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ARTICLES |
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Year : 1979 | Volume
: 27
| Issue : 2 | Page : 10-11 |
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Effect of maternal malnutrition and/or Vitamin-A deficiency of the development of eye in rats
C Ratnakar, AL Aurora
Department of Pathology, Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry 605006, India
Correspondence Address: A L Aurora Department of Pathology, Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry 605006 India
Source of Support: None, Conflict of Interest: None | Check |
PMID: 541025
How to cite this article: Ratnakar C, Aurora A L. Effect of maternal malnutrition and/or Vitamin-A deficiency of the development of eye in rats
. Indian J Ophthalmol 1979;27:10-1 |
Maternal protein and vitamin-A malnutrition abounds in the developing nations of the world. The detrimental effects of this malnutrition on the growing foetus have been studied by several workers bringing to light the effect of such malnutrition, especially on the brain. The eye which is embryologically an extension of the brain has so far been relatively neglected in such studies. The reasons is the inherent difficulty in obtaining eyeballs of the developing foetuses at various stages vis a vis maternal malnutrition. In this context, it was felt that an experimental model might give necessary information. The rat's eye mostly develops postnatally and therefore can be accurately timed. The present study was therefore carried out on rats born to dams placed on protein deficient diet with or without vitamin-A deficiency.
Material And Methods | | |
Twenty female albino rats were placed on a stock diet (Diet A) for 3 weeks before mating. The dams were separated 4 to 5 days before delivery, divided into 4 groups and placed on different diets [Table - 1] as shown below.
1. Control group (Diet A): Consisted of 5 animals.
II. Group B (Diet B): Five animals were placed on diet B.
III. Group C (Diet C): Five animals were placed on diet C.
IV. Group D (Diet D): Five animals were placed on diet D.
The diets were given ad lib. The diets were started 4 to 5 days before delivery and continued till the experiment was over, except diet A which was given throughout the pregnancy as well. The offsprings born were kept with the mother without change in the number to be nursed by a particular darn. The offsprings were sacrificed at following intervals using anaesthetic ether.
Newborn--2 offsprings; 24 hours-2 offsprings; 48 hours-2 offsprings; 72 hours-2 offsprings; 96 hours-2 offsprings; 6th day-2 offsprings; 8th day-2 offsprings; 12th day-2 offsprings; 16th day-2 offsprings; 20th day-2 offsprings.
The eyeballs removed were processed, grossed and sectioned as described by Jayanthi and Aurora[2].
The sections were stained with Haematoxylin and Eosin, Alcian Blue (pH 2 5) Periodic Acid Schiff method (PAS) (Luna[3]) and Verhoeff's elastin stain according to standard procedures[4].
The thickness of whole retina and thickness of different layers of retina were measured using micrometer. The cells of the retina were classified into 3 categories viz. spindle cells, oval cells and round cells to assess their degree of differentiation. The spindle cells were most undifferentiated, whereas round cells were most differentiated. The oval cells formed the intermediate groups. Mitosis were also counted along the outer border of the neuroblastic layer. On each day studied, two measurements were taken from each eye of the sacrificed animal. The measurements were averaged and the standard error for each mean calculated.
Results | | |
The animals fed on protein deficient diet with or/without Vitamin-A deficiency weighed 27%. less at birth compared to group A. The weight gain in these animals in the first 20 days was only 50% of that of the group A.
Eyes
No gross abnormality could be trade out in any of the eyeballs. The cornea did not show any significant change in any of the groups.
Lens
Vacuolation and granular degeneration of lens fibres was seen in one newborn animal in each of the groups C and D, and in two animals on 3rd and 4th day, in group D.
Retina
The total thickness of retina on different days is shown in [Table - 2] and [Figure - 1]. The differentiation of various layers of the retina occured normally in all the groups. No morphological changes were seen in the retina in any of the groups except for thinning of various layers of retina in the experimental groups (Groups B, C and D), There was no difference in the differentiation of cells in the neuroblastic layers viz. the spindle, oval and round cells in any of the groups [Table - 3]. The mitotic activity in the outer part of the neuroblastic layer was reduced in the experimental groups. The difference in the total thickness of retina between groups A and B and between groups A and D was statistically highly significant on all days. From day 0 to day 4 this difference in the thickness of retina was mainly due to thinning of the neuroblastic layer in experimental groups. From day 6 to day 20 the thickness of different layers of retina was reduced in all the experimental groups, mainly in the inner plexiform layer, inner nuclear layer and in the layer of rods and cones. [Table - 4].
