[Protective effect of eptazocine, a novel analgesic, against cerebral ischemia in mice and rats].

The cerebral protective effect of eptazocine, an opioid mu-antagonist-kappa-agonist, was investigated using mice and rats subjected to ischemia. 1) Decapitation or concussive head injury (20 g, 30 cm)-induced ischemia in mice: Eptazocine (3,10 mg/kg) prolonged the gasping duration or the survival time in a dose-dependent manner. 2) Ischemic brain edema induced by bilateral carotid arterial occlusion (BLCO) in rats: Administration of eptazocine just after BLCO treatment significantly prevented the incidence of ischemic seizures, lethality and an increase in cerebral water content. 3) Acute ischemic changes in cerebral energy metabolism in mice: 2-min BLCO treatment decreased the cerebral contents of phosphocreatine and ATP, and it increased the contents of AMP and lactate, resulting in a 34% decrease in energy charge potential and an increase in lactate/pyruvate ratio. Such changes were improved by eptazocine (3, 10 mg/kg) and ethylketocyclazocine (3 mg/kg), a kappa-agonist. 4) Respiratory function in mouse brain mitochondria preparations: Eptazocine increased the State 3 respiration and respiratory control index (RCI:State 3/State 4), and it prevented a decrease in RCI induced by 3-min ischemia. These results suggest that eptazocine may improve cerebral ischemic disorders through an activation and/or protection of mitochondrial energy-producing systems.

Effects of eptazocine, a novel analgesic, on KCN-induced changes in the cerebral contents of glycolytic metabolites and high-energy phosphates in mice.

Effects of eptazocine on cerebral metabolic changes due to a sublethal dose of KCN were investigated in mice. KCN (2 mg/kg, i.v.) induced a temporary loss of consciousness being moderated by eptazocine (1-10 mg/kg) in a dose-dependent manner. The KCN injection decreased the contents of phosphocreatine (PCr), ATP and glucose and increased the contents of AMP and lactate, resulting in a 34% decrease in energy charge potential (ECP) and an increase in lactate/pyruvate (L/P) ratio. Such changes were improved by eptazocine (10 mg/kg) and EKC (3 mg/kg), but not by pentazocine (10 mg/kg) and morphine (3 mg/kg), and the improving effect of eptazocine was completely inhibited by MR-2266 (3 mg/kg), a relatively selective opioid kappa-receptor antagonist. On the other hand, eptazocine (3, 10 mg/kg) was found to increase the glucose content in normal mice, but not to give significant changes in the contents of glycolytic metabolites and high-energy phosphates. These results suggest that eptazocine may improve anoxic changes in cerebral energy metabolism.

[Protective effect of eptazocine, a novel analgesic, against cerebral hypoxia-anoxia in mice].

Cerebral protective effect of eptazocine, a mu-antagonist-kappa-agonist, was investigated using mice subjected to hypoxia-anoxia. Eptazocine (1 to 10 mg/kg) prolonged the survival time of mice subjected to KCN (3 mg/kg, i.v.) injection in a dose-dependent manner, and this effect was completely inhibited by naloxone (5 mg/kg). EKC, U50,488H, opioid kappa-agonists, also had such an effect, but were weaker than eptazocine. In mice exposed to hypobaric hypoxia (190 mmHg), eptazocine (3, 10 mg/kg) and EKC (10 mg/kg) prolonged the survival time, but morphine (5 mg/kg) and pentazocine (10 mg/kg) shortened the time. The eptazocine effect was attenuated by either naloxone (5 mg/kg) or atropine (0.5 mg/kg), different from what was seen in the case of physostigmine and diazepam, and the combination of eptazocine (1 mg/kg) and physostigmine (0.075 mg/kg) had a potentiating effect. MR-2266, a selective kappa-receptor antagonist, inhibited the eptazocine effect more potently than naloxone. These results suggest that eptazocine elicited its cerebral protective effect via its binding with opioid kappa-receptors and probably an activation of the central cholinergic system.

[Preferential action of eptazocine, a novel analgesic, with opioid receptors in isolated guinea pig ileum and mouse vas deferens preparations].

