Introduction
Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder marked by social deficits, repetitive behaviors, and restricted interests. Traditional treatments, like behavioral interventions and medication, often offer limited improvements and can be costly. Acupuncture, a traditional Chinese medicine technique, has shown promise in improving symptoms of ASD, but its underlying mechanism remains unclear. This study, conducted by a team of researchers from Fujian, China, explored the effects of scalp acupuncture on rats modeled with autism through the lens of synaptic function and brain plasticity.
Study Design and Methodology
The researchers utilized a well-established autism rat model, induced by prenatal exposure to valproic acid (VPA). This model mimics several core behaviors of ASD, such as social deficits, anxiety-like behaviors, and repetitive actions. The study involved three groups of rats:
Wild-type (WT): Rats not exposed to VPA, serving as the control group.
VPA group: Rats exposed to VPA during pregnancy, modeling autism-like behaviors.
VPA + acupuncture group: Rats exposed to VPA, then treated with scalp acupuncture.
The acupuncture treatment targeted specific acupoints (GV24 and bilateral GB13), believed to regulate brain function and calm neurological disturbances. The intervention started on postnatal day 23 and continued for four weeks. Post-treatment, the researchers conducted behavioral tests, RNA sequencing, and electron microscopy to assess changes in the brain.
Behavioral Improvements with Acupuncture
- Anxiety and Exploration: In the open-field test, VPA rats exhibited reduced exploratory behavior and spent more time in the periphery of the test arena, indicating anxiety-like behaviors. However, after acupuncture treatment, these rats showed significant improvements in exploration, spending more time in the central area. Although acupuncture did not drastically improve motor activity, it alleviated anxiety-like symptoms in the rats.
- Social Interaction: The three-chamber social test revealed that VPA rats had reduced social interaction and novelty preference, core symptoms of ASD. Acupuncture-treated rats displayed an improvement in these behaviors, with increased interaction with unfamiliar rats compared to objects, suggesting a restoration of social preference.
- Repetitive Behaviors: VPA rats showed prolonged grooming behavior, a hallmark of repetitive actions in ASD. Acupuncture notably reduced both the duration and frequency of grooming, highlighting its potential to mitigate stereotypical behaviors in autism models.
Synaptic and Neurological Findings
- RNA Sequencing: The researchers conducted RNA sequencing on the prefrontal cortex (PFC), a brain region implicated in social behavior and cognition. Significant differences in gene expression were observed between the groups, particularly in genes related to synaptic function and immune-inflammatory responses. In the VPA + acupuncture group, key genes involved in synaptic plasticity, such as Arc and Per1, were upregulated, suggesting that acupuncture enhances synaptic adaptability and regulation of circadian rhythms.
- Synaptic Plasticity and Function: Electron microscopy revealed structural differences in the synapses of the PFC. VPA rats exhibited fewer synaptic vesicles and abnormal mitochondria, which are essential for energy and neuronal communication. In contrast, acupuncture-treated rats displayed more normal synaptic structures, with an increased number of synaptic vesicles and healthy mitochondrial membranes. This improvement in synaptic function aligns with the observed behavioral recovery.
- Immune and Inflammatory Pathways: Acupuncture also appeared to modulate immune responses in the brain. Genes involved in immune regulation, such as Fkbp5, were differentially expressed between the groups, pointing to acupuncture’s role in reducing neuroinflammation, which is commonly linked to autism.
Mechanism of Acupuncture’s Effectiveness
The study posits that acupuncture improves ASD symptoms by targeting several key mechanisms:
- Synaptic Function: By enhancing synaptic plasticity and increasing the number of synapses and vesicles, acupuncture aids in restoring normal communication between neurons, especially in regions like the PFC that are critical for social behavior.
- Neuronal Signal Transduction: Acupuncture also modulates neurotransmitter systems, such as GABA and glutamate pathways, which are often disrupted in ASD.
- Regulation of Immune Responses: The findings suggest that acupuncture can reduce neuroinflammation, a factor implicated in the development of ASD.
- Circadian Rhythm: Improvements in the expression of genes related to circadian rhythms, such as Per1, could also help address sleep disorders, which are common comorbidities in autism.
Conclusion
This research highlights the potential of acupuncture as a non-invasive treatment for ASD by demonstrating its ability to improve core autism-like behaviors in rat models. Through its impact on synaptic function, neuronal signaling, and immune regulation, acupuncture presents a promising alternative for managing ASD symptoms. However, further studies, particularly clinical trials in humans, are needed to confirm its effectiveness and explore its broader applications.
Source:
https://www.sciencedirect.com/science/article/pii/S2405844024131611