Permanent URI for this collection


Recent Submissions

Now showing 1 - 13 of 13
  • Item
    The impact of tyrosine hydroxylase loss on dopamine signaling during nigrostriatal neuron loss in a rat Parkinson’s disease model
    (2023) Chaudhari, Sampada; Navarrate-Barahona, Walter; McManus, Robert; Centner, Ashley; Bishop, Christopher; Salvatore, Michael
    Purpose: Parkinson’s disease (PD) is a neurological disorder resulting from the degeneration of nigrostriatal dopamine (DA) neurons. DA plays a major role in the control of movement initiation via the nigrostriatal pathway. The relationship between DA tissue levels and synaptic levels is poorly understood, and the impact of tyrosine hydroxylase (TH) loss upon synaptic DA levels is not well defined either. As the rate limiting enzyme of DA synthesis, tyrosine hydroxylase (TH) protein was evaluated against these indices of DA function. Since PD involves progressive loss of the nigrostriatal neurons and TH protein, understanding how synaptic DA levels may change against this decrease will shed light on whether compensatory processes are engaged to maintain synaptic DA levels, and can outline possible limits of such processes and their influence upon the timing of onset of hypokinesia, a major PD symptom. Methods: We used the established rat neurotoxin model 6-hydroxydopamine (6-OHDA) utilizing stereotactic surgery to lesion the nigrostriatal pathway and emulate the pathological course of human PD, which features DA and TH loss in the Str proceeding at a faster rate than in the SN. Following microdialysis, brain tissue punches from the SN and Str regions of both lesioned and control rats were harvested at 7 and 28 days, and then analyzed by high-performance liquid chromatography to quantify both synaptic and tissue DA. We followed with TH protein analyses to statistically quantify the relationships between TH protein, DA tissue, and synaptic DA. Results: Our results show that TH protein levels had a highly significant correlation against DA tissue levels in the lesioned Str and SN; however, only synaptic DA release levels in the Str following depolarizing stimulation had a significant correlation with TH protein. Additionally, only 15% of the variance in lesioned Str synaptic DA levels can be explained by tissue DA and TH concentrations when using a multivariate linear regression model. These results show that compensatory processes are engaged during nigrostriatal lesion to maintain synaptic levels, but these mechanisms are inadequate to offset major TH protein loss in the Str. Conclusions: The particular significance of this study lies in its focus on extracellular neurotransmitter analysis – something that has not been extensively explored. Our findings will provide novel insight into how synaptic DA levels are affected by expected decreases in tissue content, thus deepening the current understanding on transmission within the basal ganglia and generating areas for further research.
  • Item
    COVID-19 Parainfectious Demyelinating Lesion in a Pediatric Patient
    (2023) Armas, Ashley; Luke, Rebecca; Hamby, Tyler
    Background: Although COVID-19 primarily causes respiratory symptoms, the virus may affect other organ systems. SARS-CoV-2 neuropathology continues to be defined, but recent studies have indicated that a considerable percentage of COVID-19 patients experience neurological or psychiatric symptoms. Case Information: A previously healthy 15-year-old female presented to the emergency department with altered mental status and seizures. The patient was intubated for airway protection and transferred to intensive care. The patient was initially COVID negative but later found to be COVID positive. Extensive laboratory workup including inflammatory, infectious, oncologic, and rheumatologic studies were unrevealing. Lumbar puncture demonstrated benign cerebrospinal fluid with no malignant cells. Initial brain magnetic resonance imaging (MRI) demonstrated a diffusely heterogeneously enhancing white matter lesion in the left parietal and temporal lobes. Electroencephalogram demonstrated periodic lateralized epileptiform discharges in the left central and temporal region. Rheumatology, infectious disease, hematology, nephrology, and neuro-oncology were consulted. To control the seizures, intravenous Keppra and Ativan were administered. High-dose steroids and plasma exchange were initiated as treatment for possible demyelinating lesion as demonstrated on MRI. The first MRI after completion of plasma exchange showed expansion of the lesion although the patient clinically improved significantly. Follow-up MRIs indicate that the lesion has continued to demonstrate regression over time. Her clinical symptoms have also shown improvement. Conclusion: SARS-CoV-2 is a pathogen capable of causing severe illness affecting a variety of different organ systems. There is potential for a variety of neurological complications in patients who are COVID-19 positive, and patients can present with neurologic complications even in the absence of more typical symptoms. Successful treatment in this patient included high dose intravenous steroids and plasma exchange as well as seizure management. Long-term immunotherapy was not necessary for continued improvement.
