4-P-PDOT is a potent, selective and affinity Melatonin receptor (MT2) antagonist. 4-P-PDOT is >300-fold more selective for MT2 than MT1. 4-P-PDOT significantly counteracts Melatonin-mediated antioxidant effects (GSH/GSSG ratio, phospho-ERK, Nrf2 nuclear translocation, Nrf2 DNA-binding activity)^[1][2][3][4]. IC50 & Target: MT2 receptor^[1] In Vitro: In CHO-mt1 cells the amidotetraline 4-P-PDOT (10 mM) has no e€ect on forskolin-stimulated cyclic AMP levels, either alone, or in the presence of Melatonin. In contrast, in CHO-MT2 cells, 4-P-PDOT is an agonist, producing a concentration-dependent inhibition of forskolin stimulated cyclic AMP, with a pEC₅₀ value of 8.72 and intrinsic activity of 0.86^[1]. In Vivo: 4-P-PDOT (0.5-1.0 mg/kg; intravenous injection; klotho mutant mice) treatment significantly reverses antioxidant effects mediated by Melatonin. And significantly reverses the changes in the levels of these GSH-related parameters. 4-P-PDOT treatment significantly reverses the memory function of Melatonin-treated klotho mutant mice. 4-P-PDOT also counteracts Melatonin-mediated attenuation in response to the decreases in phospho-ERK expression, Nrf2 nuclear translocation, Nrf2 DNA-binding activity, and GCL mRNA expression in the hippocampi of klotho mutant mice^[2].