Buyang Huanwu decoction facilitates neurorehabilitation through an improvement of synaptic plasticity in cerebral ischemic rats

Abstract

Background: Loss of neural function is a critical but unsolved issue after cerebral ischemia insult. Neuronal plasticity and remodeling are crucial for recovery of neural functions after brain injury. Buyang Huanwu decoction, which is a classic formula in traditional Chinese medicine, can positively alter synaptic plasticity. This study assessed the effects of Buyang Huanwu decoction in combination with physical exercise on neuronal plasticity in cerebral ischemic rats.

Methods: Cerebral ischemic rats were administered Buyang Huanwu decoction and participated in physical exercise after the induction of a permanent middle cerebral artery occlusion. The neurobehavioral functions and infarct volumes were evaluated. The presynaptic (SYN), postsynaptic (GAP-43) and cytoskeletal (MAP-2) proteins in the coronal brain samples were evaluated by immunohistochemistry and western blot analyses. The ultrastructure of the neuronal synaptic junctions in the same region were analyzed using transmission electron microscopy.

Results: Combination treatment of Buyang Huanwu decoction and physical exercise ameliorated the neurobehavioral deficits (p < 0.05), significantly enhanced the expression levels of SYN, GAP-43 and MAP-2 (p < 0.05), and maintained the synaptic ultrastructure.

Conclusions: Buyang Huanwu decoction facilitated neurorehabilitation following a cerebral ischemia insult through an improvement in synaptic plasticity. Graphical abstract The Buyang Huanwu decoction (BYHWD) combined with physical exercise (PE) attenuates synaptic disruption and promotes synaptic plasticity following cerebral ischemia (stroke).

Keywords: Buyang Huanwu decoction; Cerebral ischemia; Neurorehabilitation; Synaptic plasticity.

Graphical abstract

The Buyang Huanwu decoction (BYHWD) combined with physical exercise (PE) attenuates synaptic disruption and promotes synaptic plasticity following cerebral ischemia (stroke).

Fig. 1

Laboratory techniques used in this study. A 4–0 suture coated with silicone rubber (a) was used for the MCAO induction. A programmable and motorized running wheel apparatus (b) was employed for the physical exercises post-cerebral ischemia. The design of this study (c). The intragastric administration of BYHWD began 2 h after the MCAO induction and was administered daily from Day 1 to 14 or until euthanasia. The physical exercises began on Day 3 post-ischemia and ended on Day 14 or euthanasia. The analytic modalities (neurobehavioral assessment, immunohistochemistry, and western blot) were performed on Day 3, 7 and 14 after the MCAO induction. Other techniques (TTC and TEM) were performed on Day 3 or 14 after the MCAO induction. BYHWD, Buyang Huanwu decoction; IHC, immunohistochemistry; MCAO, middle cerebral artery occlusion; NBA, neurobehavioral assessment; TEM, transmission electron microscope; TTC, triphenyltetrazolium chloride staining; WB, western-blot

Fig. 2

Comparisons of the mortalities and neurobehavioral assessment in all groups. Mortalities of all groups (a). Evaluations of the neurological deficits in all groups (n = 6 at each time point) (b). Scores of neurological deficits are expressed as the means ± standard error of the means; ns, not significant, p > 0.05; *, p < 0.05, compared to the MCAO group

Fig. 3

Representative TTC-stained slices and the infarct volumes in all groups. Representative TTC-stained slices of the coronal brain sections (a) from all groups exhibit the pale infarct area induced by a permanent MCAO. The infarct volumes in all groups on Day 3 after the MCAO induction (n = 5) (b). The bars indicate the means ± the standard errors of the means; ns, p > 0.05; *, p < 0.05, relative to the MCAO group

Fig. 4

High magnification micrographs of the immunohistochemical fluorescent labeling of SYN (SYN-1), GAP-43 and MAP-2. The immunohistochemistry micrographs display the locations of the SYN (a), GAP-43 (b) and MAP-2 (c) proteins in sham (a), MCAO (b), MCAO + BYHWD (c), MCAO + PE (d) and MCAO + BYHWD + PE (e) groups. The scale bars =20 μm. The bars indicate the means ± the standard errors of the means; *, p < 0.05, relative to the MCAO group

Fig. 5

Expression levels of SYN (SYN-1), GAP-43 and MAP-2 in all groups at each time point. The proteins expression levels at each time point following the MCAO are presented in representative western-blotting autoradiograms (a). We detected SYN at 77 kDa, GAP-43 at 48 kDa, MAP-2 at 70 kDa and the β-actin loading control at 43 kDa. Lane 1, sham group; Lane 2, MCAO group; Lane 3, MCAO + BYHWD group; Lane 4, MCAO + PE group; Lane 5, MCAO + BYHWD + PE group. The quantitative analyses (n = 6) of the western blot results for the expression levels of SYN, GAP-43 and MAP-2 are presented in the bar graphs (b). The bars indicate the means ± standard errors of the means. *, p < 0.05, compared to the MCAO group

Fig. 6

TEM micrograms. Representative synapse ultrastructures of all groups. An intact synaptic ultrastructure is shown in panel sham, and a disorderly synaptic ultrastructure is illustrated in panels MCAO, MCAO + BYHWD, MCAO + PE and MCAO + BYHWD + PE. The arrowheads presented in panels MCAO, MCAO + BYHWD, MCAO + PE and MCAO + BYHWD + PE indicate the synaptic disruptions. Scale bars =200 nm