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Updated: Jul 28, 2026
Non-Invasive Model of Neuropathogenic Escherichia coli Infection in the Neonatal Rat
Published on: October 29, 2014
Efficacy of oryzalin and associated histological changes in Cryptosporidium-infected neonatal rats
1Centre for Biomolecular Control of Disease, Western Australian Biomedical Research Institute, Murdoch University, Perth. armson@numbat.murdoch.edu.au
Abstract:
This paper reports the anti-cryptosporidial effects of, and concomitant amelioration of the histological changes in the gut of neonatal rats with intestinal cryptosporidiosis treated with the dinitroaniline, oryzalin. The ED50 was determined to be 7 mg/kg using twice daily doses administered for 3 consecutive days. A maximum inhibition of 85.5% was achieved at 25 mg/kg and this inhibition remained constant despite increasing the oryzalin dose to 200 mg/kg. Cryptosporidiosis significantly decreased the intestinal villus/crypt (VC) ratio by approximately 50% (duodenum = 2.3, jejunum = 2.5 and ileum = 1.7) when compared to uninfected untreated controls (duodenum = 4.3, jejunum = 5.9 and ileum = 4.5). Treatment with oryzalin doubled the VC ratio in the duodenum, jejunum and ileum following doses of 5 mg, 50 mg and 200 mg/kg respectively. Oryzalin concentrations in the small intestine contents and plasma were determined, using HPLC, at 0.5, 1 and 2 h after dosing. The much greater dose required to return VC ratios to normal in the ileum (200 mg/kg) compared to the duodenum (6.25 mg/kg) appeared to reflect the decreased concentration of the drug in the distal small intestine. Concentrations of oryzalin equivalent to the in vitro IC50 were maintained for 2 h in the first half of the small intestine following a single dose of 100 mg/kg.
Insights
Oryzalin, a dinitroaniline herbicide, effectively treats cryptosporidiosis in neonatal rats by restoring intestinal villus/crypt ratios. This study determined its efficacy and optimal dosage for combating intestinal damage caused by the parasite.
Area of Science:
- Veterinary Medicine
- Parasitology
- Pharmacology
Background:
- Cryptosporidiosis is a significant cause of intestinal disease in neonatal animals.
- Histological changes, including decreased villus/crypt ratio, characterize intestinal cryptosporidiosis.
- Oryzalin, a dinitroaniline herbicide, has demonstrated potential therapeutic effects.
Purpose of the Study:
- To investigate the anti-cryptosporidial effects of oryzalin.
- To evaluate the amelioration of histological gut changes in neonatal rats with intestinal cryptosporidiosis treated with oryzalin.
- To determine the effective dose (ED50) and dose-response relationship of oryzalin.
Main Methods:
- Neonatal rats with induced intestinal cryptosporidiosis were treated with varying doses of oryzalin.
- The efficacy of oryzalin was assessed by measuring the inhibition of parasite growth.
- Histological analysis of intestinal tissues was performed to evaluate the villus/crypt (VC) ratio.
- Oryzalin concentrations in intestinal contents and plasma were quantified using High-Performance Liquid Chromatography (HPLC).
Main Results:
- The ED50 of oryzalin was determined to be 7 mg/kg.
- A maximum inhibition of 85.5% was achieved at 25 mg/kg, with sustained efficacy up to 200 mg/kg.
- Oryzalin treatment significantly increased the VC ratio in the duodenum, jejunum, and ileum, with dose-dependent effects.
- Drug concentration in the distal small intestine was lower, requiring higher doses to restore normal VC ratios in the ileum compared to the duodenum.
Conclusions:
- Oryzalin exhibits significant anti-cryptosporidial activity and effectively ameliorates intestinal damage in a neonatal rat model.
- The efficacy of oryzalin is dose-dependent, with optimal therapeutic concentrations achieved in the small intestine.
- Oryzalin demonstrates potential as a therapeutic agent for intestinal cryptosporidiosis.
