• The Effects of Acute and Repeated Exposure/s to the Organophosphate Pesticide Chlorpyrifos at Subthreshold Doses on Brain Structural Integrity

      Lalani, Ashish; Murphy, Shannon; Beck, W. Dan; Poddar, Indrani; Terry, Alvin V.; Hernandez, Caterina M.; Medical College of Georgia (2015-08-11)
      Organophosphates are a class of chemicals that are used in pesticides, herbicides, and also as nerve agents. Organophosphate pesticides are ubiquitous among agricultural fields and the prolonged effects of organophosphates are not well understood. It is believed that exposure to Organophosphates can cause neurological deficits and impaired neurobehavioral function. We hypothesize that the organophosphate pesticide chlorpyrifos (CPF) is associated with mechanisms that directly and/or indirectly disrupt axonal transport in brain regions integral for learning and memory. To assay this claim, rats were treated acutely with CPF at a subtoxic dose (18 mg/kg) or with repeated exposures for 14 consecutive days at subtoxic doses (3.0, 10.0 or 18 mg/kg). Whole brain was collected 6 or 24 hours after acute exposure or directly following 14 days of repeated exposure or a 30-day drug-free washout period. For my project, I focused on the prefrontal cortex, a brain region important for executive function. Prefrontal cortex was processed using a subcellular fractionation protocol and extracts were assessed by immunoblotting methods to measure the expression of a-tubulin, a microtubule protein critical for axonal transport. Our results will help us gain insight into a potential mechanism by which CPF affects axonal transport.
    • Effects of monoamine uptake inhibitors in an assay of pain-related depression of behavior in male mice

      Alexander, Khadijah; College of Science and Mathematics; MIller, Laurence (2015-10-09)
      Consequences of pain include stimulation of some behaviors (e.g. vocalization, reflexive withdrawal from stimuli), and depression of others (e.g. exercise, and work). Pain-related decreases in behavior are among the primary diagnostic and treatment concerns for physicians, but preclinical research has often ignored this important endpoint. This discrepancy between basic research and clinical application may be one obstacle to the development of new pain treatments. In the present study, we modeled pain-related depression of behavior by examining nesting behavior in male ICR mice. Nest building is an innate mouse behavior that is sensitive to depression by a pain stimulus, and pain-related depression of nesting is blocked by the clinically effective nonsteroidal anti-inflammatory drug (NSAID) ketoprofen. This project examines effects of monoamine uptake inhibitors with varying selectivity for serotonin (5HT), norepinephrine (NE) and dopamine (DA) on pain-related depression of nesting. Citalopram (5HT-selective), nisoxetine (NE-selective), milnacipran (mixed action, 5HT/NE-selective), and bupropion (DA-selective) were evaluated for their ability to block pain-related depression of nesting. Results show that the monoamine uptake inhibitors lacking significant dopamine had no effect on pain-depressed nesting. This finding is consistent with previous work suggesting that dopamine may be a key neurochemical target in the treatment of pain-related depression of behavior. Begin Time: 09:28 End Time: 28:00
    • Effects of regular exercise vs sedentary after school program on mood and quality of life of overweight children

      Davis, Catherine L.; Bustamonte, Eduardo E.; Williams, Celestine; Waller, Jennifer L.; Georgia Regents University (2014)
    • Efficacy of Hand Hygiene Compliance Interventions: A Systematic Review

      Hobbs, A. N.; Stone, Rebecca; Georgia Regents University (2015-07)
    • Electronic health.

