HIV gp120 upregulates tonic inhibition through α5-containing GABA A Rs

Matthew V. Green, Stanley A Thayer

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

HIV-Associated Neurocognitive disorder (HAND) affects nearly half of infected patients. The HIV envelope protein gp120 is shed by infected cells and is a potent neurotoxin in vitro that reproduces many aspects of HAND when expressed in vivo. Here, we show that HIV gp120 increases the amplitude of a tonic current mediated by γ-aminobutyric acid type-A receptors (GABA A Rs). Treating rat hippocampal cultures with 600 pM gp120 IIIB for 4 h increased a tonic bicuculline-sensitive current, which remained elevated for 24 h. The increased current resulted from upregulation of extrasynaptic α5-containing GABA A Rs, as indicated by inhibition with the selective inverse agonist basmisanil. Treatment with gp120 increased α5-GABA A R immunoreactivity on the cell surface without new protein synthesis. The increase in tonic inhibition was prevented by a C-X-C chemokine receptor type 4 (CXCR4) antagonist or elimination of microglia from the culture. Treatment with interleukin-1β (IL-1β) increased the tonic current and an IL-1 receptor antagonist blocked the gp120-evoked response. Pharmacological or genetic inhibition of p38 mitogen-activated protein kinase (MAPK) prevented the gp120-evoked increase in tonic current and direct activation of a mutant form of p38 MAPK expressed in neurons increased the current. Collectively, these data show that gp120 activates CXCR4 to stimulate microglia to release IL-1β. Subsequent stimulation of IL-1 receptors activates p38 MAPK in neurons leading to the upregulation of α5-containing GABA A Rs. Increased tonic inhibition impairs neuroplasticity and inhibition of α5-containing GABA A Rs improves cognitive function in disease models. Thus, gp120-induced upregulation of α5-containing GABA A Rs presents a novel therapeutic target for HAND.

Original languageEnglish (US)
Pages (from-to)161-168
Number of pages8
JournalNeuropharmacology
Volume149
DOIs
StatePublished - May 1 2019

Bibliographical note

Funding Information:
The authors declare no conflicts of interest. This work was supported by a grant from the National Institute on Drug Abuse , National Institutes of Health ( DA07304 ) to S.A.T.

Publisher Copyright:
© 2019 Elsevier Ltd

Keywords

  • Basmisanil
  • Basmisanil, 1,1-Dioxidothiomorpholino) (6-((3-(4-fluorophenyl)-5-methylisoxazol-4-yl)methoxy)pyridin-3-yl)methanone (PubChem CID: 57336276)
  • HAND
  • HIV gp120
  • α5 GABA R subunit

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