|Year : 1991 | Volume
| Issue : 4 | Page : 151-153
Synergetic effects of U-V radiations and malnutrition of lens (experimental study)
SK Angra, PBSV Prasad, RL Mathur
Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All Institute of Medical Sciences, Ansari Nagar, New Delhi 110 029, India
S K Angra
Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All Institute of Medical Sciences, Ansari Nagar, New Delhi 110 029
Source of Support: None, Conflict of Interest: None
The synergistic effects of protein deficiency and U-V radiation is cataractogenic as seen in our experimental model though individually these had no damaging effect on enzymatic profile and clinical appearance.
|How to cite this article:|
Angra S K, Prasad P, Mathur R L. Synergetic effects of U-V radiations and malnutrition of lens (experimental study). Indian J Ophthalmol 1991;39:151-3
| Introduction|| |
The incidence of cataract is more in India and other tropical countries, where sunlight (UV light) is in abundance ,. Basic research strongly supports the concept that UV wavelength of sunlight can enhance the cataract process . The chronic malnutrition is also prevalent in India. Its relationship to human cataract is not established with certainty though evidence for the nutritional aetiology involving several different nutrients has been reported in a number of animal species ,
To ascertain if there is some synergism between these factors, we undertook the experimental study to evaluate the effects of UV radiation and malnutrition (protein deficiency) on the crystalline lens in rats.
| Material and methods|| |
40 Wistar strain albino rats, 12-20 weeks old were grouped as follows:
Group I Control
Group II Malnourished (protein deficiency)
Group III UV irradiated
Group IV Malnourished and UV radiated
Groups I and III were fed on normal diet at libitum and groups II and IV were maintained on a protein deficient diet . The diets were normally supplemented with salts and vitamins as our intention was to study the lack of protein intake only.
The group III & IV rats were exposed to three 15 watts, U-V black light tubes (Philips - Holland) with average radiation of 305 nm. fitted in wooden boxes of 28"X18"X18". The animals were exposed 12 hours a day for a period of 1 month. The general activity, weight, appetite and hair pattern were noted. These parameters were quantified and graded.
The ocular examination was done noting lid changes, cornea and lens transparency on slit lamp biomicro scope. After 1 month the animals were sacrificed, the lenses removed and subjected to histochemical study for LDH (Lactate dehydrogenase) and SDH (Succinate dehydrogenase) activity.
| Observations|| |
A. The rats were examined periodically to record various parameters for a follow up of one month [Figure - 1], [Table 1]
B. Ocular changes:
i) The lids remained normal in all groups except group IV which manifested wasting around the lids starting in the second week. In the 4th week there was pseudoproptosis in group IV.
ii) The cornea remain clear through the follow up in all the groups.
iii) The lens changes started only in group IV by the 3rd week initiating as a slight haze. These progressed to cortical and nuclear lenticular opacities by the 4th week [Figure - 2][Figure - 3]
C. Histochemical study
i) Histochemical study showed that there was good activity of LDH in the epithelium with high activity in the cortex and nucleus of lenses of the control group.
ii) The lens epithelium did not show any significant decrease in LDH or SDH activity as compared to normal controls.
iii) There was no statistically significant decrease in LDH activity in lenses of groups II and Ill. However, group. IV (protein malnourished and UV irradiated) showed a considerably significant decrease in activity in the cortex and nucleus of these lenses [Figure - 3].
iv) The SDH was lowered significantly in the cortex and nucleus in group II and IV and in the epithelium in group III. [Figure - 4]
| Discussion|| |
Many risk factors have been identified to have cataractogenic potentials like U-V radiations, malnutrition etc. However the experiments are acute and are mainly on experimental animals. Clinical epidemiological research has stressed the relation of UV radiation with cataractogenesis.
The data regarding the association of protein deficiency and cataract formation is scanty. We have recently shown the association of deficiency of proteins with different types of cataracts in humans 
There have been experimental studies probing into the effect of UV radiation on the lens ,Cataracts have been produced in animals after prolonged exposure to UV radiation. There is experimental evidence of cataract formation in single amino acid deficiency diseases in animals but the same with protein deficiency is not established . However, Bagchi  could demonstrate cataract in pigs with low protein diet.
Our observations showed that the rats of malnourished group II had a decrease of 10 gm/month body weight compared to the control group but no other changes are seen. This is in conformity with observations of McLaren .
The group with UV light exposure did not show any changes in the lens. This observation is not in agreement with those of Zigman . This could be due to the use of low exposure to U-V radiation in our study. We intentionally utilised low grade exposure of U-V rays as we wanted to simulate the day (12 hours) exposures only.
Secondly, we wanted to test protein deficiency and not the general malnutrition. In our study the lack of protein alone in the diet did not produce cataract. When protein deficiency and UV radiations were combined, the changes appeared in skin, lids and lens (cataract). It is noteworthy that individually these had not produced any change.
We have studied the effects of UV exposures and protein malnutrition on glycolysis by measuring LDH activity. We observed that LDH is not affected by protein deficiency or UV irradiation alone. I.DH activity is much more affected when the protein deficiency is associated with UV irradiations, indicating that glycolysis is affected by these risk factors. The enzyme activity of the epithelium remained the same while that of lens fibres is altered predominantly.
The cataractogenesis also started in these lens fibres only.
However SDH activity which is mainly present in mitochondria is not significantly altered by protein malnutrition. On UV exposure alone or when combined with malnutrition SDH activity decreases considerably.
This shows that in both the aerobic and anaerobic pathway, the glucose breakdown is affected by the cumulative effect of U-V exposure and malnutrition. Thus our observations of production of cataract and decreased activity of LDH and SDH indicate that protein malnutrition and UV exposure is cataractogenic, when used together, while individually these parameters did not produce cataract under our experimental conditions.
| References|| |
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[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4]