A new focus on interoceptive properties of adrenal medulla.

The adrenal medulla is an important part of the sympathoadrenal system. Chromaffin cells of the adrenal medulla respond to a broad spectrum of stressful situations by releasing epinephrine and norepinephrine. Originally, it was accepted that this response is controlled exclusively by central nervous system structures. However, it was also demonstrated that a surgically denervated adrenal medulla can respond directly by secreting epinephrine and norepinephrine during an imbalance of internal environment (hypoglycemia, asphyxia). Published data had documented the innervation of the adrenal medulla by sensory neurons of spinal dorsal root ganglia. In addition, recent data showed that ganglion cells of the adrenal medulla project ascending axons. These data suggested potential transmission of information from the adrenal medulla to the central nervous system regarding metabolic changes in the blood. This paper presents an overview of possible involvement of adrenal medullary chromaffin cells in the detection of changes in the internal environment and in the transmission of this information to the central nervous system.