Fig. 4

Constitutive CCR5 loss affects neuron survival differently than short-term CCR5 blockade. Maraviroc was applied to the co-culture to compare the effects of a CCR5 antagonist to a genetic knockout. Maraviroc was applied in two different paradigms that permitted us to manipulate the time period of CCR5 loss. The first was a short-term pre-treatment immediately before adding Tat and/or morphine (ST-MVC; n = 4); in this paradigm, maraviroc was on the cultures for a period of 72 h, during the time of Tat and morphine treatments. The second was a longer-term exposure starting 3 days after glia were plated and continuing for the entire 2-week duration of the experiment with replacement of the media every 48 h (LT-MVC; n = 4). The Tat + morphine + LT-MVC survival curve matched that of cultures with CCR5-deficient glia. The Tat + morphine + ST-MVC eliminated the morphine–Tat interaction and only showed a trend towards eliminating Tat toxicity (p = 0.08 vs control). This set of studies suggests that compensatory effects occur over time with CCR5, which dramatically alter morphine–Tat interaction and neurotoxicity