Biology subjects

Pardue, M.

Publications and source records attributed to Pardue, M..

6 recordsLinked to original sources

bioRxiv2026

L-DOPA treatment promotes sustained neurovascular and synaptichomeostasis in the diabetic retina

While previous work has shown a sustained protective effect of levodopa (L-DOPA) on retinal function in early-stage diabetic retinopathy (DR) in humans, its underlying biology is unknown. Using noninvasive measures in diabetic mice, we found L-DOPA protects retinal neurovascular function as measured by oscillatory potential timing and flicker-evoked retinal vasodilation, as well as visual behavior, for at least two weeks past treatment end. Assessing changes in retinal gene expression, differentially expressed genes were broadly comparable between diabetic mice experiencing washout of L-DOPA versus continued L-DOPA treatment, with gene co-expression network analysis identifying distinct modules across L-DOPA-treated diabetic mice associated with synaptic function and cytoskeletal organization that correlated with functional protection. Together, these findings demonstrate that L-DOPA restores and sustains retinal neurovascular function in early DR and links this protection to transcriptional programs supporting synapse activity and structural integrity. TeaserL-DOPA restores neuronal and vascular performance in the diabetic retina, with benefits that lasted after treatment stopped.

neuroscience↗

bioRxiv2025

Forced exercise modulates retinal inflammatory response and regulates miRNA expression to promote retinal neuroprotection during degeneration

BackgroundOur labs have demonstrated exercise is protective in animal models of retinal degeneration (RD). Inflammation drives RD progression, and is regulated by the recruitment and reactivity of glia cells as well as through small non-coding RNAs, microRNAs (miRNAs). Here, we explore the effects of treadmill exercise on the recruitment and reactivity of retinal inflammatory cells within the neural retina and miRNA expression in a light-induced retinal degeneration model (LIRD) that exhibits phenotypes found in patients with RD. MethodsMale 6-week-old BALB/c mice were randomly assigned to either active or inactive groups. Active groups were exercised by treadmill 1 hour a day for two weeks at a speed of 10m/min, meanwhile inactive groups were placed on static treadmills for the same duration. Light induced retinal degeneration (LIRD) was induced during the second week of exercise using light exposure of 5000 lux, control animals were kept at 50 lux. Retinal function was assessed using electroretinography (ERG) 5 days after LIRD. Retinas were collected 1-day and 5-days post-LIRD, sagittal sections were stained for inflammatory markers (GFAP and Iba1), TUNEL (cell death), and photoreceptor nuclei (outer nuclear layer; ONL) were quantified. RNA was extracted and miRNA expression quantified with GeneChip miRNA 4.0 array. ResultsActive+LIRD mice demonstrated significant preservation of retinal function, evidenced by higher a-wave and b-wave amplitudes in ERG 5-days post-LIRD, compared to inactive+LIRD mice. Retinal sections from active+LIRD mice had fewer Iba1+ cells and decreased GFAP labeling 5-days post-LIRD compared to inactive+LIRD mice. Active+LIRD mice had fewer ONL TUNEL+ cells compared to inactive+LIRD mice. Inactive+LIRD mice showed a decline in ONL counts 1-day post-LIRD with significant loss 5-days post-LIRD compared to active+LIRD mice. In active groups, exercise promoted significant differences in miRNA expression, such as miR-302b, miR-192-5p, miR-187 compared to inactive groups. ConclusionsOur results indicate that treadmill exercise preserved photoreceptor density, slowed and or prevented apoptosis in the ONL, and decreased the presence/recruitment of inflammatory cells in the neural retina. Altered miRNA expression profiles in active groups are associated with cell survival (miR-302b), oxidative stress regulation (miR-192-5p) and photoreceptor homeostasis (miR-187). These results reveal how exercise alters the retinal inflammatory response over the course of 1-day to 5-days, providing insight into exercise-based therapies and treatments for RD and neuroinflammatory diseases.

neuroscience↗

bioRxiv2025

All-trans retinoic acid and fluid transport in myopigenesis

Myopia, or near-sightedness, is rapidly growing in prevalence, with significant long-term implications for ocular health. There is thus great impetus to better understand molecular signaling pathways leading to myopia. We and others have reported that all-trans retinoic acid (atRA) is involved in myopigenic signaling, yet the understanding of how atRA is transported and exerts a myopigenic influence is poor. Here we measured the concentrations of atRA in the serum in wild-type C57BL/6 mice under control conditions and after atRA feeding, previously shown to induce myopia. We also developed a mathematical model that describes fluid fluxes and the advective-diffusive transport of atRA in choroid and sclera, including atRA synthesis in the choriocapillaris, atRA degradation by scleral cells, and binding of atRA to the carrier protein serum albumin. This model, developed for both mice and humans, showed that atRA produced in the choriocapillaris was able to permeate well into the sclera in both mice and humans at biologically-relevant concentrations, and that atRA feeding greatly increased tissue levels of atRA across both the choroid and sclera. We were also able to identify which parameters most influence atRA concentration in ocular tissues, guiding future experimental work. Our findings support atRAs role in myopigenic signaling.

