Behavioral deficits, learning impairment, and enhanced hippocampal excitability in co-isogenic PrnpZH3/ZH3 mice

BackgroundThe cellular prion protein (PrPC) has been associated with numerous cellular processes, such as cell differentiation and neurotransmission. Moreover, it was recently demonstrated that some functions were misattributed to PrPC since results were obtained from mouse models with genetic artifacts. Here we elucidate the role of PrPC in the hippocampal circuitry and its related functions, like learning and memory, using the new strictly co-isogenic Prnp0/0 mouse (PrnpZH3/ZH3). Behavioral and operant conditioning tests were performed to evaluate memory and learning capabilities. In vivo electrophysiological recordings were carried out at CA3-CA1 synapses in living behaving mice, and spontaneous neuronal firing and network formation were monitored in primary neuronal cultures of PrnpZH3/ZH3 vs. wild-type mice. ResultsResults showed decreased motility, impaired operant conditioning learning, and anxiety-related behavior in PrnpZH3/ZH3 animals. PrPC absence enhanced susceptibility to high-intensity stimulations and kainate-induced seizures. However, long-term potentiation (LTP) was not enhanced in the PrnpZH3/ZH3 hippocampus. In addition, we observed a delay in neuronal maturation and network formation in PrnpZH3/ZH3 cultures. ConclusionIn conclusion, PrPC mediates synaptic function and protects the synapse from excitotoxic insults. Its deletion might evoke a susceptible epileptogenic brain that would fail to perform highly cognitive-demanding tasks such as associative learning and anxiety-like behaviors.