The Dual Role of HIV-1 gp120 V3 Loop-Induced Autophagy in the Survival and Apoptosis of the Primary Rat Hippocampal Neurons

HIV-1 gp120, an important subunit of the envelope spikes that decorate the surface of virions, is known to play a vital role in neuronal injury during HIV-1-associated neurocognitive disorder (HAND), although the pathological mechanism is not fully understood. Our previous studies have suggested that the V3 loop of HIV-1 gp120 (HIV-1 gp120 V3 loop) can induce neuronal apoptosis in the hippocampus, resulting in impairment in spatial learning and memory in Sprague–Dawley (SD) rats. In this study, we demonstrated that autophagy was significantly increased in rat primary hippocampal neurons in response to treatment of HIV-1 gp120 V3 loop. Importantly, HIV-1 gp120 V3 loop-induced autophagy played a dual role in the cell survival and death. An increase in autophagy for a short period inhibited apoptosis of neurons, while persistent autophagy over an extended period of time played a detrimental role by augmenting the apoptotic cascade in rat primary hippocampal neurons. In addition, we found that the HIV-1 gp120 V3 loop induced autophagy via AMPK/mTOR-dependent and calpain/mTOR-independent pathways, and the ERK/mTOR pathway plays a partial role. These findings provide evidence that HIV-1-induced autophagy plays a dual role in the survival and apoptosis of the primary rat hippocampal neurons and persistent autophagy may contribute to the pathogenesis of HAND, and autophagy modulation may represent a potential therapeutic strategy for reducing neuronal damage in HAND.