      Chen, Hui; Nicogossian, Arnauld; Olsson, Silas; Rafiq, Azhar; Stachura, Max E; Watanabe, Mamoru; Whitten, Pamela; Xiao, Yang; Center for Telehealth (2009-04-03)
    • Encoding of emotion-paired spatial stimuli in the rodent hippocampus

      Nalloor, Rebecca Ipe; Bunting, Kristopher M.; Vazdarjanova, Almira; Brain & Behavior Discovery Institute; Department of Neurology (2012-06-14)
      Rats can acquire the cognitive component of CS-US associations between sensory and aversive stimuli without a functional basolateral amygdala (BLA). Thus, other brain regions should support such associations. Some septal/dorsal CA1 (dCA1) neurons respond to both spatial stimuli and footshock, suggesting that dCA1 could be one such region. We report that, in both dorsal and ventral hippocampus, different neuronal ensembles express immediate-early genes (IEGs) when a place is experienced alone vs. when it is associated with foot shock. We assessed changes in the size and overlap of hippocampal neuronal ensembles activated by two behavioral events using a cellular imaging method, Arc/Homer1a catFISH. The control group (A-A) experienced the same place twice, while the experimental group (A-CFC) received the same training plus two foot shocks during the second event. During fear conditioning, A-CFC, compared to A-A, rats had a smaller ensemble size in dCA3, dCA1, and vCA3, but not vCA1. Additionally, A-CFC rats had a lower overlap score in dCA1 and vCA3. Locomotion did not correlate with ensemble size. Importantly, foot shocks delivered in a training paradigm that prevents establishing shock-context associations, did not induce significant Arc expression, rejecting the possibility that the observed changes in ensemble size and composition simply reflect experiencing a foot shock. Combined with data that Arc is necessary for lasting synaptic plasticity and long-term memory, the data suggests that Arc/H1a+ hippocampal neuronal ensembles encode aspects of fear conditioning beyond space and time. Rats, like humans, may use the hippocampus to create integrated episodic-like memory during fear conditioning.
    • Energy Balance, Myostatin, and GILZ: Factors Regulating Adipocyte Differentiation in Belly and Bone.

      Shi, Xing-Ming; Hamrick, Mark; Isales, Carlos M; Institute of Molecular Medicine and Genetics; Department of Pathology; Department of Cellular Biology and Anatomy; Department of Orthopaedic Surgery (2008-02-29)
      Peroxisome proliferator-activated receptor gamma (PPAR-gamma) belongs to the nuclear hormone receptor subfamily of transcription factors. PPARs are expressed in key target tissues such as liver, fat, and muscle and thus they play a major role in the regulation of energy balance. Because of PPAR-gamma's role in energy balance, signals originating from the gut (e.g., GIP), fat (e.g., leptin), muscle (e.g., myostatin), or bone (e.g., GILZ) can in turn modulate PPAR expression and/or function. Of the two PPAR-gamma isoforms, PPAR-gamma2 is the key regulator of adipogenesis and also plays a role in bone development. Activation of this receptor favors adipocyte differentiation of mesenchymal stem cells, while inhibition of PPAR-gamma2 expression shifts the commitment towards the osteoblastogenic pathway. Clinically, activation of this receptor by antidiabetic agents of the thiazolidinedione class results in lower bone mass and increased fracture rates. We propose that inhibition of PPAR-gamma2 expression in mesenchymal stem cells by use of some of the hormones/factors mentioned above may be a useful therapeutic strategy to favor bone formation.
    • Enhanced glutamatergic and decreased GABAergic synaptic appositions to GnRH neurons on proestrus in the rat: modulatory effect of aging.

