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Activation of stress signaling molecules in bat brain during arousal from hibernation
Author(s) -
Lee Moonyong,
Choi Inho,
Park Kyoungsook
Publication year - 2002
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.2002.01022.x
Subject(s) - protein kinase a , biology , protein kinase b , endocrinology , kinase , medicine , hibernation (computing) , extracellular , microbiology and biotechnology , signal transduction , biochemistry , state (computer science) , algorithm , computer science
Induction of glucose‐regulated proteins (GRPs) is a ubiquitous intracellular response to stresses such as hypoxia, glucose starvation and acidosis. The induction of GRPs offers some protection against these stresses in vitro , but the specific role of GRPs in vivo remains unclear. Hibernating bats present a good in vivo model to address this question. The bats must overcome local high oxygen demand in tissue by severe metabolic stress during arousal thermogenesis. We used brain tissue of a temperate bat Rhinolopus ferrumequinum to investigate GRP induction by high metabolic oxygen demand and to identify associated signaling molecules. We found that during 30 min of arousal, oxygen consumption increased from nearly zero to 11.9/kg/h, which was about 8.7‐fold higher than its active resting metabolic rate. During this time, body temperature rose from 7°C to 35°C, and levels of TNF‐α and lactate in brain tissue increased 2–2.5‐fold, indicating a high risk of oxygen shortage. Concomitantly, levels of GRP75, GRP78 and GRP94 increased 1.5–1.7‐fold. At the same time, c‐Jun N‐terminal protein kinase (JNK) activity increased 6.4‐fold, and extracellular signal‐regulated protein kinase (ERK) activity decreased to a similar degree (6.1‐fold). p38 MAPK activity was very low and remained unchanged during arousal. In addition, survival signaling molecules protein kinase B (Akt) and protein kinase C (PKC) were activated 3‐ and 5‐fold, respectively, during arousal. Taken together, our results showed that bat brain undergoes high oxygen demand during arousal from hibernation. Up‐regulation of GRP proteins and activation of JNK, PKCγ and Akt may be critical for neuroprotection and the survival of bats during the repeated process.