Eye Candy has a Whole New Meaning!- Don't Deprive Your Eyes!
James Hurley at the University of Washington in Seattle and his colleagues may have solved the mystery of how the rods and cones in your eyes receive and utilize energy.
Woo Freakin Hoo…
There are two types of photoreceptors in the human retina, rods and cones. Rods are responsible for vision at low light levels called scotopic vision. They do not mediate color vision, and have a low spatial acuity. Cones are active at higher light levels called photopic vision, are capable of color vision and are responsible for high spatial acuity. There are 3 types of cones which we will refer to as the short-wavelength sensitive cones, the middle-wavelength sensitive cones and the long-wavelength sensitive cones or S-cone, M-cones, and L-cones for short.
Rods- low level light- scotopic vision- no color- low spatial acuity
Cones-high level light- photopic vision-color- 3 types- high spacial acuity
The team found a coupling mechanism between the two parts of the eye. Rods and cones are very active, and they need a lot of energy to do their jobs. Exactly how they get this energy has long been a mystery. Previously, studies have found a layer of cells beneath the retina, the retinal pigment epithelium or RPE, transports glucose from blood to the retina. The quandary from this finding was, why doesn’t the RPE keep the glucose for itself?
We may now know!
James Hurley at the University of Washington in Seattle and his colleagues have shown that the retina’s rods and cones use the glucose and convert the leftovers into a fuel called lactate. This lactate is then fed back to the RPE- retinal pigment epithelium.
The team discovered that RPE’s power plants—the mitochondria—burn lactate to power the RPE. Hurley explains, “That allows the glucose to go through without being consumed.” If the RPE is deprived of lactate, then those cells switch to burning the glucose instead of delivering it to the retina and with glucose shut off, the retina cells can die. No Bueno!!!
THE RESEARCH PROCEDURE
In order to map the way glucose and lactate move around in the eye precisely, Hurley and colleagues grew human RPE in a lab dish and studied its biochemistry. They also studied isolated mouse retinas in conjunction. This is how they discovered that the power plants of the RPE’s—the mitochondria—burn lactate to power the RPE.
Researchers are looking at the profitability of this discovery already. One possibility is synthesizing a drug or supplement that will prevent this type of starvation. They are thinking it could have wide implications for many diseases that involve glucose starvation caused by a wide array of gene malfunctions.
One neato of a find with this research was also the mystery of why when cones allow us to see color die, when rods (who dim light) are not working properly. Now researchers are putting the puzzle together and realizing that if you have a defective rod it wont make lactate and this will in turn cause the RPE whom are energy deprived to steal all the glucose which then essentially starves both rods and cones. Scientists are now starting to think that aging in the eyes can be contributed by this glucose-lactate imbalance.
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