  • Item
    Enhancing the translational relevance of the nicotine drug discrimination paradigm in rat model
    (2023) Kusi-Boadum, Nana Kofi
    Purpose: Drug discrimination has over the past 50 years been used as a tool for understanding mechanisms of drug addiction. As an operant conditioning-based technique, it is largely influenced by the specific rat training conditions such as training dose and pre-treatment time (PT). A nicotine training dose of 0.4 mg/kg at a PT of 15 min is widely used in nicotine discrimination studies. This dose in rats, however, produces a peak plasma concentration that comparatively exceeds the peak plasma concentration in tobacco smokers. Pharmacokinetic studies have shown that smaller doses of nicotine in rats produce peak plasma concentrations that closely resemble that in human cases. The question that remains is whether rats can be trained to discriminate these smaller doses of nicotine. Our goal was therefore to re-evaluate nicotine training conditions in rats and find that which is trainable and produces a translatable pharmacokinetic profile. Methods: Using a two-bar drug discrimination operant chamber, six rats trained to discriminate 0.4 mg/kg of nicotine tartrate at a PT of 15 min were tested at a fixed dose (0.4 mg/kg) of nicotine tartrate, but at different intervals after injection (0, 5, 15, 30, 60, 120, 240 min). This test was repeated but at a fixed dose of 0.1 mg/kg. Subsequently, a nicotine dose effect (0.01, 0.025, 0.05, 0.1, 0.2, 0.4 mg/kg) was conducted at a fixed pre-treatment time (5 min). Percentage of drug lever responses were recorded in all studies to measure substitution and analyzed using repeated measures ANOVA. Results: The time course study conducted with 0.4 mg/kg showed full substitution (100% nicotine lever response) at a PT of 5 min, with 240 min as the longest duration of action. The dose effect study at a fixed PT of 5 min showed full substitution at 0.1 mg/kg. At that, the discriminative effects of nicotine faded within 15 min. Conclusion: These findings show even at lower doses and shorter PTs, rats can perceive nicotine, and therefore can be trained using a lower nicotine dose of 0.1 mg/kg and at a shorter PT of 5 min (an onset that more closely resembles the onset in humans after smoking a cigarette compared to 15 min PT) Using these training conditions in place of the high training dose (0.4 mg/kg) and the long PT (15 min) provides a nicotine discrimination model of higher translational relevance to nicotine smoking studies in humans.
  • Item
    The Effects of ERAS Protocol on Complex Spine Surgery Complications and Length of Stay: a Single Institution Study
    (2023) Weber, Theodore
    Background: With the goal of improving patient outcomes, the Integrated Spine Center at UT Southwestern Medical Center implemented an Enhanced Recovery After Surgery (ERAS) protocol which includes pre and post surgery guidelines. The goal of this study was to investigate the impact of the ERAS protocol on complication rates in the perioperative period, as well as length of stay in hospital and ICU. Materials and Methods: A retrospective cohort study was performed on all patients (3,495) who underwent spine surgery between September 2016 and September 2021. Of those, 2,472 met inclusion criteria as complex spine cases, and were divided into non-ERAS (2,147) and ERAS (325) groups. Patients in each group were matched for gender, age range, BMI range, comorbidities, and surgery type. Post-operative complications such as surgical site infection, acute kidney injury, deep vein thrombosis, myocardial infarction, sepsis, pneumonia, pulmonary embolism, stroke, shock, and other complications were recorded, as was length of stay. A two-tailed Fisher's exact test was used to establish significance. Results: Significant differences between the ERAS and non-ERAS groups were found in complication rates of UTI (7.3% vs. 1.4%, respectively; P=0.011), and any complications (30% vs. 19.6%, respectively; P=0.032). Length of stay was also significantly different between the ERAS and non-ERAS groups (5.4 ± 3.4 vs. 4.7 ± 3.7 d, respectively; P=0.018). There was no significant difference in the rates of other complications, or in length of ICU stay. Conclusions: Implementation of the ERAS protocol did not decrease complication rates or length of stay, and ERAS patients had significantly higher rates of UTI or any complications, as well as average length of stay. There may have been confounding factors due to the type of cases where ERAS was followed. Key Words: perioperative protocol, complex spine surgery, complication rates, length of sta
  • Item
    Sleep Insufficiency, Circadian Rhythms, and Metabolomics: The Connection to Metabolic and Sleep Disorders
    (2023) Russell, Katherine; Pak, Victoria; Rodman, Hillary
