Melatonin modulates adiponectin expression on murine colitis with sleep deprivation

Abstract

Aim: To determine adiponectin expression in colonic tissue of murine colitis and systemic cytokine expression after melatonin treatments and sleep deprivation.

Methods: The following five groups of C57BL/6 mice were used in this study: (1) group I, control; (2) group II, 2% DSS induced colitis for 7 d; (3) group III, 2% DSS induced colitis and melatonin treatment; (4) group IV, 2% DSS induced colitis with sleep deprivation (SD) using specially designed and modified multiple platform water baths; and (5) group V, 2% DSS induced colitis with SD and melatonin treatment. Melatonin (10 mg/kg) or saline was intraperitoneally injected daily to mice for 4 d. The body weight was monitored daily. The degree of colitis was evaluated histologically after sacrificing the mice. Immunohistochemical staining and Western blot analysis was performed using anti-adiponectin antibody. After sampling by intracardiac punctures, levels of serum cytokines were measured by ELISA.

Results: Sleep deprivation in water bath exacerbated DSS induced colitis and worsened weight loss. Melatonin injection not only alleviated the severity of mucosal injury, but also helped survival during stressful condition. The expression level of adiponectin in mucosa was decreased in colitis, with the lowest level observed in colitis combined with sleep deprivation. Melatonin injection significantly (P < 0.05) recovered the expression of adiponectin. The expression levels of IL-6 and IL-17 were increased in the serum of mice with DSS colitis but decreased after melatonin injection.

Conclusion: This study suggested that melatonin modulated adiponectin expression in colonic tissue and melatonin and adiponectin synergistically potentiated anti-inflammatory effects on colitis with sleep deprivation.

Keywords: Adiponectin; Colitis; Melatonin; Sleep deprivation.

Figure 1

Experimental procedure. Experimental colitis of mice was induced by feeding mice with 2% DSS in group II. Melatonin was administered to mice for 4 d with 2% DSS in group III. Sleep deprivation was induced partially with 2% DSS in group IV. 2% DSS with partial sleep deprivation and melatonin was administered to mice in group V. M: Melatonin; SD: Sleep deprivation.

Figure 2

Changes in body weight of each group. Group I: control, Group II: 2% DSS induced colitis, Group III: 2% DSS induced colitis with melatonin treatment, Group IV: 2% DSS induced colitis with sleep deprivation, Group V: 2% DSS induced colitis with sleep deprivation and melatonin treatment). Data were presented as mean ± SD. M: Melatonin; SD: Sleep deprivation.

Figure 3

Survival rate of each group. Group I: control, Group II: 2% DSS induced colitis, Group III: 2 % DSS induced colitis with melatonin treatment, Group IV: 2 % DSS induced colitis with sleep deprivation, Group V: 2% DSS induced colitis with sleep deprivation and melatonin treatment). M: Melatonin; SD: Sleep deprivation.

Figure 4

Immunohistochemical staining of adiponectin (A: × 100, B-E: × 200). A: control; B: DSS: 2% DSS induced colitis; C: DSS + M: 2% DSS induced colitis with melatonin treatment; D: DSS + SD: 2% DSS induced colitis with sleep deprivation; E: DSS + SD + M: 2% DSS induced colitis with sleep deprivation and melatonin treatment.

Figure 5

Adiponectin immunoreactivity based on immunohistochemical staining. Melatonin injection significantly recovered adiponectin expression, ^aP < 0.05 vs control. M: Melatonin; SD: Sleep deprivation.

Figure 6

Western blot analysis of adiponectin. The expression of adiponectin was reduced in DSS colitis and DSS colitis with sleep deprivation. Melatonin injection significantly recovered adiponectin expression, ^aP < 0.05 vs control. M: Melatonin; SD: Sleep deprivation.

Figure 7

Cytokine levels in serum of mice. Pro-inflammatory cytokines such as IL-6 (A), IL-17 (B), and TNFα (C) were reduced by melatonin injection; IL-10 (D) expression was not significantly changed. ^aP < 0.05 vs control. M: Melatonin; SD: Sleep deprivation.