Febrigenic signaling to the brain does not involve nitric oxide.
1. The involvement of peripheral nitric oxide (NO) in febrigenic signaling to the brain has been proposed because peripherally administered NO synthase (NOS) inhibitors attenuate lipopolysaccharide (LPS)-induced fever in rodents. However, how the unstable molecule of NO can reach the brain to trigger fever is unclear. It is also unclear whether NOS inhibitors attenuate fever by blocking febrigenic signaling or, alternatively, by suppressing thermogenesis in brown fat. 2. Male Wistar rats were chronically implanted with jugular catheters; their colonic and tail skin temperatures (T(c) and T(sk)) were monitored. 3. Study 1 was designed to determine whether the relatively stable, physiologically relevant forms of NO, that is, S-nitrosoalbumin (SNA) and S-nitrosoglutathione (SNG), are pyrogenic and whether they enhance LPS fever. At a neutral ambient temperature (T(a)) of 31 degrees C, afebrile or LPS (1 microg kg(-1), i.v.)-treated rats were infused i.v. with SNA (0.34 or 4.1 micromol kg(-1); the controls received NaNO(2) and albumin) or SNG (10 or 60 micromol kg(-1); the controls received glutathione). T(c) of SNA- or SNG-treated rats never exceeded that of the controls. 4. In Study 2, we tested whether the known fever-attenuating effect of the NOS inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) at a subneutral T(a) (when fever is brought about by thermogenesis) also occurs at a neutral T(a) (when fever is brought about by skin vasoconstriction). At a subneutral T(a) of 24 degrees C, L-NAME (2.5 mg kg(-1), i.v.) attenuated LPS (10 microg kg(-1), i.v.) fever, presumably by inhibiting thermogenesis. At 31 degrees C, L-NAME enhanced LPS fever by augmenting skin vasoconstriction (T(sk) fall). 5. In summary, both SNA and SNG had no pyrogenic effect of their own and failed to enhance LPS fever; peripheral L-NAME attenuated only fever brought about by increased thermogenesis. It is concluded that NO is uninvolved in febrigenic signaling to the brain.
Systemic Inflammation Laboratory, Trauma Research, St Joseph's Hospital and Medical Center, 350 W. Thomas Rd., Phoenix, AZ 85013, USA.
Alexandre A
AA
Steiner
Alla Y
AY
Rudaya
Andrei I
AI
Ivanov
Andrej A
AA
Romanovsky
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001833:Body Temperature Regulation / Q000187:drug effects / Q000502:physiology*; D001921:Brain / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D005260:Female; D005544:Forecasting; D005978:Glutathione / Q000008:administration & dosage / Q000493:pharmacokinetics; D007262:Infusions, Intravenous; D007536:Isomerism; D008070:Lipopolysaccharides / Q000008:administration & dosage / Q000009:adverse effects; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000008:administration & dosage / Q000493:pharmacokinetics; D009569:Nitric Oxide / Q000502:physiology*; D009603:Nitroso Compounds; D051381:Rats; D017208:Rats, Wistar; D026422:S-Nitrosoglutathione / Q000008:administration & dosage / Q000493:pharmacokinetics; D012710:Serum Albumin, Bovine / Q000008:administration & dosage / Q000493:pharmacokinetics; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D012867:Skin / Q000098:blood supply / Q000187:drug effects; D012881:Skin Temperature / Q000187:drug effects / Q000502:physiology; D012977:Sodium Nitrite / Q000008:administration & dosage / Q000493:pharmacokinetics; D014661:Vasoconstriction / Q000187:drug effects
D008070:Lipopolysaccharides; D009603:Nitroso Compounds; C091665:S-nitrosoalbumin; D012710:Serum Albumin, Bovine; D009569:Nitric Oxide; D026422:S-Nitrosoglutathione; D005978:Glutathione; D012977:Sodium Nitrite; D019331:NG-Nitroarginine Methyl Ester