1991 Fiscal Year Final Research Report Summary
Retinoids metabolism and its regulation in the rhodopsin-porphyropsin visual system.
| Project/Area Number |
01540610
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
動物発生・生理学
|
|---|
| Research Institution | Hyogo College of Medicine |
|---|
Principal Investigator |
SUZUKI Tatsuo Hyogo Coll. Med. Fac. Med. Lecturer, 医学部, 講師 (90068544)
|
|---|
| Project Period (FY) |
1989 – 1991
|
| Keywords | Rhodopsin / Porphyropsin / Retinol / Dehydroretinol / 3-Hydroxyretional / Retinoids metabolism |
|---|
| Research Abstract |
Four kinds of chromophore of visual pigment were found in invertebrate retina ; retinal, dehydroretinal, 3-hydroxyretinal and 4-hydroxyretinal.
The hypothesis is that these four retinoids are closely related compounds in the metabolic pathways. Retinoids metabolism was studied in the crayfish retina which has three of the four retinoids.
1. A polar compound found in the retina was identified to be 11-cis 3-hydroxyretinol. This compound existed in esterified form and its aldehyde was not detected, indicating the hydroxyl compound is not used for chromophore. When the animals were exposed to higher temperature conditions, 3-hydroxyretinol was decreased and disappeared with the same time course as that of dehydroretinol. The results suggested that the hydroxyretinol is a possible precursor of dehydroretinol.
2. The proportion of dehydroretinol in the stored ester is far higher than that of dehydroretinal in the chromophore. Two enzymes, retinyl ester hydrolase and retinol dehydrogenase, were studied in special reference to substrate specificity. Both enzymes were specific to 11-cis retinoids but not selective between retinol and dehydrorerinol. The results suggested a possible reaction converting retinol to dehydroretinol in the retina.
3. [3H]-retinol was incubated with retina homogenate to investigate the reti. nol-dehydroretinol conversion. Radioactivity of dehydroretinol was increased with the incubation time up to 3 hrs, and it was significantly reduced by boiling the homogenate. Radioactivity of 3-hydroxyretinol retained a low level during the incubation.
These results indicated that retinol is converted to dehydroretinolthrough 3-hydroxyretinol in the crayfish retina. A part of the hypothesis was supported by the present study.
|
Research Products
(14 results)
