RESUMO
The avoidance response is present in pathological anxiety and interferes with normal daily functions. The aim of this article is to shed light on performance markers of active avoidance (AA) using two different rat strains, Sprague-Dawley (SD) and Wistar. Specifically, good and poor performers were evaluated regarding anxiety traits exhibited in the elevated plus maze (EPM) and corticosterone levels and motor activity in the open field test. In addition, the plasma levels of Interleukin-6 (IL-6), Interleukin-1Beta (IL-1beta), Nerve Growth Factor Beta (NGF-beta), Tumor Necrosis Factor-Alpha (TNF-alpha) and cytokine-induced neutrophil chemoattractant 1 (CINC-1) were compared in the good and poor performers to better understand the role of the immunologic system in aversive learning. Behavioral criteria were employed to identify subpopulations of SD and Wistar rats based on their behavioral scores during a two-way AA test. The animals were tested for anxiety-like behavior in the EPM and motor activity in the open-field test. Plasma corticosterone levels were measured at the end of the avoidance test. Cytokine levels of IL-6, IL-1beta, NGF-beta, TNF-alpha, and CINC-1 were measured in the plasma of the Wistar rats. Sixty-six percent of the Wistar rats and 35% of the SD rats exhibited a poor performance. This feature was associated with a decrease in anxiety-like behavior in the EPM. The poor and good performers exhibited lower levels of corticosterone compared with the control animals, which suggests that training alters corticosterone levels, thereby leading to hypocortisolism, independent of the performance. The CINC-1 levels were increased in the poor performers, which reinforces the role of immunologic system activation in learning deficits. Our study provides a better understanding of the complex interactions that underlie neuroimmune consequences and their implications for performance.
RESUMO
INTRODUCTION: Immunosuppressant agents modulate the activity of the immune system and control adipose tissue inflammatory responses associated with obesity. Controlling adipose tissue inflammation represents an interesting option for inhibiting the low-grade inflammatory state in obese subjects and for preventing obesity-associated pathologies. In this work, we assessed the effects of thalidomide on the inflammatory response in adipose tissue as well as on systemic inflammatory marker expression in the well-established high-fat diet-induced obesity mouse model. METHODS: Swiss male mice were fed a high-fat diet (60% kcal from fat) for 12 weeks and received thalidomide for the last 10 days (100 mg.kg-1). Adipokine levels were measured in serum and adipose tissue by EIA and real-time quantitative PCR, respectively. Adipose tissue infiltrating macrophages were identified by immunohistochemistry and western blot analysis of F4/80 marker expression. Other inflammatory markers, such as c-Jun N-terminal kinase (JNK) phosphorylation and monocyte chemoattractant protein-1 (MCP-1) production, were also evaluated by western blot analysis. In vitro assays using 3T3-L1 adipocytes were also conducted to evaluated adipokine release. RESULTS: In obese mice, thalidomide administration induced a reduction in adiposity accompanied by a reduction of tumor necrosis factor-α (TNF-α), leptin and MCP-1 adipose tissue production, macrophage infiltration and JNK activation. TNF-α and leptin serum levels were also reduced by thalidomide treatment in obese mice. In vitro, the release of basal TNF-α and lipopolysaccharide (LPS)-induced MCP-1 was inhibited in 3T3-L1 cells. SIGNIFICANCE: Our results suggest that drugs that can modulate the inflammatory status as well as control adipose tissue expansion could represent an interesting approach in the management of obesity, highlighting the need for further development of such compounds.