Actions of eptazocine, a novel analgesic, on isolated smooth muscle preparations were investigated. Eptazocine (10(-5) M) slightly inhibited electrically-driven twitch-tension in guinea pig ileum preparations sensitive to mu- and kappa-agonists, and this effect was antagonized by 10(-7) M naloxone. Eptazocine (10(-5)-10(-4) M) inhibited such an effect by the mu-agonist morphine. In mouse vas deferens preparations having delta-, mu- and kappa-receptors, eptazocine (10(-7) M-) inhibited the twitch-tension in a dose-dependent manner, being hardly inhibited by naloxone. On the other hand, MR-2266 (10(-6) M), a relatively selective kappa-receptor antagonist, inhibited the eptazocine effect. The Ke (equilibrium dissociation constant) value of naloxone against eptazocine was 325 nM and the Ke value of MR-2266 against eptazocine was 33.2 nM, showing that MR-2266 was 9.79-fold more effective than naloxone. These results suggest that eptazocine acted as a mu-receptor antagonist and as a kappa-receptor preferential agonist in isolated smooth muscle preparations.

[Cardiohemodynamic and respiratory effects of eptazocine, a new analgesic agent, in anesthetized dogs].

Cardiohemodynamic and respiratory effects of eptazocine, a new analgesic agent, were studied and compared with those of pentazocine and butorphanol in anesthetized dogs. Eptazocine (1 mg/kg, i.v.) increased the heart rate (HR), left ventricular dP/dt (LVdP/dt) and cardiac output (CO), and scarcely affected the blood pressure (BP), left ventricular end-diastolic pressure (LVEDP), right atrial pressure, pulmonary arterial pressure (PAP) and pulmonary capillary wedge pressure. On the other hand, eptazocine (3 mg/kg, i.v.) decreased BP, LVdP/dt, CO and LVEDP and did not influence the pulmonary circulation. Pentazocine (1 mg/kg and 3 mg/kg, i.v.) increased BP, LVdP/dt and CO, while HR was not altered. Pentazocine also increased PAP. Butorphanol (0.1 mg/kg and 0.3 mg/kg, i.v.) decreased BP, HR and LVdP/dt, while other hemodynamic parameters were not changed. In spontaneously breathing anesthetized dogs, eptazocine (1 mg/kg and 3 mg/kg, i.v.) caused a decrease of respiratory minute volume. The fall in PO2 and pH, and a rise in PCO2 were simultaneously observed in blood gas analysis. These respiratory depressant effects of eptazocine were short-lasting, and they were less potent than those of pentazocine. Butorphanol scarcely affected the respiration. These results suggest that eptazocine has different cardiohemodynamic effects than other analgesics and produces mild respiratory depression.

Ouabain-sensitive insulin stimulation of ion and glucose transport in rat ventricular slices.

This study was designed to determine whether ouabain could inhibit insulin-stimulated ion and/or glucose transport in rat ventricular slices. In the slices which were obtained by tearing with forceps from the inside surface of the ventricle, insulin (0.1-100 ng/ml, 20-min treatment) stimulated ATP hydrolysis (nmol inorganic phosphate/mg tissue/20 min) and 86Rb uptake (nmol Rb/mg tissue/8 min) in a concentration-dependent fashion by up to about 25%, compared with control experiment. About 10-fold higher concentrations of insulin stimulated glucose-[14C] uptake by the slices (nmol glucose/mg tissue/30 min). Both the stimulant effects of insulin on ion and glucose transport were inhibited by ouabain (0.1-1 mM, 20-min treatment) in a similar concentration-response relationship. It thus never appears that two or more independent transmembrane signals would be generated simultaneously in response to the insulin-receptor interaction to operate ion and glucose transport systems in rat cardiac muscle. In addition, rat ventricular slices were shown to provide a sensitive tool for the evaluation of insulin effects on ion transport systems in the muscle.

Effects of a hypoglycemic component of ginseng radix on insulin biosynthesis in normal and diabetic animals.

DPG-3-2, a component of ginseng radix, which lowers the blood glucose level and stimulates insulin release in diabetic animals, was studied for its effects on insulin biosynthesis in different preparations of pancreas from animals with normoglycemia and with hyperglycemia (alloxan diabetic rats and genetically diabetic mice, KK-CAy). We measured incorporation of radioactive leucine into insulin and other protein fractions during a 2-h perfusion of rat pancreas, and into insulin during a 3-h incubation of mouse islets. Biosynthesis of insulin during a long-term culture of islets from KK-CAy mice was also measured. DPG-3-2 was found practically not to increase the incorporation into insulin in the pancreatic preparations from animals with normoglycemia, but in such preparations from animals with hyperglycemia DPG-3-2 (0.2-1.0 mg/ml) caused 1.5-1.8-fold incorporation into insulin. In addition, a long-term treatment of DPG-3-2 (0.5 mg/ml) was shown to stimulate insulin biosynthesis in islets from KK-CAy mice. Ginsenoside-Rb1 and -Rg1 decreased the insulin content of islet to the undetectable level. Thus, DPG-3-2 was shown to stimulate insulin biosynthesis in different preparations of pancreas from animals with hyperglycemia.