bioengineering↗

bioRxiv2021

Treadmill exercise promotes retinal astrocyte plasticity and protects against retinal degeneration

Exercise has been shown to be an effective neuroprotective intervention that preserves retinal function and structure in several animal models of retinal degeneration. However, retinal cell morphology and cell types governing exercise-induced retinal neuroprotection remain elusive. Previously, we found that the protective effects of exercise in animal models of retinal disease were accompanied by increased levels of circulating and retinal brain derived neurotrophic factor (BDNF) and required intact signal transduction with its high-affinity receptor, tropomyosin kinase B (TrkB). Studies of neurodegenerative diseases in the brain demonstrate that neurons and astrocytes express BDNF and TrkB. Additionally, astrocytes have been shown to alter their morphology in response to exercise. Here, we have investigated the role of retinal astrocytes as mediators of exercise-induced retinal neuroprotection in a light-induced retinal degeneration mouse model (LIRD). We found that treadmill exercise in both our dim (control maintenance light levels) and LIRD groups promote increased retinal astrocytic population, GFAP expression, branching and endpoints, dendritic complexity, and promotes BDNF-astrocyte interaction. In contrast, LIRD animals that were inactive had significant reductions in all measured parameters. Our findings indicate that exercise is sufficient to rescue retinal astrocyte morphology in a LIRD model maintaining branching and dendritic arborization similar to retinal astrocytes that are not undergoing degeneration. These studies provide essential information to current knowledge gaps in regards to exercise-induced neuroprotection and will additionally provide knowledge in exercise intervention optimization as a rehabilitative method. Significance statementThis study represents an essential step in determining the cell-types governing and morphological alterations elicited from exercise which may provide neural repair and protection. Similar to astrocytes in the brain, retinal astrocytes alter their morphology in response to exercise. Our studies demonstrate exercise promotes increased interactions between retinal astrocytes and neural growth factors in healthy retinas as well as in retinas undergoing degeneration, which may ultimately protect dying retinal neurons. These studies provide insight into the potential neuroprotective role astrocytes play in neurodegenerative diseases.

neuroscience↗

bioRxiv2021

Developmental Circadian Disruption Alters Placental Signaling in Mice

Circadian disruption has been largely overlooked as a developmental exposure. The placenta, a conduit between the maternal and fetal environments, may relay circadian cues to the fetus. We have previously shown that developmental chronodisruption causes visual impairment and increased retinal microglial and macrophage marker expression. Here, we investigated the impacts of environmental circadian disruption on fetal and placental outcomes in a C57BL/6J mouse (Mus musculus) model. Developmental chronodisruption had no effect on embryo count, placental weight, or fetal sex ratio. When measured with RNAseq, mice exposed to developmental circadian disruption (CD) had differential placental expression of several transcripts including Serpinf1, which encodes pigment-epithelium derived factor (PEDF). Immunofluorescence of microglia/macrophage markers, Iba1 and CD11b, also revealed significant upregulation of immune cell markers in CD-exposed placenta. Our results suggest that in utero circadian disruption enhances placental immune cell expression, potentially programming a pro-inflammatory tissue environment that increases the risk of chronic disease in adulthood.

developmental biology↗

bioRxiv2019

Diminished cortical excitation during perceptual impairments in a mouse model of autism

Sensory impairments are a core feature of autism spectrum disorder (ASD). These impairments affect visual perception (Robertson and Baron-Cohen, 2017), and have been hypothesized to arise from imbalances in cortical excitatory and inhibitory activity (Rubenstein and Merzenich, 2003; Nelson and Valakh, 2015; Sohal and Rubenstein, 2019); however, there is little direct evidence testing this hypothesis in identified excitatory and inhibitory neurons during impairments of sensory perception. Several recent studies have examined cortical activity in transgenic mouse models of ASD (Goel et al., 2018; Antoine et al., 2019; Lazaro et al., 2019), but have provided conflicting evidence for excitatory versus inhibitory activity deficits. Here, we utilized a genetically relevant mouse model of ASD (CNTNAP2-/- knockout, KO; Arking et al., 2008; Penagarikano et al., 2011) and directly recorded putative excitatory and inhibitory population spiking in primary visual cortex (V1) while measuring visual perceptual behavior (Speed et al., 2019). We found quantitative impairments in the speed, accuracy, and contrast sensitivity of visual perception in KO mice. These impairments were simultaneously associated with elevated inhibitory and diminished excitatory neuron activity evoked by visual stimuli during behavior, along with aberrant 3 - 10 Hz oscillations in superficial cortical layers 2/3 (L2/3). These results establish that perceptual deficits relevant for ASD can arise from diminished sensory activity of excitatory neurons in feedforward layers of cortical circuits.

neuroscience↗