Cyclic AC253, a novel amylin receptor antagonist, improves cognitive deficits in a mouse model of Alzheimer's disease

INTRODUCTION Amylin receptor serves as a portal for the expression of deleterious effects of amyloid β-protein (Aβ), a key pathologic hallmark of Alzheimer's disease. Previously, we showed that AC253, an amylin receptor antagonist, is neuroprotective against Aβ toxicity in vitro and abrogates Aβ-induced impairment of hippocampal long-term potentiation. METHODS Amyloid precursor protein-overexpressing TgCRND8 mice received intracerebroventricularly AC253 for 5 months. New cyclized peptide cAC253 was synthesized and administered intraperitoneally three times a week for 10 weeks in the same mouse model. Cognitive functions were monitored, and pathologic changes were quantified biochemically and immunohistochemically. RESULTS AC253, when administered intracerebroventricularly, improves spatial memory and learning, increases synaptic integrity, reduces microglial activation without discernible adverse effects in TgCRND8 mice. cAC253 demonstrates superior brain permeability, better proteolytic stability, and enhanced binding affinity to brain amylin receptors after a single intraperitoneal injection. Furthermore, cAC253 administered intraperitoneally also demonstrates improvement in spatial memory in TgCRND8 mice. DISCUSSION Amylin receptor is a therapeutic target for Alzheimer's disease and represents a disease-modifying therapy for this condition.