Sex differences in sympathetic gene expression and cardiac neurochemistry in Wistar Kyoto rats

Study Purpose: The stellate ganglia are the predominant source of sympathetic innervation to the heart. Remodeling of sympathetic nerves projecting to the heart has been observed in several cardiovascular diseases, and sympathetic dysfunction contributes to cardiac pathology. Wistar Kyoto rats are a common model for the study of cardiovascular diseases, but we lack a profile of the baseline transcriptomic and neurochemical characteristics of their cardiac sympathetic neurons. Most studies of cardiovascular disease have used male animals only, but in the future both male and female animals will be used for these types of studies; therefore, we sought to characterize the transcriptome of male and female stellate ganglia and to correlate that with catecholamine and acetylcholine content in the heart.

Data Collected: We have generated a dataset of baseline RNA expression in male and female Wistar Kyoto rat stellate ganglia using RNA-seq, and have measured neurotransmitter levels in heart and stellate ganglia using HPLC and mass spectrometry. We identified numerous gene expression differences between male and female stellates, including genes encoding important developmental factors, receptors and neuropeptides.

Primary Conclusion: Female hearts had significantly higher neurotransmitter content than male hearts; however, no significant differences were detected in expression of the genes encoding neurotransmitter synthetic enzymes. Similarly, no statistically significant differences were identified between the sexes in cardiac tyrosine hydroxylase levels.

Curator's Notes

Experimental Design: Rats were sedated with isoflurane, and the heart and sympathetic ganglia were rapidly dissected. Left and right atria and ventricles were separated, as were the left and right stellate and superior cervical ganglia (SCG). The left ventricles were further separated into apex, mid, and base sections. Tissues collected for RNA were placed in RNAlater (Qiagen) and stored at -20°C. RNA was extracted from ganglia using the RNAqueous Micro kit (Ambion) according to the manufacturer’s instructions. Sequencing libraries were prepared using the TruSeq Stranded Total RNA Library Prep Kit with Poly A enrichment (Illumina) using 130 ng of RNA per sample. Paired-end sequencing (100 bp reads, 2 lanes of 6 samples per lane, sexes evenly randomized) was performed using an Illumina HiSeq 2500 through the Massively Parallel Sequencing Shared Resource at OHSU. Tissues from a second set of animals collected for neurochemical analyses were snap-frozen and stored at -80°C.

Completeness: This dataset is complete.

Subjects & Samples: Female (n=13) and Male (n=11) adult Winstar (RRID:RGD_13508588) rats were used in the study.

Primary vs derivative data: The primary data comprises tabular data for all subjects in the study in the form of .xlsx files. When exploring the primary data folder, you will encounter a subfolder for neurochemistry, which includes data on neurotransmitter and metabolite levels. Additionally, there is another subfolder containing gene identities and raw count expression data for all subjects in the study. In the derivative data folder, you will find summarative analysis results presented as .docx tables.