The neuronal excitability time-dependently changes after lipopolysaccharide administration in mice: possible role of cyclooxygenase-2 induction.
The parameters of pentylenetetrazol (PTZ)-induced seizures have been evaluated at various time intervals after lipopolysaccharide (LPS; Escherichia coli O111:B4, 100 microg/kg, i.p.) administration in mice. A proconvulsant effect occurred 4h after LPS injection with decreased seizure latency and enhanced seizure intensity. In contrast, the incidence of seizures was reduced 18 h after LPS injection. There were no significant alterations on seizure parameters 2, 8, 12, and 24h after LPS treatment. SC-58236, a selective cyclooxygenase (COX)-2 inhibitor (20 or 40 mg/kg, s.c.) treatment alone had no effect on PTZ-induced seizures, but reversed the antiseizure activity observed 18 h after LPS injection. However, SC-58236 treatment partially restored the proconvulsant changes that were observed 4h after LPS administration. On the other hand, COX-1-selective inhibitor valeryl salicylate (20 or 40 mg/kg, s.c.) itself facilitated PTZ-induced seizures. Thus, it was not possible to evaluate the effects of valeryl salicylate on the excitability changes after LPS injection. These results indicate that the parameters of PTZ-induced seizures change time-dependently after LPS treatment, in which proconvulsant and anticonvulsant states could be seen in a sequence. It seems that COX-2 isoenzyme may be involved in the neuronal excitability changes due to LPS.
Akarsu
Eyup S
ES
Ankara University, School of Medicine, Department of Pharmacology and Clinical Pharmacology, Ankara, Turkey. akarsu@dialup.ankara.edu.tr
Ozdayi
Sema
S
Algan
Esin
E
Ulupinar
Funda
F
D000818:Animals; D003292:Convulsants; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D004008:Diclofenac / Q000494:pharmacology; D004926:Escherichia coli; D007213:Indomethacin / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009043:Motor Activity / Q000187:drug effects*; D010433:Pentylenetetrazole; D011720:Pyrazoles / Q000494:pharmacology*; D012459:Salicylates / Q000494:pharmacology; D012640:Seizures / Q000139:chemically induced / Q000503:physiopathology*; D013449:Sulfonamides / Q000494:pharmacology*; D013997:Time Factors; D000096926:Benzenesulfonamides
D003292:Convulsants; D016861:Cyclooxygenase Inhibitors; D004008:Diclofenac; D007213:Indomethacin; D008070:Lipopolysaccharides; D010433:Pentylenetetrazole; D011720:Pyrazoles; D012459:Salicylates; D013449:Sulfonamides; C119130:4-(5-(4-chlorophenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl)benzenesulfonamide; D000096926:Benzenesulfonamides; C440499:lipopolysaccharide, Escherichia coli O111 B4; C401835:valerylsalicylate