Activation of the neural pathways arising from rostral structures located along the lamina terminalis and running caudally to the spinal cord are normally activated by the physiological stressors of falls in blood volume and blood pressure. In components of the neural network, structures located along the lamina terminalis [i.e., subfornical organ (SFO), median preoptic nucleus (MnPO), organum vasculosum (OVLT)] and the hypothalamic paraventricular nucleus (PVN) have been implicated as structures where stressors produce neuroplasticity that mediates a sensitized hypertensive response.
The SFO is the primary forebrain target for ANG II and cells in the OVLT function as osmo- or Na+ -receptors. The MnPO, which lies inside the blood-brain barrier, receives input from both the SFO and OVLT and probably functions to process information about the status of intracellular and extracellular fluid compartments and blood pressure. The SFO, MnPO, and OVLT all provide input to the PVN. In turn, the PVN integrates this information with input from other sources (not shown) to influence preganglionic sympathetic neurons in the spinal cord [interomediolateral cell column (IML)] both directly and via the rostral ventrolateral medulla (RVLM). Represented are some additional areas implicated in cardiovascular control. These include the area postrema (AP), caudal ventrolateral medulla (CVLM), nucleus of the solitary tract (NTS) and parabrachial nucleus (PBN), which either directly or indirectly influence activity in the RVLM. Additional abbreviations: AC, anterior commissure; OC, optic chiasm. (Modified Figure based on figure in reference 116)