Sleep disorders in Parkinson's disease: clinical features, iron metabolism and related mechanism

OBJECTIVE

To investigate clinical features, iron metabolism and neuroinflammation in Parkinson's disease (PD) patients with sleep disorders (SD).

METHODS

211 PD patients were evaluated by Pittsburgh Sleep Quality Index (PSQI) and a body of scales for motor symptoms and non-motor symptoms. 94 blood and 38 cerebral spinal fluid (CSF) samples were collected and iron and its metabolism-relating proteins, neuroinflammatory factors were detected and analyzed.

RESULTS

136 cases (64.5%) of PD patients were accompanied by SD. Factor with the highest score in PSQI was daytime dysfunction. Depression, restless leg syndrome, autonomic symptoms and fatigue contributed 68.6% of the variance of PSQI score. Transferrin level in serum and tumor necrosis factor-α level in CSF decreased, and the levels of iron, transferrin, lactoferrin and prostaglandin E2 in CSF increased in PD patients with SD compared with those without SD. In CSF, prostaglandin E2 level was positively correlated with the levels of transferrin and lactoferrin, and tumor necrosis factor-α level was negatively correlated with the levels of iron, transferrin and lactoferrin in CSF.

CONCLUSIONS

Depression, restless leg syndrome, autonomic disorders and fatigue are the important contributors for the poor sleep in PD patients. Abnormal iron metabolism may cause excessive iron deposition in brain and be related to SD in PD patients through dual potential mechanisms, including neuroinflammation by activating microglia and neurotoxicity by targeting neurons. Hence, inhibition of iron deposition-related neuroinflammation and neurotoxicity may cast a new light for drug development for SD in PD patients.

Hydra biological detection of biologically active peptides in rat cerebrospinal fluid

The Hydra bioassay system utilizes a tentacle ball formation (TBF), a component of the feeding response of hydra, elicited by S-methyl-glutathione. TBF is modulated by many biologically active peptides in a specific way to individual peptides, and is useful in investigating biologically active peptides in a complex biological sample. We applied the hydra bioassay to explore a possible biologically active substance responsible for the decrease in the motor activity of the mice. The suppression of the CSF obtained from rats after exhaustive exercise was marked lower than that of sedentary rats. Addition of transforming growth factor-beta (TGF-beta), which is the only substance known to nullify TBF, to CSF of the sedentary rat reproduced this change in the suppression of the TBF. This system is useful to screen active peptides in small amounts of biological samples containing very low concentrations of peptides.