Additive antidepressant-like effects of fasting with β-estradiol in mice

Abstract

Our recent study has shown that acute fasting produces antidepressant-like effects in male mice. However, there is little evidence regarding the antidepressant-like effects of acute fasting in female mice. Moreover, it is not yet clear whether estrogen produces additive effects with acute fasting. Therefore, this study aims to investigate the antidepressant-like effects of acute fasting plus estrogen treatment. In this study, the acute fasting produced antidepressant-like effects in female mice and the antidepressant-like effects of 9 hours fasting with those of β-estradiol (E2) were additive. Activity of the cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB)-brain-derived neurotrophic factor (BDNF) pathway in the prefrontal cortex (PFC) and hippocampus (HP) was increased, as well as neurogenesis in the subgranular zone of the hippocampus. Serum ghrelin and estrogen were also increased by fasting plus E2. Furthermore, RNA-seq analysis indicated that fasting and E2 co-regulate similar gene expression pathways, underlying similar neurological functions. Taken together, these data suggest that E2 produces additive antidepressant-like effects with fasting by activating the CREB-BDNF pathway in the PFC and HP. Genome-wide transcriptome mapping suggests that fasting may be used as an adjunct to estrogen replacement therapy for the treatment of depression associated with reduced estrogen function.

Keywords: RNA-seq; antidepressant; fasting; β-estradiol.

Figure 1

Effects of acute 9 h fasting, E2 and TMX on immobility time in the FST and locomotor activity in the OPT. FST: A and D; OFT: B, C, E and F. N = 6 per group. Data represented as mean ± SEM were analysed by two‐way (diet × treatment) ANOVA followed by post hoc comparisons for the data presented in A, B and C, or by one‐way ANOVA followed by post hoc analysis for the data presented in D, E and F. *** P < 0.001 compared with the non‐fasting + vehicle group; & P < 0.05 compared with the fasting + vehicle group; ### P < 0.001 compared with the E2 + fasting group. VEH: vehicle; E2: 17 β‐estradiol; TMX: tamoxifen

Figure 2

Effects of acute 9 h fasting, E2, and TMX on the CREB/BDNF signalling pathway in the PFC and HP. N = 6 per group. A, E: CREB/ β‐actin in PFC. B, F: p‐CREB/ β‐actin in PFC. C, G: CREB/ β‐actin in HP. D, H: p‐CREB/ β‐actin in HP. I, K: BDNF/ β‐actin in PFC. J, L: BDNF/ β‐actin in HP. Data represented as mean ± SEM were analysed by two‐way (diet × treatment) ANOVA followed by pairwise comparisons for the data presented in A‐D and I, J or one‐way ANOVA followed by post hoc analysis for the data presented in in E‐H and K, L. * P < 0.05; ** P < 0.01; *** P < 0.001 compared with the non‐fasting + vehicle group; & P < 0.05, && P < 0.01 compared with the fasting + vehicle group. # P < 0.05; ## P < 0.01; ### P < 0.001 compared with the E2 + fasting group. VEH: vehicle; E2: 17 β‐estradiol; TMX: tamoxifen.

Figure 3

Fasting increased the number of BrdU‐ positive cells in the hippocampal dentate gyrus, E2 treatment had additional effects when combined with fasting, and the effect was antagonized by TMX. N = 6 per group. Representative fluorescence photomicrographs of these effects on the number of BrdU‐positive cells of the dentate gyrus. E2: 17 β‐estradiol; TMX: tamoxifen

Figure 4

Effects of acute 9 h fasting, E2 and TMX, on serum ghrelin, E2 and CORT levels. Columns represent mean ± SEM. * P < 0.05; ** P < 0.01 compared with the non‐fasting control (vehicle) group. & P < 0.05 compared with the fasting group. # P < 0.05 compared with the E2 + fasting group. VEH: vehicle; E2: 17 β‐estradiol; TMX: tamoxifen

Figure 5

DEGs and Gene Ontology (GO) analyses of fasting and E2 treatment in the PFC and HP in mice. Both treatments were compared with the non‐fasting control (vehicle) group. N = 3 per group. Venn diagrams in A and B representing overlap in significantly up‐regulated or down‐regulated mRNAs in the PFC (A) and HP (B) treated with fasting or E2 in mice. Bar graphs at right show the neurological functions that are enriched in DEGs after fasting and E2 treatment in the PFC (C) and HP (D) in mice. The threshold of DEGs and GO enrichment was set to P value ≤ 0.05, red line in C and D indicates P = 0.05. Table in E shows the representative genes that were up‐ or down‐regulated in the PFC and HP by fasting or E2 treatment. The threshold was set to P ≤ 0.05, fold change >1.3 (↑) or fold change <0.83 (↓). PFC: prefrontal cortex; HP: hippocampus; E2: 17 β‐estradiol; VEH: vehicle.