Neuroscience
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12503/21662
Browse
Browsing Neuroscience by Author "Ghorpade, Anuja"
Now showing 1 - 2 of 2
- Results Per Page
- Sort Options
Item Altered gene expression in HIV gp120 transgenic mouse brains: Effects of methamphetamine treatment.(2018-03-14) Ghorpade, Anuja; Molles, BrianPurpose: Antiretroviral therapy (ART) has extended lifespans by decades for HIV-infected individuals. However, the prevalence of HIV-associated neurocognitive disorders (HAND) continues to be high despite successful ART therapy. Brain astrocytes can harbor provirus and express neurotoxic HIV proteins such as gp120 and TAT, potentially contributing to HAND. In addition, neurocognitive decline is exacerbated in individuals who use methamphetamine (METH). We hypothesize that METH treatment in gp120+ mice will cause changes in gene expression and damage/death to specific cell populations. Methods: To examine the role of METH in HAND, we used a transgenic mouse line expressing GFAP-controlled HIV gp120 protein (gp120+). Mice were injected intraperitoneally with either 0.9% saline vehicle or successive weekly escalating doses of 1, 5, 10, or 30 mg/kg METH, and their brains were harvested 7 days post-injection for qPCR, immunohistochemistry and protein analyses. Results: In qPCR experiments, gp120+ mice showed dramatically increased levels of GFAP mRNA, suggesting chronic gp120 expression causes astrocyte activation. However, a qPCR probe designed to distinguish the transgene versus the endogenous GFAP transcripts showed lower levels of GFAP activation, suggesting that some of the GFAP mRNA expression is read-through from the transgene construct. GFAP expression in the rostral portion of the brain (anterior to ~0 bregma) was lower than the caudal portion in the gp120- mice, whereas GFAP was higher in the rostral portion in the gp120+ mice, suggesting enhanced astrocyte activation in the rostral portion of the brain encompassing the striatum and frontal cortex. Tissue inhibitor of metalloproteinase-1 (TIMP1) and interleukin 1-beta (IL1b) mRNA levels were increased in gp120+ mice compared to gp120- mice. Gene expression levels of excitatory amino acid transporter-2, tyrosine hydroxylase, and dopamine transporter were not changed in gp120+ mice. None of the METH treatments changed in gene expression in either mouse group at 7 days post-injection. Conclusions: Long-term expression of gp120 in brain leads to altered gene expression of neuroinflammatory mediators. Single-dose METH treatment did not alter gene expression for the targets studied in either the gp120- or gp120+ mouse lines. Future experiments will focus on changes in protein expression and functional properties of specific cell populations in the brain at different times post-METH treatment.Item Neurocognitive decline and dysregulation of Astrocyte-TIMP-1 in a Tat-transgenic mouse model(2018-03-15) Sumien, Nathalie; Ghorpade, Anuja; Joshi, ChaitanyaPurpose: Despite antiretroviral therapy, HIV-associated neurocognitive disorders (HAND) persist in 60-70% of patients. In the brain, HIV-1 non-productively infects astrocytes, which produce and release HIV-1 proteins such as transactivator of transcription (Tat). Tat induces neuronal death and inflammation by direct and indirect mechanisms. During HAND, elevated matrix metalloproteinases (MMPs) aid ECM breakdown facilitating disease progression; whereas, tissue inhibitors of MMPs (TIMPs) impede their activity. Astrocyte TIMP-1 is an inducible protein and its neuroprotective effects have been shown. Astrocyte TIMP-1 expression increases with acute neuroinflammation in vitro, but its levels are reduced during chronic inflammatory brain diseases; indicative of a concomitant loss of TIMP-1 mediated neuroprotection. However, little is known about Tat regulation of astrocyte TIMP-1 expression. We hypothesize that HIV-1 Tat downregulates astrocyte TIMP-1 and induces inflammatory changes that contribute to neurocognitive decline. Methods: A doxycycline-inducible, glial fibrillary acidic protein (GFAP) promoter-restricted HIV-1 Tat mouse model (GT-Tg) was used to investigate astrocyte associated disease mechanisms. Neurocognitive decline was assessed using a battery of behavior tests in GT-Tg and wild-type (WT) mice. Subsequently, mouse brains were harvested to evaluate gene and protein expression. Results: GT-Tg mice had higher anxiety and lower initiation latency in elevated plus maze and locomotor activity tests, respectively. While GT-Tg mice swam faster in Morris water maze, latency and pathlength were comparable to WT. Discriminated reversal test and novel object recognition did not differ significantly between GT-Tg and WT mice. Although TIMP-1 gene expression was elevated in GT-Tg verses WT mice, it negatively correlated with Tat expression consistent with human astrocytes chronic responses. Gene and protein expression for other inflammatory biomarkers and GFAP were evaluated, and correlated with Tat expression. Conclusions: Collectively, our data from GT-Tg mouse model confirmed that TIMP-1 dysregulation is associated with neurocognitive decline in the context of HAND suggesting replenishing TIMP-1 levels could be used as a novel therapeutic option.