Biology subjects

Hines, A. D.

Publications and source records attributed to Hines, A. D..

4 recordsLinked to original sources

bioRxiv2023

Synapse-specific trapping of Syntaxin1a into nanoclusters by the general anesthetic isoflurane

General anesthetics disrupt brain network dynamics through multiple pathways, predominately through post-synaptic potentiation of GABAAR and pre-synaptic inhibition of neuroexocytosis. Common clinical general anesthetic drugs, such as propofol and isoflurane, have been shown to interact and interfere with a core component of the exocytic release machinery, Syntaxin1A, to cause impaired neurotransmitter release. Recent in vitro studies however suggest that these drugs to not affect all synapse subtypes equally. We investigated the role of Syntaxin1A in multiple neurotransmitter systems under isoflurane general anesthesia in the adult Drosophila brain using live-cell super resolution microscopy and optogenetic readouts of exocytosis. We found that effects of isoflurane anesthesia were neuron specific and only impaired Syntaxin1A activity in excitatory neurons at cholinergic synapses, but not inhibitory GABAergic or glutamatergic neurons. These results indicate that general anesthetics could work by producing successive bouts of inhibition across the brain, by reducing neuroexocytosis from excitatory neurons specifically as well as silencing arousal systems through GABAAR potentiation.

neuroscience↗

bioRxiv2022

Activated gliosis, accumulation of amyloid beta and hyperphosphorylation of tau in aging canines with and without cognitive decline

Canine cognitive dysfunction (CCD) syndrome is a well-recognized naturally occurring disease in aged dogs, with a remarkably similar disease course, both in its clinical presentation and neuropathological changes, as humans with Alzheimers disease (AD). Similar to human AD patients this naturally occurring disease is found in the aging canine population however, there is little understanding of how the canine brain ages pathologically. It is well known that in neurodegenerative diseases, there is an increase in inflamed glial cells as well as an accumulation of hyperphosphorylation of tau (P-tau) and amyloid beta (A{beta}1-42). These pathologies increase neurotoxic signaling and eventual neuronal loss. We assessed these brain pathologies in aged canines and found an increase in the number of glial cells, both astrocytes and microglia, and the activation of astrocytes indicative of neuroinflammation. A rise in the aggregated protein A{beta}1-42 and hyperphosphorylated tau, at Threonine 181 and 217, in the cortical brain regions of aging canines is seen. We then asked if any of these aged canines had CCD utilizing the only current diagnostic, owner questionnaires, verifying positive or severe CCD had pathologies of gliosis and accumulation of A{beta}1-42 like their aged matched controls. However uniquely the CCD dogs had P-tau at T217. Therefore, this phosphorylation site of tau at threonine 217 may be a predictor for CCD.

neuroscience↗

bioRxiv2022

Targeting neuroinflammatory pathways using Nanoligomer is neuroprotective in prion disease

Neuroinflammation plays a crucial role in the development of neurodegenerative protein misfolding disorders. This category of progressive diseases includes, but is not limited to, Alzheimers disease, Parkinsons disease, and prion diseases. Shared pathogenesis involves the accumulation of misfolded proteins, chronic neuroinflammation, and synaptic dysfunction, ultimately leading to irreversible neuronal loss, measurable cognitive deficits, and death. Presently, there are little to no effective treatments to halt the advancement of neurodegenerative diseases. We hypothesized directly targeting neuroinflammation by downregulating the transcription factor, NF-{kappa}B and the inflammasome protein, NLRP3, with the brain-penetrant, non-toxic, SB_NI_112, would be neuroprotective. To achieve this, we used a cocktail of RNA targeting therapeutics (SB_NI_112) shown to be brain-penetrant, non-toxic, and targeting both NF-|B and NLRP3. We utilized a mouse-adapted prion strain as a model for neurodegenerative diseases to assess aggregation of misfolded proteins, glial inflammation, neuronal loss, cognitive deficits, and lifespan. Prion-diseased mice were treated either intraperitoneally or intranasally with SB_NI_112. Behavioral and cognitive deficits were significantly protected by this combination of NF-{kappa}B and NLRP3 down-regulators. Treatment reduced glial inflammation, protected against neuronal loss, prevented spongiotic change, rescued cognitive deficits, and significantly lengthened lifespan of prion-diseased mice. We have identified a non-toxic, systemic pharmacologic that down-regulates NF-|B and NLRP3, prevents neuronal death and slows the progression of neurodegenerative disease. Though mouse models do not always predict human patient success, and the study was limited due to sample size and number of dosing methods utilized, these findings serve as a proof of principle for continued translation of the therapeutic SB_NI_112 for prion disease and other neurodegenerative diseases. Based on success in a murine prion model, we will be continual testing SB_NI_112 in a variety of neurodegenerative disease models, including Alzheimers Disease and Parkinsons Disease.

neuroscience↗

bioRxiv2020

Tracking single molecule dynamics in the anesthetized Drosophila brain

Super-resolution microscopy provides valuable insight for understanding the nanoscale organization within living tissue, although this method is typically restricted to cultured or dissociated cells. Here, we develop a method to track the mobility of individual proteins in ex vivo adult Drosophila melanogaster brains, focusing on a key component of the presynaptic release machinery, syntaxin1A. We show that individual syntaxin1A dynamics can be reliably tracked within neurons in the whole fly brain, and that the mobility of syntaxin1A molecules increases following conditional neural stimulation. We then apply this preparation to the problem of general anesthesia, to address how different anesthetics might affect single molecule dynamics in intact brain synapses. We find that propofol, etomidate, and isoflurane significantly impair syntaxin1A mobility, while ketamine and sevoflurane have little effect. Resolving single molecule dynamics in intact fly brains provides a novel approach to link localized molecular effects with systems-level phenomena such as general anesthesia. Impact statementA new approach to track the mobility of individual molecules using intact fly brains reveals a common presynaptic effect for different intravenous and volatile general anesthetics.

neuroscience↗