[Electroacupuncture alleviates anxiety-like behavior in PTSD rats via modulating glycolysis/H4K12la/HIF-1α signaling pathway].

OBJECTIVES: To observe the effect of electroacupuncture (EA) on anxiety-like behavior and activity of glycolysis/histone H4 lysine 12 lactylation (H4K12la)/hypoxia-inducible factor 1α (HIF-1α) signaling in rats with post-traumatic stress disorder (PTSD), so as to explore its underlying molecular mechanisms in the improvement of PTSD-induced anxiety-like behavior.

METHODS: Male SD rats were randomly divided into control, PTSD model, and EA groups, with 10 rats in each group. The PTSD model was established by using a modified single prolonged stress and shock (SPS&S) protocol. The rats in the EA group received EA stimulation (2 Hz/100 Hz, 1 mA) at bilateral "Ganshu"(BL18) and "Shenshu"(BL23), and acupuncture at "Baihui"(GV20), "Shenting" (GV24). The anxiety-like behavior was assessed by using both open field (OF) test and elevated plus maze (EPM) test, separately. Morphological changes of hippocampal neurons were observed by HE staining. Glycolysis-related metabolites including lactate, glucose, ATP and pyruvate were measured using biochemical kits. The expressions of H4K12la, HIF-1α, and key glycolytic enzymes [lactate dehydrogenase (LDHA)and pyruvate kinases type M2 (PKM2) ] in the hippocampal tissue were evaluated by qPCR and Western blot, separately. The spatial distribution of H4K12la and HIF-1α in the hippocampus was further analyzed by immunohistochemistry (IHC).

RESULTS: The anxiety-like behavior tests showed that the percentages of entries and time spent in the open arms of the EPM test, the total distance and the distance travelled in the center zone of OF test were apparently lower in the model group than in the control group (P<0.01), and significantly higher in the EA group than in the model group (P<0.01). In contrast to the control group, the model group displayed a decrease in the ATP content (P<0.01), and an increase in the contents of glucose, lactic acid, and the expression levels of PKM2 and LDHA mRNAs and proteins, and H4K12la and HIF-1α proteins and immunoactivity in the hippocampal tissues (P<0.05, P<0.01). After EA intervention, the decreased level of ATP and the increased levels of glucose, lactic acid, and expression levels of PKM2 and LDHA mRNAs and proteins, and H4K12la and HIF-1α proteins and immunoactivity were reversed (P<0.05, P<0.01). No significant changes were found in the levels of pyruvate, and expression of H4K12la and HIF-1α mRNAs after modeling and after EA intervention. H.E. staining showed that many hippocampal pyramidal cells were shriveled, with irregular cell shapes, reduced volume and a small number of tiny vacuoles in the model group, while a large number of pyramidal cells were found to have regular shapes, neat and dense arrangement, and a few of shrunken pyramidal cells in the EA group.

CONCLUSIONS: EA intervention can improve the anxiety-like behavior in PTSD rats, which may be related to its functions in down-regulating the glycolysis/H4K12la/HIF-1α pathway and mitigating inflammation in the hippocampus.