Prenatal benzo[a]pyrene exposure impairs hippocampal synaptic plasticity and cognitive function in SD rat offspring during adolescence and adulthood via HDAC2-mediated histone deacetylation

Benzo[a]pyrene (B[a]P) is a widespread carcinogenic pollutant in the environment. Although previous studies have demonstrated the neurodevelopmental toxicity of B[a]P, the precise mechanisms underlying the neurotoxic effects induced by prenatal B[a]P exposure remain largely unknown. In the present study, pregnant Sprague-Dawley (SD) rats were injected intraperitoneally with 0, 10, 20, or 40 mg/kg-bw of B[a]P for three consecutive days on embryonic days 17-19. The learning and memory abilities of offspring were determined by Morris Water Maze (MWM) test, while the number of dendritic branches and the density of dendritic spines in hippocampal CA1 and DG regions were evaluated by Golgi-Cox staining at PND 45 and PND 75. The mRNA expression of BDNF, PSD-95, and SYP in offspring hippocampus were detected by qRT-PCR, and the protein expression of BDNF, PSD-95, SYP, HDAC2, acH3K9, and acH3K14 were measured by Western blotting or immunohistochemistry. CHIP-PCR was performed to further detect the levels of acH3K9 and acH3K14 in the promoter regions of BDNF and PSD-95 genes. Our results showed that rats prenatally exposed to B[a]P exhibited impaired spatial learning and memory abilities and the number of dendritic branches and the density of dendritic spines in the hippocampal CA1 and DG regions were significantly reduced during adolescence and adulthood. The expression of HDAC2 protein was significantly upregulated, while acH3K9, acH3K14, BDNF, PSD-95, and SYP protein levels were significantly downregulated in the hippocampus of B[a]P- exposed rats. In addition, CHIP results showed that prenatal B[a]P exposure markedly decreased the level of acH3K9 and acH3K14 in the promoter region of BDNF and PSD-95 gene in the hippocampus of PND 45 and PND 75 offspring. All of the results suggest that prenatal B[a]P exposure impairs cognitive function and hippocampal synaptic plasticity of offspring in adolescence and adulthood, and HDAC2-mediated histone deacetylation plays a crucial role in these deficits.

Short-Chain Fatty Acids Attenuate Renal Fibrosis and Enhance Autophagy of Renal Tubular Cells in Diabetic Mice Through the HDAC2/ULK1 Axis

BACKGRUOUND

This study investigated the effect of short-chain fatty acids (SCFAs) on diabetes in a mouse model.

METHODS

Autophagy in Akita mice and streptozocin (STZ)-induced diabetic C57BL/6 mice was determined by Western blots and immunohistochemistry (IHC). Western blots, IHC, hematoxylin and eosin staining, Masson staining, periodic acid-Schiff staining, and picrosirius red staining were conducted to detect whether autophagy and renal function improved in Akita mice and STZ-induced diabetic C57BL/6 mice after treatment of SCFAs. Western blots, IHC, and chromatin immunoprecipitation were performed to determine whether SCFAs affected diabetic mice via the histone deacetylase (HDAC2)/unc-51 like autophagy activating kinase 1 (ULK1) axis. Diabetic mice with kidney-specific knockout of HDAC2 were constructed, and IHC, Masson staining, and Western blots were carried out to detect whether the deletion of endogenous HDAC2 contributed to the improvement of autophagy and renal fibrosis in diabetic mice.

RESULTS

Reduced autophagy and severe fibrosis were observed in Akita mice and STZ-induced diabetic C57BL/6 mice. Increased autophagy and reduced renal cell fibrosis were found in SCFA-treated Akita diabetic mice and STZ-induced diabetic C57BL/6 mice. Diabetic mice treated with SCFAs had lower HDAC2 expression and more enriched binding of ULK1 promoter sequences to H3K27Ac. Endogenous knockout of HDAC2 caused enhanced autophagy and decreased renal fibrosis in diabetic mice treated with SCFAs.

CONCLUSION

SCFAs enhanced autophagy of renal tubular cells and attenuated renal fibrosis in diabetic mice through the HDAC2/ULK1 axis.