Y-25510

The serum concentrations of interleukin(IL)-1 alpha and IL-6 in C57BL/6 and C3H/HeN mice reached the maximum at 12-16 h after the intravenous treatment with (+/-)-3-[4-(2-dimethylamino-1-methylethoxy)- phenyl]-1H-pyrazolo[3,4-b]pyridine-1-acetic acid (Y-25510) at a dose of 3 mg/kg, and the concentration of IL-10 did at 20 h after the treatment. By repeated treatments with Y-25510 to C57BL/6 mice for 14 days, the maximal values of IL-1 alpha and IL-6 at day 14 were respectively 6.6 times and 5.7 times relative to those on day 1. Neither the counts of peripheral leukocytes nor those of platelets were, however, increased until day 15. The repeated treatment with Y-25510 followed by anti-IL-10 antibody for 14 days was significantly more effective than that with Y-25510 alone in increasing the concentrations of IL-1 alpha and IL-6 in C3H/HeN mice. In addition, both the counts of peripheral leukocytes and platelets were significantly increased at day 18. In conclusion, Y-25510 enhanced not only the production of endogenous IL-1 alpha and IL-6 but also that of IL-10 in healthy mice. As a result, in normal conditions, both the counts of peripheral leukocytes and platelets were never increased because of the inhibitory effect of endogenously produced IL-10.

The effect of a novel synthetic compound, Y-25510, (+-)-3-[4-(2-dimethylamino-1-methylethoxy)phenyl]-1H-pyrazolo[3,4 -b] pyridine-1-acetic acid, on recovery from long-lasting leukopenia induced by 5-fluorouracil was compared with that of recombinant human granulocyte colony-stimulating factor (rhG-CSF). When mice were administered i.p. with 5-FU (200 mg/kg) on days 0 and 7, intravenous administration of Y-25510 (100 and 1000 micrograms/kg) prevented the decrease in the peripheral leukocyte and neutrophil number and accelerated the recovery from leukopenia. Subcutaneous administration of rhG-CSF (50 micrograms/kg) did not prevent leukopenia but accelerated the recovery from leukopenia. In particular, peripheral neutrophil number increased over a normal level. The administration of Y-25510 (10, 100 and 1000 micrograms/kg) restored the decrease in the number of bone marrow cells, spleen cells, lymphocytes, neutrophils and monocytes. The administration of rhG-CSF (50 micrograms/kg) restored the decrease in the number of bone marrow cells, spleen cells, and neutrophils but not that of lymphocytes and monocytes. In fractions of bone marrow cells on day 21, the administration of Y-25510 (1000 micrograms/kg) showed a tendency of restoring the decrease in neutrophil number. In conclusion, the administration of Y-25510 prevented leukopenia and accelerated the recovery from leukopenia in the 5-FU-treated mice. It is suggested that the mechanism of the restorative action of Y-25510 is different from that of rhG-CSF. In a number of immature bone marrow cells Y-25510 has a potent stimulatory effect on the recovery from the decrease in number of hematopoietic cells, keeping a balance in number of each blood cell.