Allosteric Activation of α7 Nicotinic Acetylcholine Receptors by Novel 2-Arylamino-thiazole-5-carboxylic Acid Amide Derivatives for the Improvement of Cognitive Deficits in Mice

Enhancing α7 nAChR function serves as a therapeutic strategy for cognitive disorders. Here, we report the synthesis and evaluation of 2-arylamino-thiazole-5-carboxylic acid amide derivatives 6–9that as positive allosteric modulators (PAMs) activate human α7 nAChR current expressed in Xenopusooctyes. Among the 4-amino derivatives, a representative atypical type I PAM 6pexhibits potent activation of α7 current with an EC50of 1.3 μM and the maximum activation effect on the current over 48-fold in the presence of acetylcholine (100 μM). The structure–activity relationship (SAR) analysis reveals that the 4-amino group is crucial for the allosteric activation of α7 currents by compound 6pas the substitution of 4-methyl group results in its conversion to compound 7b(EC50= 2.1 μM; max effect: 58-fold) characterized as a typical type I PAM. Furthermore, both 6pand 7bare able to rescue auditory gating deficits in mouse schizophrenia-like model of acoustic startle prepulse inhibition.