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| ARTICLE |
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| Year : 1969 | Volume
: 17
| Issue : 5 | Page : 201-207 |
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Proteins of visual pathways having varied retinal receptors in altered conditions of visual stimuli
S Goswamy, LP Agarwal, SL Pahuja
Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All-India Institute of Medical Sciences, New Delhi - 16, India
| Date of Web Publication | 11-Jan-2008 |
Correspondence Address:
S Goswamy
Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All-India Institute of Medical Sciences, New Delhi - 16
India
 Source of Support: None, Conflict of Interest: None  | Check |
How to cite this article:
Goswamy S, Agarwal L P, Pahuja S L. Proteins of visual pathways having varied retinal receptors in altered conditions of visual stimuli. Indian J Ophthalmol 1969;17:201-7 |
After assessing the role of light in maturing visual pathways by electrophysiological (Goswamy, [3] ) and some biochemical parameters, (Goswamy and Mandel, [2] and Goswamy [4] ) we observed that the absence of visual stimuli since birth may bring about the functional and/or biochemical alterations in the functional maturation of visual pathways. In the last gathering of the XXVIII All-India Ophthalmological Conference (Goswamy, 1968 a), we presented the data which was thought to contribute towards a better understanding of mechanism of amblyopia in cases devoid of adequate visual stimuli during maturation of visual pathways.
In an effort to further substantiate our previous studies we have undertaken the investigation of protein levels in visual pathways having varied retinal receptors (Rod mainly, cone only, or mixed rod and cone retinae). The changes of proteins in these visual pathways have been studied under altered conditions of visual stimuli which resemble closely some of the causes of arnblyopia in human beings, e.g. corneal or lenticular opacities.
| Materials and Methods | |  |
The distribution of total proteins in different regions of visual pathways of normal adult animals having either rod (frog-R. Tigrina), or cone (domestic pigeon), or mixed rod and cone (albino rabbit) retinae has been determined. The various areas of visual pathways taken for the study of protein levels in each animal are given in the different tables and figures below.
The corneal or lenticular opacification has been produced by trauma with a cataract knife under sterile and aseptic conditions as far as possible. Besides this the infection and inflammation was prevented by a regular local use of chloromycetin and atropine ophthalmic ointments. The pigeons were kept devoid of all visual stimuli in a completely dark room with a thick black paper firmly stuck over the eyes with sticking plaster. This in addition was secured by a black bandage specially designed for the pigeons head.
The total proteins were determined by the method of Lowry, Rosebrough Farr and Randall, [8] as modified by Cowgill and Pardee. [1]
| Observations and Comments | | |
[Table - 1] presents in a concise form the distribution of proteins in various regions of the visual pathways of rabbit which has mixed rods and cones, pigeon which has cones only and frog which has rods mainly as reported in a previous contribution by us-Goswamy Agarwal and Pahuja. [7]
It can be seen that the total proteins in the corresponding visual pathways in the three groups are almost equal.
From [Table - 1], it is evident that the retina has the least amount of proteins, while the lower visual centres (that is, lateral geniculate body, superior colliculus, or optic lobes) have the maximum. The protein content in the visual cortex (higher visual centre) is between these two extremes. Although the difference in protein contents of retina, lower visual centres, and higher visual centres is small, it is statistically significant (p. < 0.01). However, there is no statistical difference in the protein contents of visual cortex as compared to frontal or olfactory lobes in the three animals.
From this one may infer that no matter what is the type of visual system, habitat, or the visual requirements, demanding either predominantly day or night vision in its own special environments, the proteins per unit of the individual component of visual system of the three animals studied, is more or less constant and identical, under normal circumstances of the different visual behaviours.
With this base for the normal protein levels in visual pathways, we have started to observe the changes in protein contents of visual system after visual deprivation either by total exclusion of visual stimuli (patching of eyes in dark), or by a more natural process of corneal or lenticular opacification which provides only a partial blockage to the light stimulus. The initial results of this study are presented here under.
In [Table - 2] and [Figure - 1], we find that the presence of partial or total traumatic cataract in frog's eyes brings about the lowering of proteins in the optic lobes (the main visual centre in frog) by 1.6 times as compared to normal. This difference is highly significant statistically (p. < 0.001). However, this traumatic cataract for 10 days in adult frog does not alter the protein contents in the retina or olfactory lobe of the same animals.
Similarly from [Table - 3] and [Figure - 2], we observe that traumatic cataract in adult rabbits lowers the protein levels in a significant manner (p < 0.01) in the lateral geniculate body and occipital (visual) cortex, that is, in the lower and higher visual centres in rabbit respectively. Again there is no statistically significant change in protein contents of other parts of visual system studied in these animals with traumatic cataract for four weeks.
