Effects of manual acupuncture on microglial polarization and the Sirt1/NF-κB pathway in a rat model of post-stroke depression

Abstract

Background:

In the treatment of post-stroke depression (PSD), acupuncture has emerged as a therapeutic option; however, the exact mechanisms underlying its efficacy remain unclear. Prior research suggests acupuncture may improve PSD symptoms by regulating M1/M2 microglial polarization, reducing the release of inflammatory factors and inflammatory-associated damage.

Objective:

The aim of the present study was to explore whether manual acupuncture (MA) can mediate microglial polarization via the silence information regulator/nuclear factor κB (Sirt1/NF-κB) pathway, thereby reducing inflammatory responses in the brains of rats exhibiting PSD and improving depressive behavior.

Methods:

Thirty male rats were divided into a middle cerebral artery occlusion (MCAO) group, PSD group, PSD + MA group, PSD + MA + Sirt1 inhibitor group, and PSD + MA + NS (normal saline) group. Acupuncture was applied 6 days a week for 4 weeks at GV26, GV20 and bilateral PC6 and SP6. In the PSD + MA + Sirt1 inhibitor group, nicotinamide (NAM), a specific inhibitor of Sirt1, was slowly injected into the frontal lobe with a stereotactic injector 1 h before acupuncture. Behavioral tests were conducted after modeling and intervention, including the sucrose preference test (SPT) and open field test (OFT), and body weight was monitored. Following the tests, specimens of the dorsolateral frontal lobe were taken to evaluate molecular markers. Immunofluorescence staining was employed to determine the expression levels of M1 microglial markers CD16/Iba1 and M2 microglial markers CD206/Iba1 in the dorsolateral prefrontal cortex. mRNA expression of CD16/intrinsic nitric oxide synthase (iNOS) and CD206/arginase (Arg)-1 was detected by q-RT-PCR. Western blot analysis was used to quantify protein expression of Sirt1, total p65 and phosphorylated p65 (p-p65) proteins. Interleukin (IL)-1β, IL-6, IL-10 and tumor necrosis factor (TNF)-α levels were quantified using ELISA.

Results:

Depression-like behavior of PSD model rats was reduced by MA. Acupuncture promoted transformation of microglia from M1 to M2 in the prefrontal lobe, thereby decreasing expression of pro-inflammatory factors (IL-1β, IL-6 and TNF-α) and increasing expression of anti-inflammatory IL-10 after PSD. In addition, expression of Sirt1 in the prefrontal lobe increased following MA, while expression of p65/p-p65 was reduced, indicating activation of the Sirt1/NF-κB pathway. These findings suggest that M1 to M2 microglial polarization was closely related to Sirt1/NF-κB pathway activation following MA.

Conclusion:

MA promoted the transformation of microglia from M1 to M2 in the prefrontal lobe of PSD rats, reduces the inflammatory response and improves depression-like behavior in rats. These effects were associated with activation of the Sirt/NF-κB pathway.