    Purpose The majority of US adults who report experiencing insufficient sleep are more likely to suffer from metabolic disorders such as hyperlipidemia, diabetes, and obesity than those with sufficient sleep. Less is understood about the underlying molecular mechanisms connecting these phenomena. A systematic, qualitative review of metabolomics studies exploring metabolic changes in response to sleep insufficiency, sleep deprivation, or circadian disruption was conducted in accordance with PRISMA guidelines. Methods An electronic literature review in the PubMed database was performed considering publications through May 2021 and screening and eligibility criteria were applied to articles retrieved. The following keywords were used: "metabolomics” and "sleep disorders” or "sleep deprivation” or "sleep disturbance” or "circadian rhythm.” After screening and addition of studies included from reference lists of retrieved studies, 16 records were identified for review. Results Consistent changes in metabolites were observed across studies between individuals experiencing sleep deprivation as compared to non-sleep deprivation controls. Significant increases in phosphatidylcholines, acylcarnitines, sphingolipids, and other lipids are consistent across studies. Increased levels of amino acids such as tryptophan and phenylalanine are also noted. However, studies are limited to small samples of young, healthy, mostly male participants conducted in short inpatient sessions, limiting generalizability. Conclusion Changes in lipid and amino acid metabolites accompanying sleep deprivation and/or circadian rhythms may indicate cellular membrane and protein breakdown underlying the connection between sleep disturbance, hyperlipidemia, and other metabolic disorders. Larger epidemiological studies examining changes in the human metabolome in response to chronic insufficient sleep would help elucidate this relationship.
  • Item
    Acute sex difference in response to repeated mild traumatic brain injury in mice
    (2023) Kuo, Aaron; Schreihofer, Derek; Sumien, Nathalie; Vann, Philip; Ahmed, Affan
    Acute sex difference in response to repeated mild traumatic brain injury in mice Aaron Kuo, Philip Vann, Nathalie Sumien, Ahmed Affan, Derek Schreihofer Background: Repetitive mild traumatic brain injury (rmTBI), such as that occurring in contact sports, is associated with the development of neurodegenerative diseases of aging. Severe TBI and repetitive concussions are associated with chronic traumatic encephalopathy (CTE), Alzheimer’s disease (AD), and Parkinson’s disease (PD), among others. However, less severe injuries may also lead to delayed neurological disfunction if repeated often and without sufficient rest time between injuries. Previously, we found that the progression of behavioral deficits in males and female mice differed from 5 to 15 weeks after 25 rmTBI. Both sexes showed motor deficits at 5 weeks, but only males showed affective and cognitive deficits at 15 weeks. Purpose: This study tested the hypothesis that rmTBI neurological deficits in male mice will appear earlier after rmTBI than in female mice. Methods: C57BL/6 male and female mice (8 wk old) were assigned to sham and rmTBI groups (n=20/group). Lightly anesthetized mice received 7 mild head injuries, once a day (M-F) using a weight drop model (75 g from 1 meter) that included a free fall with rotational injury. Five minutes after the final injury, mice were tested on a balance beam. Additional behavioral assessments began the following day. Results: No sex differences in balance beam performance were observed 5 minutes after the final injury. There were no significant effects of rmTBI on vestibular motor function assessed with a rotarod; cognition assessed with the Morris water maze; or affective behavior assessed with the elevated plus maze. However, in the open field test there was a significant increase in total distance traveled in rmTBI mice (F1,35 = 6.47, P=0.016). Post-hoc analysis revealed that this effect was only significant in male mice (Fisher LSD, P<0.05), supporting the hypothesis that males exhibit earlier deficits than females. Conclusion: At extended time points following rmTBI, both male and female mice develop motor deficits. However, up to 15 weeks after injury, only male mice experience cognitive and affective deficits. The current study reveals that male mice also display hyperactivity in the week after rmTBI that is not observed in female mice. Thus, sex differences in response to rmTBI are apparent both in the acute and chronic phase of injury and suggest that interventions to reduce brain injury may require different timing for males and females. Ongoing studies are examining potential differences in biochemical and histological responses in the brains of male and female mice. AUP: 2021-0035
  • Item
    Prediction of Ligand Selectivity and Efficacy Using Artificial Intelligence Algorithms
