['The aim of this study was to explore the possible pharmacoresistant mechanism by developing a kind of astrocyte model induced by Coriaria lactone (CL).', 'Astrocyte cells from natal Sprague-Dawley rats (within 24 hours of birth) were cultured. Different volumes of CL (1 microL, 3 microL, 9 microL, 15 microL) were added to the cultures for 7, 14, 21 or 28 days. The expression of P-glycoprotein (Pgp), the protein product of multidrug resistance 1 (MDR1), was investigated with immunocytochemistry and image analysis.', 'CL induced the overexpression of Pgp in astrocytes in a time-dependent manner. The up-regulation of Pgp expression was detected to any concentration of CL from day 14 to 28 (P < 0.01). On the day 21, 28, the up-regulation of Pgp expression level was no dose-dependent manner (P > 0.05).'] Does [ Coriaria lactone induce in vitro the overexpression of multidrug resistance P-glycoprotein in astrocyte from rat brain ]?