Psychopharmacological activity of immune complexes in rat brain is complement dependent.
Sprague-Dawley male rats implanted with chronic indwelling cannulae at the perifornical hypothalamus eat excessively during the sixth hour following administration of exogenous immune-complexing reactants to the brain site. Rabbit anti-HSA was injected, followed in 30 min by a 20-fold excess of antigen. Anaphylatoxin C5a has also been shown to induce excessive intake, an effect similar to that of norepinephrine at this brain site. If the anaphylatoxins or other byproducts or consequence of the complement cascade were responsible for the immune complex effect, interference with the initiation of the cascade or with the conversion of C3 to C3a and C3b should abolish the behavioral response. These experiments demonstrate that immune complexes formed with the non-complement-fixing F(ab')2 fragment of the rabbit anti-HSA do not induce eating, and that normally active IgG antibody complexes do not induce eating if the site has been pretreated with goat anti-rat C3. This latter treatment had no effect, however, on the ability of the animals to respond to norepinephrine or to C5a. We conclude that the immune complex effect is complement dependent.
D000818:Animals; D000936:Antigen-Antibody Complex / Q000502:physiology*; D003176:Complement C3 / Q000502:physiology; D003182:Complement C5 / Q000502:physiology; D015936:Complement C5a; D003165:Complement System Proteins / Q000502:physiology*; D004327:Drinking Behavior / Q000187:drug effects / Q000502:physiology; D005247:Feeding Behavior / Q000187:drug effects / Q000502:physiology*; D007031:Hypothalamus / Q000502:physiology; D007074:Immunoglobulin G / Q000502:physiology; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D012709:Serum Albumin / Q000276:immunology
D000936:Antigen-Antibody Complex; D003176:Complement C3; D003182:Complement C5; D007074:Immunoglobulin G; D012709:Serum Albumin; D015936:Complement C5a; D003165:Complement System Proteins; D009638:Norepinephrine