    (2023) Mathew, Ezek; Wang, Duen-Shian; Liu, Kevin; Pham, Tyler; Madugula, Sita Sirisha; Emmitte, Kyle; Liu, Jin
    Purpose: Identifying target-specific ligands is extremely challenging in drug discovery, especially in cases where receptors display high structural similarity. Such is the case for metabotropic glutamate receptor subtype 2 (mGlu2) and metabotropic glutamate receptor subtype 3 (mGlu3), which are prime targets for various neurological treatments. However, signal transduction through these two receptors often yields opposing physiological function and differentially affects pathologies. The purpose of this study is to develop artificial intelligence (AI) methods to predict ligand selectivity and efficacy on similar targets. Methods: Understanding the need to differentiate ligands based on their binding to mGlu2 and mGlu3, we employed a machine learning approach. Using patent-derived datasets, data was pre-processed into an eight-dimension vector space. Afterwards, the data was flattened, and a Multiple Input and Output (MIO) Model was designed to receive the incoming vectors. A classification arm was designated as an output, differentiating input structures as mGlu2 or mGlu3 ligands. In addition, this novel MIO Model with Functional application program interface (API) architecture also has the capacity to estimate efficacy of an input ligand by outputting Half-maximal inhibitory concentration (IC50) value. Results: The model yielded greater than 96% accuracy in the classification task to predict the binding selectivity of the ligands, while simultaneously delivering satisfactory performance when predicting efficacy. With regards to the regression arm, the model attained about 81% accuracy in correctly identifying high-affinity mGlu2 compounds, and 62% accuracy in correctly identifying high-affinity mGlu3 compounds. We then used docking studies, and the trained model to screen an available ZINC database, selecting the top 39 compounds out of 9270 ligands. Conclusions: This approach can pave the way for computer aided searches which screen for high efficacy ligands belonging to a certain class of interest. More specifically, this model can be used in combination with other established structure-based methodology like molecular docking, allowing for screening of even more drug candidates for further study and validation. With access to other high-quality datasets, this model has the potential to apply to other ligand classes of interest, posing great potential for drug repurposing studies.
  • Item
    Development of a mouse model to study the long-term effects of chemotherapy on brain function
    (2023) Trinh, Oanh; Vann, Philip; Davis, Delaney; Luedtke, Robert R.; Basha, Riyaz; Singh, Meharvan; Sumien, Nathalie
    Purpose: While remaining an effective life-saving intervention for cancer patients, chemotherapy has been associated with many neurotoxic side effects, including chemotherapy-related cognitive impairments (CRCI). Chemotherapy exposure leads to a decline in learning, memory, processing speed, attention, and executive functions, which may persist for more than 20 years post-treatment, impairing the quality of daily lives of survivors. Childhood cancer survivors are particularly vulnerable to chemotherapy and have been impacted in their educational achievements, employment, social relationships, and even life expectancy. Most common childhood cancers are often treated with the folate-inhibitor methotrexate (MTX). Our study aimed at establishing a tumor-free mouse model of MTX-induced brain impairments. We hypothesized that early exposure to MTX would induce impairment in cognition, as well as motor and affective functions. Methods: Male and female C57BL6/J postnatal day 15 pups received intraperitoneal injections of saline or MTX (2 mg/kg) once a day for 3 days. Pups were weaned on PND21, and subsets were behaviorally characterized at 1 or 7 months after MTX exposure (n=6-8 for 1.5 months old, and n=11-13 for 8 months old) for motor, affective and cognitive functions using a comprehensive behavioral test battery. Results: At 1.5 months, coordination and motor learning was significantly impaired in males and improved in females. All other measures did not reveal any other significant effects, however trends of impaired motor and cognitive functions could be discerned. At 8 months, there were no effects of MTX on motor, affective and some cognitive functions. However, MTX exposure led to an impairment on spatial learning and memory and increased swimming speed. Conclusions: Studies at 1.5 months will need to be repeated to increase power and ascertain conclusions on brain functions. Early exposure to MTX treatment led to long-term impairments in both male and female mice and could be used as a model to test interventions to limit CRCI.
