related to pain inhibitory systems such as the serotonergic and noradrenergic systems at the supraspinal level.

Six trigalactosylceramides from the leech (Hirudo nipponica).

Six neutral glycosphingolipids were isolated in the pure state from the leech, Hirudo nipponica (Annelida). In contrast to the zwitterionic monogalactosylceramides carrying a choline phosphate group so far obtained, all compounds are non-zwitterionic glycosphingolipids, trigalactosylceramides. Five compounds possess a Ga1 alpha 1-6Ga1 alpha 1-6Ga1 beta 1-Cer core, and one is unique in having a Ga1 alpha 1-6Ga1 beta 1-Cer structure. Their full structures have been determined on the bases of chemical and spectral evidence.

Effects of Ca2+ channel blockers on cortical hypoperfusion and expression of c-Fos-like immunoreactivity after cortical spreading depression in rats.

1. We examined the effects of two Ca2+ channel blockers, lomerizine (KB-2796) and flunarizine, on the cortical hypoperfusion (measured by hydrogen clearance and laser Doppler flowmetry methods) and cortical c-Fos-like immunoreactivity that follow KCl-induced cortical spreading depression in anaesthetized rats. Cortical spreading depression was induced by application of 1 M KCl for 30 s to the cortical surface, 3.0 mm posterior to the area of cerebral blood flow measurement. 2. In control rats, KB-2796 (0.3 and 1 mg kg-1, i.v.) dose-dependently increased cerebral blood flow significantly at 30 min and 15 min, respectively, after its administration. Flunarizine (1 mg kg-1, i.v.) significantly increased cerebral blood flow 15 min after its administration. In contrast, dimetotiazine (3 mg kg-1, i.v.), a 5-HT2 and histamine H1 antagonist, failed to affect cerebral blood flow significantly. 3. After KCl application to the cortex, cerebral blood flow monitored by the laser Doppler flowmetry method increased transiently, for a few minutes, then fell and remained approximately 20 to 30% below control for at least 60 min. Cerebral blood flow monitored by the hydrogen clearance method was also approximately 20 to 30% below baseline for at least 60 min after KCl application. KB-2796 (0.3 and 1 mg kg-1, i.v.) and flunarizine (1 and 3 mg kg-1, i.v.) administered 5 min before KCl application inhibited the cortical hypoperfusion that followed KCl application, but dimetotiazine (1 and 3 mg kg-1, i.v.) did not. 4. An indicator of neuronal activation, c-Fos-like immunoreactivity, was detected in the ipsilateral, but not in the contralateral frontoparietal cortex 2 h after KCl application. No c-Fos-like immunoreactivity was seen on either side of the brain in the hippocampus, thalamus, striatum or cerebellum. 5. KB-2796 (1 mg kg-1, i.v.) and flunarizine (3 mg kg-1, i.v.), but not dimetotiazine (3 mg kg-1, i.v.), significantly attenuated the expression of c-Fos-like immunoreactivity in the ipsilateral frontoparietal cortex. 6. These findings suggest that the inhibitory effects of KB-2796 and flunarizine on the cortical hypoperfusion and expression of c-Fos-like immunoreactivity induced by spreading depression are mediated via the effects of Ca(2+)-entry blockade, which may include an increase in cerebral blood flow and the prevention of excessive Ca2+ influx into brain cells. KB-2796 and flunarizine may prove useful as inhibitors of cortical spreading depression in migraine.

Binding properties of KB-5492, a novel anti-ulcer agent, at sigma receptors in porcine gastric fundic mucosa.

We examined the effects of KB-5492, 4-methoxyphenyl 4-(3,4,5-trimethoxybenzyl)-1-piperazine acetate monofumarate monohydrate, a novel anti-ulcer agent and a selective sigma receptor ligand, on specific [3H](+)-N-allyl-normetazocine (SKF 10,047) and [3H]1,3-di(2-tolyl)guanidine (DTG) binding in porcine gastric fundic mucosa. KB-5492 inhibited specific [3H](+)-SKF 10,047 binding in a competitive manner and specific [3H]DTG binding in a non-competitive manner. The Ki value of KB-5492 on specific [3H]DTG binding (Ki = 4.6 microM) was 8.4-fold higher than that on specific [3H](+)-SKF 10,047 binding (Ki = 0.55 microM). Computer-assisted analysis of the displacement curve of KB-5492 for specific [3H]DTG binding indicated the best fit for a two-site model rather than a one-site model, but not for specific [3H](+)-SKF 10,047 binding. Anti-ulcer agents such as omeprazole, cetraxate, cimetidine, sofalcone, sucralfate, teprenone and troxipide had weak or little effect on specific [3H](+)-SKF 10,047 and [3H]DTG binding at a concentration of 100 microM, except that omeprazole exhibited a low affinity for specific [3H](+)-SKF 10,047 binding. These findings suggest that KB-5492 is a unique anti-ulcer agent which binds to sigma receptors in porcine gastric fundic mucosa.

[The effects of a novel Ca2+ channel blocker, KB-2796, on 5-HT-induced responses].

