Self-reported intake of high-fat and high-sugar diet is not associated with cognitive stability and flexibility in healthy men

Paternal obesity induces subfertility in male offspring by modulating the oxidative stress-related transcriptional network

BACKGROUND/OBJECTIVE

The effects of fathers' high-fat diet (HFD) on the reproductive health of their male offspring (HFD- F1) remain to be elucidated. Parental obesity is known to have a negative effect on offspring fertility, but there are few relevant studies on the effects of HFD-F1 on reproductive function.

METHODS

We first succeeded in establishing the HFD model, which provides a scientific basis in the analysis of HFD-F1 reproductive health. Next, we assessed biometric indices, intratesticular cellular status, seminiferous tubules and testicular transcriptomic homeostasis in HFD-F1. Finally, we examined epididymal (sperm-containing) apoptosis, as well as antioxidant properties, motility, plasma membrane oxidation, DNA damage, and sperm-egg binding in the epididymal sperm.

RESULTS

Our initial results showed that HFD-F1 mice had characteristics similar to individuals with obesity, including higher body weight and altered organ size. Despite no major changes in the types of testicular cells, we found decreased activity of important genes and noticed the presence of abnormally shaped sperm at seminiferous tubule lumen. Further analysis of HFD-F1 testes suggests that these changes might be caused by increased vulnerability to oxidative stress. Finally, we measured several sperm parameters, these results presented HFD-F1 offspring exhibited a deficiency in antioxidant properties, resulting in damaged sperm mitochondrial membrane potential, insufficient ATP content, increased DNA fragmentation, heightened plasma membrane oxidation, apoptosis-prone and decreased capacity for sperm-oocyte binding during fertilization.

CONCLUSION

HFD- F1 subfertility arises from the susceptibility of the transcriptional network to oxidative stress, resulting in reduced antioxidant properties, motility, sperm-egg binding, and elevated DNA damage. Schematic representation of the HFD-F1 oxidative stress susceptibility to subfertility. Notably, excessive accumulation of ROS surpasses the physiological threshold, thereby damaging PUFAs within the sperm plasma membrane. This oxidative assault affects crucial components such as mitochondria and DNA. Consequently, the sperm's antioxidant defense mechanisms become compromised, leading to a decline in vitality, motility, and fertility.

Working memory gating in obesity: Insights from a case-control fMRI study

Computational models and neurophysiological data propose that a 'gating mechanism' coordinates distractor-resistant maintenance and flexible updating of working memory contents: While maintenance of information is mainly implemented in the prefrontal cortex, updating of information is signaled by phasic increases in dopamine in the striatum. Previous literature demonstrates structural and functional alterations in these brain areas, as well as differential dopamine transmission among individuals with obesity, suggesting potential impairments in these processes. To test this hypothesis, we conducted an observational case-control fMRI study, dividing participants into groups with and without obesity based on their BMI. We probed maintenance and updating of working memory contents using a modified delayed match to sample task and investigated the effects of SNPs related to the dopaminergic system. While the task elicited the anticipated brain responses, our findings revealed no evidence for group differences in these two processes, neither at the neural level nor behaviorally. However, depending on Taq1A genotype, which affects dopamine receptor density in the striatum, participants with obesity performed worse on the task. In conclusion, this study does not support the existence of overall obesity-related differences in working memory gating. Instead, we propose that potentially subtle alterations may manifest specifically in individuals with a 'vulnerable' genotype.

Habitual intake of fat and sugar is associated with poorer memory and greater impulsivity in humans

The vicious cycle model of obesity suggests that repeated habitual intake of a diet high in fat and sugar (HFS) results in impairment in hippocampal function which in turn increases impulsive behaviours, making it harder to resist unhealthy diet choices. Evidence from studies with rodents consistently show switching to a HFS diet impairs performance on hippocampally-sensitive memory tasks. The limited literature in humans also suggest impaired memory and increased impulsivity related to higher habitual HFS intake. However, these changes in memory and impulsivity have been looked at independently. To investigate how these effects are inter-related, three experiments were conducted where relative HFS intake was related to measures of memory and impulsivity. In Experiment 1 (90 female participants), HFS was associated with higher scores on the Everyday Memory Questionnaire-revised (EMQ), and higher scores on the total, Attention (BISatt) and Motor (BISmot) sub-scales of the Barratt Impulsiveness Scale (BIS11). Experiment 2 (84 women and 35 men), replicated the association between HFS and EMQ, and also found HFS related to poorer performance on the hippocampally-sensitive 4 mountain (4MT) memory task. The association between HFS intake and the BISatt replicated, but there were no significant associations with other BIS11 measures or delay-discounting for monetary rewards. Experiment 3 (199 women and 87 men) replicated the associations between DFS and 4MT and EMQ, and also found an association with overall recall, but not response inhibition, from a Remembering Causes Forgetting task: HFS was also significantly associated with BIS total, BISatt and BISmot. In all three studies these associations remained when potential confounds (BMI, age, gender, hunger state, restrained and disinhibited eating) were controlled for. Mediation analysis found that the effect of HFS on memory at least part mediated the relationship between HFS and impulsivity in Experiments 1 and 3, but not 2. Overall these data provide some support for the vicious cycle model, but also suggest that trait impulsivity may be a risk factor for poor dietary choice.