BACKGROUND A subarachnoid hemorrhage (SAH) is a bleed into the subarachnoid space surrounding the brain. This disease affects roughly 30,000 Americans each year and approximately one in six affected individuals die at the time of the ictal event. Individuals that do survive suffer from many complications including delayed cerebral vasospasm (DCV), cerebral edema, fever, and increased intracranial pressure (ICP) amongst others. These patients often suffer from brain damage due to neuronal apoptosis as a consequence of excess neuroinflammation. Microglia, the resident macrophage of the central nervous system, and Toll-like Receptor-4 (TLR4), a pro-inflammatory transmembrane receptor, have both been shown to play a role in the neuroinflammation seen in SAH. RBC components have been shown to activate microglial TLR4, and this event is suggested to trigger downstream mechanisms leading to neuronal apoptosis. The presented research takes a closer look at the role of microglial TLR4 in early neuronal apoptosis seen in an SAH model. METHODS All mice used were 10- to 12-week-old males on a C57BL/6 background: TLR4−/−, MyD88−/−, TRIF−/− and wild type (WT). To induce an SAH, a total of 60 ul of arterial blood from a donor WT mouse was injected for over 30 seconds into another mouse. For in vitro experiments, either primary microglia (PMG) or murine microglial BV2 cells were used. Microglia were separated from murine neuronal HT22 cells by 3um cell culture inserts or transwells, before being stimulated with lipopolysaccharide (LPS), red blood cells (RBCs), or RBC components including hemin (structurally similar to heme) and hemoglobin. In vivo samples were studied using either immunohistochemistry (IHC) or Fluorescence Activated Cell Sorting (FACS), and in vitro cells were studied using IHC and Light Microscopy. Neuronal cell death was measured using TUNEL and/or FloroJade C (FJC) assays. Cognitive function after SAH was measured using the Barnes Maze protocol. RESULTS In a 24-hour time course, more death occurred in the HT22 cells associated with BV2s treated with RBCs for 12-hour and 24-hour incubation time points as compared to 1-hour and 3-hour time points. Similar results were seen in the WT PMGs, as HT22 apoptosis increased in the RBC treated WT groups as the incubation time points increased. The WT PMG and MyD88−/− RBC treated PMGs showed significant death as compared to a WT untreated control (p<0.05) using a FJC assay, and both showed more death in a TUNEL assay as compared to an untreated control. WT mice treated with whole blood and hemoglobin had significantly more apoptosis as compared with a normal saline (NS)-treated control mouse (p<0.05). WT PMGs treated with whole blood and hemoglobin had more apoptosis as compared with an untreated control. MyD88-/- treated with RBC, hemoglobin, and hemin had more HT22 cell death compared with other genotypes treated with the same component. For the Barnes Maze, TLR4−/− mice performed significantly less total errors than WT mice on POD5 and 6 (p<0.01), and took significantly less time to reach the goal chamber on POD4, POD5 (p<0.05), and POD6 (p<0.01). CONCLUSION Our experimental results suggest that a microglial TLR4-dependent, MyD88-independent pathway is involved in neuronal apoptosis very early in an SAH model via RBC and hemoglobin activation, and that neuronal cell apoptosis due to TLR4 expression may be related to SAH-related cognitive and behavioral deficits. Our results suggest that TRIF may be the intracellular adaptor that is involved in this mechanism, but further experiments are needed to confirm this.

Alcohol use disorder (AUD) and post-traumatic stress disorder (PTSD) are debilitating conditions that often co-occur, with an estimated 41-79% comorbidity rate. A major concern with the co-occurrence of these disorders is the tendency for one to exacerbate the other. Specifically, symptoms related to PTSD are a significant risk factor for the development of AUD, and alcohol abuse worsens PTSD symptoms. This cycle, along with a lack of effective pharmacological treatment options, leads to significant behavioral and physiological deficits. Additionally, remission for comorbid AUD and PTSD is much more difficult to attain due to exacerbated symptomology and a lack of FDA-approved medications. In recent years, cannabidiol (CBD), a non-psychoactive compound found in cannabis, has been a focus of study due to its therapeutic potential. Researchers have demonstrated the anxiolytic and anti-inflammatory effects of CBD in both humans and animals, showing its promise as a novel therapeutic agent in the treatment of psychiatric disorders. The purpose of this study is to investigate the hypothesis that CBD will reduce fear-related behaviors and neuroinflammation in a rat model of comorbid AUD and PTSD. Our AUD/PTSD model utilized restraint stress and chronic intermittent ethanol exposure procedures. To investigate changes in future stress sensitivity all animals were exposed to a contextual fear conditioning paradigm, which was used to train the animals to associate environmental and auditory cues (environment appearance and tone) with an aversive stimulus (mild foot-shock). 30 minutes prior to each conditioning session, rats received an intraperitoneal injection of CBD (20mg/kg) or 0.9% Saline. Once the animals learned to associate the cues with a shock, they were exposed to an extinction learning procedure that involved presentation of the cue alone (no shock). This procedure parallels exposure therapy in humans, allowing for the assessment adaptations to fear learning. The amount of time the rats remain still (freezing) during the tone represents fear-related behavior. Our current results indicate rats with a history of stress and alcohol exposure displayed significantly higher freezing behaviors and this effect was significantly decreased with CBD treatment. This suggests that when CBD is administered during fear learning, it is able to attenuate heightened stress sensitivity associated with AUD/PTSD. To evaluate how CBD mediates the neuroinflammatory response associated with AUD and PTSD, brains from the rats were extracted and analyzed for the inflammatory cytokine tumor necrosis factor a (TNF-a). Specific regions of interest included the medial prefrontal cortex and hippocampus, areas associated with anxiety, memory, and addiction. Neuroinflammation analyses are still ongoing, however it is predicted that rats who received CBD will show a reduction in inflammation in the medial prefrontal cortex and hippocampus. Taken together, the current results show promise for CBD to reduce enhanced fear-related behavior associated with comorbid AUD and PTSD.

