Project description:Tobacco cigarette smoking, with nicotine (NIC) as the addictive component, is a large risk factor for human mortality. In animals, repeated NIC exposure leads to sensitization (SST) and enhances self-administration (SA) of NIC. However, the molecular basis of SST and SA and their genetic relevance to smoking behavior are poorly understood. Using F1 progeny of inbred Envigo rats (F344/BN), we carried out a transcriptional profiling of NIC SST and SA in ventral tegmental area (VTA), nucleus accumbens core (Nac) and shell (Nash). We observed male-specific NIC SST and a parental effect of NIC with SA only present in paternal F344 crosses. Gene differential expression (DE) analysis revealed sex and brain region-specific transcriptomic signatures of SST and SA, with genes downregulated in male VTA associated with both SST and SA, while genes upregulated in male Nac were associated with SA. DE genes associated with SST and SA are enriched for those related to synaptic processes, myelin sheath, and tobacco use disorder or chemdependency. Interestingly, we found that for SST the downregulated genes in the male VTA tended to be upregulated in female VTA, and the overlapping genes were strongly enriched for smoking genome-wide association study (GWAS) risk variants, which may thus explain male-specific SST. To gain mechanistic insight on the observed parental effect of SA, we analyzed the allelic imbalance of expression (AIE) in reciprocally crossed F1 rats that exhibited differential tendency of SA and found widespread region-specific AIE. For the SA-inclined rats, the genes showing AIE bias towards paternal F344 alleles in Nac were strongly enriched for genes upregulated in Nac DE—the gene set most relevant to NIC SA—and also for GWAS risk variants of smoking initiation. These findings show a prominent role for sex and region-specific gene expression and imprinting in NIC SST and SA, and suggest a mechanistic link between genes underlying these processes and human NIC addiction. This study provides a resource for understanding the biology underlying the genetic findings on human smoking phenotypes.

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A genetic basis for the variable effect of smoking/nicotine on Parkinson's disease.

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A genetic basis for the variable effect of smoking/nicotine on Parkinson's disease.

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