HIV-1 Tat-Induced Changes in Synaptically-Driven Network Activity Adapt During Prolonged Exposure

Title:HIV-1 Tat-Induced Changes in Synaptically-Driven Network Activity Adapt During Prolonged Exposure

Volume: 12 Issue: 6

Author(s): Kelly A. Krogh, Matthew V. Green and Stanley A. Thayer

Affiliation:

Keywords: Adaptation, Ca²⁺ signaling, excitotoxicity, fura-2, hippocampal culture, HIV associated neurocognitive disorders (HAND), lipoprotein receptor, synaptic network.

Abstract: HIV-associated neurocognitive disorders (HAND) afflict approximately half of HIVinfected patients. The HIV-1 transactivator of transcription (Tat) protein is released by infected cells and contributes to the pathogenesis of HAND, but many of the underlying mechanisms remain poorly understood. Here we used fura-2-based Ca²⁺ imaging and whole-cell patch-clamp recording to study the effects of Tat on the spontaneous synaptic activity that occurs in networked rat hippocampal neurons in culture. Tat triggered aberrant network activity that exhibited a decrease in the frequency of spontaneous action potential bursts and Ca²⁺ spikes with a simultaneous increase in burst duration and Ca²⁺ spike amplitude. These network changes were apparent after 4 h treatment with Tat and required the low-density lipoprotein receptor-related protein (LRP). Interestingly, Tat-induced changes in network activity adapted during 24 h exposure. The activity returned to control levels in the maintained presence of Tat for 24 h. These observations indicate that Tat causes aberrant network activity, which is dependent on LRP, and adapts following prolonged exposure. Changes in network excitability may contribute to Tat-induced neurotoxicity in vitro and seizure disorders in vivo. Adaptation of neural networks may be a neuroprotective response to the sustained presence of the neurotoxic protein Tat and could underlie the behavioral and electrophysiological changes observed in HAND.

Cite this article as:

Krogh A. Kelly, Green V. Matthew and Thayer A. Stanley, HIV-1 Tat-Induced Changes in Synaptically-Driven Network Activity Adapt During Prolonged Exposure, Current HIV Research 2014; 12 (6) . https://dx.doi.org/10.2174/1570162X13666150121110402