Acupuncture treatment for post-stroke depression: Intestinal microbiota and its role

Depression after a stroke is a very common neuropsychiatric complication that affects more than one-third of stroke survivors. This condition not only significantly compromises patients' quality of life but also represents an important public health problem requiring urgent attention. Conventional treatments include antidepressant medications such as selective serotonin reuptake inhibitors and tricyclic antidepressants, in addition to psychotherapy. However, these medications often cause undesirable adverse effects, including sexual dysfunction, gastrointestinal symptoms, and neuropsychiatric effects, as well as the development of drug resistance.

This scenario has motivated the search for safer and more effective therapeutic alternatives.

Acupuncture has emerged as a promising "green treatment" option for post-stroke depression. Several standardized clinical studies show that acupuncture not only promotes nerve function recovery after stroke but also offers significant benefits in treating depressive symptoms and improving patients' quality of life. When compared with conventional medications, acupuncture has greater biological safety and important socioeconomic advantages. What makes this topic even more relevant is the growing understanding that post-stroke depression manifests not only through neurologic and psychiatric symptoms but is often associated with digestive tract dysfunction, creating a complex picture involving multiple body systems.

This scientific article's main objective was to examine the relationship between gut microbiota and post-stroke depression, specifically investigating how acupuncture can act as a regulator of gut microbial balance. The study used a comprehensive narrative review methodology, analyzing research that demonstrates how acupuncture can alter the composition of the gut microbiota in different disease states. The researchers examined studies that used advanced techniques such as 16S rRNA gene sequencing to identify changes in microbial structure, along with metabolomic analyses to understand changes in bacterial metabolism products. The review included both animal model studies and clinical research in humans, providing a comprehensive view of the mechanisms involved.

The findings revealed that acupuncture can treat post-stroke depression through six main mechanisms related to gut microbiota. First, the technique regulates gut microbial structure, increasing the abundance of beneficial bacteria such as Candidatus Arthromitus, Lactobacillus, and Bacteroides, while reducing pathogens such as Escherichia-Shigella and Proteobacteria. Second, it strengthens the gut mucosal barrier, increasing the expression of tight junction proteins such as ZO-1, occludin, and claudin-5, thereby preventing bacterial translocation and the entry of inflammatory substances into circulation. Third, it regulates hypothalamic-pituitary-adrenal axis disturbances, restoring hormone levels such as ACTH, CRH, and cortisol.

Fourth, it modifies metabolites and metabolic pathways, including tryptophan metabolism, short-chain fatty acid production, and neurotransmitters such as serotonin and dopamine. Fifth, it reduces both local and systemic inflammatory responses, decreasing pro-inflammatory cytokines such as IL-1β, IL-6, and TNF-α. Finally, it protects central neurons by reducing neuroinflammation and increasing neuroprotective factors.

For patients suffering from post-stroke depression, these findings offer significant hope. Acupuncture emerges as a therapeutic alternative that acts on multiple levels, from gut microbiota modulation to direct protection of the central nervous system. For health professionals, these results suggest that acupuncture can be safely integrated into existing treatment protocols, potentially reducing reliance on medications and their associated adverse effects. The understanding that acupuncture functions as a "special microecologic regulator" provides a solid scientific basis for its clinical application.

In addition, the fact that the technique can influence the gut-brain axis suggests that patients with concurrent gastrointestinal symptoms may particularly benefit from this therapeutic approach.

It is important to recognize the inherent limitations of this review and the studies analyzed. The main study is a narrative review that examines correlations between acupuncture and alterations in the gut microbiota, but does not establish definitive causal relationships. Many of the studies included were conducted in animal models, which may limit direct applicability to humans. In addition, the heterogeneity of the acupuncture protocols used in the different studies, including variations in selected acupuncture points and duration and frequency of treatments, makes it difficult to establish standardized guidelines.

The dynamics of microbiological modulation in vivo remain a major scientific challenge requiring further investigation. Future research should focus on larger randomized controlled clinical trials that can determine causal relationships among acupuncture, microbiota alterations, and improvement of depressive symptoms, thus contributing to the development of more precise and effective treatment protocols.