The effects of KB-2796, a new Ca(2+)-channel blocker, on 5-hydroxytryptamine (5-HT)-induced responses were investigated in comparison with those of other Ca(2+)-channel blockers such as verapamil, flunarizine, diltiazem and nimodipine. In rat cortical membrane, KB-2796 inhibited specific [3H]spiperone binding to 5-HT2 receptors in a competitive manner (Ki = 0.57 microM), but exhibited negligible affinity for radioligand binding to other 5-HT receptor subtypes such as 5-HT1, 5-HT1A, 5-HT1B, 5-HT1C and 5-HT3 at a concentration of 10 or 100 microM. KB-2796 inhibited both 5-HT-stimulated shape change and 5-HT and collagen-stimulated aggregation in rabbit platelet-rich plasma with IC50 values of 13.4 microM and 96.4 microM, respectively. KB-2796 also inhibited the 5-HT-induced increase of [Ca2+]i in washed rabbit platelets with the IC50 value of 25.7 microM. Furthermore, KB-2796 (3-30 mg/kg, p.o.) dose-dependently inhibited the 5-HT-induced paw edema in rats. In these experiments, the inhibitory effects of KB-2796 and other Ca2+ channel blockers were related to their affinities for the 5-HT2 receptor; and the potency of KB-2796 was stronger than those of diltiazem and nimodipine and almost equal to that of flunarizine, although all these inhibitors had weaker potencies than that of verapamil. These findings indicate that KB-2796 may possess antagonistic effect on the 5-HT2 receptor.

Characterization of specific (+)-[3H]N-allylnormetazocine and [3H]1,3-di(2-tolyl)guanidine binding sites in porcine gastric fundic mucosa.

We have identified and characterized sigma receptor sites in porcine gastric fundic mucosa by receptor binding assay techniques using two highly selective radioligands of sigma receptor, (+)-[3H]N-allylnormetazocine (SKF 10,047) and [3H]1,3-di(2-tolyl)guanidine (DTG). Specific binding of (+)-[3H]SKF 10,047 and [3H]DTG in porcine gastric fundic mucosa were saturable, reversible and of high affinity and capacity with Kd: 90.5 nM, Bmax: 1058 fmol/mg of protein and Kd: 53.6 nM, Bmax: 3573.3 fmol/mg of protein, respectively. The inhibitory effects of sigma receptor ligands on specific (+)-[3H]SKF 10,047 binding decreased in the following order: haloperidol > DTG > or = (+)-3-(3-hydroxyphenol)-N- (1-propyl)piperidine (3-PPP) > (+)-SKF 10,047 > (-)-3-PPP > or = dextromethorphan > rimcazole > (-)-SKF 10,047. Specific (+)-[3H]SKF 10,047 binding sites showed stereoselectivity for stereoisomers of SKF 10,047 and 3-PPP and were highly correlated with the profile of sigma-1 sites. On the other hand, the inhibitory effects on specific [3H]DTG binding decreased in the following order: DTG > haloperidol > rimcazole > (+)-3-PPP > or = (-)-3-PPP > dextromethorphan > (+)-SKF 10,047 = (-)-SKF 10,047. Specific [3H]DTG binding sites did not show stereoselectivity and were highly correlated with the profile of sigma-2 sites. These findings indicate that porcine gastric fundic mucosa contains sigma receptor sites with the characteristic of sigma-1 sites and sigma-like sites showing several of the characteristics of sigma-2 sites (putative sigma-2 sites).

Receptor binding profiles of KB-5492, a novel anti-ulcer agent, at sigma receptors in guinea-pig brain.

We studied the receptor binding profile of 4-methoxyphenyl 4-(3,4,5-trimethoxybenzyl)-1-piperazine acetate monofumarate monohydrate (KB-5492), a novel anti-ulcer agent, for the sigma receptor in guinea-pig brain membranes. KB-5492 selectively inhibited specific [3H]1,3-di(2-tolyl)guanidine (DTG) binding to the sigma receptor (IC50 = 3.15 microM) with a pseudo-Hill coefficient of 0.33. Computer-assisted analysis revealed that KB-5492 bound to high- and low-affinity sites. Although KB-5492 had weak affinity for alpha 2-adrenoceptors at 10 microM, it was almost inactive at a concentration of 10 microM in 33 other binding assays for receptors, second messenger systems and ion channels. sigma Receptor ligands such as haloperidol, DTG, (+)-3-(3-hydroxyphenol)-N-(1-propyl)piperidine (3-PPP), rimcazole and (-)-3-PPP inhibited specific [3H]DTG binding and their IC50 values were 0.003, 0.044, 0.33, 0.67 and 1.03 microM, respectively. On the other hand, various anti-ulcer agents such as cetraxate, cimetidine, omeprazole, sofalcone, sucralfate, teprenone and troxipide could hardly displace specific [3H]DTG binding at 100 microM. Scatchard-Rosenthal analysis indicated that [3H]DTG bound to a single site, and KD and Bmax values for [3H]DTG were 87.3 nM and 679.3 fmol/mg protein, respectively. KB-5492 significantly decreased the Bmax value, but did not affect the KD value. In contrast, haloperidol and DTG significantly increased the KD values, but did not affect the Kmax values. These findings indicate that KB-5492 selectively bound to the [3H]DTG-labeled sigma receptor and that other anti-ulcer agents had little affinity for the sigma receptor.(ABSTRACT TRUNCATED AT 250 WORDS)