In vitro study | JTC-801 showed 12.5-,129-, and 1055-fold selectivity for ORL1 receptors (K I = 8.2 nM) over μ-,κ-, and δ-opioid receptors, respectively. In HeLa cells expressing the human ORL1 receptor, JTC-801 did not inhibit Forskolin-stimulated cyclic AMP accumulation, while it prevented the inhibition of pain-sensitive peptide on cyclic AMP accumulation, it shows that JTC-801 has complete antagonistic activity. In the rat cerebral cortex, JTC-801 inhibits the ORL1 receptor with an IC50 of 472 nM and inhibits the μ-receptor with an IC50 of 1831 nM. JTC-801 completely antagonizing the inhibition of Forskolin-induced cyclic AMP accumulation by the pain-sensitive peptide, The IC50 was 2.58 μm in HeLa cells expressing ORL1 receptors. |
In vivo study | Oral administration of JTC-801 (0.3-3 mg/kg) antagonized the nociceptive hypersensitivity induced by the nociceptide in mice and demonstrated analgesic effects in the electrohotplate test in mice and the formalin test in rats. In the mouse electric hot plate test, the lowest effective dose was 0.01 mg/kg JTC-801 prolonging the escape response latency (ERL) or the thermal stimulus of exposure, I. v. Or 1 mg/kg,p.o. In the rat formalin test, JTC-801 reduced the first and second phase pain responses, MED was 0.01 mg/kg 71, I. v., or 1 mg/kg,p.o. JTC-801 dose-dependent normalization of heat-stimulated paw withdrawal latency (PWL). While JTC-801 did not inhibit chronic compressive nerve injury (CCI)-induced decreases in bone mineral content (BMC) and bone mineral density (BMD), it inhibited the increase in osteoclasts. Tactile pain hypersensitivity induced by L5/L6 spinal nerve ligation was dose-dependently reversed by JTC-801 administration under systemic (3-30 mg/kg) and spinal anesthesia (22.5 and 45 pg). In addition, systemic JTC-801 administration reduced Fos-like immunoreactivity in the spinal cord (slice I/II) gray matter posterior horn. JTC-801 produced a dose-dependent mechanical and complete anti-allodynic effect with ED50 of 0.83 mg/kg and 1.02 mg/kg, respectively. |