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Jeremy Day @daylab.bsky.social · 09/10/2026

#FluorescenceFriday image from UAB undergraduate Aditya Pradeep, with @odrake.bsky.social. Red = tyrosine hydroxylase (TH) protein Cyan = DAPI TH is the rate-limiting step in the synthesis of dopamine, and is densely expressed in axon terminals from midbrain dopamine neurons in the rat striatum.

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Jeremy Day @daylab.bsky.social · 07/10/2026

Incredible FASEB #NeuroExpSRC meeting over the last couple of days including field leaders such as Michael Greenberg and Richard Tsien - congratulations to the organizers @ennatsew.bsky.social, @ramensaha.bsky.social, and @spiegel-lab.bsky.social on organizing such a fantastic conference.

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Jeremy Day @daylab.bsky.social · 30/09/2026

A few days of seeing sunrises while fishing in Louisiana is a pretty good life reset hack. A massive yellowfin tuna catch also helps!

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Jeremy Day @daylab.bsky.social · 18/09/2026

#FluorescenceFriday Location of different classes of GABAergic interneurons derived from the medial ganglionic eminence in the mouse brain. Identified using the 10X Xenium platform, with @odrake.bsky.social and Jasper Heinsbroek.

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Jeremy Day @daylab.bsky.social · 28/08/2026

Thrilled to have an incredible keynote lecture from the Allen Institute’s @hongkuizeng.bsky.social for the @uabneuro.bsky.social annual retreat! Tools and cellular atlases generated by @alleninstitute.org provide a deep framework that serves as the foundation for mechanistic exploration.

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Jeremy Day @daylab.bsky.social · 14/08/2026

Quick #FluorescenceFriday post to show off these beautiful orexin neurons in the perifornical area of the lateral hypothalamus (red) in the rat brain. This small population of neurons plays a major role in regulation of sleep, feeding, and arousal. Image credit to @odrake.bsky.social

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Jeremy Day @daylab.bsky.social · 07/08/2026

Lot of dopamine papers/preprints on Bluesky this week - here is a fun #FluorescenceFriday image of a rat brain coronal section containing ventral tegmental area dopamine neurons, with nuclei in cyan and tyrosine hydroxylase protein (a marker of dopamine neurons) in red. Image by @odrake.bsky.social.

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Jeremy Day @daylab.bsky.social · 30/07/2026

In control conditions, we observed development of a strong place preference for fentanyl, which is interpreted as rewarding effects. However, in animals that lacked µOR expression in Chst9-MSNs, fentanyl reward was completely lost!

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Jeremy Day @daylab.bsky.social · 30/07/2026

To determine if the µOR expressed by Chst9-MSNs contributes to opioid reward, we developed an AAV-mediated CRISPR-based deletion strategy, resulting in selective loss of µOR in Chst9-MSNs.

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Jeremy Day @daylab.bsky.social · 30/07/2026

Consistent with this, in vivo administration of fentanyl increased levels of phosphorylated pyruvate dehydrogenase (pPDH, a marker of neuronal inhibition) in Chst9-MSNs, but not in nearby Chst9- regions. This agrees with prior literature showing activation of canonical D1-MSNs by opioids.

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Jeremy Day @daylab.bsky.social · 30/07/2026

The µOR is coupled to inhibitory G protein-coupled receptor pathways, leading us to predict that these neurons should be inhibited by opioid agonists. This is exactly what we found - the µOR agonist DAMGO silences Chst9-MSNs and this is reversed by application of naloxone (a µOR antagonist).

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Jeremy Day @daylab.bsky.social · 30/07/2026

Given their high expression of the µ opioid receptor (µOR) in Chst9-MSNs, we suspected a potential role for this population in opioid actions.

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Jeremy Day @daylab.bsky.social · 30/07/2026

Using a cre-dependent viral tracing strategy, we show that Chst9-MSNs surprisingly target the ventral pallidum (outlined here using a substance P stain), and do not project to the midbrain in the same way that classic D1-MSN populations do.

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Jeremy Day @daylab.bsky.social · 30/07/2026

To study this cell population, we generated a transgenic Chst9-Cre-tdTomato rat line, which allowed labeling and genetic access to this population.

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Jeremy Day @daylab.bsky.social · 30/07/2026

Using the 10X Xenium platform for spatial transcriptomics, we identified that Chst9-MSNs occupy unique spatial domains along the boundary of the nucleus accumbens (shown here in magenta).

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Jeremy Day @daylab.bsky.social · 30/07/2026

Notably, Chst9-MSNs show high transcriptional similarity to D1-MSN populations identified in the ventral striatum of other species (including humans), suggesting conservation between species.

