Comparison of the feeding responses to bacterial lipopolysaccharide and interleukin-1 beta.
To further investigate the idea that endogenous interleukin-1 plays a major role in the anorectic effect of bacterial lipopolysaccharide (LPS), feeding responses to recombinant human interleukin-1 beta (rhIL-1 beta) and LPS, as well as crosstolerance or -sensitization between both compounds, were investigated in rats. Intraperitoneally (IP) injected paracetamol (50 mg/kg body weight = b.wt.) markedly attenuated the anorectic effect of rhIL-1 beta (50,000 LAF units/kg b.wt., IP), but was clearly less effective in attenuating the anorectic effect of LPS (100 micrograms/kg b.wt., IP). As in previous experiments of ours, repeated IP injections of rhIL-1 beta (three injections of 50,000 LAF units/kg b.wt. on experimental days 1, 4, and 10) resulted in sensitization to the anorectic effect rhIL-1 beta, whereas repeated IP injections of LPS (three injections of 100 micrograms/kg b.wt. every second day) resulted in LPS-tolerance. Sensitization to the anorectic effect of rhIL-1 beta did not affect the anorectic response to LPS. Likewise, LPS-tolerance did not alter the anorectic response to rhIL-1 beta. RhIL-1 beta suppressed feeding by reducing meal frequency and meal size. In contrast, the anorectic effect of LPS was due entirely to a reduction of meal frequency. The results indicate that rhIL-1 beta and LPS do not affect feeding through exactly the same mechanism.
Langhans
W
W
Institute for Animal Sciences, Swiss Federal Institute of Technology, Zurich.
Savoldelli
D
D
Weingarten
S
S
D000082:Acetaminophen / Q000494:pharmacology; D000818:Animals; D001066:Appetite / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects* / Q000502:physiology; D006815:Hunger / Q000187:drug effects / Q000502:physiology; D007274:Injections, Intraperitoneal; D007375:Interleukin-1 / Q000494:pharmacology* / Q000502:physiology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000494:pharmacology
D007375:Interleukin-1; D008070:Lipopolysaccharides; D011994:Recombinant Proteins; D000082:Acetaminophen