β-Catenin Knockout in the Olfactory Bulb and Hippocampus Reveals Dual Roles in Olfactory Discrimination and Working Memory

Mice rely heavily on their sense of smell to provide crucial environmental information. The intricate organization of neural circuits within the olfactory bulb (OB) and the communication across the OB-hippocampus network in mice underpin their ability to discriminate and adapt to odors and perform odor-guided behaviors. Wnt/β-catenin signaling has been shown to regulate neural stem cell proliferation and migration during embryogenesis and adult neurogenesis. However, the potential role of β-catenin in adult OB and hippocampus in olfaction, odor-guided behavior and working memory is not known. Here, we report the unexpected expression of collagen, type X, alpha 1 (Col10a1), in the postnatal mouse OB and the hippocampus starting at approximately postnatal day 14. We exploited this finding to generate OB and hippocampus conditional Ctnnb1 knockout (Ctnnb1cKO) mice. We found Ctnnb1cKO mice displayed impaired odor habituation and discrimination abilities, whereas food foraging ability was unaffected. Surprisingly, Ctnnb1cKO mice displayed modestly improved working memory in the Radial Arm Maze test. Together, these findings identify behavioral phenotypes associated with Col10a1-Cre-driven Ctnnb1 deletion and establish this mouse line as a useful tool for studying β-catenin function in adult OB–hippocampal circuits.