| Background and objectivesOrexin-A,a neuropeptide primarily secreted by neurons in the lateral hypothalamus,has been implicated in Parkinson’s disease(PD).Although previous studies have investigated the changes of orexin-A levels in the cerebrospinal fluid of patients with PD,few studies have explored the level of orexin-A in the plasma of patients with PD and its correlations with motor and non-motor symptoms of PD.This study aimed to assess levels of plasma orexin-A in the progression of PD and to evaluate the correlations between orexin-A levels and motor and non-motor symptoms in PD patients.Materials and methods1.One hundred and twenty-one patients with primary PD were randomly recruited from the Department of Neurology of Zhengzhou University people’s Hospital,and clinical data such as name,age,gender,years of education,disease duration and medication status were recorded in detail.In the same period,one hundred and seventeen healthy controls matched with the age and gender of PD patients were recruited.2.The motor symptoms in PD patients were evaluated by Parkinson’s Disease Rating Scale(UPDRS)Part III,and the severity of the disease was evaluated by Hoehn–Yahr scale.3.The non-motor symptoms in PD patients,such as sleep disorders,neuropsychiatric symptoms,sensory disorders and autonomic nervous dysfunction,were assessed by clinically recognized and widely used scales.4.The peripheral blood samples of subjects were collected within the same period of time,and the levels of orexin-A in plasma were measured by enzyme-linked immunosorbent assay kits.5.The data were processed by SPSS statistical software to analyze the differences in plasma orexin-A levels between the control group and the different clinical stages of PD groups,and to evaluate the correlations between orexin-A levels and motor and nonmotor symptoms of PD.Results1.Levels of plasma orexin-A were significantly higher in the patients with PD than in the healthy controls(1.13±0.27 vs 0.94±0.26,t=5.418,p<0.001).One-way ANOVA showed that orexin-A levels were significantly higher in the early-stage and mediumstage PD patients than in the healthy controls(p<0.001;p=0.002,respectively),and orexin-A levels were significantly lower in the advanced-stage PD patients than in the healthy controls(p=0.014).2.ROC analysis showed that plasma orexin-A had good diagnostic value for PD,and the area under the curve was 0.688(0.621,0.755).3.The levels of plasma orexin-A in patients with PD were negatively correlated with the disease duration,the scores of UPDRS Part III and the equivalent daily doses of dopamine receptor agonists(p<0.001).4.The levels of plasma orexin-A in patients with PD were significantly positively correlated with scores of the Pittsburgh Sleep Quality Index(PSQI),REM-sleep Behavior Disorder Questionnaire-Hong Kong(RBDQ-HK),14-item Hamilton Anxiety Scale(HAMA-14),Mini-Mental State Examination(MMSE)and Non-Motor Symptom Scale(NMSS)items 22–24(p<0.05).Plasma orexin-A levels in patients with PD were higher in the insomnia subgroup,RBD subgroup,anxiety subgroup,urinary dysfunction subgroup and without cognitive dysfunction subgroup than those in the non-insomnia subgroup,non-RBD subgroup,non-anxiety subgroup,non-urinary dysfunction subgroup and cognitive dysfunction subgroup,respectively(1.20±0.29 vs1.05±0.23,t=3.072,p=0.003;1.19±0.29 vs 1.08±0.24,t=2.224,p=0.028;1.20±0.29 vs1.07±0.24,t=2.801,p=0.006;1.16±0.27 vs 1.01±0.27,t=2.313,p=0.022;1.17±0.28 vs1.02±0.23,t=2.808,p=0.006,respectively).Conclusions1.The high levels of plasma orexin-A are present only in early-stage and mediumstage PD,whereas in advanced-stage PD they are significantly decreased.These findings suggest that monitoring orexin-A levels may be a potential treatment or prevention strategy for PD.2.The levels of plasma orexin-A are correlated with motor symptoms and doses of dopamine receptor agonists in patients with PD.3.The levels of plasma orexin-A are correlated with PD non-motor symptoms such as anxiety,insomnia,RBD,cognitive dysfunction and urinary dysfunction.There was no correlation between orexin-A levels and remaining non-motor symptoms. |
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