      Khan, Mohammad; De Sevilla, Liesl; Mahesh, Virendra B; Brann, Darrell W; Institute of Molecular Medicine and Genetics (2010-04-26)
      BACKGROUND: Previous work by our lab and others has implicated glutamate as a major excitatory signal to gonadotropin hormone releasing hormone (GnRH) neurons, with gamma amino butyric acid (GABA) serving as a potential major inhibitory signal. However, it is unknown whether GABAergic and/or glutamatergic synaptic appositions to GnRH neurons changes on the day of the proestrous LH surge or is affected by aging. METHODOLOGY/PRINCIPAL FINDINGS: To examine this question, synaptic terminal appositions on GnRH neurons for VGAT (vesicular GABA transporter) and VGLUT2 (vesicular glutamate transporter-2), markers of GABAergic and glutamatergic synaptic terminals, respectively, was examined by immunohistochemistry and confocal microscopic analysis in young and middle-aged diestrous and proestrous rats. The results show that in young proestrous rats at the time of LH surge, we observed reciprocal changes in the VGAT and VGLUT2 positive terminals apposing GnRH neurons, where VGAT terminal appositions were decreased and VGLUT2 terminal appositions were significantly increased, as compared to young diestrus control animals. Interestingly, in middle-aged cycling animals this divergent modulation of VGAT and VGLUT2 terminal apposition was greatly impaired, as no significant differences were observed between VGAT and VGLUT2 terminals apposing GnRH neurons at proestrous. However, the density of VGAT and VGLUT2 terminals apposing GnRH neurons were both significantly increased in the middle-aged animals. CONCLUSIONS/SIGNIFICANCE: In conclusion, there is an increase in glutamatergic and decrease in GABAergic synaptic terminal appositions on GnRH neurons on proestrus in young animals, which may serve to facilitate activation of GnRH neurons. In contrast, middle-aged diestrous and proestrous animals show a significant increase in both VGAT and VGLUT synaptic terminal appositions on GnRH neurons as compared to young animals, and the cycle-related change in these appositions between diestrus and proestrus that is observed in young animals is lost.
    • eNOS Regulation by Phosphorylation and Protein-Protein Interactions

      Li, Chunying; Vascular Biology Center (2006-08)
      Endothelial nitric oxide synthase (eNOS) catalyzes the conversion of L-arginine to L-citrulline and nitric oxide (NO). Protein phosphorylation and protein-protein interactions are two major mechanisms for eNOS regulation at the post-translational level, three aspects of which have been investigated in this study. The first aspect of eNOS regulation that we have examined is whether endostatin (ES) is a novel eNOS-activating agonist responsible for stimulating multi-site eNOS phosphorylation in endothelial cells. We show that ES induces acute endothelial NO release accompanied by eNOS phosphorylation events in cultured bovine aortic endothelial cells (BAECs). ES also induces relaxation of rat aortic rings. The second aspect of eNOS regulation that we have examined is the role of individual eNOS serine and threonine phosphorylation sites in the regulation of eNOS activity in BAECs. We mutated all five Thr- and Ser- sites of eNOS phosphorylation to aspartate or alanine and overexpressed the proteins in BAECs using adenoviral-mediated gene transfer. We show that mimicking phosphorylation of Ser-116 and Thr-497 is inhibitory, and mimicking phosphorylation of Ser-617, Ser-635 and Ser-1179 is stimulatory. Mimicking phosphorylation of Ser-635 and Ser-1179 together does not show synergistic effects on endothelial NO release. In addition, removal of any of the five Ser/Thr phosphorylation sites does not affect thapsigargin- or VEGF-stimulated NO release. A final aspect of eNOS regulation that we have investigated is the role of protein-protein interactions of eNOS with the CAT (cationic amino acid transporter)-1 arginine transporter. We show that eNOS interacts directly with CAT-1 and that overexpression of CAT-1 proteins in BAECs results in significant increases in NO release which is not altered by the CAT-1 inhibitor, L-lysine, suggesting that NO production in this in vitro model is independent of CAT-1 mediated arginine transport. Furthermore, eNOS enzymatic activity is increased in lysates of CAT-1-overexpressing cells accompanied by increased eNOS association with CAT-1, alterations of eNOS phosphorylation and eNOS association with caveolin-1. The present study adds to the knowledge of the regulation of eNOS by multi-site phosphorylation and protein-protein interactions.
    • Environmental Aesthetics, Ethics, and the Land-Community: An Ecocritical Reading of Flannery O’Connor’s “A View of the Woods”

