Sub-chronic oral propylene glycol administration sustained normal liver function and histology: A suitable alternative vehicle for hydrophobic test-compounds

Abstract

Background: An undocumented controversy exists on the suitability/unsuitability of propylene glycol as a solvent or vehicle for hydrophobic test-compounds in animal experimentation(s). This is partly due to the paucity of evidence that aims to probe its histological effects beyond Hematoxylin and Eosin assessment. Objective: To determine the potential suitability/unsuitability of oral propylene glycol as a vehicle for hydrophobic test-compounds by assessing its histological and biochemical effects in female Wistar rats. Methods: The study recruited 10 Wistar rats which were divided into two groups of five rats each as follows: Group 1 received distilled water (2 ml/kg, po) for four consecutive weeks while group 2 received propylene glycol (2 ml/kg, po) for the same period of time. Results: Propylene glycol caused no alteration in liver function as indicated by the plasma levels of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and hepatic total protein level when both groups were compared (p > 0.05). No significant difference between both groups was also recorded in the oxidative stress status (glutathione and catalase) of their liver homogenates. Histological examinations using Hematoxylin and Eosin (H&E) (general histoarchitecture) as well as special stains such as Gordon and Sweet (reticular fiber formation), Masson’s trichrome (collagen fibers), and periodic acid-Schiff (glycogen content) did not reveal any feature of pathology. Quantification analyses of their liver sections, using image J, further revealed no significant difference (p > 0.05) in their histoarchitectural features. Conclusion: Propylene glycol is a suitable alternative vehicle for hydrophobic test-compounds in experimental studies, as its sub-chronic administration sustained normal liver function and histology