To investigate the destructive process of connective tissues in gastric ulcer, both collagenolytic and gelatinolytic activities were examined in the homogenates of rat acetic acid-induced gastric ulcer, a typical model of chronic ulcer. Gelatinolytic activity in the ulcerous lesion was significantly higher than that in the normal tissue. However, collagenase was not detected in both normal and ulcerated tissues either by the enzyme assay or by the immunoblotting. By gelatin-gel-zymographic analyses, the gelatinolytic activity was found to be composed of a number of species, mainly 60-, 72-and 92-kDa, all of which were inhibited by ethylenediaminetetraacetic acid. Among the induced matrix metalloproteinases, one crossreacted with a sheep anti-(rabbit prostromelysin) antibody. Thus, in chronic gastric ulcer, it is likely that several metalloproteinases participate in degradation of connective tissue matrices including components of basement membranes. The elevated levels of gelatinolytic activities in the ulcerous tissues and ulcer index were significantly suppressed by treating the animals with famotidine or a new H₂-receptor antagonist, 3-amino-4-[4-[4-(1-piperidinomethyl)-2-pyridyloxy]-cis-2-butenylamino]-3-cyclobutene-1, 2-dione hydrochloride (IT-066).

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The in vivo and in vitro effects of platelet-activating factor (PAF, 1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphorylcholine) and acetylcholine (ACh) on vascular relaxation responses were examined in streptozotocin-induced diabetic rats. Intravenous injection of PAF and ACh (0.03 to 10 μg/kg) decreased the mean blood pressure in both control and diabetic rats in a dose-dependent fashion. Initial blood pressure in diabetic rats did not significantly differ from that in control rats. However, depressor responses induced by PAF and ACh in diabetic rats were attenuated more than those in control rats. In perfused mesenteric arterial bed preconstricted with methoxamine (10^-5-10^-4M), PAF (10^-11-3×10^-10M) produced a concentration-dependent relaxation. However, this relaxation was significantly attenuated in the diabetic preparation compared with the control preparation. ACh also produced a concentration-dependent vasodilation in perfused mesenteric arterial bed. The concentration-response curve for the relaxation of the mesenteric arterial bed to ACh in diabetic preparation was shifted to the right compared with that in control preparation. A pretreatment with oxyhaemogloblin (10^-6M) also shifted the concentration-response curves for relaxation to ACh in both control and diabetic preparation to the right. There was no difference in relaxation induce by sodium nitroprusside between the diabetic and the control preparation. From the present results and previous work, which PAF showed an endothelium-dependent vasodilation in the perfused mesenteric arterial bed, it is suggested that impairment of endothelium-dependent relaxation in the perfused mesenteric arterial bed of diabetic rats may account, in part, for the attenuation of PAF-and ACh-induced depressor effect observed in diabetic rats in vivo.

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The effect of fasting and sialoadenectomy on the binding of human epidermal growth factor (hEGF), β-urogastrone, to plasma membranes isolated from rat gastric mucosa was studied to investigate the physiological changes in gastric EGF receptors for developing hEGF as an anti-ulcer drug. The binding of [¹²⁵I] hEGF to the gastric membranes was significantly decreased after 40 h of fasting. Maximal binding was decreased to 74% of the control value without alteration of the binding affinity (K_d=0.42 and 0.44 nM for the control and fasting group, respectively). There was little change in the binding of [¹²⁵I] insulin to the gastric plasma membranes in response to fasting. Removal of the submandibular glands did not decrease EGF binding to the gastric membranes. These results indicate that changes in EGF binding to its receptors occur on plasma membranes of the rat gastric mucosa depending on the nutrient state.

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Tranilast, an anti-asthmatic drug with anti-allergic properties, inhibited endothelin (ET)-induced asthmatic like respiratory obstruction in guinea pigs when administered orally at 200 mg/kg 1 h prior to the intravenous injection of ET. ET also caused a bronchoconstriction detected as an increase in inflation pressure in Konzett-Rossler apparatus. Tranilast (200 mg/kg, p.o. 1 h before ET) inhibited ET-induced increased inflation pressure. ET-induced bronchoconstriction detected as an increase in inflation pressure was clearly inhibited by the administration of indomethacin (used as a reference drug) at doses of 1 and 5 mg/kg 30 min prior to onset of the reaction. In addition to the above in vivo experiments, tranilast at concentrations between 10^-5 and 10^-4 g/ml inhibited ET-induced contraction of isolated guinea pig tracheal muscle, whereas indomethacin did not affect this in vitro response. In order to elucidate the inhibitory mechanism of tranilast on ET-induced bronchoconstriction, the effects in Ca²⁺-free medium and on ET-induced histamine and prostaglandin F_2α release from tracheal muscle were investigated. Consequently, tranilast did not affect ET-induced contraction of guinea pig tracheal muscle in Ca²⁺-free Tyrode's solution and ET induced neither histamine nor PGF_2α release. These results suggest that tranilast inhibits ET-induced bronchoconstriction by inhibiting the ET-induced calcium influx into tracheal muscle.

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Binding characteristics of α₁-adrenoceptors in the bovine prostate were examined using a radioligand binding assay. [³H] Bunazosin was used as a radioligand. The optimal incubation conditions for the radioligand binding assay were determined : incubation time (30 min), protein concentration (0.2 mg/tube) and temperature (30°C). Scatchard plots for α₁-adrenoceptors in bovine prostates were linear and the K_d and B_max values were 0.61 nM and 49.8 fmol/mg protein, respectively. The pK_i value of terazosin was significantly higher than those of prazosin, bunazosin or phentolamine in the bovine prostate. Since this radioligand binding assay using [³H] bunazosin demonstrated the presence of α₁-adrenoceptors in bovine prostates, this method is useful for the assessment of α₁-blockers of new chemicals synthesized for the treatment of the benign prostatic hyperplasia.

