ABSTRACT. The effects of two Peruvian folk medicines, Lepidium meyenii Walp and Jatropha macrantha, on mouse sex steroid hormones and embryo implantation were investigated. Progesterone levels increased significantly in mice that received L. meyenii Walp, while testosterone levels increased significantly in mice that received L. meyenii Walp as well as in those that received both L. meyenii Walp and J. macrantha. However, there were no marked changes in blood levels of estradiol-17β or the rate of embryo implantation. KEY WORDS: Jatropha macrantha, Lepidium meyenii Walp, mouse.J. Vet. Med. Sci. 65(10): 1145-1146, 2003 L. meyenii Walp is a root vegetable that only grows in the Peruvian Andes at elevations higher than 4,000 m [2, 4-7, 9-13, 16, 17, 19], while J. macrantha is sap collected from trees that grow naturally in the Peruvian Andes [3,8,18]. Because they are crude drugs, there are slight differences in components and compositions depending on where they are grown and when they are harvested. Both crude drugs have been widely used as folk medicines in Peru and have been administered to treat impotence, climacteric disorders and infertility in Europe and America [2][3][4][5][6][7][8][9][10][11][12][13][16][17][18][19]. However, no reports have investigated administration of these natural substances to animals or determined changes in sex steroid hormone levels and rates of embryo implantation. Therefore, we conducted the present study to investigate whether these crude drugs are also effective in animals.The level of estradiol-17β and progesterone measured in female mice, and the level of testosterone was measured in male mice. Three week-old ICR mice were divided into the following four groups: Control group, L group (only L. meyenii Walp was administered), J group (only J. macrantha was administered) and LJ group (both L. meyenii Walp and J. macrantha were administered). Each group consisted of ten mice, and prior to the study, mice were acclimatized for seven days in the same cage (room temperature: 22 ± 3°C, humidity: 60%, light: 14 hr, darkness: 10 hr). The crude drugs were administered for 30 days.Three-week-old mice were used in the present study because although mice are not sexually mature at the age of 3 weeks, by the end of the study, mice were able to breed. The design of the present study also allowed the female mice to have similar estrous cycles, thus minimizing individual differences. Furthermore, a vaginal smear test was conducted on every female mouse, and a blood sample was collected in estrus.Crude drugs were administered as follows: In the control group, 100 ml of plain water was poured into a 100 ml water bottle; in the L group, 5.0 g of L. meyenii Walp powder was dissolved in 100 ml of water; in the J group, 5.0 g of J. macrantha powder was dissolved in 100 ml of water; and in the LJ group, 2.5 g of L. meyenii Walp powder and 2.5 g of J. macrantha powder were dissolved in 100 ml of water. In all groups, mice had free access to drinking water.At the end of the administration period, e...