Inverted day-night feeding during pregnancy affects the brain health of both maternal and fetal brains through increasing inflammation levels associated with dysbiosis of the gut microbiome in rats.

Abstract

Background: In both humans and rodents, inappropriate feeding times during pregnancy can cause maternal metabolic abnormalities, increasing the risk of neurodevelopmental disorders in both the mother and offspring. Using a rat model, this study investigates whether feeding only during the inactive phase in rats leads to anxiety-like behaviors and abnormal brain development in fetuses through gut microbiota imbalance.

Methods: 10-week-old female rats in the inactive-phase feeding group (IF group) were first trained for daytime feeding, ensuring that energy intake was statistically insignificant and different from that of the normal diet feeding group (ND group). They were then paired with male rats, and the previous feeding regimen was continued after pregnancy. Anxiety-like behavior was evaluated using the open-field test. Maternal caecal microbiota was analyzed using 16S rRNA sequencing. Enzyme-linked immunosorbent assay (ELISA) measured serum inflammation factors. RT-PCR was employed to assess mRNA levels of integrity genes and inflammatory cytokines in the maternal hippocampi, intestines, fetal brains, and placentae.

Results: There were no statistically significant differences in energy intake or body weight gain between the IF and ND groups. In the open field test, dams in the IF group exhibited anxiety-like behavior, as indicated by fewer entries into and shorter duration in the central zone. Active-phase fasting elevated maternal serum inflammatory cytokine levels and impaired antioxidant capacity. It also increased intestinal permeability and induced gut microbiota dysbiosis, characterized by a decrease in Akkermansia and an increase in Dubosiella. Changes in the expression of intestinal circadian genes and elevated intestinal inflammatory cytokines were observed. Lipopolysaccharide (LPS) translocated into the maternal circulation, activated Toll-like receptor 4 (TLR 4), and passed through the compromised placental barrier into the fetal brain, leading to increased expression of inflammatory cytokines in the fetal brain.

Conclusions: The misalignment between maternal feeding time and the biological clock during pregnancy disrupts the balance of the gut microbiota and peripheral rhythms. The impaired intestinal and placental barriers allow LPS from the gut to infiltrate the maternal hippocampus and fetal brain, increasing inflammation and impacting both maternal and fetal brain health.