Intestinal microbiota and melatonin in the treatment of secondary injury and complications after spinal cord injury

Frontiers in Neuroscience, 2022 · DOI: 10.3389/fnins.2022.981772 · Published: November 9, 2022

Spinal Cord Injury Endocrinology Gastroenterology

Simple Explanation

Spinal cord injury (SCI) can cause sensory and motor impairment. Current treatments focus on secondary injury and complications. Studies show SCI leads to an imbalance of intestinal microbiota, which is linked to complications after SCI, possibly through the microbial-brain-gut axis. Melatonin, secreted in the pineal gland and gut, protects the spinal cord from secondary damage. Its secretion is affected by circadian rhythms, and SCI can disrupt melatonin secretion. Melatonin protects the gut barrier and increases intestinal microbiota abundance. This review summarizes the relationship between intestinal microbiota, melatonin, and SCI, providing new ideas for clinical research in SCI treatment. Intestinal microbiota can influence melatonin formation by regulating tryptophan and serotonin metabolism.

Study Duration

Not specified

Participants

Not specified

Evidence Level

Level: Review

Key Findings

1
SCI leads to gut dysbiosis, impacting SCFA production and associated with inflammation and infection. Gut microbiota modulates functional recovery after SCI through SCFA and the immune system. FMT may improve gastrointestinal dysfunction after SCI.
2
Melatonin regulates intestinal microbiota, improving diversity and abundance. It also enhances the abundance of bacteria and decrease the ratio of ﬁrmicum to Bacteroides in a high-fat diet-induced obesity mouse model.
3
Melatonin protects the intestinal barrier by strengthening tight connections between cells, regulating intestinal permeability, and enhancing gastrointestinal function. Melatonin can regulate the immune response by regulating intestinal TLRs and nod like receptors, and aﬀect the type 2 immune response by inhibiting ILC2s.

Research Summary

Complications after SCI significantly impact quality of life, especially gastrointestinal and bladder dysfunction. The intestinal microbiota is closely related to gastrointestinal dysfunction. After SCI, the loss of advanced central control of the sympathetic nerve, the destruction of intestinal immune homeostasis, the impairment of intestinal barrier function, inﬂammation and the use of antibiotics will lead to the imbalance of intestinal microbiota and further cause gastrointestinal dysfunction. Melatonin effectively blocks the secondary injury process after SCI and promotes the recovery of intestinal microbiota structure. Melatonin plays an important role in the treatment of acute and subacute SCI, including anti-apoptosis, anti-inﬂammation, anti-free radical damage, alleviating edema, protecting BSCB, promoting neurons, reducing the accumulation of astrocytes, and further aﬀecting disease’s development in the chronic phase, such as regulating chronic inﬂammation and reducing scar formation. There is no direct research proving that melatonin and intestinal microbiota have synergistic eﬀects on the treatment of SCI. Therefore, melatonin and gut microbiota may act synergistically in the treatment of SCI and further studies will be needed to conﬁrm their role and underlying mechanisms.

Practical Implications

Therapeutic Potential

Melatonin and gut microbiota regulation may offer new avenues for treating SCI complications and improving patient outcomes.

Personalized Treatment

Understanding the specific imbalances in gut microbiota and melatonin levels after SCI could lead to personalized treatment strategies.

Early Intervention

Early use of FMT and melatonin to regulate the structure of intestinal microbiota may produce signiﬁcant therapeutic eﬀects on SCI

Study Limitations

1
Lack of direct research on synergistic effects of melatonin and intestinal microbiota in SCI treatment.
2
Current FMT studies mostly occur in the chronic stage after SCI, limiting understanding of early intervention benefits.
3
Few studies concluding that melatonin has diﬀerent sensitivity in diﬀerent segments, which still needs to be further veriﬁed by other experiments.

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