Inhibition of the postsynaptic density protein 95 on the protective effect of Ang-(1-7)–Mas on cerebral ischaemia injury

BACKGROUND: Postsynaptic density protein-95 (PSD95) plays an important role in cerebral ischaemia injury, but its mechanism needs further research. This study aimed to explore the role of PSD95 in (Ang-(1-7))-Mas-mediated cerebral ischaemia protection and its regulatory mechanism. METHODS: Oxygen–glucose deprivation (OGD) neuron and rat middle cerebral artery occlusion (MCAO) models were used as in vitro and in vivo models, respectively. TAT-MAS9C was used to disrupt the interaction between PSD95 and Mas. The recombinant PSD95 adenovirus (Ad-PSD95) was used to overexpress PSD95 in neurons. RESULTS: Results showed that in OGD neurons, Ang-(1-7) could promote cell viability; reduce cell apoptosis; reduce the cell membrane localisation of Mas; upregulate the expression levels of pAKT, bcl-2 and I-κB; and downregulate the expression levels of Bax, pI-κB, tumour necrosis factor alpha and interleukin-1β. TAT-MAS9C could enhance the aforementioned effects of Ang-(1-7). However, the PSD95 overexpression inhibited the aforementioned effects of Ang-(1-7). In the MCAO rat model, the 2,3,5-triphenyltetrazolium chloride (TTC) staining showed that Ang-(1-7) reduced the infarct volume. The Morris water maze test showed that the number of crossings over the platform area in the Ang-(1-7) group was significantly increased. TAT-MAS9C could promote the protective effect of Ang-(1-7). CONCLUSIONS: Results suggested that PSD95 alleviated the activation of AKT and the inhibition of nuclear factor kappa B signalling pathway mediated by the Ang-(1-7)–Mas complex, thereby reducing neuronal activity, increasing apoptosis and inhibiting the Ang-(1-7)–Mas-mediated cerebral ischaemia protection.