Network analysis of the hair-based nine hormones from four neuroendocrine systems

The stress response maintains the homeostasis of the body's internal environment and normal physiological activities, involving several neuroendocrine systems, such as the HPA axis, the HPG axis, the endocannabinoid system, and the melatonin system. However, studies on the intricate interactions among the four neuroendocrine systems are lacking, and it is not clear how these interactions are affected by demographic variables. The aim of this study was to investigate the network characteristics of hormonal networks comprising nine hormones from four neuroendocrine systems and how they were affected by demographic variables.

252 healthy current students were recruited from Southeast University, China. The concentrations of nine hormones in their hair were measured by LC/MS methods, and hormonal network was constructed. Network analysis was used to characterize the interrelationships between hormones or neuroendocrine systems, central hormones, bridge hormones, hormonal network characteristics, and their changes in response to demographic variables.

Complex interactions between the HPA axis, the HPG axis, the ECS and the melatonin system formed a sparse and stable network, with cortisol and cortisone being the central hormones and melatonin as the bridge hormone. Demographic variables did not affect the overall characteristics of the network or the central hormone, but a number of specific connections in the network changed and the bridge hormones became cortisone and progesterone.

The interactions between the four stress-related neuroendocrine systems were relatively stable and were centered and initiated by the HPA axis. Demographic variables did not affect the overall structure of the network, but influenced local features of the network, such as edge weights and bridge centrality.