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首页> 外文期刊>The European Journal of Neuroscience >Developmental and circadian changes in Ca2+ mobilization mediated by GABAA and NMDA receptors in the suprachiasmatic nucleus.
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Developmental and circadian changes in Ca2+ mobilization mediated by GABAA and NMDA receptors in the suprachiasmatic nucleus.

机译：裂上眼核中GABAA和NMDA受体介导的Ca2 +动员的发育和昼夜节律变化。

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摘要

The hypothalamic suprachiasmatic nucleus (SCN) develops as the circadian pacemaker during postnatal life. Although both GABAA and NMDA receptors are expressed in the majority of SCN neurons, postnatal development of their functions has not been analysed. Thus, we studied the receptor-mediated Ca2+ responses in mouse hypothalamic slices prepared on postnatal days (P) 6-16. The NMDA-induced Ca2+ flux was prominent in the SCN and maximal Ca2+ responses in Mg2+-free conditions had no day-night variations in P14-16 mice. At P6-7, extracellular Mg2+ reduced the NMDA-induced Ca2+ flux irrespective of the circadian time whereas, after P9-10, Mg2+ produced a larger reduction at night than during the daytime. Muscimol also significantly increased Ca2+ in the developing SCN. Voltage-sensitive Ca2+ channel blockers inhibited the muscimol-induced Ca2+ increase whereas tetrodotoxin had no effect, suggesting that stimulation of postsynaptic GABAA receptors depolarizes SCN neurons to increase Ca2+. Macroscopic imaginganalysis demonstrated a developmental reduction in the muscimol-induced Ca2+ increase preferentially in the nighttime group older than P9-10. The day-night variation in the magnitude of the Ca2+ response was due to two cell populations, one of which exhibited an increase and the other a decrease in Ca2+ in response to muscimol. Because the critical developmental stages for exhibiting day-night variations in the receptor-mediated Ca2+ responses overlapped the maturation of firing rhythms in SCN neurons, the Ca2+ signalling may be necessary for or regulated by the mature circadian clock.
机译：下丘脑视交叉上核（SCN）在产后生活中作为昼夜节律起搏器发展。尽管大多数SCN神经元均表达GABAA和NMDA受体，但尚未分析其功能的产后发育。因此，我们研究了在出生后第6-16天制备的小鼠下丘脑片中受体介导的Ca2 +反应。在SCN中，NMDA诱导的Ca2 +流量显着，在无Mg2 +的条件下，最大的Ca2 +反应在P14-16小鼠中无昼夜变化。在P6-7，细胞外Mg2 +降低了NMDA诱导的Ca2 +通量，而与昼夜节律无关，而在P9-10之后，Mg2 +在夜间的减少量要大于白天。 Muscimol还显着增加了发育中的SCN中的Ca2 +。电压敏感的Ca2 +通道阻滞剂抑制了麝香酚诱导的Ca2 +的增加，而河豚毒素则没有作用，这表明刺激突触后GABAA受体使SCN神经元去极化，从而增加Ca2 +。宏观成像分析表明，在夜间组中，比P9-10年龄更大的组中，麝香酚诱导的Ca2 +的增长减少。 Ca2 +响应幅度的昼夜变化是由于两个细胞种群，其中一个对麝香酚的响应显示出增加的Ca2 +减少。因为在受体介导的Ca2 +反应中表现出昼夜变化的关键发育阶段与SCN神经元的发射节律的成熟重叠，所以Ca2 +信号对于成熟的生物钟可能是必需的或受其调控的。

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