Conference Agenda

Eamonn Duffy^2,4, Luanne Hale¹, Jonathan Ward¹, Kyle Brown¹, Andrew Kwilasz¹, Erika Mehrhoff^2,4, Daniel Frank⁵, Laura Saba^2,3, Ryan Bachtell^1,2, Marissa A. Ehringer^2,4

Little work has addressed how genetic background and the gut microbiome contribute to Opioid Use Disorder. Here, we present findings from an oxycodone self-administration protocol in male and female rats from the ACI/EurMcwi and M520/N strains, two genetically divergent inbred strains from the Hybrid Rat Diversity Panel. Gut microbiome samples were collected before and after oxycodone self-administration and 16S rRNA sequencing was performed to assess how oxycodone exposure alters the fecal and cecal microbiome. Both strains showed similar patterns of acquiring and escalating oxycodone self-administration, although the M520/N strain administered more oxycodone than the ACI/EurMcwi strain during the acquisition (F_1,49 = 17.8, p < 0.001) and escalation (F_1,39 = 33.4, p < 0.001) periods. Males consumed more oxycodone than females during the acquisition (F_1,49 = 6.5, p = 0.01) but not the escalation (F_1,39 = 0.3, p = 0.6) phase. Preliminary results suggest that both strain and oxycodone self-administration contribute to microbiome diversity and composition. In oxycodone-naive animals, baseline differences in beta diversity between strains highlight the importance of host genetics in shaping the gut microbiome. We observed strain-specific effects in the gut microbiome diversity and composition following oxycodone self-administration. For example, oxycodone increased cecal microbiome OTU richness in the M520 strain (t_7.2=3.2, p = 0.01), as compared to saline-administering controls. Our results suggest that the gut microbiome is shaped by both host genetics and chronic oxycodone exposure.

¹ Department of Psychology and Neuroscience, University of Colorado Boulder; ² Institute for Behavioral Genetics, University of Colorado Boulder; ³ Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus; ⁴ Department of Integrative Physiology, University of Colorado Boulder;
⁵ Department of Medicine, Division of Infectious Diseases, University of Colorado Anschutz Medical Campus

Funding Support: NIDA U01 DA051937, NIDA T32 DA017637.

R Hazani 1,2,3, JM Breton, 4, A Maman 1,2, B Kantor 5,6, E Trachtenberg 5,6, E Bigelman 5,6, A Weller 1,2, and I Ben-Ami Bartal 5,6.

Prosocial behavior is influenced by both external and internal factors, though the neural mechanisms underlying helping are not well known. Using the Helping Behavior Test (HBT), we examined behavioral and neural differences between rats who released trapped cagemates and those who did not. In Experiment 1, 32 rat pairs underwent the HBT along with boldness, social interaction, and open field tests. Then, brains and plasma were collected. In Experiment 2, we quantified c-Fos+ cells across 137 brain regions for 13 pairs that underwent the HBT. After the experiments ended, rats were classified as ‘openers’ (helpers) and ‘non-openers’ according to their performance during the HBT. In experiment 1, 14 rats consistently released their trapped cagemate (and classified as ‘openers’), and 18 rats did not. We found that openers showed more affiliation to their trapped cagemate, and synchronized stress responses as expressed in corticosterone levels and peeking latencies. RNAseq for the Nucleus Accumbens identified transcription factors that were differentially expressed between the groups and increased Oxytocin receptor levels in the openers. In Experiment 2, analysis of brain-wide neural activity revealed increased activity in the brains of openers compared to non-openers in Orbitofrontal regions, Anterior Cingulate Cortex, Insular regions, Mediofrontal regions (Infralimbic, Prelimbic), Nucleus Accumbens, lateral Habenula, and other regions. We also found functional connectivity between main social brain regions based on correlations between the c-Fos expressions. These findings demonstrate social closeness and multiple brain regions associated with helping behavior, suggesting future neural targets for investigating prosociality.

1Psychology Department, Bar-Ilan University, Ramat Gan, Israel; 2Gonda Brain Research Center, Bar-Ilan University, Ramat Gan, Israel; 3Geha Mental Health Center, Petah Tikva, Israel; 4Department of Psychiatry, Columbia University, New York, NY 10027, USA; 5School of Psychological Sciences, Tel-Aviv University, Tel Aviv, Israel; 6Sagol School of Neuroscience, Tel-Aviv University, Tel Aviv, Israel.

