Volume Transmission in Transmitter Peptide Costoring Neurons in the Medulla Oblongata

This chapter provides some indications that inter alia angiotensin (ANG), neuropeptide Y, vasopressin, and cholecystokinin immunoreactive nerve terminal systems within the nucleus tractus solitaries may mainly operate via volume transmission (VT) and form chemical networks. It shows how these neuropeptide systems may interact with synaptic transmission through receptor-receptor interactions. In contrast to synaptic transmission, the VT is a slow mode of communication, having a high degree of divergence and being involved in the holistic elaboration of information handling. A transmitter/receptor match for ANG transmission exists within other parts of the medulla oblongata such as the area postrema, and the substantia gelatinosa of the caudal part of the nucleus tractus spinalis nervi trigemini and of the inferior olive. In the neuropeptide Y/adrenaline costoring terminals the integration of the VT and the synaptic transmission signals may facilitate the switching from a synaptic to a volume transmission mode of communication in these terminal networks.