Discussion | | |
Cornea
Mclaren[6] described atrophy of the corneal epithelium with hyperkeratosis and parakeratosis in rats fed on Vitamin-A deficiency after 6 weeks of placement on deficient diet. In the present study cornea did not show any significant change in any of the groups. The changes described above were not seen in the present study possibly due to short duration of observations.
Lens
Mclaren[5] described absence of normal fibre formation and disorganization of lens substance in the newborn rats born to dams fed on protein deficient diet. In the present study one newborn animal in each of the groups C and D [Figure - 2] and two (3rd and 4th day) in Group D showed vacuolation and granular degenration of lens fibres. However at later stages of development, the organization of lens fibres appeared normal. It is possible that at the critical peak levels of accelerated formation of lens fibres, the deficient diets adversely affected the fibre formation.
Retina
In the present study the thickness of retina was less in all the experimental groups when compared to the control group mainly due to decrease in the thickness of neuroblastic layer in the first 4 postnatal days. From day 6 there was gradual thinning of inner plexiform layer, inner nuclear layer, and the layer of rods and cones. This was quite obvious at day 20, where as the control animal shows normal development of the retina [Figure - 3]. Protein deficient animal shows thinning of layer of rods and cones, the outer nuclear layer and also of the outer plexiform layer [Figure - 4]. In animals given vitamin-A deficient diet there was thinning of all the layers [Figure - 5]. In the animals placed on both vitamin-A and protein defictent diet, the thinning of the retina was profound affecting all its layers [Figure - 6], more so than in animals placed on protein or vitamin-A deficient diets. This indicated that protein and vitamin-A deficiency together very adversely affected the growth of the retina.
It is obvious that as the differentiation of cells progressed normally, the thinning of the retina in groups B, C and D was obviously due to lesser number of cells and their processes, Deo et al' have described that protein deficiency affected growth and development of several tissues of body, particularly in infancy by altering the normal balance between the four biologic processes viz. cell formation. migration differentiation and death. Winick and Ross[7] observed that malnutrition during early development affected both protein and DNA synthesis resulting in stunted brain containing fewer cells of normal size.
In the present study, there was thinning of the retina, the differentiation being normal. It shows that cell formation was affected in protein deficiency with or without vitamin-A deficiency but more adversely in combined deficiency Another evidence to show that cell formation was affected in experimental groups was the reduction in mitotic activity in the experimental groups. The decreased mitotic activity may be due to: (i) the number of cells entering the mitotic cycle being less in a given time or/and (ii) the cells may be entering GO phase, but are unable to enter the mitotic cycle. Whatever be the mechanism, the cell mass is reduced accouning for the decrease in thickness of retina.
The present study has highlighted that the retina, which for all practical purposes is an extension of the brain, is severely affected in protein deficiency and to a still greater extent by the synergistic action of protein and VitaminA deficiencies.
Summary | | |
Twenty pregnant albino rats were placed on protein rich or protein deficient diets with or without Vitamin-A deficiency for 4 to 5 days before delivery. The diet was continued postpartum. The eyeballs of offsprings of these animals were studied histologically from day 0 (Newborn) to day 20. It was noted that protein deficiency and/or Vitamin-A deficiency caused thinning of the retina especially of the neuroblastic layer and layer of rods and cones. The effect was more profound with combined deficiency. This suggested that the cell population of the retina was severely affected in the aforesaid deficient states.
References | | |
1. | Deo, M.G. et al, 1975, Growth and development of the Brain. Edited by M.A.B. Brazier, Raven Press, 1-15, |
2. | Jayanthi, K. and Aurora, A.L., 1977, Indian J. Ophthal., 25, 11-31. |
3. | Luna, C.G., 1968, Manual of Histologic Staining Methods of the Armed Forces Institute of Pathology, 3rd edition. Mcgraw-Hill Book Company, New York. |
4. | Manual of Histologic Staining Methods of the Armed Forces institute of Pathology, 2nd edition, 1960, Mcgraw-Hill Book Company, New York. |
5. | Mclaren, D.S., 1959, J. Nutr. 43,78-87. |
6. | Mclaren, D.S., 1963, Malnutrition and the eye, Academic Press, New York, 1963. |
7. | Winick, M. and Ross, P., 1975, Protein-calorie malnutrition, edited by Olsen, R.E., Academic Press, New York. |
[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6]
[Table - 1], [Table - 2], [Table - 3], [Table - 4]
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