      Atkins, Hunter; Katherine Reese Pamplin College of Arts, Humanities, and Social Sciences; Armstrong, Rhonda (2015-09-25)
      The human impact on the environment is more relevant than ever, but comparatively little attention is given to the way cultural media such as literature, film, and art have shaped our ideas about how we interact with the land and its inhabitants. Ecocriticism is literary theory that examines representations of the environment in order to better understand our attitudes toward the natural world. This presentation is an ecocritical analysis of the 1957 short story “A View of the Woods” by southern female author Flannery O’Connor. In “A View of the Woods,” O’Connor portrays a tension between the agrarian landscape and the changes brought about by economic progress and urbanization. Published in 1957, this story predates a great deal of American cultural media that would later address this same tension. O’Connor’s agrarian orientation gives her a uniquely advanced perspective for her time, and in this presentation, I examine the ways in which O’Connor’s narrative presages those later environmental theories and attitudes popularized by writers including Rachel Carson and Allen Carlson. In doing so, I argue that careful analysis of a literary narrative can help lead us to clearer understandings and articulations of our environmental values and attitudes. Begin Time: 07:35 End Time: 34:05
    • Estrogen-astrocyte interactions: implications for neuroprotection.

      Dhandapani, Krishnan M.; Brann, Darrell W; Institute of Molecular Medicine and Genetics; Department of Neurology (2003-03-31)
      BACKGROUND: Recent work has suggested that the ovarian steroid 17beta-estradiol, at physiological concentrations, may exert protective effects in neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease and acute ischemic stroke. While physiological concentrations of estrogen have consistently been shown to be protective in vivo, direct protection upon purified neurons is controversial, with many investigators unable to show a direct protection in highly purified primary neuronal cultures. These findings suggest that while direct protection may occur in some instances, an alternative or parallel pathway for protection may exist which could involve another cell type in the brain. PRESENTATION OF THE HYPOTHESIS: A hypothetical indirect protective mechanism is proposed whereby physiological levels of estrogen stimulate the release of astrocyte-derived neuroprotective factors, which aid in the protection of neurons from cell death. This hypothesis is attractive as it provides a potential mechanism for protection of estrogen receptor (ER)-negative neurons through an astrocyte intermediate. It is envisioned that the indirect pathway could act in concert with the direct pathway to achieve a more widespread global protection of both ER+ and ER- neurons. TESTING THE HYPOTHESIS: We hypothesize that targeted deletion of estrogen receptors in astrocytes will significantly attenuate the neuroprotective effects of estrogen. IMPLICATIONS OF THE HYPOTHESIS: If true, the hypothesis would significantly advance our understanding of endocrine-glia-neuron interactions. It may also help explain, at least in part, the reported beneficial effects of estrogen in neurodegenerative disorders. Finally, it also sets the stage for potential extension of the hypothetical mechanism to other important estrogen actions in the brain such as neurotropism, neurosecretion, and synaptic plasticity.
    • Evaluation of blood stool test utilization for colorectal cancer screening in Georgia

      Ansa, Benjamin E.; Lewis, Nicolette; Hoffman, Zachary; Johnson, J. Aaron; Augusta University (2018)
    • Evaluation of colonoscopy and sigmoidoscopy utilization for colorectal cancer screening in Georgia

      Ansa, Benjamin E.; Hoffman, Zachary; Lewis, Nicolette; Johnson, J. Aaron; Augusta University (2018)
    • Evidence Supporting Glial Derived TGF-B1 as a Modulator of Luteinizing Hormone-Releasing Hormone

