ABSTRACT
Objective To investigate the role of P2X7 receptor in learning and memory dysfunction induced by HIV-1 enveloped protein gp120 in rats. Methods The imitating HIV-1 associated dementia (HAD) animal models were established by intracerebroventricular (ICV) infusion of gp120 in rats. The effect of gp120 on the learning and memory dysfunction in rats was evaluated by Morris water maze (MWM) test. The role of P2X7 receptor (P2X7R) was studied by Western blot and PCR assay. Results The ICV infusion of gp120 for 3 days in rats could imitated the HAD animal model. Results of MWM test showed that the rats in the model group had longer escape latencies and errors compared with those in the control group (P < 0.01); Results of Western blot and PCR assay showed that the expressions of P2X7R and P2X7 mRNA in hippocampus of rats in the model group were significantly increased (P < 0.01). Conclusions The ICV infusion of gp120 in rats could imitate the HIV-1 associated dementia (HAD) animal models, and P2X7R may be involved in the pathophysiological process of learning and memory dysfunction caused by gp120.
ABSTRACT
We previously demonstrated that the lentivirus lytic peptide 1 (LLP-1) corresponding to the carboxyl terminus of HIV-1 gp41 induced cell death in human neuronal cells. Present study was conducted to further elucidate the pathogenic mechanisms involved in HIV-1 gp41-induced neurodegeneration in AIDS patients with cognitive deficits. The effect of LLP-1 on activation of calpain-1, a calcium-activated cysteine protease, which has been implicated in neuronal degeneration and death, was monitored by the proteolysis of spectrin in rat organotypic hippocampal slice cultures. Protease specific spectrin breakdown products revealed that LLP-1 generated~150/145-kDa fragments characteristic of calpain-1 activation in hippocampus undergoing cell death as evidenced by LDH release. This spectrin cleavage pattern was further confirmed by in vitro calpain-1 proteolysis. Futhermore, calpectin and MDL28170, inhibitors of calpain activity, blocked calpain-1-mediated spectrin cleavage. Spectrin cleavage likely occurred in the absence of overt synaptic loss, as suggested by the preserved levels of synaptophysin. Among pharmacological agents tested, apocynin, NADPH oxidase inhibitor, ameliorated the LLP-1-induced spectrin. Given the role of spectrin essential for synapse stabilization, LLP-1-induced spectrin cleavage as occurs with the activation of calpain-1 may be an important effector in LLP-1mediated cell injury in hippocampus, which is primarily linked to cognitive dysfunction.