Alzheimer’s Disease (AD) is a chronic neurodegenerative disease commonly characterized by the aggregation and deposition of insoluble amyloid beta plaques throughout the brain, and by an associated neuroinflammatory response to these plaques involving astrocytes and microglia. Choline is an essential nutrient with diverse functional roles that has emerged as a promising candidate for the treatment of AD. Localized plaque regions in the polymorphic layer in the medial dentate gyrus of the hippocampus and in the cortex were examined in 9-month-old APP-NL-G-F knock-in AD model mice to determine the effects of perinatal choline supplementation on astrocytosis and gliosis associated with amyloid beta. The size of ionized calcium-binding adaptor molecule 1 (Iba1)-positive cells and clusters were larger in control diet APPNL-G-F mice, although the number and total area covered by Iba1+ cells/clusters were decreased compared to those of control diet C57BL6/J mice. In comparison, choline supplementation significantly reduced the size of Iba1+ cells/clusters in APPNL-G-F mice. These results suggest that perinatal choline supplementation ameliorates neuroinflammatory processes associated with amyloid plaques in these 9-month-old APPNL-G-F mice, and that dietary supplementation of choline might serve as an effective treatment for AD. / 2026-02-14T00:00:00Z

ATP is stored in millimolar concentrations within the intracellular medium but may be released to extracellular sites either through the damaged plasma membrane or by means of various transporters. Extracellular ATP or its enzymatic breakdown products, ADP, AMP, and adenosine, may then stimulate a range of membrane receptors (Rs). These receptors are classified as belonging to two types termed P2 or P1. P2Rs can be, in addition, subdivided into the ligand-activated P2X and the G protein-coupled P2Y types. Adenosine acts on the P1 type of receptor. A further classification identifies seven mammalian subtypes of P2X1-7 and eight mammalian subtypes of P2YRs (P2Y1, P2Y2, P2Y4, P2Y6, P2Y11, P2Y12, P2Y13, P2Y14). P1Rs are either positively (A2A, A2B) or negatively (A1, A3) coupled to adenylate cyclase via the respective G proteins. Already, such a high number of receptors suggests that purine-mediated effects at the cellular but especially whole organism level have an immense variability. Whereas P2XRs respond only the ATP, P2YRs are sensitive to ATP/ADP, UTP/UDP, or UDP–glucose. Inspection of some articles in this Special Issue will teach us that the nucleoside guanosine probably possesses a receptor of its own, that nucleotides can be gradually degraded metabolically to functionally active nucleotides/nucleosides (see above), and indirect effects by stimulating the synthesis or decomposition of purines/pyrimidines may also increase functional diversity. Eventually, P2/P1Rs may interact both with each other as well as with other neurotransmitter receptors. It is, of course, important to note that, in many cases, receptor (sub)type-preferential agonists and highly selective antagonists are available for pharmacological analysis.

One of the major focuses for our lab involves examining the immunosuppressive properties of various agents and receptors in the experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis (MS). This dissertation encompasses an investigation of cannabidiol in the EAE model, the endocannabinoid CB1 receptor in the EAE model, staphylococcal superantigens (SAgs) as immunosuppressive agents, and various aspects of the EAE model. The first chapter covers the existing literature pertinent to these studies, the second and third chapters cover the material, methods, and results from the studies, and the fourth chapter is a discussion of how those results fit into the existing body of literature. A fifth chapter has also been included which covers two additional studies designed to develop alternative EAE models for our lab; however, both studies turned out differently than expected. One of the most interesting developments from this final chapter was the discovery of an age dependent difference in the memory T cell response of older mice, which allows for more robust disease to be induced when cells from 6 month old mice are used in the passive EAE (P-EAE) model as opposed to mice 10 weeks of age.

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