Project Summary/AbstractThe Blood-Brain Barrier (BBB) comprises a physical and enzymatic interface between the CNS and theperipheral circulation. Communication between the CNS and vasculature is mediated through what has beentermed the neurovascular unit (NVU) a highly dynamic structure. Migraine with aura is a multiphaseneurological disorder that affects 32 million Americans (14.2% of US adults) with an estimated annual cost of17 billion dollars in the United States that is characterized by excruciating pain and cortical dysfunction (i.e.cortical spreading depression CSD). Both CSD and pain weaken the integrity of the BBB. A clearcomprehension of biological mechanisms regulating migraine-induced alterations of the BBB is vital tounderstand the efficacy of antimigraine drugs during migraine. In response to PA-14-068 (Neurobiology ofMigraine) investigating changes in BBB permeability (i.e. blood to CNS uptake of brain impermeantcompounds) and tight junction composition (i.e. occludin claudins etc.) will enable an improvedunderstanding of the role of the BBB in the development of episodic migraine. Disruption of the BBB by painand CSD may alter analgesic efficacy or CNS toxicity of anti-migraine therapeutics including first-line therapieslike triptan compounds. Elucidating how these migraine features (i.e. pain CSD) contribute to the functionalexpression of drug transporters (i.e. organic anion transporting polypeptides (OATPs) and Na+-H+ exchangers(NHEs)) may uncover mechanisms required for triptan analgesia at varying stages of migraine (prodromalheadache and postdrome phases) and lead to the identification of novel therapeutic strategies to treatmigraine. Completion of these studies will advance our understanding of BBB integrity during episodic migraineand determine how CNS uptake of antimigraine therapeutics is regulated during attacks. Our preliminary datastrongly suggest that the BBB integrity is dynamically compromised with migraine progression whichin turn alters antimigraine medication blood to CNS uptake. We demonstrate that dural pinprick corticalKCl in freely moving non-anesthetized female rats: 1) induces CSD and 2) induces long-lasting periorbitalallodynia and head-tucking behavior. Moreover we show evidence supporting that BBB integrity changes afterdural pinprick KCl including: 3) enhanced whole brain uptake of 14C-sucrose Evans Blue Albumin and 3H-sumatriptan; 4) increased protein expression of OATP1A4 a transporter implicated in CNS uptake ofnumerous medications; and 5) decreased levels of NHE1 protein a proton exchanger as compared tocontrols; these may alter sumatriptan uptake kinetics. These preliminary findings led to our hypothesis thatdysregulation of BBB integrity is driven by the different migraine phases increasing the severity andduration of headache while regulating anti-migraine medication blood-to-CNS uptake to mitigate thedisorder. The aims of this grant will be investigated using a combination of electrophysiological behavioralmeasurements in situ perfusion and molecular techniques established and working in our laboratories.Specifically Aim 1 proposes studies to determine the BBB integrity including permeability and molecularcomposition during the three phases of migraine (prodromal headache and postdrome phases) while Aim 2studies will elucidate the CNS uptake of antimigraine agents during migraine. Completed studies will addresssignificant gaps in our knowledge regarding BBB integrity during episodic migraine and CNS uptake ofantimigraine therapeutics to aid in the treatment of patients suffering from migraine.