PIP increases P-gp-mediated transport of morphine at the BBB.

<p>The effect of λ-carrageenan treatment on brain uptake [³H]morphine (36.7 µg/rat) was determined by <i>in situ</i> brain perfusion. Animals received subcutaneous injections of saline or λ-carrageenan into the plantar surface of the right hind paw. 3 h post paw treatment animals were perfused with [³H]morphine (0.5 mCi/mL) for 10 min. As previously shown, λ-carrageenan treatment induced an increase in P-gp function as exemplified by decreased brain morphine uptake. P-gp specific efflux of morphine was confirmed using the P-gp selective inhibitory peptide reversin 205. Animals were perfused with reversin 205 for 10 min prior to perfusion with [³H]morphine. Animals were then perfused with [³H]morphine (.5 mCi/mL) for 10 min in the presence of reversin 205. Results are expressed as mean ± SEM of at least 6 individual animals per treatment group. Asterisks represent data points that are significantly different (*p<0.05).