Endomorphin-1 attenuates Aß42 induced impairment of novel object and object location recognition tasks in mice.

ABSTRACT

A growing body of evidence suggests that the agglomeration of amyloid-ß (Aß) may be a trigger for Alzheimer׳s disease (AD). Central infusion of Aß42 can lead to memory impairment in mice. Inhibiting the aggregation of Aß has been considered a therapeutic strategy for AD. Endomorphin-1 (EM-1), an endogenous agonist of µ-opioid receptors, has been shown to inhibit the aggregation of Aß in vitro. In the present study, we investigated whether EM-1 could alleviate the memory-impairing effects of Aß42 in mice using novel object recognition (NOR) and object location recognition (OLR) tasks. We showed that co-administration of EM-1 was able to ameliorate Aß42-induced amnesia in the lateral ventricle and the hippocampus, and these effects could not be inhibited by naloxone, an antagonist of µ-opioid receptors. Infusion of EM-1 or naloxone separately into the lateral ventricle had no influence on memory in the tasks. These results suggested that EM-1 might be effective as a drug for AD preventative treatment by inhibiting Aß aggregation directly as a molecular modifier.