Effects of Different Extinction for Morphine-CPP on Hippocampal EEG Power Spectrum in Mice

Abstract

The relationship between hippocampal electroencephalogram (EEG) power spectrum and the extinction of addiction memory was investigated. Forty KM mice (Kunming mice) that had successfully established morphine (MOR)-conditioned place preference (CPP) were divided into four groups: saline-training extinction (SAL-TE), SAL-natural extinction (SAL-NE), MOR-TE, MOR-NE, for extinction treatment and EEG recording in the dorsal and ventral hippocampus (DH/VH). Results show that the CPP score of MOR-TE significantly decreased and the total, β and γ bands power spectrum of MOR-TE was suppressed. Notably, the total power from the VH was more correlated with the extinction method, and the TE total power was always lower than NE in SAL or MOR group. Naloxone enhanced the EEG total power and all bands (DH) or β and γ bands (VH) power in the SAL group. However, in the MOR-TE group, only β and γ bands power in VH increased (P<0.05). The results suggest that TE can promote the extinction of opiate addictive memory more effectively than NE, and the extinction of MOR-CPP may have a stronger correlation with changes of VH-EEG power spectrum.