Defense Date

2010

Document Type

Thesis

Degree Name

Master of Science

Department

Anatomy & Neurobiology

First Advisor

Pamela Knapp

Abstract

HIV-infected individuals who abuse opiates have been found to have a higher incidence and a faster progression of HIV encephalitis. Astrocytes, the major support cells in the CNS, are known to play a critical role in the HIV neuropathy. Although astrocytes tend not to be productively infected by the HIV-1 virus, dysregulation of their pro- and anti- inflammatory cytokines/chemokines secretion is usually neurotoxic. Glutamate transport in astrocytes is reported to be impaired as well, which result in extrasynaptic excitatory neurotransmitter accumulation and over stimulation of postsynaptic neurons. It is long known that astrocytes from different brain regions have diverse responses to extracellular stimulants. However, few publications discuss the regional heterogeneity of astrocytes in HIV infected central nervous system. Based on the above information, we hypothesize that astroglia from different brain regions vary in their responses to HIV proteins and the responses could be influenced by co-treatment of morphine. To test this we cultured astrocytes from cerebral cortex, cerebellum and spinal cord, treated them with HIV-1 proteins Tat and gp120 with or without morphine and opioid receptor (mu, delta and kappa receptor) antagonist, naloxone. After 12-18 hours, conditioned medium from each group was analyzed using a Bio-Plex array. Cells from striatal cultures were harvested and lysed; proteins were extracted and evaluated with Western blotting to see whether EAAT2 expression on astrocytes is changed. Results showed that there were significant regional differences among three brain regions in cytokine/chemokine release, both in their basal secretion and in response to viral proteins. Astrocytes from spinal cord and cerebellum had a significantly higher basal secretion than those from cortical glia. All regions had increased cytokine/chemokine secretion when treated with Tat. Astroglia from the cortex showed the highest overall accumulation of cytokines/chemokines. Astroglia from the spinal cord had a slightly lower response overall, although KC expression was highest than other two groups in response to HIV-1 proteins. Astroglia from the cerebellum had a noticeably low response to Tat compared with those from spinal cord and cortex. However, concurrent morphine administration did not have a synergistic effect. No significant change in cytokines/chemokines release was seen when treated by gp120 with or without morphine. No significant change was found in EAAT2 expression on astrocytes either. In conclusion, astrocytes from different brain regions had different baseline secretion pattern and responses to viral protein. Tat had a noticeable effect in inducing cytokines/chemokines production in astrocytes from all brain regions, while limited change could be found with gp120 and morphine treatments. No significant change was found in EAAT2 expression on astrocytes.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

August 2010

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