P2X7 receptor in the hippocampus is involved in gp120-induced cognitive dysfunction.

To investigate the role of the P2X7 receptor in learning and memory dysfunction induced by HIV-1 envelope glycoprotein gp120 (gp120), we established HIV-1-associated dementia (HAD) animal models by intracerebroventricular (ICV) infusion of gp120 in rats. We observed gp120-induced cognitive dysfunction in the radial arm water maze test. Results showed that rats in the gp120 groups had longer escape latencies and more errors compared to those in the control group. For example, the average trial time in the 50-ng/day-gp120 group on day eight (16.57 ± 1.71 s, N = 90) was significantly longer than that of control rats (9.93 ± 0.68 s, N = 90). The relative expression of P2X7 mRNA in the control, 50-, 70-, and 100-ng/day-gp120 groups were 0.43 ± 0.06, 0.48 ± 0.07, 0.83 ± 0.05, and 0.84 ± 0.10, respectively; relative P2X7 protein expression in those groups was 0.63 ± 0.07, 1.08 ± 0.06, 0.90 ± 0.07, and 1.03 ± 0.11, respectively. According to immunohistochemistry analysis, the staining intensity values for P2X7 protein expression in the control, 50-, 70-, and 100-ng/d-gp120 groups were 0.88 ± 0.07, 1.41 ± 0.12, 1.28 ± 0.13, and 1.31 ± 0.10, respectively. The above results showed that the expression of P2X7 increased significantly in the hippocampus of gp120 rats compared to that of the control group. These results suggest that ICV infusion of gp120 can successfully mimic HAD in rats, and P2X7 may be involved in gp120-induced cognitive dysfunction. This could provide a theoretical foundation and potential drug target for research and treatment of ADC.

Protective effects of naringin against gp120-induced injury mediated by P2X7 receptors in BV2 microglial cells.

This study was aimed at exploring the effects of P2X7 receptors on gp120-induced injury and naringin's protective effects against gp120-induced injury in BV2 microglia. BV2 microglia injury model was established by gp120 treatment and MTS assay was used to verify whether naringin has a cell-protective effect against gp120-induced injury. Changes in P2X7 receptor expression were assayed using RT-PCR, qPCR, and western blot. Results showed that the ODs of the Ctrl, gp120, gp120+naringin, and gp120+BBG groups were 0.91 ± 0.10, 0.71 ± 0.09, 0.83 ± 0.10, and 0.83 ± 0.10, respectively. Compared to the control group, the gp120 group showed a significantly decreased cell survival rate. Cell survival rates of the gp120+naringin group increased significantly compared to those of the gp120 group, while no difference was observed when compared to the gp120+BBG group. The relative P2X7 mRNA expression levels in the Ctrl, gp120, gp120+naringin, and gp120+BBG groups were 0.73 ± 0.06, 1.05 ± 0.06, 0.78 ± 0.05, and 0.81 ± 0.04, respectively. The corresponding P2X7 protein expression levels were 0.46 ± 0.04, 0.79 ± 0.04, 0.38 ± 0.07, and 0.42 ± 0.06. P2X7 mRNA and protein expression in the gp120 group increased significantly compared to those in the control group, and declined in the gp120+naringin group compared to those in the gp120 group. Therefore, P2X7 receptors might be involved in gp120-induced injury in BV2 microglia, and naringin might play a protective role by inhibiting the up-regulated expression of P2X7 receptors.