Reversal of LPS-induced immobility in mice by green tea polyphenols: possible COX-2 mechanism.
An endotoxin (lipopolysaccharide, LPS) is known to activate the hypothalamo-pituitary adrenocortical axis, as well as norepinephrine and indolamine metabolism. Systemically administered LPS produces depression in the forced swimming-induced despair behaviour model in mice. The present study was designed to investigate the effect of green tea extract (GTE) on LPS-induced despair behaviour and to explore the mechanism involved in modulation of LPS-induced immobility by GTE. GTE (10-100 mg/kg) pretreatment reversed LPS-induced immobility in a dose-dependent manner. Rofecoxib (2 mg/kg) and nimesulide (2 mg/kg), COX-2 inhibitors, also reversed the LPS-induced immobility, which was significantly potentiated by concomitant administration of GTE. On the other hand, GTE did not show any potentiating effect on immobility with naproxen (10 mg/kg), which is a nonselective COX blocker. Interestingly the antioxidant, carvedilol (2 mg/kg) did not produce any effect on immobility either in normal or in LPS treated mice. The results of the study implicate the role of COX-2 inhibition by GTE in the reversal of LPS-induced immobility.
Singal
Anjali
A
Pharmacology Division, University Institute of Pharmaceutical Sciences, Panjab University, Chandigarh-160014, India.
Tirkey
Naveen
N
Chopra
Kanwaljit
K
D000818:Animals; D000928:Antidepressive Agents / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D001522:Behavior, Animal / Q000187:drug effects; D051546:Cyclooxygenase 2; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D005260:Female; D005419:Flavonoids / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D007527:Isoenzymes / Q000037:antagonists & inhibitors*; D008070:Lipopolysaccharides; D008297:Male; D051379:Mice; D010636:Phenols / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D008517:Phytotherapy; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D059808:Polyphenols; D011451:Prostaglandin-Endoperoxide Synthases; D013662:Tea
D000928:Antidepressive Agents; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007527:Isoenzymes; D008070:Lipopolysaccharides; D010636:Phenols; D010936:Plant Extracts; D059808:Polyphenols; D013662:Tea; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases