Degradation of Perineuronal Nets in the Medial Prefrontal Cortex and the Impact on Memory

WSU Vancouver Honors ThesisMemory is a crucial asset to proper daily functioning. One important brain area involved in memory is the medial prefrontal cortex or mPFC. Perineuronal nets (PNNs) are structures that envelop specific neurons in many parts of the brain, including the mPFC. The degradation of these nets in the mPFC has been shown to weaken memories associated with drugs of abuse. Recognition memory is a type of memory housed in the mPFC that can be tested using a novel object recognition task (NOR). The purpose of our study was to investigate how degrading PNNs in the mPFC impacts recognition memory. The enzyme chondroitinase ABC (Ch-ABC) was used to degrade the PNNs in the mPFC. The rats were separated into two groups: 1) animals treated with Ch-ABC two weeks prior to training in the NOR task and 2) animals treated with Ch-ABC 24 hours prior to training in the NOR task. After completion of the memory task, we stained brain slices and examined the PNN intensities using fluorescent microscopy. The results show that removal of PNNs in the mPFC two weeks prior to testing and 24 hours prior to testing had no effect on recognition memory. This is an important finding in terms of potential treatments for relapse as it further strengthens the candidacy of Ch-ABC as a possible relapse-preventing drug and PNNs as therapeutic targets for impairment of drug-associated memory