Changes in the Secretion of Melatonin and Selected Adipokines during the Progression of Parkinson's Disease-Preliminary Studies

Abstract

Parkinson's disease (PD) is one of the most common neurodegenerative diseases affecting elderly people. Considering the gap in the literature on melatonin and adipokine levels in PD patients at various stages of the disease, we conducted a study to investigate the levels of selected parameters in PD patients at the disease's early (ES) and advanced (AS) stages. Melatonin, leptin, adiponectin, and resistin concentrations were measured in the blood serum of 20 PD patients without dyskinesia (ES), 24 PD patients with dyskinesia (AS), and 20 healthy volunteers as a control group (CG). The data were analyzed using ANOVA. Melatonin was significantly lower in ES (p < 0.05) and higher in AS patients (p < 0.05) compared to CG. The level of leptin was increased both in ES (p < 0.001) and AS (p < 0.001) versus CG, while resistin was increased only in patients with dyskinesia (p < 0.05). Higher melatonin (p < 0.001) and resistin (p < 0.05) and lower leptin (p < 0.05) levels were found in AS versus ES. The main findings of the study include the changes in inflammatory markers' levels during PD and a surprising increase in melatonin level in dyskinesia patients. Further research is necessary, which will be aimed at modulating the secretion of melatonin and adipokines as a treatment target for PD.

Keywords: Parkinson’s disease; adiponectin; dyskinesia; leptin; melatonin; resistin.

Figure 1

Outcomes of biochemical analyses (mean values) that demonstrated statistically significant differences in the Parkinson’s disease (PD) groups and healthy volunteers (control group). (A): leptin; (B): resistin; (C): melatonin. A value of p < 0.05 was considered statistically significant. If p < 0.05: * PD no dyskinesia vs. PD with dyskinesia; # PD no dyskinesia vs. control; & PD with dyskinesia vs. control.

Figure 2

Results of hematological analyses (mean values) that demonstrated statistically significant differences in Parkinson’s disease (PD) groups and healthy volunteers (control group). (A): numeric values; (B): percentages. A value of p < 0.05 was considered statistically significant. If p < 0.05: * PD no dyskinesia vs. PD with dyskinesia; & PD with dyskinesia vs. control. Abbreviations used: LYM—lymphocytes; MONO—monocytes; NEU—neutrophils; WBC—white blood cells.

Figure 3

Correlations between the measured biochemical parameters and the severity of the Parkinson’s disease evaluated by Hoehn–Yahr scale in the group of all examined patients (n = 44). (A): adiponectin and Hoehn–Yahr scale (r = 0.408; p = 0.017); (B): resistin and Hoehn–Yahr scale (r = 0.477; p = 0.004); (C): melatonin and Hoehn–Yahr scale (r = 0.478; p = 0.002). The regression line is marked with a solid line. A value of p < 0.05 was considered statistically significant.

Figure 4

Putative mechanisms of melatonin, resistin, leptin, and adiponectin participation in the progression of Parkinson’s disease. BBB, blood–brain barrier; IL-1 β, interleukin 1β; IL-6, interleukin 6; IL-8, interleukin 8; IL-10, interleukin 10; MCP-1, monocyte chemoattractant protein 1; PD, Parkinson’s disease; TNF-α, tumor necrosis factor α; TLR-4, toll- like receptor 4.