ANOXIA TOLERANT ANIMALS FROM A NEUROBIOLOGICAL PERSPECTIVE

Citation
Pl. Lutz et al., ANOXIA TOLERANT ANIMALS FROM A NEUROBIOLOGICAL PERSPECTIVE, Comparative biochemistry and physiology. B. Comparative biochemistry, 113(1), 1996, pp. 3-13
Citations number
100
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biology
ISSN journal
0305-0491
Volume
113
Issue
1
Year of publication
1996
Pages
3 - 13
Database
ISI
SICI code
0305-0491(1996)113:1<3:ATAFAN>2.0.ZU;2-7
Abstract
This paper discusses the mechanisms for brain anoxia survival seen in crucian carp (Carassius carassius) and a few species of freshwater tur tle (Chrysemys and Trachemys species). Comparisons are made with the h ypoxic tolerant mammalian neonate brain. In the anoxic tolerant specie s the basic strategy for anoxia survival appears to be the maintenance of ion gradients, and thereby the avoidance of anoxic depolarization. Important facilitating factors involve having huge glycogen stores, i ncreased blood supply to the brain, the suppression of electrical acti vity, increased release of inhibitory neuromodulators ana neurotransmi tters, upregulation of inhibitory neuroreceptors, the down-regulation of excitatory ion conductance and the down-regulation of Ca2+ channels . By contrast, for the mammalian neonate the most important causes of its increased hypoxia tolerance may be just simple consequences of the comparatively undifferentiated state of the brain of the newborn, wit h its lower energy requirements, slower decline in ATP and lower excit ability levels acting to delay depolarization.