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Journal of the Anatomical Society of India

Effect of Prenatal Vitamin A in Low Doses on the Liver and Kidney of Rat Fetuses- A Histological Study

Author(s): Mehrotra N. & *Shah G. L.

Vol. 53, No. 2 (2004-07 - 2004-12)

H.I.M.S. Dehradun, *I.M.S., B.H.U. , Varanasi.

Abstract:

Vitamin-A plays a key role in many biological processes including growth and differentiation of epithetial tissues, vision, spermatogenesis and embryonic development. In present study, vitamin - A in very low doses (7.5 mg/kg body weight ) was injected intraperitoneally to albino rats on gestation day 11 (sperm +ve = 0 day ) An equivalent amount of the vehicle (normal saline) was similarly injected to corresponding control rats. On 20th day of gestation, the rats were sacrificed. Histological evaluation of liver and kidney were done. Severe degeneration with hydronephorosis was found in kidney while disrupted normal architecture pattern along with severe hamorrhage was found in liver.

Keywords: Vitamin A , retinoic acid, liver, kidney.

Introduction:

Retinoic acid(RA) is in oxidative metabolite of vitamin A which exists in two forms trans and cis RA. A constellation of birth defects termed Retinoic Acid Embryopathy (RAE) results from oral administration of13 cis Retinoic Acid, Lammer et al (1985). Studies havedescribed a RAE consisting of craniofacial, cardiac, thymic and central nervous system abnormalities,Gudas(1994) and Madan (1994). The effects of RA are mediatedby two major groups of peptides, the nuclear receptorproteins and the cytoplasmic binding proteins. Thereare two members of retinoic receptors : Retinoic acid receptors (RAR) and Retinoic X receptor (RXR), Mangelsdorf et al (1994). RAR and their ligands may beinvolved in normal as well as abnormal embryonicdevelopment, Chambon (1993). The RAR and RXRfamilies of RA receptors show a very distinct spatial aswell as temporal distribution within the developingembryos, Dolle et al (1990) and Yamagata et al (1994). The present investigation has been undertaken to studythe effect of low doses of vitamin- A administered in pregnant rats of Charles Foster (C.F.) strain on 11th dayto see its teratogenic effects.

Material and Methods:

In present study Charles- Foster strain rats were used. The total number of female rats used in the present experiment was 40 out of which 30 were treated with desired drug and 10 were kept as control.

Male and female Charles- Foster strain rats (150200 gm) were placed together (1:3) overnight for mating and presence of sperm in the vaginal smear was taken as gestation day zero (GD 0) . Vitamin A (7.5mg / kg body weight ) was administered intraperitoneally once in a single dose at 9.00 hr on gestation day 11 (GD 11). Control group of pregnant rats were administered similarly with equal volume of vehicle (normal saline). Both control and treated groups were sacrificed on day 20 of gestation (GD 20) by ether anesthesia. In an average 46 fetuses were collected from each pregnant rat.Liver and kidney were collected from control and treated groups of fetuses and fixed in 10% formalin. These were processed for paraffin sections and were stained by Haematoxylin - Eosin method.

Results:

On histological evaluation of kidney from treated group of fetuses, it was observed that there was severe degeneration of glomeruli showing shrinkage (Fig. 1b) along with disrupted proximal and distal convoluted tubules. There was increased periglomerular space (Fig. 1b) in sections of treated group of kidney which showed hydronephrosis.

On histological examination of liver from treated group of fetuses, it was found that central vein was found to be elongated in appearance because of disruption and it was surrounded by degenerative hepatocytes with inflammatory cells (Fig. 2b). There was disruption of normal architecture pattern of classical lobule along with severe haemorrhage infiltrating many areas (Fig. 2c).

In control group, kidney (Fig. 1a) and liver (Fig. 2a) showed no pathological appearances.

Discussion:

Results of the present study clearly reveal that prenatal exposure of vitamin-A even in very low doses (7.5mg/kg body weight) produces histopathological changes like hydronephrosis of kidney and haemorrhagic patches in liver. In previous studies, Elmazar et al (1996) found hypoplasia of kidney, hydronephrosis, hydroureter and dark haemorrhagic liver after administration of RA (37.5 mg/kg body weight).

9-cis-RA is a natural metabolite of all trans RA. Trans RA is present endogenously in the embryo and shows a specific distribution within certain areas such as the floor plate of neural tube, Wagner et al (1990), in Hensen's node, Chen et al (1992) and in the developing limb bud Thaller and Eichele (1999).

9-cis-RA can bind to both the RAR and RXR receptors while all trans RA acts as ligand for the RAR receptors, Heyman et al (1992) and Levin et al (1992). Temporal and spatial expression of retinoid receptors, binding proteins and ligands within the embryo could allow for an extremely wide range of signaling pathways which control normal development. These specific expression of retinoid receptor in the mouse embryo could be possibly related to the teratogenic effects induced by excess of 3 selective retinoid receptor ligands as reported by Agnish and Kochar (1993), Kastner et al (1995), Kochhar et al (1998) and Elmazar (1999).

Fig 1.a.

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Photo micrograph of transvers section of control kidney. Arrow showing normal size of glomeruli and its periglomerular space. H.E. X 256.00

Fig 1.b.

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Arrow showing increased periglomerular space in treated kidney. Arrow heads showing atrophied glomeruli. H.E. X 256.00

Fig 2.a.

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Photo micrograph of section of control liver. Arrow showing central vein. H.E. X 256.00

Fig 2.b.

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Photo micrograph of section of treated liver. Arrow showing elongation of central vein with distorted margins surrounded by degenerative hepatocytes with inflammatory cells. H.E. X 256.00

Fig 2.c.

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Photo micrograph of section of treated liver. Arrow showing a wide area of severe haemorrhagic patch in liver parenchyma. H.E. X 256.00

We can conclude that vitamin A adminstration at early stages of pregnancy need careful surveillance for developmental toxicity because this is a sensitive period of developing embryonic organs.

Acknowledgement:

I am sincerely thankful to Prof. S.L. Jethani, Head of the Department of Anatomy, H.I.M.S., Dehradun and Prof. Mandavi Singh (BHU) for their invaluable suggestions and wise counseling.

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