Abstract
ObjectiveMelatonin is the major hormone produced and secreted at night by the pineal gland into the cerebrospinal fluid (CSF) and circulation. The relationship between plasma melatonin levels and Parkinson’s disease is not clear. The aim of the current study was to assess plasma melatonin levels in Parkinson’s disease (PD) patients and to analysis the relationship between plasma melatonin levels and non-motor symptoms.Participants and MethodsIn this cross-sectional study, we evaluated 61 patients with idiopathic PD [males n = 30 (49.2%), average age 62.4 years (range: 46–73 years)] and a total of 58 healthy volunteers [males n = 30 (51.7%), average age 64.3 years (range: 45–70 years)] who participated in the study. Plasma melatonin levels were measured using an enzyme-linked immunosorbent assay. The severity of disease in PD patients was scored by the Unified Parkinson’s Disease Rating Scale and the Hoehn and Yahr Staging scale. The quality of life in PD patients was assessed by the 39-item Parkinson’s Disease Questionnaire. The non-motor symptoms were assessed by the 14-item Hamilton Anxiety Rating Scale, the 24-item Hamilton Depression Rating Scale, the Parkinson Disease Sleep Scale, the Epworth Sleepiness Scale and the Non-Motor Symptoms Scale for PD.ResultsCompared with the healthy controls, the plasma melatonin levels were significantly higher in PD patients (12.82 ± 4.85 vs. 19.40 ± 4.23, P < 0.001). Plasma melatonin levels were significantly associated with the levodopa equivalent daily dose (r = −0.262, P < 0.05, n = 61). Higher plasma melatonin concentrations were detected in the negative cardiovascular symptom group than in the cardiovascular symptom group (20.13 ± 3.74 vs. 16.93 ± 3.74, P < 0.05). Higher plasma melatonin concentrations were detected in the non-sleep-disorders group than in the sleep disorders group (22.12 ± 5.93 vs. 18.86 ± 3.66, P < 0.05). In addition, the plasma melatonin concentration was higher in the group without gastrointestinal dysfunction than in the gastrointestinal dysfunction group (21.71 ± 4.44 vs. 18.35 ± 3.74, P < 0.05).ConclusionThis study revealed that the plasma melatonin levels in PD patients were significantly higher than those in healthy controls. Non-motor symptoms that were significantly negatively correlated with plasma melatonin levels were cardiovascular symptoms, sleep disorders, and gastrointestinal dysfunction. Plasma melatonin levels have the closest relationship with sleep disorders. There was a correlation between plasma melatonin levels and sleep quality in patients with PD. The remaining non-motor symptoms were not related to plasma melatonin levels.
Highlights
Parkinson’s disease (PD) is a complex neurodegenerative disease characterized by the loss of dopaminergic neurons in the pars compacta (SNpc), resulting in the classic motor manifestations in PD patients
There were no significant differences on the basis of gender or age in plasma melatonin levels between PD patients and healthy controls (P > 0.05) (Figure 1)
Consistent with the results of Catalá et al (1997) and Lin et al (2014), plasma melatonin levels were significantly higher in PD patients than in healthy controls
Summary
Parkinson’s disease (PD) is a complex neurodegenerative disease characterized by the loss of dopaminergic neurons in the pars compacta (SNpc), resulting in the classic motor manifestations in PD patients. The clinical diagnosis of PD mainly relies on the presence of motor symptoms as the disease progresses. The classic motor characteristics of PD can be attributed to the loss of nigrostriatal dopaminergic cells, while various of non-motor symptoms reflect more complex causes, including mitochondrial dysfunction, oxidative stress, circadian rhythm dysfunction, neuroendocrine, and metabolic abnormalities (Shen et al, 2017). Most PD patients have abnormal circadian rhythm in the course of disease, but the relationship between circadian rhythm dysfunction and PD has not been fully clarified (Musiek and Holtzman, 2016)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
