ENDOCRINE EFFECTS OF LYCOPUS-EUROPAEUS L. FOLLOWING ORAL APPLICATION

Lycopus extracts are used in folk medicine for the treatment of hypert hyroid symptoms. Diverse effects on the pituitary thyroidal system as well as on the pituitary gonadal system could be confirmed in experime ntal studies. But till now endocrine effects of Lycopus extracts in ex perimental animals were observed after parenteral application only. Th erefore in this investigation an ethanolic extract of Lycopus europaeu s was applied orally to rats, diverse endocrine parameters were measur ed between 3 and 24 hr later and the effects compared to an i.p. treat ed group. The plant extract given p.o. caused a long lasting (for a pe riod of more than 24 h) decrease of T-3 levels, presumably as a conseq uence of a reduced peripheral T-4 deiodination. A pronounced reduction of T-4 and thyroid stimulating hormone (TSH) concentrations was obser ved 24 h after application of the test solution by gavage. The luteini zing hormone (LH) decrease as well as the TSH decrease, which was pron ounced in spite of reduced T-4 and T-3 levels indicate a central point of attack of the plant extract. Differences in the biological activit y in the dependence on the route of application may be explained e.g. by differences in absorption of plant constituents.