title: Sex-specific effects of daily exposure to sucrose on spatial memory performance in male and female rats, and implications for estrous cycle stage.
abstract: Excessive consumption of sugar sweetened drinks is proposed to produce functional changes in the hippocampus, leading to perturbations in learning and memory. In this study we examined the impact of 2h daily access to 10% sucrose (or no sucrose in controls) on recognition memory tasks in young male and female rats. In Experiment 1 we tested rats on memory tasks reliant on the hippocampus (place recognition), perirhinal cortex (object recognition), and a combination of hippocampus, prefrontal cortex and perirhinal cortex (object-in-place memory). Exposure to sucrose for 2h a day for 14days prior to behavioral testing did not affect object recognition, but impaired spatial memory to an extent in both male and female rats. Male rats exposed to sucrose were impaired at both place recognition and object-in-place recognition, however female rats showed no impairment in object-in-place performance. Plasticity within the hippocampus is known to increase during the proestrus phase of the estrous cycle and is related to higher levels of circulating estrogens. In Experiment 2 we tested place recognition and object-in-place memory in 10% sucrose exposed or non-exposed control female rats both during the metestrus (low estrogen) and proestrus (high estrogen) phases of their cycle on place recognition and object-in-place memory. Both sucrose exposed and control female rats were able to perform place object-in-place recognition correctly during metestrus and proestrus, however sucrose exposed rats were only able to perform place recognition correctly during proestrus. This indicates that when hippocampal function is compromised, endogenous estrogens may boost memory performance in females, and that males may be at more risk of high sugar diet induced cognitive deficits.
authors.affiliation: School of Psychology, UNSW Australia, Sydney 2052, Australia.
authors.forename: Kirsten N
authors.initials: KN
authors.lastname: Abbott
authors.affiliation: School of Medical Sciences, UNSW Australia, Sydney 2052, Australia.
authors.forename: Margaret J
authors.initials: MJ
authors.lastname: Morris
authors.affiliation: School of Psychology, UNSW Australia, Sydney 2052, Australia.
authors.forename: R Fred
authors.initials: RF
authors.lastname: Westbrook
authors.affiliation: School of Psychology, UNSW Australia, Sydney 2052, Australia. Electronic address: a.reichelt@unsw.edu.au.
authors.forename: Amy C
authors.initials: AC
authors.lastname: Reichelt
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001835:Body Weight / Q000187:drug effects / Q000502:physiology; D004967:Estrogens / Q000378:metabolism; D030762:Estrous Cycle / Q000187:drug effects*; D005106:Exploratory Behavior / Q000502:physiology; D005260:Female; D008297:Male; D011374:Progesterone / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D021641:Recognition, Psychology / Q000502:physiology*; D012727:Sex Characteristics; D065852:Spatial Memory / Q000187:drug effects* / Q000502:physiology; D013395:Sucrose / Q000494:pharmacology*; D013549:Sweetening Agents / Q000494:pharmacology*
chemical_list: D004967:Estrogens; D013549:Sweetening Agents; D011374:Progesterone; D013395:Sucrose
keywords: Estrogen; Hippocampus; Sex; Spatial memory; Sucrose; Synaptic plasticity