  • Item
    Probable genetic vulnerabilities that can account for the pathophysiology of cerebral palsy
    (2023) Ntekim, Nedeke; Butson, Carter; Hamby, Tyler; Acord, Stephanie; Marks, Warren
    PURPOSE:Cerebral palsy (CP) is a nonprogressive brain and movement disorder that manifests as abnormal muscle tone. Despite the increase in cesarean sections, the rates of CP have remained constant. Research has shown that 14% of CP cases of cases have a likely causative single gene mutation and up to 31% have several genetic variations. However, no single gene has been found to explain all the symptoms of CP. The aim of the present study was to use patient’s genetic reports to determine what percentage of patients had a causative/putative gene to explain symptoms and to identify the role of those genes. The pathogenic alleles identified may warrant screenings to assess for secondary risks. METHODS: Using Invitae CP spectrum disorders panel, we analyzed the positive CP genetic reports of the 31 patients tested from November 2020 and July 2022 from a single pediatric neurology practice. We collected information about patient demographics, pathogenic alleles, and variants of uncertain significance (VUS). RESULTS: Of the 31 positive genetic reports, 30 patients (97%) had at least one pathogenic allele found; Twenty-nine pathogenic alleles were identified: four (13.8%) with autosomal dominant (AD) diseases, and seven (24.1%) with both AD and recessive (AR) diseases. Some of the pathogenic alleles found were CACNA1A (n=2), CREBBP (n=1), CTNNB1 (n=1), ATM (n=1). CONCLUSION: Many of the genes identified were associated with a movement disorder that shares features of CP, including spasticity or dystonia. The incidence of genetic findings and the high yield of dominant disorders and potential secondary risks suggest the need for both patient management and family counseling.
  • Item
    Sex and age differences in social and cognitive function in offspring exposed to late gestational hypoxia
    (2023) Mabry, Steve; Wilson, E. Nicole; Bradshaw, Jessica L.; Gardner, Jennifer J.; Fadeyibi, Oluwadarasimi; Vera Jr., Edward; Karamichos, Dimitrios; Goulopoulou, Styliani; Cunningham, Rebecca L.
    Background: Gestational sleep apnea affects 8-26% of pregnancies and can increase the risk for autism spectrum disorder (ASD) in offspring. ASD is a neurodevelopmental disorder associated with social dysfunction, repetitive behaviors, anxiety, and cognitive impairment. To examine the relationship between gestational sleep apnea and ASD, we used a chronic intermittent hypoxia (CIH) protocol between gestational days (GD) 15-19 in pregnant rats to model gestational sleep apnea during the third trimester of pregnancy. We hypothesized that late gestational CIH would produce sex- and age-specific social, mood, and cognitive impairments in offspring. Methods: Timed pregnant Long-Evans rats were exposed to CIH or room air normoxia from GD 15-19. Behavioral testing of offspring occurred during either puberty or young adulthood. To examine ASD phenotype, we quantified ASD-associated behaviors (social function, repetitive behaviors, anxiety-like behaviors, and spatial memory and learning), hippocampal activity (glutamatergic NMDA receptors, dopamine transporter, monoamine oxidase-A, neuronal activation, and neurogenesis), and circulating hormones in offspring. Results: Late gestational CIH induced sex- and age-specific differences in social, repetitive and memory functions in offspring. These effects were mostly transient and present during puberty. In female pubertal offspring, CIH impaired social function, increased repetitive behaviors, suppressed circulating estradiol but did not impact memory. In contrast, CIH impaired spatial memory and suppressed circulating estradiol in pubertal male offspring but did not impact social or repetitive functions. Long term effects of gestational CIH were only observed in female offspring, wherein CIH induced social disengagement and suppression of circulating estradiol during puberty was maintained in young adulthood. No effects of gestational CIH were observed on anxiety-like behaviors, hippocampal activity, circulating testosterone, or circulating corticosterone, regardless of sex or age of offspring. Conclusions: Our results indicate that hypoxia-associated pregnancy complications during the third trimester can increase the risk for ASD, such as pubertal social dysfunction, neuroendocrine suppression, and memory impairments. Current clinical recommendations support ASD screening for all children up to their 24-month checkup. Based on our findings, children from hypoxia-associated pregnancies should be screened for ASD throughout puberty.
