Hisashi Shibata

Inhibitions of acid secretion by E3810 and omeprazole, and their reversal by glutathione

A substituted benzimidazole ([4-(3-methoxypropoxy)-3-methylpyridine-2-yl]methylsulfinyl)- 1H-benzimidazole sodium salt (E3810), is a gastric proton pump (H+, K(+)-ATPase) inhibitor. E3810 and omeprazole inhibited acid accumulation dose dependently as measured with aminopyrine uptake in isolated rabbit gastric glands, their IC50 values being 0.16 and 0.36 microM, respectively. The addition of exogenous reduced glutathione (GSH) to the gland suspension reactivated dose dependently the acid secretion which had been inhibited by 2 microM E3810 or omeprazole as a function of the incubation time. Furthermore, GSH at 1 and 3 mM reversed the antisecretory effect of E3810 more quickly than it did that of omeprazole. The antisecretory effect of E3810 was slightly greater than that of omeprazole in histamine-stimulated fistula dogs in vivo. The duration of the antisecretory activity of E3810 at concentrations of 2 and 4 mg/kg was shorter than that of omeprazole at the same concentrations in pentagastrin-stimulated fistula dogs. The reversal of the antisecretory activity of the inhibitors in dogs is suggested to be due to the action of endogenous extracellular GSH, in addition to de novo synthesis of the proton pump, because bullfrog gastric mucosae were found in the present study to secrete GSH into the mucosal solution at the rate of about 0.25 nmol/min/g tissue.

Synthesis and structure-activity relationships of pyrazolo[1,5-a]pyridine derivatives: potent and orally active antagonists of corticotropin-releasing factor 1 receptor.

Design, synthesis, and structure-activity relationships of a series of 3-dialkylamino-7-phenyl pyrazolo[1,5-a]pyridines (I) as selective antagonists of the corticotropin-releasing factor 1 (CRF(1)) receptor are described. The most prominent compound to emerge from this work, 46 (E2508), exhibits potent in vitro activity, excellent drug-like properties, and robust oral efficacy in animal models of stress-related disorders. It has advanced into clinical trials.

Effects of the Proton Pump Inhibitor, E3810, on Gastric Secretion and Gastric and Duodenal Ulcers or Erosions in Rats

SummaryThe effects of E3810, a potent proton pump inhibitor, on gastric secretion and gastric or duodenal ulcers or erosions were studied in rats. Intraduodenal administration of E3810 dose dependently inhibited gastric secretion (volume and acid outputs) in pylorus-ligated rats. The effective dose required to inhibit volume output by 50% (ED50) was 12 mg/kg and that for acid output was 3.4 mg/kg. Acutely induced gastric ulcers or erosions, such as cold-restraint stress erosions, Shay ulcers and mercaptamine (cysteamine)-induced duodenal ulcers, were significantly inhibited by oral, intraduodenal or subcutaneous administration of E3810 at 1 to 100 mg/kg. The protective effects of E3810 in these acute models were compared with those of omeprazole at the same doses. At low doses, 10 mg/kg (intraduodenally) in Shay ulcers and 3 mg/kg (subcutaneously) in mercaptamine-induced ulcers, E3810 was significantly more effective than omeprazole. But at high doses, there was no significant difference between the 2 drugs in efficacy. In the cold stress erosion model, the drugs were equally effective.

Prediction of relaxin-3-induced downstream pathway resulting in anxiolytic-like behaviors in rats based on a microarray and peptidome analysis

Abstract The effect of the intracerebroventricular (i.c.v.) injection of relaxin-3 (RLX3) was evaluated using anxiety-related behavioral tests in rats. RLX3-injected animals showed normal locomotion activity in a habituated environment and declined anxiety cognition in the elevated plus maze test and the shock probe-burying test. The measurement of spontaneous locomotor activity in a novel environment also suggested that RLX3 reduced the stress response. To elucidate the regulatory mechanisms of the downstream signaling pathways underlying RLX3 activity and its relation to anxiolytic and hyperphagic behavior phenotypes, RLX3-i.c.v.-injected rat hypothalamic responses were examined using a microarray analysis. Ingenuity Pathway Analysis software listed the phenotype-relating genes and they showed characteristic expression patterns in the rat hypothalamus. When peptidome data sets for the same listed genes was analyzed using a semi-quantitative approach, the expressions of two neuropeptides were found to have increased. One of these neuropeptides, oxytocin (Oxt), exhibited increased expression in both the microarray and the peptidomic analysis, and a Western blot analysis validated the mass spectrometry results. A cross-omics data analysis is useful for predicting downstream signaling pathways, and the anxiolytic-like behavior of RLX3 may be mediated by an oxytocin signaling pathway in rats. These results suggest that RLX3 acts as an anxiolytic peptide and that the downstream pathways mediated by its receptors may be potential candidates for the treatment of anxieties in the future.

