Soluble cytokine receptors (sIL-2Rα, sIL-2Rβ) induce subunit-specific behavioral responses and accumulate in the cerebral cortex and basal forebrain

• Published in: PloS one Vol. 7; no. 4; p. e36316
• Main Authors: Zalcman, Steven S, Patel, Ankur, Mohla, Ruchika, Zhu, Youhua, Siegel, Allan
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 27.04.2012; Public Library of Science (PLoS)
• Subjects: Animals; B cells; Basal forebrain; Behavior disorders; Behavior, Animal - drug effects; Biology; Biomarkers; Body fluids; Brain; Brain research; c-Fos protein; Caudate-putamen; Cerebral cortex; Cerebral Cortex - drug effects; Cerebral Cortex - metabolism; Cytokine receptors; Cytokines; Disorders; Disturbances; Dopamine; Forebrain; Fos protein; Grooming; Head; Humans; Immunology; Interleukin 1; Interleukin 2; Interleukin-2 Receptor alpha Subunit - chemistry; Interleukin-2 Receptor alpha Subunit - metabolism; Interleukin-2 Receptor beta Subunit - chemistry; Interleukin-2 Receptor beta Subunit - metabolism; Interleukin-2 Receptor beta Subunit - pharmacology; Laboratories; Male; Medical research; Medical schools; Mental disorders; Mice; Mice, Inbred BALB C; Neostriatum; Neostriatum - drug effects; Neostriatum - metabolism; Neurons; Nucleus accumbens; Permeability; Prefrontal cortex; Proto-Oncogene Proteins c-fos - metabolism; Psychiatry; Putamen; Receptors; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; Recombinant Proteins - pharmacology; Rodents; Schizophrenia; Signal transduction; Solubility; Spools; Turning behavior; United States > US; New Jersey
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0036316

Soluble cytokine receptors are normal constituents of body fluids that regulate peripheral cytokine and lymphoid activity. Levels of soluble IL-2 receptors (sIL-2R) are elevated in psychiatric disorders linked with autoimmune processes, including ones in which repetitive stereotypic behaviors and motor disturbances are present. However, there is no evidence that sIL-2Rs (or any peripheral soluble receptor) induce such behavioral changes, or that they localize in relevant brain regions. Here, we determined in male Balb/c mice the effects of single peripheral injections of sIL-2Rα or sIL-2Rβ (0-2 µg/male Balb/c mouse; s.c.) on novelty-induced ambulatory activity and stereotypic motor behaviors. We discovered that sIL-2Rα increased the incidence of in-place stereotypic motor behaviors, including head up head bobbing, rearing/sniffing, turning, and grooming behavior. A wider spectrum of behavioral changes was evident in sIL-2Rβ-treated mice, including increases in vertical and horizontal ambulatory activity and stereotypic motor movements. To our knowledge, this is the first demonstration that soluble receptors induce such behavioral disturbances. In contrast, soluble IL-1 Type-1 receptors (0-4 µg, s.c.) didn't appreciably affect these behaviors. We further demonstrated that sIL-2Rα and sIL-2Rβ induced marked increases in c-Fos in caudate-putamen, nucleus accumbens and prefrontal cortex. Anatomical specificity was supported by the presence of increased activity in lateral caudate in sIL-2Rα treated mice, while sIL-2Rβ treated mice induced greater c-Fos activity in prepyriform cortex. Moreover, injected sIL-2Rs were widely distributed in regions that showed increased c-Fos expression. Thus, sIL-2Rα and sIL-2Rβ induce marked subunit- and soluble cytokine receptor-specific behavioral disturbances, which included increases in the expression of ambulatory activity and stereotypic motor behaviors, while inducing increased neuronal activity localized to cortex and striatum. These findings suggest that sIL-2Rs act as novel immune-to- brain messengers and raise the possibility that they contribute to the disease process in psychiatric disorders in which marked increases in these receptors have been reported.