據(jù)日本《朝日新聞》8月15日報道，日本北海道大學的科學家研究發(fā)現(xiàn),，咖啡和茶含有的咖啡因可以刺激人腦中的記憶細胞發(fā)生變化，從而于增強人類的記憶力,。研究成果已經(jīng)在美國《國家科學院院刊》網(wǎng)站發(fā)表,。
人為什么能記憶？科學家們對這個問題的爭論從未停止,。一般的看法是,，神經(jīng)細胞產(chǎn)生變化，使得外界信號能夠在神經(jīng)系統(tǒng)中發(fā)生傳遞,，人才能產(chǎn)生記憶,。神經(jīng)細胞的變化速度和細胞的鈣濃度有關(guān)，而調(diào)節(jié)細胞鈣濃度的是一種特殊的蛋白質(zhì)——肌質(zhì)網(wǎng)如蘭尼堿受體,。
日本北海道大學的神經(jīng)生物學研究實驗室經(jīng)過對老鼠反復(fù)試驗發(fā)現(xiàn),，飲用含有咖啡因的茶或者咖啡后，肌質(zhì)網(wǎng)如蘭尼堿受體受到刺激,，神經(jīng)細胞的鈣濃度就會上升,，從而使得外界信號更容易在神經(jīng)細胞中得到傳遞，老鼠因此變得越來越”聰明”,。
研究小組的組長,、北海道大學教授神谷溫之稱，這種新的刺激反應(yīng)和以往人們認為的刺激系統(tǒng)完全不同,。據(jù)悉,，新發(fā)現(xiàn)將應(yīng)用到醫(yī)學領(lǐng)域，開發(fā)治療,、改善癡呆癥和記憶障礙癥的藥物,。（生物谷Bioon.com）
生物谷推薦原始出處：
PNAS Published online before print August 7, 2008, doi: 10.1073/pnas.0802175105
Use-dependent amplification of presynaptic Ca2+ signaling by axonal ryanodine receptors at the hippocampal mossy fiber synapse
Hidemi Shimizu*, Masahiro Fukaya*, Miwako Yamasaki*, Masahiko Watanabe*, Toshiya Manabe?,?,§, and Haruyuki Kamiya§,?,‖
Abstract
Presynaptic Ca2+ stores have been suggested to regulate Ca2+ dynamics within the nerve terminals at certain types of the synapse. However, little is known about their mode of activation, molecular identity, and detailed subcellular localization. Here, we show that the ryanodine-sensitive stores exist in axons and amplify presynaptic Ca2+ accumulation at the hippocampal mossy fiber synapses, which display robust presynaptic forms of plasticity. Caffeine, a potent drug inducing Ca2+ release from ryanodine-sensitive stores, causes elevation of presynaptic Ca2+ levels and enhancement of transmitter release from the mossy fiber terminals. The blockers of ryanodine receptors, TMB-8 or ryanodine, reduce presynaptic Ca2+ transients elicited by repetitive stimuli of mossy fibers but do not affect those evoked by single shocks, suggesting that ryanodine receptors amplify presynaptic Ca2+ dynamics in an activity dependent manner. Furthermore, we generated the specific antibody against the type 2 ryanodine receptor (RyR2; originally referred to as the cardiac type) and examined the cellular and subcellular localization using immunohistochemistry. RyR2 is highly expressed in the stratum lucidum of the CA3 region and mostly colocalizes with axonal marker NF160 but not with terminal marker VGLUT1. Immunoelectron microscopy revealed that RyR2 is distributed around smooth ER within the mossy fibers but is almost excluded from their terminal portions. These results suggest that axonal localization of RyR2 at sites distant from the active zones enables use dependent Ca2+ release from intracellular stores within the mossy fibers and thereby facilitates robust presynaptic forms of plasticity at the mossy fiber-CA3 synapse.