  • Item
    Pituitary Apoplexy in an Adult Male
    (2023) Reinsmith, Stephen; Smith, Spencer
    Background: The pituitary gland is a major regulator of endocrine function, located at the base of the skull behind the eyes and inferior to the optic chiasm. Pituitary adenomas are noncancerous growths of pituitary tissue. Most pituitary adenomas will arise from the anterior lobe of the pituitary, due in part to the anterior lobe accounting for most of the pituitary’s size. Most are small microadenomas, measuring <1 cm in diameter. Lesions larger than 1 cm are called macroadenomas. Despite popular belief, pituitary adenomas are perhaps not as rare as previously thought, and it is estimated that one in ten people will develop a pituitary adenoma in their life. Because of the pituitary’s endocrine function, some of these growths will produce hormones or hormone precursors. The most common functioning adenoma secretes prolactin and is known as a prolactinoma. Pituitary adenomas which do not produce hormones are termed nonfunctioning adenomas. Pituitary apoplexy is the occurrence of a sudden onset of symptoms due to spontaneous hemorrhage or infarction of the pituitary, usually precipitated by the presence of an adenoma. Case Study: A 35-year-old male presented to the emergency department, reporting two days of severe headache and nausea. Neurological examination revealed diminished right sided peripheral vision. An abnormally prominent sella turcica was noted on CT scan, which led to follow up magnetic resonance imaging. This revealed moderate pituitary enlargement and heterogeneously hyperintense T1W signal characteristic for hemorrhagic pituitary apoplexy. The patient was observed for several days before a transsphenoidal hypophysectomy was successfully performed. Endocrinology assays done, both preceding and following the surgery, indicated that the adenoma that bled was nonfunctioning. The patient reports a history of an asymptomatic pituitary mass that was incidentally discovered in childhood. The patient was given instructions at that time to follow up with a physician concerning this mass should symptoms arise. Conclusion: This case presents an example of a benign, nonfunctioning pituitary adenoma with apoplexy to the literature, with endocrinological, histological and radiographic contributions. Given the high prevalence of pituitary adenomas, there should be a strong emphasis on educating physicians about pituitary apoplexy and about adenoma detection methods in patients with endocrinological imbalances related to the pituitary. Raising awareness can result in early detection to promote noninvasive treatments that would avoid potential complications of surgery and the toll of the disease.
  • Item
    Relationship between Inflammatory Markers (IL-6, IL-10, TNF-alpha, CRP), Physical Performance Measures and Ethnic Differences
    (2023) Meza, Sebastian; Campbell, Blake; Hurt, Paige; Lee, Yein; Petersen, Melissa; Patterson, Rita
    Title: Relationship between Inflammatory Markers (IL-6, IL-10, TNF-alpha, CRP), Physical Performance Measures and Ethnic Differences Authors: Sebastian Meza, OMS-II, Yein Lee, DO, MMS, Blake Campbell, OMS-II, Paige Hurt, OMS-II, Melissa Petersen, PhD, Rita M. Patterson, PhD Background: Hispanics remain highly underrepresented in Alzheimer's Disease (AD) research. This study explores the possible relationship between the inflammatory markers commonly studied in AD and Physical Performance Tests for gait and mobility in patients self-identified as Mexican American and Non-Hispanic White. In addition, this study will elaborate on the variations found in this biomarker-functional measure relationship among different ethnic groups. Methods: Publicly available data were analyzed on n=1705 participants (n=890 Mexican Americans; n=815 Non-Hispanic Whites) from the Health and Aging Brain Study- Health Disparities (HABS-HD). Participants completed a full study protocol including a clinical interview, cognitive testing, blood work, and functional exam. Targeted proteomics were analyzed on a Meso Scale Discovery Platform using ECL techniques and included markers of inflammation (CRP, IL6, IL10, TNFα). The functional testing included the following measures: Tug Time Test, Balance Test, Gait Speed Test, and Chair Stand Test. Linear regression models were run with select inflammatory markers (CRP, IL6, IL10, and TNFα) as the independent variables and the different musculoskeletal functional tests as the dependent variables. The analyses were conducted in a split method to compare the output by ethnic group (Hispanic and Non-Hispanic White). Results: This study showed that physical performance measures had a more direct relationship with the inflammatory markers in the Mexican American group as compared to the Non-Hispanic White group. Among Mexican Americans, all physical performance measures were found to be significantly related to IL-6 and TNFα while Gait speed was found to be significantly related to CRP, IL-6, IL-10 and TNFα. Although non-significant, there was a trend for the relationship between IL-10 with both Tug Time and Total Balance Test. Among Non-Hispanic Whites, IL-10 was found to be significantly related to the functional measure of Total Balance while TNFα was significantly related to the Chair Standing Test. IL-6 was found to be significantly related to all physical performance measures. CRP was not found to be related to any of the functional/physical performance tests. Discussion: The results demonstrate differences in the relationship between inflammatory markers and physical performance measures across ethnic groups. Our findings support the research community's need to focus more on differences among ethnic groups. Surprisingly, CRP was not found to be related to physical performance measures (in the Non-Hispanic White group) despite being a widely used inflammatory marker in clinical settings. To examine the potential utility for understanding the impact of inflammatory markers on functional abilities and the potential application for clinical use, future work is planned to look at this relationship among those with AD.
