AN APPROACH TO STUDY MOLECULAR MECHANISMS INVOLVED IN CYTOKINE-INDUCED ANOREXIA

Cytokines are released during pathophysiological processes. Cytokines (e.g., interleukin-1 beta or IL-1 beta) induce neurological manifestat ions including anorexia. Here, we show an integrative approach to inve stigate the cellular and molecular basis of cytokine-induced anorexia. In this approach: (1) the chronic intracerebroventricular (icv) micro infusion (via osmotic minipumps) of cytokines, at doses that will yiel d estimated pathophysiological concentrations reported in the cerebros pinal fluid, is used. (2) General and computerized behavioral monitori ng characterizes the microstructure of behavioral modifications induce d by a cytokine, and the time course for cytokine action. (3) Brain re gions and subregions (nuclei/areas) from animals exhibiting significan t anorexia in response to cytokine(s) are dissected, and RNA and prote in are isolated. (4) The profile of cytokine subsystems (ligands, rece ptors, endogenous inhibitors; for example, IL-1 alpha and beta, IL-1 r eceptor types I and II, and IL-1 receptor antagonist) is characterized in the same brain samples with polymerase chain reaction, sensitive R Nase protection assays and immunoblots. (5) The relationship between c hanges in cytokine subsystems at the molecular level and cytokine-indu ced anorexia within an animal is determined, and the general profile i s analyzed with statistical methods. This approach is also pertinent t o study neurotransmitter and neuropeptide profiles, and cytokine-cytok ine, cytokine-neuropeptide and cytokine-neurotransmitter interactions in vivo. The results show that this integrative and novel strategy can be used to study the molecular basis of anorexia and other neurologic al manifestations (e.g., fever, sleep changes) induced by cytokines.