High-fat and combined high-fat–high-fructose diets impair episodic-like memory and decrease glutamate and glutamine in the hippocampus of adult mice

ABSTRACT

Background

Diet-induced obesity is associated with premature cognitive decline. Elevated consumption of fats and sugars in humans and rodents has been associated with deficits in recognition memory, which is modulated by the hippocampus. Alterations in excitatory and inhibitory neurotransmitters in this area have been observed after hypercaloric diets, but the effects on episodic-like memory are not conclusive.

Objective

To investigate the effects of hypercaloric diets on memory and their relationship with γ-aminobutyric acid (GABA), glutamate and glutamine and their genetic expression in the hippocampus.

Design

A control diet (CD), a high-fat diet (HFD) and a combined high-fat–high-fructose diet (HFFrD) were administered to 30 C57BL/6 adult mice for 10 weeks. The discrimination indexes and exploration time of the novel object recognition (NOR) and novel object location (NOL) tasks were evaluated and GABA, glutamate and glutamine concentrations and their genetic expression were obtained from the hippocampus.

Results

The HFFrD induced lower discrimination indexes, decreased exploration time in the recognition memory tasks, and lowered the concentrations of glutamate and glutamine, and HFD increased their expression in the hippocampus.

Conclusions

These findings suggest that a possible adaptative long-term mechanism in the hippocampal neurotransmitters, and this possibility may underlie the episodic-like memory deficits in mice fed HFD and HFFrD.

KEYWORDS:

• Recognition memory
• fat diet
• high-fat–high-fructose diet
• GABA
• glutamine
• glutamate
• hippocampus
• C57BL/6

Acknowledgments

We thank Dra. Jessica González Noris for proofreading the manuscript. Humberto Martínez-Orozco received scholarship No. 706012 from CONACYT, Mexico for the completion of his PhD. He also received scholarship No.182030514 of academic excellence from the TELMEX-TELCEL Foundation, Mexico for graduate studies. Consuelo Lomas-Soria is a CONACYT Cátedras Program. This paper was written during Silvia Solis-Ortiz's sabbatical year.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was funded by grant 123-2019 from the University of Guanajuato (PAPIIT-UNAM IN-204519).

Notes on contributors

Humberto Martínez-Orozco

Humberto Martínez-Orozco. Investigation, methodology, formal analysis, data curation, visualization, writing - original draft.

Luis A. Reyes-Castro

Luis A. Reyes-Castro. Resources (diets), methodology formal analysis and data discussion.

Consuelo Lomas-Soria

Consuelo Lomas-Soria. Metodology, determination of the gene expression analysis and data discussion.

Cuauhtémoc Sandoval-Salazar

Cuauhtémoc Sandoval-Salazar. Methodology, funding acquisition, resources, and data discussion

Joel Ramírez-Emiliano

Joel Ramírez-Emiliano. Resources (instrumentation).

Sofía Díaz-Cintra

Sofía Díaz-Cintra. Methodology, resources, funding acquisition, formal analysis, supervision writing review and editing.

Silvia Solís-Ortiz

Silvia Solís-Ortiz. Conceptualization, funding acquisition, resources, methodology, project administration, formal analysis, investigation, data curation, - original draft- review and editing.