  • Item
    Optogenetic Activation of PVN-projecting MnPO Neurons Induces Changes in Type I PVN Neurons
    (2023) Paundralingga, Obed; Cunningham, J. Thomas
    The paraventricular nucleus of the hypothalamus (PVN) is an important autonomic control center that receives afferent inputs from the median preoptic nucleus (MnPO). The link between the MnPO and the PVN is essential in generating chronic intermittent hypoxia hypertension. An optogenetic intersectional viral approach was used to gain more insight into the contribution of MnPO inputs to changes in PVN function that could contribute to hypertension. Adult male Sprague-Dawley rats were anesthetized with isoflurane and injected with 100 nL of AAV9.hSyn.HI.eGFP-cre.WPRE.SV40 in the PVN bilaterally and AAV1-Ef1a-DIO-hChR2(H134R)-mCherry-WPRE-HGHpA in the MnPO. This method induced a CRE-dependent expression of channel rhodopsin in PVN-projecting MnPO neurons. Three weeks after the injections, the rats were sacrificed and oblique brain slices containing PVN were made. Postsynaptic currents (PSCs) were recorded from PVN neurons (VHold = -70 mV) with an aCSF (2-3 ml/min) bath solution. MnPO axon terminals in the PVN were stimulated with 15 Hz LED-generated blue light (470nM) pulses of 20-ms duration for a total of 1 min with an optical fiber directed at PVN. The stimulation train was repeated 5 times at 5 minutes intervals. PSCs were recorded for 40 minutes, including 5 min baseline periods before stimuli and 10 min post-stimulation period. Intrinsic excitability was assessed before the first baseline and after the last stimulation. Cells were characterized as type I, type II, or type III PVN neurons based on the presence of transient outward rectification. Amplitude and frequency data were analyzed offline using Easy Electrophysiology v2.5.0 software from a total of 17 Type I PVN neurons. Optogenetic stimulation evoked EPSC or mixed EPSC/IPSCs in 13 Type I neurons. From the 13 photo-evoked neurons, 10 neurons showed a significant increase in EPSC frequency following intermittent stimulation as compared to the preceding baseline (1st: 6.149±1.438 Hz vs 27.377±5.474 Hz, p=0.0187; 2nd 7.532±1.670 Hz vs 27.562±5.514 Hz, p=0.0161; 3rd 7.395±1.659 Hz vs 25.415±5.028 Hz, p=0.0170; 4th 7.343±1.466 Hz vs 24.225±4.750 Hz, p=0.0183; 5th 6.709±1.375 Hz vs 21.837±4.464 Hz, p=0.0220). In the same neurons, spontaneous EPSC frequency in the first minute after stimulation trains 1 to 4 also was significantly higher than the first pre-stimulus baseline but the effect gradually decreased over time (baseline 6.149±1.438 Hz vs 14.615±3.260 Hz, p=0.0236; vs 12.055±2.519 Hz, p=0.0213; vs 10.904±2.340 Hz, p=0.0247; vs 9.801±2.027 Hz, p=0.0331). There were no changes in EPSC amplitude. More type I neurons with photo-evoked PSCs showed increased excitability after the last stimulus (4 out of 7) than those which did not respond to the optogenetic light (2 out of 6). Repetitive optogenetic stimulation of MnPO inputs to Type I PVN neurons increased EPSC frequency and intrinsic excitability in a time-dependent manner. Additional experiments will be needed to specify the mechanism behind the increase in frequency and whether this phenomenon occurs in other PVN cell types.