Photoendocrine Transduction in Cultured Chick Pineal Cells: IV. What Do Vitamin A Depletion and Retinaldehyde Addition Do to the Effects of Light on the Melatonin Rhythm?
Photoendocrine Transduction in Cultured Chick Pineal Cells: IV. What Do Vitamin A Depletion and Retinaldehyde Addition Do to the Effects of Light on the Melatonin Rhythm?
复制标题
培养鸡松果体细胞中的光内分泌转导：IV。
DOI：
10.1046/j.1471-4159.1994.62052001.x
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发表时间：
1994
影响因子：
4.7
通讯作者：
M. Zatz
中科院分区：
文献类型：
--
作者：
M. Zatz
摘要：光对静态培养中分散的雏鸡松果体细胞显示的褪黑激素输出的昼夜节律至少有两种明显的影响：褪黑激素输出的急性抑制和底层起搏器的夹带（相移）。先前的结果表明，光的这两种效应是由不同的机制途径介导的。光的急性和相移效应的路径要么从相同的单一感光颜料分支，要么从一开始就不同，从单独的感光颜料开始。如果单一视紫红质类感光色素介导光的两种效应，那么维生素 A 消耗和类视黄醇添加应该同时影响这两种反应，尽管不是成比例的。因此，我们在几种实验条件下比较了维生素 A 消耗和类视黄醇添加对光的急性和相移效应的影响。当小鸡松果体细胞缺乏维生素 A 时，对光的急性反应明显减弱。添加 11-顺式-视黄醛可特异性恢复（并增强）急性反应。当允许在恒定的红光下自由运行时，耗尽的细胞显示出褪黑激素输出的节律，其周期与对照细胞相同。与急性效应相反，耗尽细胞和对照细胞对 2 小时或 4 小时光脉冲的响应相移没有差异。向耗尽的细胞中添加视黄醛本身并不会减少褪黑激素的输出或诱导相移。视黄醛确实增加了对 4 小时光脉冲的急性反应，但没有增加随后的相移。响应随着光脉冲的持续时间而增加：4 小时光脉冲引起的急性效应和相移都比 2 小时（或 1 小时）光脉冲引起的大得多。向耗尽的细胞中添加视黄醛将 2 小时（或 1 小时）光脉冲的急性效应增加到至少 4 小时光脉冲的急性效应，但并没有增加随后相移的大小。这些结果有力地证实了先前介导光对雏鸡松果体细胞的急性和相移效应的机械途径的分离。他们还支持类视紫红质感光色素在急性反应中的作用，但不支持相移反应。他们赞成但没有证明单独的感光色素介导光的急性和夹带效应的结论。
Abstract: Light has at least two distinguishable effects on the circadian rhythm of melatonin output displayed by dispersed chick pineal cells in static culture: acute suppression of melatonin output and entrainment (phase shifts) of the underlying pacemaker. Previous results indicated that these two effects of light are mediated by different mechanistic pathways. The pathways for the acute and phase‐shifting effects of light either branch from the same, single photopigment or differ from the outset, starting from separate photopigments. If a single rhodopsin‐like photopigment mediates both effects of light, then vitamin A depletion and retinoid addition should affect both responses in parallel, although not proportionately. We therefore compared the effects of vitamin A depletion and retinoid addition on the acute and phase‐shifting effects of light under several experimental conditions. When chick pineal cells were depleted of vitamin A, acute responses to light were markedly reduced. Addition of 11‐cis‐retinaldehyde specifically restored (and enhanced) the acute response. When allowed to free run in constant red light, depleted cells displayed a rhythm of melatonin output with the same period as that of control cells. In contrast to the acute effects, phase shifts in response to 2‐ or 4‐h light pulses did not differ between depleted and control cells. Addition of retinaldehyde to depleted cells did not, by itself, reduce melatonin output or induce phase shifts. Retinaldehyde did increase the acute response to 4‐h light pulses but not the ensuing phase shifts. Responses increased with duration of the light pulse: Both the acute effect and the phase shifts induced by 4‐h light pulses were considerably larger than those induced by 2‐h (or 1‐h) light pulses. Addition of retinaldehyde to depleted cells increased the acute effect of 2‐h (or 1‐h) light pulses to at least that seen with 4‐h light pulses but did not Increase the size of the ensuing phase shifts. These results strongly confirm previous dissociations of the mechanistic pathways mediating the acute and phase‐shifting effects of light on chick pineal cells. They also support a role for rhodopsin‐like photopigment in the acute, but not phase‐shifting, response. They favor, but do not prove, the conclusion that separate photopigments mediate the acute and entraining effects of light.