The locus coeruleus (LC) is a small nucleus of noradrenergic neurons in the pons, which, despite its size, has broad projections throughout the central nervous system (CNS). Functionally, the LC is believed to be involved in various critical functions, including the physiological response to stress, as well as mediating arousal. Previous investigations have demonstrated that optogenetic activation of the LC at a tonic frequency promotes wakefulness in rodents. While this observation causally implicates LC function in wakefulness, it is still not known how the LC is endogenously controlled to mediate arousal. One potential candidate in this control is the peptide nociceptin and its cognate receptor, the nociceptin opioid peptide receptor (NOPR), both of which are highly expressed around the LC. To investigate, we first conducted two pharmacological experiments using the NOPR agonist Ro64-6918 to assess its effects on locomotion and on the activity of LC noradrenergic neurons. To determine where the endogenous nociceptin signal to the LC originates, we performed an intracranial injection of a Cre-dependent retrograde virus (AAV2-DIO-eYFP) into the LC of a mouse expressing Cre recombinase in nociceptin-expressing neurons. We observed that Ro64-6198 (10 mg/kg) strongly reduced open field locomotor activity compared to vehicle treatment. Using in vivo 2-photon calcium imaging (GCaMP6s), we found that Ro64-6198 (5 mg/kg) profoundly reduced LC noradrenergic neuron activity. Wakefulness appeared reduced in both in vivo experiments. Finally, we identified nociceptin-expressing cells projecting to the LC in the peri-LC as well as a long-range projection from the bed nucleus of the stria terminalis (BNST). Together, these studies suggest that nociceptin acting on LC noradrenergic neurons reduces arousal, and that the endogenous sources of nociceptin may originate in the peri-LC and BNST. Future studies will investigate nociceptin-expressing neuron activity during sleep/wake transitions and whether this activity is sufficient to alter wakefulness.

Gene gun technology uses DNA-coated gold microparticle bombardment to achieve DNA vaccine immunogenicity by effective intradermal transfer. This delivery system results in increased uptake of plasmids by cells, potent cellular and humoral immunity compared to other delivery methods like direct needle injection or electroporation. DNA vaccines are expected to exhibit long term stability, ease of manufacturing, low cost, reduce cold chain requirements, and reduce concern for vector immunity from repeated immunizations. Additionally, gene gun DNA vaccine technology allows for multiple antigens to be added in the same immunization. Beyond the advantages above, genetic adjuvants have the potential to further improve the immunogenicity of DNA vaccines. One strategy to improve the immunogenicity of DNA vaccination would be using chemokines like Xcl1 to recruit dendritic cells for induction of CD8+ and CD4+ T-cells. Xcl1 is a ligand that binds to and specifically activates dermal dendritic cells, which presents Xcr1 and efficiently activates T-cell responses. Two ways to introduce Xcl1 as an adjuvant are fusion and cotransfection, the latter of which is the method used in this project. In cotransfection, Xcl1 cytokines induce localized inflammatory responses which recruit dendritic cells. This allows the antigen of interest to target the dendritic cells, leading to the induction of CD8+ T-cells specific to the antigen of interest. I believe that Xcl1 has the potential to induce antigen-specific effector and memory CD8+ T-cells and enhance proliferation of CD4+ and CD8+ T-cells. I gene gun vaccinated mice with and without Xcl1 DNA and assessed the induction of appropriate T-cell responses to determine whether the addition of Xcl1 as an adjuvant enhances the T-cell and antibody response needed to protect against P. yoelii infection challenge. The results of this ongoing work will be presented. This data will inform whether genetic adjuvants have the ability to increase immunogenicity in DNA malaria vaccines.

Spinal cord injuries can result in devastating health consequences and impair voluntary muscle control. Animal models are invaluable for the development of new treatments to restore hand and arm function. In rats, we are developing a novel targeted, activity-dependent spinal stimulation (TADSS) therapy that promotes plasticity in spared pathways with a neuroprosthetic device after a C4-C5 spinal cord injury (SCI). Recovery is measured through training the rats in reaching tasks and comparing performance during therapy to the pre-injury scores. We have found that females show robust functional recovery with TADSS treatment, but males do not. One potential explanation for the difference in recovery is that females are more motivated to perform the behavioral tasks. Thus, we examined reaching performance of males and females prior to injury to see if there is any evidence of preexisting sex differences in reaching performance. Within groups of uninjured animals learning the reaching task, females on average had more trials than males, though both males and females had similar success rates. This may be evidence of greater motivation to perform the reaching task in females. Little research has been done on the role of sex and motivation in reaching tasks; however, other groups have shown that sex differences in performance of behavioral assays may be due to differences in motivation. We hypothesize differences in motivation may influence the level of functional recovery from SCI’s with TADSS therapy, as the intraspinal stimulation is dependent on muscle activity in impaired forelimbs. The aim of our future experiments is to determine the effect of sex on rodents’ motivation to perform reaching tasks before and after injury. By continuing to investigate the effect of sex-related motivation differences on motor tasks associated with SCI recovery, we hope to optimize TADSS therapy for clinical use in humans.

Toxoplasma gondii is a prevalent parasitic infection capable of vertical transmission. This particular pathogen is able to infiltrate the placenta, and subsequently cause detrimental cognitive deformities in the growing fetus. Significant factors influencing deviation from typical fetal growth are 1) the pathogenic strain and 2) gestational age at the time of infection. Through this review I will first explore how immune responses vary in relation to the previously stated factors. Then I will evaluate the potential use of focused ultrasound application to stimulate the required immune response to treat Toxoplasma gondii infections in utero. Please note that currently, all results and conclusions are theoretical. Given the adverse effects administration of antiparasitic drugs may have on a growing fetus in terms of toxicity and resistance, the aim is to explore methods which may be capable of improving treatment of vertically transmitted Toxoplasma gondii, as well as other notable in utero infections.