Permeability of the blood-brain barrier to HIV-1 Tat

William A. Banks, Sandra M. Robinson, Avindra Nath

Research output: Contribution to journalArticlepeer-review

120 Scopus citations


Infection with human immunodeficiency virus-1 (HIV-1) is associated with dysfunctions of the central nervous system (CNS). HIV-1 induces its effects on the CNS by a variety of mechanisms, including by shedding the neurotoxic viral proteins such as gp120 and Tat. Both HIV-1 and gp120 have been shown to cross the blood-brain barrier (BBB). It is has not been determined, however, whether blood-borne Tat can cross the BBB. Here, we found that Tat crosses the BBB by a nonsaturable mechanism with a unidirectional influx rate of about 0.490 μl/g/min. About 0.126% of an intravenous dose of Tat enters each g of brain. Radioactively labeled albumin injected simultaneously did not cross the BBB. The hypothalamus, occipital cortex, and hippocampus were the regions of the brain most permeable to Tat. Nonsaturable brain-to-blood efflux also occurred, most likely with reabsorption into the blood of the cerebrospinal fluid. In conclusion, we found that Tat crossed the BBB bidirectionally. Such permeability could provide a mechanism by which Tat produced on one side of the BBB could affect neural or immune function on the other side.

Original languageEnglish (US)
Pages (from-to)218-227
Number of pages10
JournalExperimental Neurology
Issue number1
StatePublished - May 2005


  • Blood-brain barrier
  • Central nervous system
  • HIV-1

ASJC Scopus subject areas

  • Neurology
  • Developmental Neuroscience


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