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In a water maze task, the goal latency and distance of swimming onto the platform of aged rats (24 months old) were slowly shortened by repeated trainings compared with those of young rats (8 weeks old). A significant decrease in choline acetyltransferase activity in the frontal cortex, parietal cortex and striatum was observed in aged rats. Moreover, the number of neuronal cells in the hippocampal CAl subfield and dentate gyrus of aged rats was smaller than that of young rats. The atrophy of striatal cells was observed. These results suggest that age-related delay of acquisition is due to the above-mentioned biochemical and histological changes, and that rates of aging in biochemical and morphological parameters are different in the discrete brain areas.

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The effects of thirty-one synthetic dyes (tar dyes in Japan), which are permitted in cosmetics, on three different enzymes were evaluated as an initial step in developing in vitro safety screens. The activities of the prostaglandin (PG)-synthetase from rabbit renal medulla and the lipoxygenases from potato tubers and guinea pig peritoneal polymorphonuclear leukocytes (PMN) were determined based on the biosyntheses of PGE₂ and 5-hydroxyeicosatetraenoic acid (5-HETE), respectively. Xanthene dyes with halogen substituents exhibited marked inhibition on the PG-synthetase. Among the dyes which are permitted for any pharmaceutics and cosmetics, only the xanthene dyes exhibitec inhibitory effects on the PG-synthetase at 2.5 mM. The xanthene dyes also showed inhibition and stimulation of potato lipoxygenase and PMN lipoxygenase, respectively.

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We examined the alteration of the responsiveness to adrenergic agonists and changes in the density of adrenoreceptors in the hearts of rats with deoxycorticosterone acetate (DOCA)-salt hypertension in order to determine the relationship between changes in adrenoreceptor responsiveness and adrenoreceptor density in this hypertension model. The maximal increase in the tension development with phenylephrine in the presence of propranolol and with isoproterenol decreased to a larger extent in the latter, but the PD₂ values for these agonists did not change. Decreases in maximal tension development with phenylephrine and Ca²⁺ were similar. The density of alpha-and betaadrenoceptors decreased similarly. In conclusion, whereas a decreased adrenoreceptor density may not significantly contribute to a decreased agonist responsiveness in DOCA-salt hypertensive rats, altered Ca²⁺ sensitivity contributes to the observed reduction in agonist responsiveness.

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A rat serum enzyme that catalyzes the conversion of a pro-drug, 7-ethyl-10-[4-(1-piperidino)-1-piperidino] carbonyloxycamptothecin (CPT-11), to an anticancer drug, 7-ethyl-10-hydroxycamptothecin (SN-38), was purified and its properties were characterized. The enzyme was purified by column chromatography on diethylaminoethyl Toyopearl 650M, QAE-Sephadex, Sephadex G-150, Con A-Sepharose and high performance liquid chromatography with an ion-exchanger column. It was most active at pH 7.5 and was stable at pH 4-9 for 1 h at 30°C. The molecular weight was estimated to be 60 and 57 kDa by gel filtration and sodium dodecylsulfate-polyacrylamide gel electrophoresis methods, respectively, and the isoelectric point was 4.6, as determined by isoelectric focusing. The K_m value for CPT-11 was 0.28 μM. This enzyme was inhibited by diisopropyl phosphorofluoridate (DFP) and phenylmethanesulfonyl fluoride (PMSF) but insensitive to eserine, p-chloromercuribenzoate (PCMB) and ethylenediaminetetraacetate (EDTA). The enzyme also hydrolyzed p-nitrophenylacetate (p-NPA), a commonly used substrate for esterases, but was not active toward acetylcholine, suggesting that the enzyme is a carboxylesterase [EC 3.1.1.1]. During the hydrolyses of CPT-11 and p-NPA, an initial burst phenomenon similar to that found in the α-chymotrypsincatalyzed hydrolysis of p-NPA was observed. Kinetic analysis revealed that the deacylation of the enzyme is the rate-limiting step in substrate hydrolysis. This enzyme was found to also split other ester derivatives of SN-38 besides CPT-11.

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Continuous infusion of quinolinic acid (QA) at low doses into the lateral ventricle has been previously shown to cause a reduction of the hippocampal and cortical ChAT activities in rats although GAD activities were unchanged. In the present study, we have studied behavioral changes in rats with continuous infusion of QA in an active avoidance task. Acquisition of active avoidance was significantly impaired in rats with QA infusion compared to control. These results suggest that continuous infusion of QA is a useful technique for the study of chronic neurodegenerative diseases associated with memory impairement.

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In mice, both swimming-stress induced analgesia (SW-SIA) and clonidine (CLO) analgesia were dose dependently antagonized by yohimbine, an α2-adrenoceptor antagonist, but not by naloxone, an opioid μ-antagonist. SW-SIA was potentiated by subanalgesic dose of CLO, and CLO analgesia was enhanced by SW-SIA. Animals tolerant to CLO analgesia were tolerant to SW-SIA, in contrast, CLO analgesia was potentiated in SW-SIA tolerant mice. Thus, SW-SIA and CLO analgesia partially share a common α2-adrenergic-dependent mechanism, for their production.

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