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Molecular hydrogen ([H.sub.2]) showed protection against various kinds of oxidative-stress-related diseases. First, it was reported that the mechanism of therapeutic effects of [H.sub.2] was antioxidative effect due to inhibition of the most cytotoxic reactive oxygen species, hydroxy radical (*OH). However, after chronic administration of [H.sub.2] in drinking water, oxidative-stress-induced nerve injury is significantly attenuated even in the absence of [H.sub.2]. It suggests indirect signaling of [H.sub.2] and gastrointestinal tract is involved. Indirect effects of [H.sub.2] could be tested by giving [H.sub.2] water only before nerve injury, as preconditioning. For example, preconditioning of [H.sub.2] for certain a period (~7 days) in Parkinson's disease model mice shows significant neuroprotection. As the mechanism of indirect effect, [H.sub.2] in drinking water induces ghrelin production and release from the stomach via [beta]1-adrenergic receptor stimulation. Released ghrelin circulates in the body, being transported across the blood-brain barrier, activates its receptor, growth-hormone secretagogue receptor. [H.sub.2]-induced upregulation of ghrelin mRNA is also shown in ghrelin-producing cell line, SG-1. These observations help with understanding the chronic effects of [H.sub.2] and raise intriguing preventive and therapeutic options using [H.sub.2]. Key words: molecular hydrogen, preconditioning, Parkinson's disease, ghrelin. L'hydrogene moleculaire ([H.sub.2]) est decrit comme etant protecteur contre divers types de maladies liees au stress oxydatif. Il a d'abord ete rapporte que le mode d'action des effets therapeutiques de l'[H.sub.2] etait un effet antioxydant cause par l'inhibition du radical hydroxyl (*OH), le derive reactif de l'oxygene le plus toxique. Cependant, apres l'administration a long terme d'[H.sub.2] dans l'eau a boire, les lesions nerveuses provoquees parle stress oxydatif sont nettement attenuees, meme en absence d'[H.sub.2]. Cela laisse entendre qu'il existerait une voie de signalisation indirecte de l'[H.sub.2] et que le tractus gastro-intestinal jouerait un role. Les effets indirects de l'[H.sub.2] pourraient etre evalues en donnant de l'eau avec [H.sub.2] seulement, avant les lesions nerveuses, en tant que preconditionnement. Par exemple, le preconditionnement par l'[H.sub.2] pendant une certaine periode (~7 jours) dans un modele murin de maladie de Parkinson permet d'obtenir une neuroprotection notable. Comme mode d'action d'un effet indirect, l'[H.sub.2] dans l'eau a boire engendre la production et la liberation de ghreline par l'estomac par l'intermediaire d'une stimulation des recepteurs [beta]1-adrenergiques. La ghreline liberee circule dans l'organisme, transportee a travers la barriere hemo-encephalique, active son recepteur secretagogue d'hormone de croissance (GHSR). Nous observons aussi la regulation a la hausse de l'ARNm de ghreline engendre par l'[H.sub.2] dans des lignees cellulaires productrices de ghreline (SG- 1). Ces observations contribuent a la comprehension des effets a long terme de l'[H.sub.2] et laissent entrevoir d'interessantes options therapeutiques et de prevention fondees sur l'utilisation de l'[H.sub.2]. [Traduit par la Redaction] Mots-cles : hydrogene moleculaire, preconditionnement, maladie de Parkinson, ghreline., Introduction Inhaling molecular hydrogen ([H.sub.2]) showed protection against brain injury induced by focal ischemia and reperfusion in rat by reducing hydroxy radical (*OH), the most toxic reactive oxygen species (Ohsawa [...]

Although many studies have demonstrated the physiological action of motilin on the migrating motor complex, the precise mechanisms remain obscure. To obtain new insights into the mechanisms, we focused on the house musk shrew (Suncus murinus, suncus used as a laboratory name) as a small model animal for in vivo motilin study, and we studied the physiological characteristics of suncus gastrointestinal motility. Strain gauge transducers were implanted on the serosa of the gastric body and duodenum, and we recorded gastrointestinal contractions in the free-moving conscious suncus and also examined the effects of intravenous infusion of various agents on gastrointestinal motility. During the fasted state, the suncus stomach and duodenum showed clear migrating phase HI contractions (intervals of 80-150 min) as found in humans and dogs. Motilin (bolus injection, 100-300 ng/kg; continuous infusion, 10-100 ng x [kg.sup.-1] x [min.sup.-1]) and erythromycin (80 [micro]g x [kg.sup.-1] x [min.sup.-1]) induced gastric phase III contractions, and motilin injection also increased the gastric motility index in a dose-dependent manner (P < 0.05, vs. saline). Pretreatment with atropine completely abolished the motilin-induced gastric phase III contractions. On the other hand, in the free-feeding condition, the suncus showed a relatively long fasting period in the light phase followed by spontaneous gastric phase III contractions. The results suggest that the suncus has almost the same gastrointestinal motility and motilin response as those found in humans and dogs, and we propose the suncus as a new small model animal for studying gastrointestinal motility and motilin in vivo. suncus; migrating motor complex; motilin; ghrelin; gastric motility doi: 10.1152/ajpregu.00278.2010.

Background: The aim of this study was to investigate the fundamental mechanisms of colonic motility in the house musk suncus (Suncus murinus) as an established animal model of gut motility. Methods: To measure gut motility in free‐moving conscious suncus, strain gauge force transducers were implanted on the serosa of the colon and gastric body. Key Results: We recorded diurnal changes in colonic motility and observed the relationship between feeding and colonic motility. Giant migrating contractions (GMCs) of the colon were invariably detected during defecation and tended to increase during the dark period, thereby indicating that colonic motility has a circadian rhythm. Given that GMCs in the suncus were observed immediately after feeding during the dark period, we assume the occurrence of a gastrocolic reflex in suncus, similar to that observed in humans and dogs. We also examined the factors that regulate suncus GMCs. Intravenous administration of 5‐HT (100 µg/kg), substance P (10 and 100 µg/kg), calcitonin gene‐related peptide (10 µg/kg), and α2 adrenergic receptor antagonist yohimbine (0.5, 1, and 3 mg/kg) induced GMC‐like contractions, as did intragastric and intracolonic administration of the transient receptor potential vanilloid 1 agonist, capsaicin (1 mg/kg). Conclusions & Inferences: These results indicate that the fundamental mechanisms of colonic motility in suncus are similar to those in humans and dogs, and we thus propose that suncus could serve as a novel small animal model for studying colonic motility. [ABSTRACT FROM AUTHOR]