Chinese J Physiol
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Hypoxia is an important topic both physiologically and clinically. Traditionally, physiology research has been focusing on the effect of acute and chronic sustained hypoxia and human adaptive response to high altitude. In the past 20 years, genetic studies by many have expanded our understanding of hypoxia to the molecular level. ⋯ Despite the lack of a uniform definition, recent data suggest that CIH may lead to multiple long-term pathophysiologic consequences similar to what we see in patients with OSA. Recent evidences also demonstrate that there are remarkable differences in the response of the physiologic systems to sustained hypoxia and intermittent hypoxia. This review is aimed to briefly discuss the clinical significance of sleep-disordered breathing and our current understanding of CIH.
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Ghrelin, an acyl-peptide gastric hormone and an endogenous ligand for growth hormone secretagogue (GHS) receptor 1a (GHS-R 1a) exerts multiple functions. It has been reported that synthetic GHS-hexarelin reduces injury of cerebral cortex and hippocampus after brain hypoxia-ischemia in neonatal rats. However, the effect of ghrelin in tolerance of the brain tissues to cerebral ischemia/reperfusion (I/R) injury has not been studied. ⋯ The results showed that I/R decreased the number of surviving neurons and induced apoptosis of the neurons in CA1 area of the hippocampus in rats. In contrast, administration of ghrelin significantly increased the number of surviving neurons and reduced the number of TUNEL-positive apoptotic neurons in the equivalent areas after I/R. In conclusion, the present data provide evidence for the first time that ghrelin can exert a neuroprotective role in vivo in the tolerance of hippocampal neurons to I/R injury, and that the mechanism underlying this effect involves an anti-apoptotic property of ghrelin.