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Jeremy Day @daylab.bsky.social · 30/07/2026

Here, we identified and characterized a new ventral striatum MSN subtype, which is marked by the carbohydrate sulfotransferase gene Chst9. Chst9-MSNs exhibit a distinct transcriptional profile from other MSNs, including high expression of the mu opioid receptor gene (Oprm1).

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Jeremy Day @daylab.bsky.social · 30/07/2026

Classically, D1-MSNs form the "direct" pathway out of the striatum, projecting to the midbrain. Conversely, D2-MSNs form an "indirect" pathway that sends projections to the external segment of the globus pallidus and ventral pallidum. www.frontiersin.org/journals/syn...

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Jeremy Day @daylab.bsky.social · 29/07/2026

Congratulations to the 2026 @acnporg.bsky.social travel award recipients! Good to see a lot of familiar names on this list, including @mictott.bsky.social, @jtuscher.bsky.social, @kmcostalab.com, @laurenmac.bsky.social, @chanjenerational.bsky.social, and @outraajeous.bsky.social!

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Jeremy Day @daylab.bsky.social · 20/07/2026

Notice of Award Monday! Grateful to NIDA for supporting some very exciting work defining the cellular and circuit mechanisms that opioids target to produce rewarding effects.

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Jeremy Day @daylab.bsky.social · 24/06/2026

Very cool original artwork by lab MD/PhD student Olivia Drake for Caroline Fiore’s successful master’s thesis defense in the lab. Congratulations Caroline! Much more to come soon on some really important findings that Caroline contributed to.

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Jeremy Day @daylab.bsky.social · 24/04/2026

New preprint led by recent PhD graduate Dalton Fitzgerald characterizing two distinct populations of VTA dopamine neurons that differ in ion channel expression, intrinsic excitability, and response to drugs of abuse. www.biorxiv.org/content/10.6...

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Jeremy Day @daylab.bsky.social · 09/04/2026

Fantastic talk from @christineliu.art as part of the UAB Neuroscience Seminar series - really intriguing to see rigorous quantification of the behavioral effects of psychedelics across several institutions, and mechanistic circuit dissections with cutting edge tools!

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Jeremy Day @daylab.bsky.social · 03/04/2026

The color indices reflect a distinct subclass ID according to the Allen Brain Atlas reference taxonomy. Thanks to the amazing team at @u-bds.bsky.social, which provided all of the analyses to generate these images.

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Jeremy Day @daylab.bsky.social · 03/04/2026

For #FluorescenceFriday, some of my favorite sections from a new 10X Xenium run at different locations in the anterior/posterior axis of the mouse brain (credit to Olivia Drake, an MD/PhD student in the lab). Each dot marks the location of a specific type of deep layer excitatory neuron.

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Jeremy Day @daylab.bsky.social · 17/03/2026

Great conversations with representatives for Senator Britt, Senator Tuberville, Rep. Palmer, and Rep. Sewell as part of @sfn.org's Hill Day activities. We discussed the need for stable and timely federal support for biomedical research and shared what this support means for Alabama. #hillday

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Jeremy Day @daylab.bsky.social · 13/03/2026

Snooping through the lab network drive for #FluorescenceFriday images and came across this stunning image from UAB master's student Caroline Fiore. 🟡 is mu opioid receptor protein in the rat brain in a coronal section that includes the nucleus accumbens and dorsal striatum.

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Jeremy Day @daylab.bsky.social · 17/02/2026

Surprise gift this morning - fresh eggs from @kacummings.bsky.social! The color variation is really neat, apparently this is mainly driven by the genetics of the breed.

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Jeremy Day @daylab.bsky.social · 16/01/2026

Honored to have made the frontal cortex (cingulate?) of @npp-journal.bsky.social reviewers this year!

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Jeremy Day @daylab.bsky.social · 06/01/2026

Now they are trying flattery to make me forget about how slow the NCBI site is...

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Jeremy Day @daylab.bsky.social · 06/01/2026

I am just bummed to see Alabama incorrectly listed second in the alphabetized states list when entering appointments! If you type "AL" it will enter Alaska for you.

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Jeremy Day @daylab.bsky.social · 14/11/2025

The Day Lab will be representing our work at the annual Society for Neuroscience conference (@sfn.org) in San Diego this week in two sessions - stop by to see updates on a lot of really cool science! #SfN2025 #Neuroscience

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Jeremy Day @daylab.bsky.social · 23/09/2025

A final note, buried in a supplemental figure but still very cool. The main place we saw interactions between pain and opioid exposure was in astrocytes as well. Here, pain states often created gene expression changes that were rescued by morphine administration!

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Jeremy Day @daylab.bsky.social · 23/09/2025

Next, we generated an astrocyte-targeted CRISPR tool to allow us to knock down NR3C1 in this population, and found that this also completely blocked the ability of cortisol to induce FKBP5.

