Caffeine Research Today is a free monthly online journal that collates and summarizes the latest research about Caffeine, including details on addiction, drugs, effects, coffee. | ||||||||
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Caffeine releasable stores of Ca2+ show depletion prior to the final steps in delayed CA1 neuronal death.Xing H, Azimi-Zonooz A, Shuttleworth CW, Connor JA Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA. In addition to their role in signaling, Ca2+ ions in the endoplasmic reticulum also regulate important steps in protein processing and trafficking that are critical for normal cell function. Chronic depletion of Ca2+ in the endoplasmic reticulum has been shown to lead to cell degeneration and has been proposed as a mechanism underlying delayed neuronal death following ischemic insults to the CNS. Experiments here have assessed the relative content of ryanodine receptor-gated stores in CA1 neurons by measuring cytoplasmic Ca2+ increases induced by caffeine. These measurements were performed on CA1 neurons, in slice, from normal gerbils, and compared with responses from this same population of neurons 54-60 h after animals had undergone a standard ischemic insult: 5-min bilateral occlusion of the carotid arteries. The mean amplitude of responses in the postischemic population were less than one-third of those in control or sham-operated animals, and 35% of the neurons from postischemic animals showed very small responses that were approximately 10% of the control population mean. Refilling of these stores after caffeine challenges was also impaired in postischemic neurons. These observations are consistent with our earlier finding that voltage-gated influx is sharply reduced in postischemic in CA1 neurons and the hypothesis that the resulting depletion in endosomal Ca2+ is an important cause of delayed neuronal death. Published 15 October 2004 in J Neurophysiol, 92(5): 2960-7.
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