Design, synthesis, and structure-activity relationships of novel pyrazolo[5,1-b]thiazole derivatives as potent and orally active corticotropin-releasing factor 1 receptor antagonists.

This paper describes the design, synthesis, and structure-activity relationships of a novel series of 7-dialkylamino-3-phenyl-6-methoxy pyrazolo[5,1-b]thiazole derivatives for use as selective antagonists of the corticotropin-releasing factor 1 (CRF(1)) receptor. The most promising compound, N-butyl-3-[4-(ethoxymethyl)-2,6-dimethoxyphenyl]-6-methoxy-N-(tetrahydro-2H-pyran-4-yl)pyrazolo[5,1-b][1,3]thiazole-7-amine (6t), showed high affinity (IC(50) = 70 nM) and functional antagonism (IC(50) = 7.1 nM) for the human CRF(1) receptor as well as dose-dependent inhibition of the CRF-induced increase in the plasma adrenocorticotropic hormone (ACTH) concentration at a dose of 30 mg/kg (po). Further, in the light/dark test in mice, the compound 6t showed anxiolytic activity at a dose of 30 mg/kg (po).

Selective corticotropin-releasing factor 1 receptor antagonist E2508 reduces restraint stress-induced defecation and visceral pain in rat models

N-Cyclopropylmethyl-7-(2,6-dimethoxy-4-methoxymethylphenyl)-2-ethyl-N-(tetrahydro-2H-pyran-4-ylmethyl)pyrazolo[1,5-a]pyridin-3-amine tosylate (E2508) is a newly discovered selective corticotropin-releasing factor 1 receptor antagonist. Here, we investigated the effects of E2508 on wrap restraint stress-induced defecation and visceral pain in rats. Oral pretreatment with E2508 dose-dependently decreased stool weights after 20min wrap restraint stress and significant effects were observed at doses of 30 and 100mg/kg. However, E2508 did not affect basal defecation at doses up to 100mg/kg. In contrast, alosetron, a 5-HT3 receptor antagonist, decreased both wrap restraint stress-induced and basal stool output at a dose of 0.1mg/kg. In a rat visceral pain model, subcutaneous injections of both E2508 (0.01 and 0.1mg/kg) and alosetron (0.001 and 0.01mg/kg) significantly decreased the number of abdominal muscle contractions induced by colonic distention, suggesting these drugs reduced visceral pain. Together, these results demonstrate E2508 has the potential to be an effective therapy for the treatment of irritable bowel syndrome with a lower risk of adverse events such as constipation compared with the current clinically used 5-HT3 receptor antagonist.

Selective corticotropin-releasing factor 1 receptor antagonist E2508 has potent antidepressant-like and anxiolytic-like properties in rodent models

Corticotropin-releasing factor (CRF) is a hormone secreted by the hypothalamus in response to stress, and CRF antagonists may be effective for the treatment of stress-related disorders including major depressive and anxiety disorders. Here, we investigated the in vivo pharmacological profile of N-cyclopropylmethyl-7-(2,6-dimethoxy-4-methoxymethylphenyl)-2-ethyl-N-(tetrahydro-2H-pyran-4-ylmethyl)pyrazolo[1,5-a]pyridin-3-amine tosylate (E2508), a recently synthesized, orally active CRF1 receptor antagonist. Oral administration of a single dose of E2508 (3 or 10mg/kg), but not fluoxetine (30mg/kg), a selective serotonin reuptake inhibitor (SSRI), significantly shortened immobility time in rats in the forced swim test. E2508 (10, 30, or 100mg/kg) also showed an antidepressant-like effect in the forced swim test in mice, with no sedative or muscle relaxant effects for doses up to 100mg/kg. Moreover, E2508 (5 or 20mg/kg) significantly reduced anxiety-like behavior in the rat defensive burying test. Diazepam, a benzodiazepine anxiolytic agent, also showed an anxiolytic effect in the defensive burying test at the same dose that induced a muscle relaxant effect in mice. Administration of E2508 (30mg/kg) for 14 consecutive days did not affect sexual behavior. By contrast, fluoxetine (30mg/kg) administration for ≥7 consecutive days decreased sexual behavior. These results indicate that E2508 has both potent antidepressant-like and anxiolytic-like effects in rodent models, and is well tolerated compared with a commonly prescribed therapeutic SSRI or benzodiazepine.