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Jeremy Day @daylab.bsky.social · 23/09/2025

Application of cortisol onto these cells robustly increased FKBP5 levels, and this effect could be blocked by pretreatment with the glucocorticoid receptor antagonist mifepristone. We observed no changes when cells were treated with the µOR agonist DAMGO.

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Jeremy Day @daylab.bsky.social · 23/09/2025

To test this directly, we generated a human-derived astrocyte model from cells with a ventral midbrain origin. As you can see here, they are beautiful and express known astrocyte marker genes like GFAP and S100B.

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Jeremy Day @daylab.bsky.social · 23/09/2025

Among the genes that was strongly induced in glial populations was Fkbp5, a co-chaperone closely linked to glucocorticoid signaling and stress response. Transcripts from this gene were increased in astrocytes, microglia, and oligodendrocytes, but not neurons.

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Jeremy Day @daylab.bsky.social · 23/09/2025

However, to our surprise, the largest effects of opioids and pain/opioid interactions were observed in glial cells, such as astrocytes and oligodendrocytes, despite a lack of µOR expression in these cells.

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Jeremy Day @daylab.bsky.social · 23/09/2025

Consistent with this model, we found enriched expression of Oprm1, the gene that encodes the µOR, in a select population of GABA neurons. Additionally, we report selective increases in immediate early genes in dopamine neurons after morphine administration.

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Jeremy Day @daylab.bsky.social · 23/09/2025

A classic circuit model for the rewarding effects of opioids posits that they decrease inhibition onto dopamine neurons by silencing GABAergic neurons that express the mu opioid receptor (µOR), the primary receptor target of commonly used opioids.

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Jeremy Day @daylab.bsky.social · 23/09/2025

We focused on the ventral tegmental area (VTA), a key brain reward region that includes dopamine neurons which project to forebrain structures. The rat VTA is complex - we find multiple types of dopamine, glutamate, and GABA neurons, as well as various glial cell classes.

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Jeremy Day @daylab.bsky.social · 23/09/2025

Excited to share this new work from the lab, in collaboration with @jtuscher.bsky.social & Rob Sorge! Here, we used single cell transcriptional profiling to define molecular adaptations induced by chronic pain and opioid experience, which often occur in conjunction. www.biorxiv.org/content/10.1...

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Jeremy Day @daylab.bsky.social · 15/09/2025

Excited to be co-chairing this @acnporg.bsky.social panel with chair @kr-maynard.bsky.social on opioid-responsive subpopulations in brain reward circuits. Special thanks to @rphillips3.bsky.social for helping to assemble the panel!

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Jeremy Day @daylab.bsky.social · 01/09/2025

Excited to be involved in the Alabama Summit on Addiction & Pain this week, featuring NIDA Director Nora Volkow. Tomorrow morning I’ll highlight how @uabneuro.bsky.social supports addiction research on campus, and Wednesday morning I’ll discuss some new work from the lab! @uabcappi.bsky.social

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Jeremy Day @daylab.bsky.social · 22/08/2025

#FluorescenceFriday image from Olivia Drake in the lab. Red = Chst9+ neurons in the ventral striatum Cyan = DAPI, a DNA marker The red cells are full of the mu opioid receptor, the major target of opioids like morphine, fentanyl, and heroin.

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Jeremy Day @daylab.bsky.social · 15/08/2025

Fun #FluorescenceFriday image from Olivia Drake in the lab of a sagittal rat brain section. Cyan = DAPI, a DNA marker Yellow = Substance P, a protein product of the Tac1 gene

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Jeremy Day @daylab.bsky.social · 07/08/2025

This part seems to be directly at odds with the Senate's version of the FY26 budget and with prior language in budgets passed by congress and signed into law. Here, "Director" is OMB head.

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Jeremy Day @daylab.bsky.social · 29/07/2025

Pretty sure my grandfather, who was a NASA engineer that worked on Saturn and Apollo missions in Alabama in the 1960s and 1970s, would be alarmed to see what’s happening now. This is faded but here is a technical drawing he produced for fiber optic viewing of the liquid oxygen supply for Saturn V.

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Jeremy Day @daylab.bsky.social · 09/07/2025

Double-blind placebo controlled trial (led by UAB faculty Dr. Timothy Garvey) demonstrates >20% weight loss with co-administration of cagrilintide (which targets amylin receptors) with semaglutide (which targets GLP-1 receptors). www.nejm.org/doi/full/10....

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Jeremy Day @daylab.bsky.social · 12/06/2025

At UAB’s annual NINDS/R25 supported NEURAL conference today and excited to learn from all of our internal and external speakers, including Corey Harwell!

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