Elevated Serum Melatonin under Constant Darkness Enhances Neural Repair in Spinal Cord Injury through Regulation of Circadian Clock Proteins Expression

Journal of Clinical Medicine, 2019 · DOI: 10.3390/jcm8020135 · Published: January 23, 2019

Spinal Cord Injury Regenerative Medicine Endocrinology

Simple Explanation

This study investigates how environmental lighting conditions, which affect the production of melatonin, impact neural repair following spinal cord injury (SCI) in rats. The study found that constant darkness, which increases melatonin levels, led to better motor recovery and neural repair after SCI. The researchers suggest that controlling light exposure in the early stages after SCI could be an important factor in improving recovery.

Study Duration

28 days

Participants

36 male Sprague–Dawley rats

Evidence Level

Not specified

Key Findings

1
Constant darkness after SCI in rats led to a significant increase in motor recovery and body weight compared to normal or constant light conditions.
2
Elevated melatonin levels under constant dark conditions facilitated neuronal differentiation and inhibited primary cell death in the injured spinal cord.
3
Constant dark conditions promoted neural remodeling, including oligodendrogenesis, excitatory synaptic formation, and axonal outgrowth, mediated by the NAS-TrkB-AKT/ERK signaling pathway.

Research Summary

This study investigated the effects of environmental lighting conditions on neural repair following experimental spinal cord injury (SCI) in rats, focusing on the role of endogenous melatonin. The key finding was that constant darkness, which elevates melatonin levels, enhanced motor recovery and neural remodeling in the acute phase after SCI, whereas constant light exacerbated inflammatory responses and neuroglial loss. The results suggest that controlling light/dark conditions in the acute phase after SCI could be a significant environmental factor for a more favorable prognosis.

Practical Implications

Clinical Lighting Strategies

Hospitals and rehabilitation centers should consider optimizing lighting conditions for SCI patients to promote melatonin production and improve neural repair.

Melatonin Supplementation

Further research could explore the potential benefits of melatonin supplementation in SCI patients, especially in those with limited exposure to darkness.

Circadian Rhythm Management

Healthcare providers should focus on managing and restoring circadian rhythms in SCI patients to support the natural healing processes in the nervous system.

Study Limitations

1
The experimental DD condition could not directly be applied to human subjects as the condition may accompany negative psychological responses.
2
Although this study elucidated the beneﬁcial inﬂuences of endogenous melatonin, the experimental DD condition could not directly be applied to human subjects as the condition may accompany negative psychological responses.
3
Although we did not measure the melatonin level in the different groups of animals after 2 weeks of pre-adaptation to controlled light cycles, this limitation is overcome by several previous studies.

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