Transcriptomic and neurochemical analysis of the stellate ganglia in mice highlights sex differences

Abstract

The stellate ganglia are the predominant source of sympathetic innervation to the heart. Remodeling of the nerves projecting to the heart has been observed in several cardiovascular diseases, however studies of adult stellate ganglia are limited. A profile of the baseline transcriptomic and neurochemical characteristics of the stellate ganglia in adult C57Bl6j mice, a common model for the study of cardiovascular diseases, may aid future investigations. We have generated a dataset of baseline measurements of mouse stellate ganglia using RNAseq, HPLC and mass spectrometry. Expression differences between male and female mice were identified. These differences included physiologically important genes for growth factors, receptors and ion channels. While the neurochemical profiles of male and female stellate ganglia were not different, minor differences in neurotransmitter content were identified in heart tissue.

Figure 1

Expression of sympathetic markers: Left stellate ganglion expression levels of genes in both male and female mice using normalized Log₁₀CPM values (Counts Per Million); Mean ± SEM. Select genes important in sympathetic function are presented in addition to 3 commonly used housekeeping genes (Actb, Tubb3 and Gapdh) for reference. Genes specific to sympathetic neurons are among the most highly expressed in the stellate.

Figure 2

Multidimensional Scaling Plot of log-CPM values: MDS plot over 2 dimensions highlighting clear separation of sexes. MST, Male Stellate (Green); FST, Female Stellate (Red). The scale indicates log2 fold difference in expression (Normalised CPM, counts per million) across each dimension.

Figure 3

qPCR quantification of selected genes of interest in the stellate ganglion: Relative gene expression levels expressed as a ratio to Gapdh expression in left stellate ganglion (Mean ± SEM, n = 6 M vs 6 F). There was strong agreement between RNAseq and qPCR results for select genes of interest. *p < 0.05, **p < 0.01, ***p < 0.001.

Figure 4

qPCR quantification of selected genes of interest in the SCG: Gene expression was assessed in the SCG as an alternative sympathetic ganglion. Relative gene expression levels expressed as a ratio to Gapdh expression in left SCG (Mean ± SEM, n = 6 M vs 4 F, n = 3 F for Ret). The gene expression levels of Ntng1, Ret and Tcfl5 were much lower in the SCG compared to the stellate. The sex differences for Slc18a1, Ret and Ntng1 only were present in both the stellate and SCG. *p < 0.05, **p < 0.01, ***p < 0.001.