Maternal nicotine exposure impairs brown adipose tissue via AMPK-SIRT1-PGC-1α signals in male offspring

The Gene Expression Profiles Associated with Maternal Nicotine Exposure in the Liver of Offspring Mice

This study aims to investigate the effect of maternal nicotine exposure on the gene expression profiles in the liver of offspring mice. Pregnant mice were subcutaneously injected with either saline vehicle or nicotine twice a day on gestational days 11-21. Total RNA from the liver samples which collected from the offspring mice of postnatal day 7 and 21 was subjected to RNA sequencing. Gene Ontology (GO) functional enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway enrichment analysis were conducted to identify the functions of differentially expressed genes (DEGs). Four genes were selected for further validation by quantitative reverse transcription polymerase chain reaction (qRT-PCR). A total of 448 DEGs and 186 DEGs were identified on postnatal day 7 and 21, respectively. GO analysis revealed that the DEGs on postnatal day 7 mainly participated in the biological functions of cell growth and proliferation, and the DEGs on postnatal day 21 mainly participated in ion transport/activity. KEGG enrichment analysis showed that the DEGs on postnatal day 7 were mainly enriched in the cell cycle, cytokine-cytokine receptor interactions, hypertrophic cardiomyopathy, and the p53 signaling pathway, while the DEGs on postnatal day 21 were mainly enriched in neuroactive ligand-receptor interactions, the calcium signaling pathway, retinol metabolism, and axon guidance. The qRT-PCR results were consistent with the RNA sequencing data. The DEGs may affect the growth of liver in early postnatal period while may affect ion transport/activity in late postnatal period.

Prenatal Effects of Nicotine on Obesity Risks: A Narrative Review

Nicotine usage by mothers throughout pregnancy has been observed to relate to numerous deleterious effects in children, especially relating to obesity. Children who have prenatally been exposed to nicotine tend to have lower birth weights, with an elevated risk of becoming overweight throughout development and into their adolescent and adult life. There are numerous theories as to how this occurs: catch-up growth theory, thrifty phenotype theory, neurotransmitter or endocrine imbalances theory, and a more recent examination on the genetic factors relating to obesity risk. In addition to the negative effect on bodyweight and BMI, individuals with obesity may also suffer from numerous comorbidities involving metabolic disease. These may include type 1 and 2 diabetes, high cholesterol levels, and liver disease. Predisposition for obesity with nicotine usage may also be associated with genetic risk alleles for obesity, such as the DRD2 A1 variant. This is important for prenatally nicotine-exposed individuals as an opportunity to provide early prevention and intervention of obesity-related risks.

Maternal nicotine exposure aggravates metabolic associated fatty liver disease via PI3K/Akt signaling in adult offspring mice

AIM

The aim of this study is to investigate the effect of maternal nicotine exposure (MNE) on the development of metabolic associated fatty liver disease (MAFLD) in adulthood offspring and the underlying mechanism.

METHODS

Pregnant mice (n = 22) were subcutaneously injected with either saline vehicle (n = 11) or nicotine (n = 11) twice a day on gestational days 11-21. Offspring mice (n = 176) from both groups were weaned at postnatal day 21, and for 6 months after postnatal day 21, 96 mice were fed either a standard chow diet (n = 48) or a high-fat diet (n = 48). Serum lipid indicators, liver function indicators, insulin, and liver mitochondrial respiration were analyzed. The expression levels of fibrosis-related proteins, phosphorylated PI3K, phosphorylated Akt, sterol regulatory element-binding transcription factor 1 (SREBP1c), and peroxisome proliferator-activated receptor alpha (PPAR-α) were detected in the liver by immunohistochemistry and Western blotting.

RESULTS

MNE significantly decreased the weight of both maternal and offspring mice (~30%) and inhibited organ growth in offspring mice (P < .05). MNE also significantly increased serum levels of total bile acid, triglycerides, total cholesterol, glucose, alanine aminotransferase, aspartate aminotransferase, low-density lipoprotein, and insulin while decreasing serum high-density lipoprotein levels and mitochondrial respiration activity in mice fed either the normal diet or high-fat diet (all P < .05). These effects of MNE on lipid metabolism and insulin resistance were mediated via PI3K and Akt phosphorylation and down-regulation of SREBP1c and PPAR-α.

CONCLUSION

Our data indicate MNE induces lipid metabolism disorder and insulin resistance to promote MAFLD progression in adult offspring through activation of PI3K/Akt signaling and suppression of SREBP1c and PPARα protein expression.