Effect of Aspergillus spp., on Liver, Kidney and Intestines of WNIN Rat (Rattus norvegicus) Fed on Fungus Inoculated Rice (Oryza sativa. L) – An Electron Microscope Study
Authors: Chary P. Madhusudhana , Venkatesan Vijayalakshmi , Rao Dharmapuri Raghunatha 
Published: December 2020

Aims: This present study was conceived with two objectives.  The first aim of the study is to establish the ultrastructural variation of normal rice grain collected from different market sources. Also, the study is aimed to investigate the fungal (Aspergillus spp.,) infection in stored rice grain and Ultrastructural variation patterns in rice due to fungal infection by Scanning Electron Microscope (SEM). Further, the changes in selected visceral organs (Liver, Kidney and Intestines) of Wistar NIN Rat when they were fed on fungal inoculated rice.

Study Design: The study was completed in to the two phases.

First Phase: Collection of different rice samples, preparation of contaminated rice inoculated with Aspergillus sp., Ultrastructure analysis of rice samples by using SEM.

Second Phase: Animal experiments, Analysis of biochemical estimations in blood serum by spectrophotometer and ultrastructural studies in the selected visceral organs viz., Liver, kidney and intestines of rat by Transmission Electron Microscope (TEM) and Histopathological changes by Light microscope in rats fed   with inoculated rice powder with Aspergillus spp.,(treated) fungus.

Control rats were fed with normal rice powder (control).

Place and Duration of the Study:  SEM Facility, Extension and Training division ICMR-National Institute of Nutrition, Tarnaka, Hyderabad. Telangana state, India. Duration from 2013 to 2015.

Methodology: Animal experiments with albino white Wistar Rat (Rattus norvigecus) weighing about approximately 120-140 grams of each rat and six (6) of each for treated group and control were taken for experimental purpose. Six rats were fed on inoculated rice with fungus Aspergillus sp., and 6 were fed without fungus inoculated rice for control. These animals were maintained under standard procedure as per the protocol of animal ethics. After 28 days of feeding, all the rats were sacrificed as per the regulations animal ethical guidelines. Tissues like liver, kidney and intestines of rats (treated and control) were processed and examined for histopathological and ultrastructural changes by using light and electron microscope. Blood serum from the treated and control rats were collected and processed for biochemical investigations by spectrophotometer.

Results:  The hepatocytes in liver of the treatment group rats showed metachromatic granules (cytoplasmic) and nuclear pleomorphism (occurrence of more than one form of glycogen granules) existence in same species of more than one morphological type but it was absent in the control rats’ livers.  In electron microscope studies, swollen mitochondria and well developed smooth endoplasmic reticulum (SER) were present in treated group rats as against normal mitochondria and rough endoplasmic reticulum (RER) in control rats were observed. The kidneys of treatment group showed patch like mononuclear cell infiltrations in the cortex including many apoptotic bodies in between the renal tubules. Intestines of treated group rat showed the damages in the inner walls of intestinal epithelium in between cells. TEM studies showed swollen mitochondria, absorptive cells of epithelium and endoplasmic reticulum tubules were highly expanded in the treated group rat intestines while normal appearance of the intestines with well developed epithelial  cells of  microvilli was observed in control rats.

Conclusion:  Improper storage of rice grains in food godowns would cause damage to the rice grains due to fungal infections. Although fungal infected grain apparently normal in appearance, from the food safety point of view the grains are not fit for human consumption. Hence, using SEM in quality control and assurance of food safety of rice grains to assess the quality to declare fitness for human consumption is required at this juncture.