A high-fat diet impairs learning that is dependent on the dorsal hippocampus but spares other forms of learning

Abstract

Two experiments were conducted to evaluate the effects of a high-fat diet (HFD) on two tasks that were either dependent on the dorsal hippocampus (DH) or independent of the DH. A total of 80 adult male Sprague Dawley rats were administered either a lard-based HFD (60% of calories from fat) or a control diet (10% of calories from fat) for 8 weeks, and then were trained and tested on either the latent cue preference (LCP) task or the conditioned cue preference (CCP) task in a 3-compartment box apparatus (2 end-compartments and 1 middle-compartment). The end compartments of the box apparatus contained either a single environmental cue (DH-independent) or multiple environmental cues (DH-dependent). During training trials for the LCP and CCP tasks, on alternating days, rats were given access to water in 1 of the 2 end compartments and no water in the opposite end compartment. Rats were water-replete during LCP training and were water-deprived during CCP training. During testing for both tasks, all rats were water-deprived and given free access to all compartments while the amounts of time spent in each compartment were recorded. Results showed that rats given the HFD demonstrated no compartment preferences during both LCP and CCP testing when the compartments contained multiple cues, while rats fed the control diet demonstrated normal compartment preference behavior. However, when the compartments contained a single environmental cue, rats given either the HFD and control diet demonstrated normal LCP and CCP learning. These results demonstrate that consumption of a HFD disrupted both LCP and CCP learning in a multiple-cue (DH-dependent) environment, but did not impair either type of learning in a single-cue (DH-independent) environment. This may be due to selective impairment of the DH caused by increased oxidative stress, inflammation, and/or disrupted neurotransmission produced by consumption of the HFD.

High-Fat Diet-Induced Obesity Causes Sex-Specific Deficits in Adult Hippocampal Neurogenesis in Mice

“…Interestingly, the current study suggests that a high-fat diet and the resulting metabolic dysfunction preferentially disturb neurogenic processes in the dorsal subregion of the hippocampus, and that this occurs in females only. Our findings of HF diet-induced disruption of neurogenic processes in the dorsal hippocampus are in agreement with studies that have shown that HF diet impairs cognitive function that is dependent on this subregion of the hippocampus (Cordner and Tamashiro, 2015), such as performance on the latent cue preference task or the conditioned cue preference task in a multiplecue environment, while other forms of learning are spared (Stouffer et al, 2015).…”

A Multi-Gene Synaptic Plasticity Array Identifies Candidate Molecular Underpinnings of Cognitive and Mood Deficits in Rats with Heart Failure

“…DH appears to be primarily responsible for the cognitive functions of the hippocampus (Moser & Moser, 1998;Sahay & Hen, 2007;Barkus et al, 2010;Fanselow & Dong, 2010), which is consistent with our finding that that genes associated with learning and memory were only impacted in DH. Our findings also add to evidence suggesting that DH is more vulnerable to neuroinflammation and other pathology than VH (Fuster-Matanzo et al, 2011;Stouffer et al, 2015;Dobryakova et al, 2017;Dobryakova et al, 2019;Tournier et al, 2019).…”

A Preliminary Investigation of the Effects of a Western Diet on Hippocampal Volume in Children

“…However, despite the moderate reliability and validity of this measure, the YAQ, along with many other food frequency questionnaires, remain the primary method used to quantify diet in research (53), although improvement of these measures represents an important area for future work. Moreover, both animal and human studies suggest that WD exposure impacts hippocampal function, assessed behaviorally (15,28,56). We were unable to look at hippocampal memory impairment, as hippocampal-sensitive memory measures were not obtained.…”