Research ReportSerum melatonin is an alternative index of Parkinson's disease severity

- Serum MLT levels in 6-OHDA-induced hemi-parkinsonian rats were higher.
- Increase of MLT correlated well with the rotational behaviour of PD model rats.
- Higher serum MLT concentrations were detected in patients with PD.
- Serum melatonin is an alternative index of Parkinson's disease severity.

The protective potential of melatonin (MLT) in Parkinson's disease (PD) is the subject of considerable controversy. The purpose of the present study was to investigate serum MLT levels in unilateral 6-hydroxydopamine (6-OHDA) lesion rats and patients with PD. Blood samples were collected from rats at 10:00 am and from patients with PD and healthy subjects between 8:00 and 10:00 am. Serum MLT levels were measured using the enzyme-linked immunosorbent assay. Our results revealed that the morning serum MLT levels either in 6-OHDA-induced hemi-parkinsonian rats or patients with PD were significantly higher than that of control group. Our results also demonstrate that serum MLT levels are correlated with severity of PD according to H & Y scale.