Effects of hypoglycemic components in ginseng radix on blood insulin level in alloxan diabetic mice and on insulin release from perfused rat pancreas.

Some fractions extracted from ginseng radix (HAKUSAN) caused hypoglycemic effect on alloxan diabetic mice. The effect was abolished by the i.v. injection of antisera against bovine insulin. The same doses of the ginseng fraction (10--50 mg/kg) produced an increase in the blood insulin level in alloxan diabetic mice. Normal mice loaded i.p. with glucose (2 g/kg or more) showed also such an increase. Insulin release from perfused rat pancreases was stimulated by the ginseng fraction (0.2 mg/ml), but the potency was not stronger than that of the sulfonylureas. It was demonstrated that glucose-induced insulin release was marked in the presence of the ginseng fraction. Impaired insulin responses to glucose in alloxan diabetic rats were increased by the fraction (0.5 mg/ml) to or above the control responses in normal rats. The enhanced effect was observed also in the presence of 100 microgram/ml cycloheximide. These results indicate that some ginseng fractions stimulated insulin release, especially glucose-induced insulin release from pancreatic islets and thereby lowered the blood glucose level.

Pharmacological sequential trials for the fractionation of components with hypoglycemic activity in alloxan diabetic mice from ginseng radix.

Three methods of fractionation of ginseng radix (Panax ginseng C.A. MEYER) components for a survey of hypoglycemic principle in alloxan diabetic mice were conducted and three groups of hypoglycemic principle in alloxan diabetic mice were conducted and three groups of components tested; fat-soluble components, ginseng saponins and a third component with hypoglycemic activity. Pharmacological sequential trials of the fractionation yielded a most active fraction which was about 100-fold more effective than the original water-soluble extract of the ginseng radix. The ED50 value was 0.4 mg/kg in lowering the blood level of glucose in alloxan diabetic mice. It was demonstrated that some ginseng fractions inhibited epinephrine-induced transient hyperglycemia in mice, increased glycogen content in rat liver, decreased the blood level of acetone bodies in alloxan diabetic mice, and inhibited the release of free fatty acid from rat epididymal fat pad. The results showed that hypoglycemic components existed in a new component of ginseng radix which is different from saponin.

Inhibition of compound 48/80-mediated histamine release from isolated rat mast cells by oosponol-related compounds (4-acyl-isocoumarins).

Oosponol (4-hydroxymethylketone-8-hydroxyisocoumarin) is a metabolic product isolated from Oospora astringens which originated from house dust in a room of an asthmatic patient. The compound and the structurally related isocoumarins were studied to determine the inhibition of histamine release induced by compound 48/80 from isolated rat peritoneal mast cells. The released histamine was assayed by fluorometry. The compounds tested were not observed to release histamine. Some of 4-acyl-isocoumarins inhibited the histamine release at doses less than 10 micrometers, whereas the 3-acyl- and the 4-alkyl-compounds were not effective at doses over 100 microns. The pretreatment of mast cell with the compound for 15 min before the application of compound 48/80 was more effective than the simultaneous administration. The mode of inhibitory action of KIT-302, 4-(4'-carboxy-benzoyl)-isocoumarin, was non-competitive antagonism to compound 48/80 on the mast cells.

Possible role of IgE-constituent carbohydrate in the mediation of histamine release.

A possible role of IgE-constituent carbohydrate in the mediation of histamine release was pharmacologically studied in isolated peritoneal rat mast cells. Among polysaccharides obtained commercially, mannan and dextran induced histamine release, and the ED50 was 4 microgram/ml and 52 microgram/ml, respectively. At doses higher than 1 mg/ml, Ficoll, hyaluronic acid and heparin induced the release, while agarose did not. The weak histamine releasing polysaccharides did not induce inhibition of the dextraninduced histamine release. Monosaccharides such as N-acetylglucosamine, mannose and N-acetylneuraminic acid induced marked inhibition of the mannan-induced histamine release, although other carbohydrate constituents of IgE fucose and galactose were weak inhibitors. The antagonism of the monosaccharides against polysaccharide-induced histamine release was found to be a competitive type. Also, antigen-induced histamine release from peritoneal mast cells actively immunized with egg albumin glucosamine. Hence it appears that IgE-constituent carbohydrate may play an important role in IgE-mediated histamine release.