Endocrine effects of lycopus europaeus L. Following oral application

Lycopus extracts are used in folk medicine for the treatment of hyperthyroid symptoms. Diverse effects on the pituitary thyroidal system as well as on the pituitary gonadal system could be confirmed in experimental studies. But till now endocrine effects of Lycopus extracts in experimental animals were observed after parenteral application only. Therefore in this investigation an ethanolic extract of Lycopus europaeus was applied orally to rats, diverse endocrine parameters were measured between 3 and 24 h later and the effects compared to an i.p. treated group. The plant extract given p.o. caused a long lasting (for a period of more than 24 h) decrease of T 3 levels, presumabely as a consequence of a reduced peripheral T 4 deiodination