Funding Support: None.

Hernandez, J.S.¹, Le, N.², Azanchi, R. ¹, Glenn, E.¹, and Kaun, K.R.¹

¹Brown University, RI. Department of Neuroscience

²Post-baccalaureate Research Education Program, Brown University, Providence, RI

Escalation of alcohol self-administration facilitates the transition from alcohol use to compulsive drinking, which is a worldwide biomedical concern. Alcohol research has largely focused on understanding the neural mechanisms underlying excessive or compulsive alcohol intake. Much less is understood of the neural substrates underlying individual differences in alcohol preference and seeking, and how escalation arises in some individuals and not others. In Drosophila melanogaster, the neural circuits required for encoding valence include identifiable connections, genetic and/or biochemical profiles, making flies an ideal model for investigating escalation of ethanol self-administration. We developed a 3-day operant paradigm to evaluate the spectrum of behaviors associated with self-administration of a pharmacologically relevant dose of volatilized ethanol. Using thermogenetic inactivation approaches, we discovered a simple 2 neuron cholinergic and dopaminergic circuit within the Drosophila mushroom body system which alters population ethanol preference to decrease and increase ethanol self-administration, respectively. Calcium responses in this simple circuit reflect inherent behavioral preference for volatilized ethanol, and how this preference changes with experience. Using RNAi approaches, we identified dopamine receptors that contribute to ethanol preference in this circuit. Our findings demonstrate how a simple 2 neuron circuit, that encodes appetitive and aversive aspects of alcohol response, contributes to the development of alcohol preference that is known to predict dependence.

Funding Support: NIAAA R01AA024434 (KK), NIDA R01DA058947(KK,KOG,EL), NIAAA 1F32AA-29595-01 (JH) and ARC funding through Brown University GR5272061 (JH)

Jay Prakash Prasad Kumal

Traumatic brain injury (TBI) is a global crisis, impacting adult well-being and cognition. Current interventions fall short in fully restoring the central nervous system post-TBI, necessitating urgent treatments. Electroacupuncture, combining low-frequency pulses with traditional Chinese acupuncture, and metformin, a type-2 diabetes medication, show promise in mitigating neural damage post-TBI. This study explores their collaborative effect on cognitive recovery, myelin regeneration, synaptogenesis, neurogenesis, and microglial suppression. C57BL/6 male mice were segregated into control, TBI, TBI+E (electroacupuncture), TBI+M (metformin), and TBI+E+M groups. Novel object recognition tests revealed significantly heightened preference for novel objects in TBI+E and TBI+M mice compared to TBI counterparts with impaired visual memory; TBI+E+M mice recovered to levels similar to uninjured controls. Hematoxylin and eosin (HE) staining exposed tissue defects, a cortical cavity, and disordered cell structure in TBI mice. Immunofluorescence analyses indicated restored MBP-positive myelinated areas in TBI+E+M mice, suggesting partial myelin regeneration. TBI+E+M mice exhibited increased SYN-positive synaptic puncta fluorescence in the cortex and hippocampal CA3 region, with synapse formation reaching healthy control levels in the cortex.TBI-induced neuroinflammatory IBA1-positive microglia increased, while TBI+E+M reversed microglial numbers to control levels. Western Blot revealed elevated Arg1 and p-AKT levels (M2 markers) in TBI+E+M, implying anti-inflammatory microglial polarization. TBI exhibited increased iNOS and p-ERK1/2 (M1 markers), reduced in TBI+E+M. Immunohistochemistry unveiled diminished SOX2-positive neural stem cells and NeuN-positive mature neurons in TBI mice; TBI+E+M restored these, suggesting enhanced neurogenesis. NeuN-positive mature neuron density in SGZ rebounded to control levels in TBI+E+M, indicating substantial recovery. Combining Electroacupuncture with metformin post-TBI enhances cognitive recovery, promotes myelin and synapse regeneration, and reduces inflammation, providing neuroprotection. This synergistic approach modulates key markers, effectively suppressing secondary inflammation and fostering adult hippocampal neurogenesis-a promising strategy for treating traumatic brain injury.

Nepalgunj Medical College, Nepal