Mechanisms of inhibitory action of TRK-130 (Naltalimide), a μ-opioid receptor partial agonist, on the micturition reflex.

Purpose: To clarify the mechanism of inhibitory action of TRK-130 (Naltalimide), a unique µ-opioid receptor partial agonist, on the micturition reflex.

Methods: The effect of TRK-130 on isovolumetric rhythmic bladder contractions (RBCs) was examined in guinea pigs, the effect of which was clarified by co-treatment with naloxone or in spinal cord transection. The effect of TRK-130 on urodynamic parameters was also observed in guinea pigs.

Characteristics of TRK-130 (Naltalimide), a novel opioid ligand, as a new therapeutic agent for overactive bladder.

We characterized TRK-130 (N-[(5R,6R,14S)-17-(cyclopropylmethyl)-4,5-epoxy-3,14-dihydroxymorphinan-6-yl]phthalimide; naltalimide), an opioid ligand, to clarify the therapeutic potential for overactive bladder (OAB). In radioligand-binding assays with cells expressing human µ-opioid receptors (MORs), δ-opioid receptors (DORs), or κ-opioid receptors (KORs), TRK-130 showed high selectivity for MORs (Ki for MORs, DORs, and KORs = 0.268, 121, and 8.

Effect of repeated administration of TRK-820, a kappa-opioid receptor agonist, on tolerance to its antinociceptive and sedative actions.

Repeated administration of micro-opioid receptor agonist, morphine induces tolerance not only to the antinociceptive effect but also to other pharmacological effects, resulting in shortened working duration and decreased efficacy. But less is known about kappa-opioid agonist-induced tolerance. The tolerance-development potency of kappa-opioid receptor agonists with a focus on TRK-820 was characterized.