Obesogenic diet induces circuit-specific memory deficits in mice

Abstract

Obesity is associated with neurocognitive dysfunction, including memory deficits. This is particularly worrisome during adolescence, which represents a crucial period for maturation of brain structures, such as the hippocampus which are crucial for cognition. In rodent models, we recently reported that memory impairments induced by obesogenic high-fat diet (HFD) intake during the periadolescent period can be reversed by chemogenetic manipulation of the ventral hippocampus (vHPC). Here, we used an intersectional viral approach in HFD-fed male mice to chemogenetically inactivate specific vHPC efferent pathways to nucleus accumbens or medial prefrontal cortex during memory tasks. We first demonstrated that HFD enhanced activation of both pathways after training and that our chemogenetic approach was effective in normalising this activation. Inactivation of the vHPC-nucleus accumbens pathway rescued HFD-induced deficits in recognition but not location memory. Conversely, inactivation of the vHPC-medial prefrontal cortex pathway restored location but not recognition memory impairments produced by HFD. Either pathway manipulation did not affect exploration, locomotion or anxiety-like behaviour. These findings suggest that HFD intake throughout adolescence impairs different types of memory through overactivation of specific hippocampal efferent pathways and that targeting these overactive pathways has therapeutic potential.