Zinc deficiency exacerbates loss in blood-brain barrier integrity induced by hyperoxia measured by dynamic MRI

Using dynamic Magnetic Resonance Imaging (dMRI), blood-brain barrier (BBB) permeability (k(PSrho)) and tissue interstitial leakage space (v(e)) were evaluated in zinc-deficient (ZnDF) male weanling Wistar rats following 3 days exposure to hyperoxia (85% O2). Temporal monitoring of T1-weighted MR image changes, following a bolus intravenous injection of gadolinium-DTPA, allowed estimation of BBB integrity. Three-day exposure of hyperoxia caused a marginal loss of BBB integrity, reflected in a slight increase in kPSrho and v(e), observed in both the animals fed adequate zinc (ZnAL) and pair-fed controls (ZnPF). However, zinc deficiency resulted in a significant increase in both kPSrho and v(e), indicating a severely disturbed BBB. In addition MR-visible free water was elevated in ZnDF brains following hyperoxia treatment indicating that a loss of BBB integrity may be associated with neuronal edema. The diminished BBB integrity may be free-radical mediated as the ratio of oxidized to reduced glutathione (GSSG:GSH) was significantly elevated.