Time-restricted feeding prevents memory impairments induced by obesogenic diet consumption in mice, in part through hippocampal thyroid hormone signaling.

Objective: The early consumption of calorie-rich diet disrupts circadian rhythms and has adverse effects on memory, yet the effects of timerestricted feeding (TRF) and the underlying molecular mechanisms are unknown. Here, we set out to identify the behavioral and molecular circadian rhythms disruptions generated by juvenile obesogenic diet consumption and their restoration by TRF in male mice. Methods: Metabolic rhythms were measured by indirect calorimetry and memory performances by behavioral tasks. Hippocampal translatome (pS6_TRAP), enrichment and co-regulated gene network analyses were conducted to identify the molecular pathways involved in memory impairments and their restoration by TRF. Differential exon usage analyses, mass spectrometry and pharmacological intervention were used to confirm thyroid hormone signaling involvement. Results: We show that four weeks of TRF restore the rhythmicity of metabolic parameters and prevents memory impairments in mice fed a high fat-high sucrose (HFS) diet since weaning, independently of body fat levels. Hippocampal translatome and differential exon usage analyses indicate that impaired memory of mice under ad libitum HFS diet is accompanied by reduced thyroid hormone signaling and altered expression of astrocytic genes regulating glutamate neurotransmission. TRF restored the diurnal expression variation of part of these genes and intrahippocampal infusion of T3, the active form of thyroid hormone, rescues memory performances and astrocytic gene expression of ad libitum HFS diet-fed mice. Conclusions: Thus, thyroid hormones contribute to the TRF positive effects on both metabolism and memory in mice fed an obesogenic diet, highlighting this nutritional approach as a powerful tool in addressing obesity brain comorbidities and paving the way for further mechanistic studies on hippocampal thyroid signaling. To investigate translatome in our groups we applied pS6-TRAP mRNA purification for each C57Bl6J mouse sample We then performed RNA sequencing at basal condition zt3 and zt15. To evaluate translatome during memory formation, we performed RNA sequencing 1h and 12h post 10 minutes Object Recognition Memory task training