Looking at [Table - 4] and [Figure - 2], we note that traumatic corneal opacification for two months or more in adult rabbit brings about some lowering of proteins in the visual cortex, lateral geniculate body, and even retina, but the p-value is less significant as compared to that in traumatic cataract series. This is possibly due to a less thick and mainly central corneal opacities produced in these animals. To clarify this doubt we are running another series of experiments with total and deep corneal opacities.
This data from [Table - 2],[Table - 3],[Table - 4] shows that visual deprivation by traumatic cataract or corneal opacification mainly lowers the protein contents of the visual centres (higher and lower), and in a less significant manner of the retina also. This means the cellular regions of the visual system are the site of alterations in proteins by a lack of visual stimuli. This compares very favourably with our previous results for the developing visual pathways of rabbits born and brought up in total darkness (Goswamy and Mandel [2] ). In this study we observed a reduction in proteins per cell in retina, lateral geniculate body and visual cortex. Also the levels of RNA and DNA at 15 or 21 days age were more close to those between birth and 8 days, that is, before the first opening of the eyes. We have also noted a retardation in the evolution of distribution and synthesis of proteins, nucleic acids, and even the functional maturation of visual pathways electrophysiologically in these rabbits reared in complete darkness. This electrophysiological work indicated to us that retardation in maturation of visual evoked responses in absence of light is mainly situated at the level of visual cortex (Goswamy, Bonaventure and Karli [5] ). Our work is further supported by the observations of Maraini, Carta, Franguelli, and Santori, [9] ) who have reported that monocular light-deprivation in new born rats, shortly after the first opening of eyes, produces a significant decrease of [3] H-leucine incorporation in the lateral geniculate nucleus, reflecting thereby a decrease in protein synthesis. They, however, did not find any modification of the amino acid uptake in the different cellular layers of the retina and visual cortex. To add to this, Talwar, Chopra, Goel and D'Monte [10] have also noted significantly lower content of proteins in the occipital cortex of 2-weeks old rabbits, who were blinded after birth by enucleation of the eyes at birth. They inferred from this that protein content of the occipital cortex is possibly dependent on the light stimulus. They also found that animals kept in dark had less incorporation of radioactive amino-acid ( 14 C-valine) in occipital cortex proteins, as compared to animals exposed to light stimulus.
The total proteins in visual pathways of pigeons devoid of all visual stimuli for 48 hours are only slightly lowered, though significant statistically, in the optic lobes [Table - 5] and [Figure - 3]. The absence of modifications in protein distribution in visual pathways may only be due to a short duration of 48 hours for the visual deprivation. Further studies with longer duration of visual deprivation are underway. This, in any case, also points to a decrease in proteins at the visual centres in stimulus deprivation.
Thus, one may deduce from these observations that no matter, what type of visual system is employed and what mode of visual deprivation is instituted, the lack of visual stimuli diminishes the contents and biosynthesis of proteins in the cellular regions of visual system, and this is more marked in the higher or lower visual centres but less so in the retina. The latter may be either due to a comparatively shorter duration of visual deprivation, or that adult retina does not show the gross alterations in proteins very easily. This is being further investigated. However this study lends some more information for the better understanding of the rather eluding mechanism of amblyopia ex anopsia.
| Acknowledgements | | |
The dexterous technical help to this work was given by Mr. Satish Kumar. This study is supported by a research grant from Indian council of medical research.
| References | | |
| 1. | Cowgill R. W. and Pardee A. B. (1957) -Experiments in biological research techniques, P. 176, pub].. John Wiley, New York.  |
| 2. | Goswamy S., Mandel P. and Karli, P.: (1966)-International symposium of ophthalmic biochemistry, held at Tutzing (W. Germany)-p. 514. Krager Baset. August, 1966. |
| 3. | Goswamy S. (1968 b)-Paper presented at the annual session of Indian Academy of Medical Sciences. held at New Delhi in December, 1968. |
| 4. | Goswamy S. (1967)-Thesis presented for the award of 'docteur es-sciences' to the University of Strasbourg (France) - in May, 1967. |
| 5. | Goswamy S., Bonaventure N. and Karli P. C. R. Soc. Biol. (France)161, 921 (1967). |
| 6. | Goswamy S. (1968 a)-Paper presented at the XXVIII All-India Ophthalmological conference, held at Ahmedabad in Jan. 1968. |
| 7. | Goswamy S., Agarwal L. P., and Pahuia S. L. (1969)-Oriental Arch. of Ophthal. 7, 93, (1969). |
| 8. | Lowry O. H., Rosebrough N. J., Farr A. L., and Randall R. J. (1951)-J. Biol. Chem.-193, 265. |
| 9. | Maraini G., Carta F., Franguelli R. and Santori M.-Exptl. Eye Res.-6, 299 (1967). |
| 10. | Talwar G. P., Chopra S. P., Goel B. K. and D'Monte B.-J. Neurochem.-13, 109 (1966). |
[Figure - 1], [Figure - 2], [Figure - 3]
[Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5]
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