      Buchanan, Clint D.; Institute of Molecular Medicine and Genetics (2000-03)
      The overall objective of this research is to elucidate mechanisms involved in glial cell regulation of reproductive function. Regulation of LHRH secretion is a complex process that involves a multiplicity of inputs of both excitatory and inhibitory nature, and recent evidence has demonstrated the significance of glial cell-neuron interactions in modifying the activity of LHRH producing neurons. Evidence exists indicating that glial derived growth factors may play a role in the functional control o f the LHRH neuronal network as conditioned medium from astrocytes has been shown to stimulate LHRH secretion from immortalized LHRH neurons (52-55,57,58). However, there is a controversy concerning the identity of the active factor from astrocytes that is responsible for the LHRH releasing activity of conditioned medium. Melcangi and colleagues have provided evidence that TGF-Pi may be responsible for astrocyte-conditioned medium induced LHRH release in the GTl-l cell line (55). However, many of these studies supporting a role for TGF-pi were performed using cortical astrocytes, and additionally, no attempt was made to measure TGF-Pi levels in astrocyte-conditioned medium and correlate it to conditioned medium ability to induce LHRH release. Furthermore, these studies did not discuss potential regulators of TGF-pi secretion and also failed to investigate whether TGF-p receptors, which are necessary for TGF-pi action, are expressed in the GT1 cell line or hypothalamic tissue of the female rat (55,57,58). A second group suggests that TGF-a rather than TGF-Pi may be the active astrocyte factor that regulates LHRH release (53). Although TGF-a mRNA expression and precursor peptide immunoreactivity have been reported in the female rat hypothalamus, these studies failed to demonstrate the ability of hypothalamic astrocyte cultures to produce Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 15 TGF-a and relied upon addition of exogenous TGF-a to astrocyte cell cultures (50ng/ml 16 hours) in formation of astrocyte TGF-a-conditioned medium (25,46,52,53,76,77).
    • An Examination of HPV Vaccine Administration in Georgia

      Denson, Samantha; Holleran, Ericka; Gaffney, Jasmine; Department of Psychological Sciences (2016-09-16)
      HPV is the leading STI in the US and Georgia (CDC, 2016). HPV is the necessary precursor for cervical cancer, other cancers and genital warts (CDC, 2016). Georgia is unique in that it tracks statewide vaccination rates by provider. This data is entered into the Georgia Registry of Immunization Transactions and Services (GRITS). Our goal was to use these data to examine: 1) How do HPV vaccination trends compare to other childhood vaccines? and 2) Are there gender differences in HPV vaccine uptake? Data was extracted from the GRITS database for all Georgia children aged 9-14 who received vaccines between 2009-2014. GRITS data variables were coded and descriptive analyses were conducted to examine vaccine uptake. Specifically, we examined the vaccines: HPV, pertussis, measles, mumps, rubella, and meningococcal. We also examined HPV vaccination rates by gender. Results: There was a total of 2,457,005 entries into GRITS during 2009-2014. Vaccination rates increased for HPV, meningococcal, and pertussis, but remained relatively low for rubella, mumps, and measles. Although HPV vaccine uptake started low, it had the highest uptake frequency from 2012-2014. In comparison to males, HPV vaccine uptake was higher for females across all years. However, HPV vaccine uptake for males increased more significantly than for females. The rates of childhood vaccine uptake in Georgia were relatively low for rubella, mumps, and measles. Females received the HPV4 vaccine more frequently than males. Learning more about vaccination patterns and provider recommendations will provide the necessary framework for improving HPV vaccine uptake.
    • Exocytotic Insertion of Calcium Channels Constrains Compensatory Endocytosis to Sites of Exocytosis

      Smith, Robert M.; Baibakov, Boris; Ikebuchi, Yoshihide; White, Benjamin H.; Lambert, Nevin A.; Kaczmarek, Leonard K.; Vogel, Steven S.; Institute of Molecular Medicine and Genetics (2000-02-21)
      Proteins inserted into the cell surface by exocytosis are thought to be retrieved by compensatory endocytosis, suggesting that retrieval requires granule proteins. In sea urchin eggs, calcium influx through P-type calcium channels is required for retrieval, and the large size of sea urchin secretory granules permits the direct observation of retrieval. Here we demonstrate that retrieval is limited to sites of prior exocytosis. We tested whether channel distribution can account for the localization of retrieval at exocytotic sites. We find that P-channels reside on secretory granules before fertilization, and are translocated to the egg surface by exocytosis. Our study provides strong evidence that the transitory insertion of P-type calcium channels in the surface membrane plays an obligatory role in the mechanism coupling exocytosis and compensatory endocytosis.
    • Expression and Treatment of Pain-Related Depression of Nesting Behavior in Male ICR Mice

