TY - JOUR
T1 - Physiological ischemia/reperfusion phenomena and their relation to endogenous melatonin production
T2 - An hypothesis
AU - Tan, Dun Xian
AU - Manchester, Lucien C.
AU - Sainz, Rosa M.
AU - Mayo, Juan C.
AU - León, Josefa
AU - Reiter, Russel J.
PY - 2005/7
Y1 - 2005/7
N2 - Ischemia/reperfusion is a frequently encountered phenomenon in organisms. Prolonged ischemia followed then by reperfusion results in severe oxidative injury in tissues and organs; however, some species can tolerate such events better than others. In nature, arousal from hibernation and resurfacing from diving causes animals to experience classic ischemia/reperfusion and, somehow, these animals cope well with the potential oxidative stress. It has been documented that during these physiological ischemia/reperfusion events, the activities of several antioxidant enzymes and the levels of some small-molecular-weight antioxidants become elevated. For example, the potent small-molecular-weight antioxidant melatonin often attains especially high levels during these physiological ischemia/reperfusion events including during arousal from hibernation or in the newborns during delivery. Highly elevated melatonin production during these physiological ischemia/reperfusion episodes exhibits several features. First, this high melatonin production is transient and fits well with the time schedule of the physiological ischemia/reperfusion period; therefore, it is not related to the normal endogenous melatonin rhythm. Yet, this transient peak protects the animals from destructive oxidative processes that occur during these transition periods. Second, these high levels of melatonin seem to derive from several organs since pinealectomy does not totally reduce circulating levels of this agent. Third, high melatonin production present at arousal from hibernation or in the newborns at birth does not appear to be controlled by light, i.e., it occurs both during the day and at night, and the amplitudes of elevated melatonin levels are equivalent at these times. The significance of these findings is discussed herein. Based on currently available data, we hypothesize that melatonin plays an important role in the physiological ischemia/ reperfusion, i.e., as a member of antioxidant defense system, to protect against the potential oxidative injury induced by the physiological ischemia/reperfusion.
AB - Ischemia/reperfusion is a frequently encountered phenomenon in organisms. Prolonged ischemia followed then by reperfusion results in severe oxidative injury in tissues and organs; however, some species can tolerate such events better than others. In nature, arousal from hibernation and resurfacing from diving causes animals to experience classic ischemia/reperfusion and, somehow, these animals cope well with the potential oxidative stress. It has been documented that during these physiological ischemia/reperfusion events, the activities of several antioxidant enzymes and the levels of some small-molecular-weight antioxidants become elevated. For example, the potent small-molecular-weight antioxidant melatonin often attains especially high levels during these physiological ischemia/reperfusion events including during arousal from hibernation or in the newborns during delivery. Highly elevated melatonin production during these physiological ischemia/reperfusion episodes exhibits several features. First, this high melatonin production is transient and fits well with the time schedule of the physiological ischemia/reperfusion period; therefore, it is not related to the normal endogenous melatonin rhythm. Yet, this transient peak protects the animals from destructive oxidative processes that occur during these transition periods. Second, these high levels of melatonin seem to derive from several organs since pinealectomy does not totally reduce circulating levels of this agent. Third, high melatonin production present at arousal from hibernation or in the newborns at birth does not appear to be controlled by light, i.e., it occurs both during the day and at night, and the amplitudes of elevated melatonin levels are equivalent at these times. The significance of these findings is discussed herein. Based on currently available data, we hypothesize that melatonin plays an important role in the physiological ischemia/ reperfusion, i.e., as a member of antioxidant defense system, to protect against the potential oxidative injury induced by the physiological ischemia/reperfusion.
KW - Antioxidant
KW - Hibernation
KW - Ischemia
KW - Melatonin
KW - Newborn
KW - Oxidative stress
KW - Reperfusion
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U2 - 10.1385/ENDO:27:2:149
DO - 10.1385/ENDO:27:2:149
M3 - Review article
C2 - 16217128
AN - SCOPUS:27644459840
SN - 1355-008X
VL - 27
SP - 149
EP - 157
JO - Endocrine
JF - Endocrine
IS - 2
ER -