Toxicological effects of Teucrium stocksianum after acute and chronic administration in rats

Because of the widespread use of T. stocksianum (Boiss) in herbal medicine and reports of the toxicity of Teucrium chamaedrys to man, the effects of acute (2 and 4 g kg-1 single dose) and chronic (4% in lieu of drinking water for 48 days) administration of an aqueous extract of T. stocksianum has been studied in rats. After acute administration no change was found in reduced liver glutathione content, plasma total protein concentration or the enzyme activities of aminotransferase or gamma glutamyl transferase. After chronic administration, no change was noticed in the plasma concentrations of total protein, total bilirubin, creatinine, urea, glucose, triglycerides, calcium or phosphorus or the enzyme activities of aminotransferase, alanine aminotransferase, creatinine kinase, gamma glutamyl transferase or lactate dehydrogenase. There was no change in food or water intake or output of urine or faeces; the body weight of the treated animals was, however, slightly reduced. No change was observed in the weight of vital body tissues. Histological examination revealed occasional hepatic 'apoptosis' and cerebral neuronal loss in the cortex and hippocampus in treated animals; focal loss of Purkinje cells in the cerebellum was particularly noticed. The results did not indicate a major hepatotoxic effect of acute or chronic administration of T. stocksianum, unlike other Teucrium spp. We report a neurotoxic effect, however, which warrants monitoring of neurological function in people taking this plant.