Seminar

Who Gets the Blood? Salt, Vasopressin, and a New Logic for Brain Perfusion in Health and Disease

Javier Stern

The brain is traditionally thought to regulate its blood supply according to a simple principle: regions that become more active receive more blood. Our work challenges this view. We discovered that activation of hypothalamic vasopressin neurons during an osmotic challenge produces the opposite response: vasopressin release within the brain constricts local vessels, reducing blood flow and tissue oxygenation, a phenomenon we termed inverse neurovascular coupling. More recent findings suggest that this mechanism may have consequences far beyond the hypothalamus. During sustained high-salt intake, enhanced vasopressin signaling is associated with constriction of major cerebral arteries, including the middle cerebral artery, hippocampal hypoxia, and cognitive deficits. These observations raise a broader question: might signals conveying the physiological state of the body actively determine how blood is distributed across the brain? I will discuss a new framework: interoceptive vascular allocation, in which homeostatic signals regulate cerebral arterial inflow and vascular reserve, potentially redistributing perfusion between brain territories according to physiological demand.