Institute of Internal Medicine, Siberian Branch of the Russian Academy of Medical Sciences, Novosibirsk, Russia.
Chronobiol Int. 2011 May;28(5):407-14. doi: 10.3109/07420528.2011.567425.
This study investigates the possibility of an endogenous circadian rhythm in retinal cone function in humans. A full-field cone electroretinogram (ERG) was performed every 2 h for 24 h under continuous rod-saturating ambient white light (53 ± 30 lux; pupils dilated) in nine healthy subjects. Distinct circadian variations were superimposed upon a gradual decrease in cone responsiveness to light, demonstrated most reliably in the implicit times of b-wave and oscillatory potentials, and to a lesser extent in amplitude and a-wave implicit times. After mathematical correction of the linear trend, the cone response was found to be greatest around 20:00 h and least around 06:00 h. The phase of the ERG circadian rhythm was not synchronized with the phase of the salivary melatonin rhythm measured the previous evening. Melatonin levels measured under constant light on the day of ERG assessments were suppressed by 53% on average compared to melatonin profiles obtained previously under near-total darkness in seven participants. The progressive decline in cone responsiveness to light over the 24 h may reflect an adaptation of the cone-driven retinal system to constant light, although the mechanism is unclear. The endogenous rhythm of cone responsiveness to light may be used as an additional index of central or retinal circadian clock time.
本研究旨在探究人类视网膜锥体功能是否存在内源性昼夜节律。在 9 名健康受试者中，在持续的 rod-saturating 环境白光（53±30lux；瞳孔扩张）下，每 2 小时进行一次全视野锥体视网膜电图（ERG）检查，持续 24 小时。在锥体对光响应逐渐下降的基础上，出现了明显的昼夜节律变化，b 波和眼动电位的潜伏期变化最为可靠，振幅和 a 波潜伏期也有一定程度的变化。对线性趋势进行数学校正后，发现锥体反应在大约 20:00 时最强，在大约 06:00 时最弱。ERG 昼夜节律的相位与前一天晚上测量的唾液褪黑素节律的相位不同步。在评估 ERG 的当天，在恒定光照下测量的褪黑素水平与 7 名参与者之前在几乎完全黑暗条件下获得的褪黑素图谱相比，平均抑制了 53%。在 24 小时内，锥体对光的反应逐渐下降，可能反映了锥体驱动的视网膜系统对恒定光的适应，但其机制尚不清楚。锥体对光的反应昼夜节律可能被用作中枢或视网膜生物钟时间的附加指标。
