Racine Julie, Behn Darren, Lachapelle Pierre
Department of Neurology-Neurosurgery, McGill University-Montreal Children's Hospital-Research Institute, Montreal, QC, Canada.
Doc Ophthalmol. 2008 Jul;117(1):13-26. doi: 10.1007/s10633-007-9098-1. Epub 2007 Nov 22.
Altricial animals, such as rats and mice, are born with their eyes closed, compared to precocial animals, such as guinea pigs and humans, which have their eyes opened at birth. The purpose of this study was to investigate if the retina of guinea pigs (precocial animal) is subjected to a postnatal maturation process similar to that previously reported for rodents.
Photopic and scotopic electroretinograms (ERG) and retinal histology were obtained from albino guinea pigs aged P1 to P75.
Photopic ERG responses reached maximal amplitudes at P5 (a-and b-waves), that is 5 days (b-wave) to 10 days (a-wave) earlier than scotopic responses. However, the postnatal gain in b-wave amplitude was significantly (P < 0.05) more important for the cone (73.38 +/- 4.4%) signal than for the rod (15.23 +/- 3.96%), suggesting that the rod function is more mature at birth. Similarly, the short latency photopic oscillatory potential (ie: OP2) reached its maximal value 5 days (P10) earlier than its scotopic equivalent (P15), while the long latency OPs (ie: OP3, OP4), reached their maximal values nearly 20 days sooner in scotopic condition. Finally retinal histology revealed a thinning of the retina with age, the latter being most pronounced at the level of the ganglion cell layer (GCL).
Our results thus confirm that despite its relative maturity at birth (compared to rodents), the retina of newborn albino guinea pigs undergoes significant postnatal maturation modifying its structure as well as its function, albeit not as extensive as that previously documented for altricial animals.
与豚鼠和人类等早成动物出生时眼睛睁开不同，大鼠和小鼠等晚成动物出生时眼睛是闭合的。本研究的目的是调查豚鼠（早成动物）的视网膜是否经历类似于先前报道的啮齿动物的出生后成熟过程。
获取出生后1天至75天的白化豚鼠的明视觉和暗视觉视网膜电图（ERG）以及视网膜组织学数据。
明视觉ERG反应在出生后5天（a波和b波）达到最大振幅，比暗视觉反应早5天（b波）至10天（a波）。然而，出生后b波振幅的增加对锥体细胞（73.38±4.4%）信号的重要性显著（P<0.05）高于对杆体细胞（15.23±3.96%），这表明杆体细胞功能在出生时更成熟。同样，短潜伏期明视觉振荡电位（即：OP2）比其暗视觉对应物（P15）提前5天（P10）达到最大值，而长潜伏期振荡电位（即：OP3、OP4）在暗视觉条件下达到最大值的时间早近20天。最后，视网膜组织学显示视网膜随年龄变薄，在神经节细胞层（GCL）水平最为明显。
我们的结果因此证实，尽管新生白化豚鼠的视网膜在出生时相对成熟（与啮齿动物相比），但其视网膜在出生后仍经历显著的成熟过程，改变其结构和功能，尽管不如先前记录的晚成动物那样广泛。
