Effect of acute lipopolysaccharide administration on (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2 aminopropane-induced wet dog shake behavior in rats: comparison with body weight change and locomotor activity.
1. Several reports have shown that serotonin (5-HT)2A receptor density and its function are altered after physiological or pharmacological stress. To examine whether an acute administration of lipopolysaccharide (LPS), a bacterial endotoxin, affected 5-HT2A receptor function, wet dog shakes of male Wistar rats were observed after a subcutaneous injection of DOI, a 5-HT2A receptor agonist following LPS treatment. Body weight change and locomotor activity were also observed. 2. DOI (1 mg/kg)-induced WDS significantly decreased after 400 or 1000 microg/kg LPS treatment compared with that of control rats 1 and 3 hr after injection, and WDS completely recovered 8 hr after LPS treatment. Treatment with 10 mg/kg indomethacin (IND) or 1 mg/kg naltrexone (NLTX) canceled the effect of 400 microg/kg LPS on DOI-induced WDS. 3. Body weight decrease was significantly greater in LPS-treated rats compared with control rats 3, 5 and 8 hr after treatment. Treatment with IND (10 mg/kg) significantly recovered the reduction in body weight induced by 400 microg/kg LPS. Treatment with NLTX (1 mg/kg) also prevented the LPS effect on body weight decrease. 4. Eight hr after treatment with LPS (400 microg/kg), the rats showed significant attenuation of locomotor activity. IND (10 mg/kg) treatment abolished the inhibitory effect of LPS on locomotor activity, and NLTX (1 mg/kg) also improved the decrease in locomotion 8 hr after LPS treatment. 5. Plasma tumor necrosis factor (TNF)-alpha concentration dramatically increased 1 hr after the injection of 400 microg/kg LPS, and returned almost to the basal level 3 hr later. Next, rats were injected with 50 microg/kg TNF-alpha intraperitoneally, and body weight change and DOI-induced WDS was determined 3 hr after TNF-alpha injection. Body weight loss was significantly greater in rats treated with TNF-alpha. On the other hand, DOI-induced WDS was not altered when rats were treated with TNF-alpha. 6. These results suggest that acute treatment with LPS inhibited 5-HT2A receptor-mediated behavior via cyclooxygenase and opioid receptor activation, but that the inhibition of the WDS by LPS appears to be independent of TNF-alpha production.
Kouhata
S
S
Department of Psychiatry and Neurosciences, Hiroshima University School of Medicine, Japan.
Kagaya
A
A
Nakae
S
S
Nakata
Y
Y
Yamawaki
S
S
D000662:Amphetamines / Q000494:pharmacology*; D000818:Animals; D001835:Body Weight / Q000187:drug effects*; D004334:Drug Administration Schedule; D004731:Endotoxins / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008297:Male; D009043:Motor Activity / Q000187:drug effects* / Q000502:physiology; D009271:Naltrexone / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin / Q000187:drug effects / Q000502:physiology*; D012486:Salmonella typhimurium; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*; D013239:Stereotyped Behavior / Q000187:drug effects* / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D000662:Amphetamines; D004731:Endotoxins; D008070:Lipopolysaccharides; D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin; D017366:Serotonin Receptor Agonists; D014409:Tumor Necrosis Factor-alpha; D009271:Naltrexone; C015952:4-iodo-2,5-dimethoxyphenylisopropylamine; D007213:Indomethacin