      Alexander, Khadijah; Rodriguez, Taylor; Sarfo, Amma; Miller, Laurence; College of Science and Mathematics (2015-08-07)
      Consequences of pain include pain-related functional impairment and depression of behavior, including decreased ability to work and exercise. Such pain-related depression of behavior is one of the primary treatment targets for clinicians. In contrast, most preclinical pain research with animal models has examined pain-stimulated behaviors such as reflexive withdrawal from a pain stimulus. This approach bears little resemblance to clinically-relevant pain-related behavioral depression. Moreover, reliance on this approach may have limited the development of novel, effective pharmacological pain treatments. The present studies rely on the innate nesting behavior of mice as a behavioral baseline to study the expression and treatment of pain-related depression of behavior. On test days, six pieces of cotton nesting material were evenly distributed on the homecage floor, and consolidation of this material was quantified over the course of a 100-min session. Control nesting was compared to nesting in sessions preceded by an intraperitoneal injection of dilute lactic acid (IP acid), a commonly used, physiologically-relevant noxious stimulus. When IP acid was administered prior to nesting sessions, the rate of nest consolidation was decreased. Ketoprofen, a clinically-effective non-steroidal anti-inflammatory drug (NSAID), blocked IP acid-induced depression of nesting. These findings support the utility of this assay of noxious stimulus-depressed nesting for research on the expression and treatment of pain-related depression of behavior. Future studies will use the procedure to examine the efficacy of monoamine uptake inhibitors with varying selectivity for blocking uptake of dopamine, serotonin, and norepinephrine.
    • Expression of GD2 and GD3 gangliosides in human embryonic neural stem cells

      Yanagisawa, Makoto; Yoshimura, Saori; Yu, Robert K.; Institute of Molecular Medicine and Genetics (2011-04-7)
      NSCs (neural stem cells) are undifferentiated neural cells endowed with a high potential for proliferation and a capacity for self-renewal with retention of multipotency to differentiate into neurons and glial cells. It has been recently reported that GD3, a b-series ganglioside, is a marker molecule for identifying and isolating mouse NSCs. However, the expression of gangliosides in human NSCs is largely unknown. In the present study, we analysed the expression of gangliosides, GD2 and GD3, in human NSCs that were isolated from human brains at gestational week 17 in the form of neurospheres, which are floating clonal aggregates formed by NSCs in vitro. Employing immunocytochemistry, we found that human NSCs were strongly reactive to anti-GD2 antibody and relatively weakly reactive to anti-GD3 antibody. Treatment of these cells with an organic solvent such as 100% methanol, which selectively removes glycolipids from plasma membrane, abolished the immunoreactivity with those antibodies, indicating that the reactivity was due to GD2 and GD3, but not to GD2-/GD3-like glycoproteins or proteoglycans. The immunoreactivity of human NSCs to antibody against SSEA-1 (stage-specific embryonic antigen-1), a well-known carbohydrate antigen of NSCs, was not decreased by the treatment with 100% methanol, indicating that SSEA-1 is mainly carried by glycoproteins and/or proteoglycans in human NSCs. Our study suggests that GD2 and GD3 can be marker gangliosides for identifying human NSCs.
    • Extracellular high-mobility group box 1 acts as an innate immune mediator to enhance autoimmune progression and diabetes onset in NOD mice.

