ABSTRACT
BACKGROUND/AIMS: Methamphetamine abuse may produce cognitive impairment. Baicalein, a bioactive flavonoid, has antioxidative, anti-inflammatory and neuroprotective effects. This study examined the effects of baicalein pretreatment on memory performance in the passive avoidance test after either one dose or an acute binge of methamphetamine in Institute of Cancer Research (ICR) mice. METHODS: Methamphetamine was administered by intraperitoneal (i.p.) injection of either one dose (3 mg/kg) or an acute binge (3 mg/kg, 4 i.p. injections at 2-hour intervals). The effects of baicalein pretreatment (1 mg/kg, i.p.) on methamphetamine-induced changes of locomotor activity and memory performance were compared with those of eticlopride, a selective dopamine D2 receptor antagonist. The effects of baicalein on acute binge methamphetamine-induced oxidative stress (malondialdehyde- and nitrotyrosine-modified protein production) in the mouse hippocampus were also examined. RESULTS: One-dose methamphetamine treatment (i.p., 30 min before or immediately after the training trial) induced hyperlocomotion and amnesia in mice, which were blocked by eticlopride but not by baicalein pretreatment. The memory performance in mice was impaired 5 days after acute binge methamphetamine, which was significantly attenuated by baicalein but not by eticlopride pretreatment. Baicalein pretreatment also attenuated acute binge methamphetamine-induced oxidative stress in the mouse hippocampus. CONCLUSIONS: Baicalein exhibits antioxidative and neuroprotective effects in attenuating acute binge methamphetamine-induced memory deficits and oxidative hippocampal damage.
Subject(s)
Amnesia/drug therapy , Flavanones/therapeutic use , Neuroprotective Agents/therapeutic use , Amnesia/chemically induced , Amnesia/metabolism , Amnesia/physiopathology , Animals , Avoidance Learning/drug effects , Flavanones/pharmacology , Hippocampus/drug effects , Hippocampus/metabolism , Male , Malondialdehyde/metabolism , Memory/drug effects , Methamphetamine , Mice, Inbred ICR , Motor Activity/drug effects , Neuroprotective Agents/pharmacology , Oxidative Stress/drug effects , Peroxynitrous Acid/metabolism , ScopolamineABSTRACT
Graves' ophthalmopathy is accompanied by hyaluronan (HA) accumulation in the orbital space and infiltration of immunocompetent cells and cytokines, including IFN-gamma, IL-1beta, and TGF-beta. We examined the signal transduction pathways by which TGF-beta induces HA synthesis in normal orbital fibroblasts, orbital fibroblasts from patients with Graves' ophthalmopathy, and abdominal fibroblasts. Calphostin C inhibited the stimulation of HA synthesis by TGF-beta. Phorbol 12-myristate 13-acetate (PMA) activation of PKC stimulated HA production. The effects of TGF-beta and PMA were not synergistic. Stimulation by TGF-beta and PMA were dependent on protein synthesis and their effects were inhibited by cycloheximide. Since TGF-beta-induced HA synthesis was inhibited by BAPTA or by PKC inhibitors, a calcium-dependent PKC was most likely involved. The PKA inhibitor H-89 enhanced TGF-beta- and PMA-induced HA synthesis, thus showing that communication between the PKA and PKC pathways was evident. TGF-beta stimulated the translocation of PKCbetaII to the cell membrane. PKCbetaII, a key enzyme in the regulation of HA synthesis by TGF-beta, might be an appropriate target for therapeutic compounds to be used to treat Graves' ophthalmopathy accompanied by inflammation.
