Effect of immune complex-forming reactants on catecholamine-modulated behaviors in the rat hypothalamus

Injection of immune complex-forming reactants via implanted cannulae to the perifornical hypothalamus stimulated eating in sated rats and increased the eating response to exogenous norepinephrine (NE). Immune complex-induced eating was not seen after carbamyl choline injection, and immune complex treatment had no effect on water intake under any of the test conditions. The effects of immune complex activity occurred only 6 hours after administration, a time associated with heavy polymorphonuclear leukocyte infiltration of the cannula site. Immune complex activity mimics that following NE injection of this site. Because the immune complex-forming reactants are not specific to any neural antigen, we propose that their effects are indirectly mediated by anaphylatoxins produced by activation of the complement cascade.