      Han, Junyan; Zhong, Jinxin; Wei, Wenzhong; Wang, Ying; Huang, Yafei; Yang, Ping; Purohit, Sharad; Dong, Zheng; Wang, Mong-Heng; She, Jin-Xiong; et al. (2008-07-29)
      OBJECTIVE: The implication of innate immunity in type 1 diabetes development has long been proposed. High-mobility group box 1 (HMGB1), an evolutionarily conserved chromosomal protein, was recently recognized to be a potent innate inflammatory mediator when released extracellularly. We sought to test the hypothesis that HMGB1 acts as an innate immune mediator implicated in type 1 diabetes pathogenesis. RESEARCH DESIGN AND METHODS: Eight- and 12-week-old NOD mice were treated with an HMGB1 neutralizing antibody once a week until 25 weeks of age and monitored for insulitis progression and diabetes onset. The underlying mechanisms of HMGB1 regulation of autoimmune response were further explored. RESULTS: During autoimmunity, HMGB1 can be passively released from damaged pancreatic beta-cells and actively secreted by islet infiltrated immune cells. Extracellular HMGB1 is potent in inducing NOD dendritic cell maturation and stimulating macrophage activation. Blockade of HMGB1 significantly inhibited insulitis progression and diabetes development in both 8- and 12-week-old NOD mice. HMGB1 antibody treatment decreased the number and maturation of pancreatic lymph node (PLN) CD11c(++)CD11b(+) dendritic cells, a subset of dendritic cells probably associated with autoantigen presentation to na??ve T-cells, but increased the number for PLN CD4(+)Foxp3(+) regulatory T-cells. Blockade of HMGB1 also decreased splenic dendritic cell allo-stimulatory capability associated with increased tolergenic CD11c(+)CD8a(+) dendritic cells. Interestingly, the number of CD8(+)interferon-gamma(+) (Tc1) T-cells was increased in the PLNs and spleen after blockade of HMGB1, which could be associated with retarded migration of activated autoreactive T-cells into the pancreatic islets. CONCLUSIONS: Extracellular HMGB1 functions as a potent innate immune mediator contributing to insulitis progression and diabetes onset.
    • Extranuclear estrogen receptors mediate the neuroprotective effects of estrogen in the rat hippocampus.

      Yang, Li-cai; Zhang, Quan-Guang; Zhou, Cai-feng; Yang, Fang; Zhang, Yi-dong; Wang, Rui-min; Brann, Darrell W; Institute of Molecular Medicine and Genetics (2010-05-18)
      BACKGROUND: 17beta-estradiol (E2) has been implicated to exert neuroprotective effects in the brain following cerebral ischemia. Classically, E2 is thought to exert its effects via genomic signaling mediated by interaction with nuclear estrogen receptors. However, the role and contribution of extranuclear estrogen receptors (ER) is unclear and was the subject of the current study. METHODOLOGY/PRINCIPAL FINDINGS: To accomplish this goal, we employed two E2 conjugates (E2 dendrimer, EDC, and E2-BSA) that can interact with extranuclear ER and exert rapid nongenomic signaling, but lack the ability to interact with nuclear ER due to their inability to enter the nucleus. EDC or E2-BSA (10 microM) was injected icv 60 min prior to global cerebral ischemia (GCI). FITC-tagged EDC or E2-BSA revealed high uptake in the hippocampal CA1 region after icv injection, with a membrane (extranuclear) localization pattern in cells. Both EDC and E2-BSA exerted robust neuroprotection in the CA1 against GCI, and the effect was blocked by the ER antagonist, ICI182,780. EDC and E2-BSA both rapidly enhanced activation of the prosurvival kinases, ERK and Akt, while attenuating activation of the proapoptotic kinase, JNK following GCI, effects that were blocked by ICI182,780. Administration of an MEK or PI3K inhibitor blocked the neuroprotective effects of EDC and E2-BSA. Further studies showed that EDC increased p-CREB and BDNF in the CA1 region in an ERK- and Akt-dependent manner, and that cognitive outcome after GCI was preserved by EDC in an ER-dependent manner. CONCLUSIONS/SIGNIFICANCE: In conclusion, the current study demonstrates that activation of extranuclear ER results in induction of ERK-Akt-CREB-BDNF signaling in the hippocampal CA1 region, which significantly reduces ischemic neuronal injury and preserves cognitive function following GCI. The study adds to a growing literature that suggests that extranuclear ER can have important actions in the brain.