Huntington's disease (HD) is a devastating autosomal dominantly inherited neurological disorder caused by an abnormal expansion of CAG trinucleotide repeats in the gene coding for the Nterminal region of the huntingtin (Htt) protein, which leads to the formation of a polyglutamine stretch. The greater the CAG repeats, the earlier the onset of the disease. The polyglutamine stretch destabilizes the Htt protein leading to misfolding, abnormal processing, aggregation, and inclusion formation. Mutant Htt protein is believed to damage and kill neurons in the striatum by a mechanism involving increased oxidative and metabolic stress, and impaired adaptive cellular stress responses. A large number of abnormalities have been reported in HD, including transcription deficits, energy impairment, excitotoxicity, and lack of trophic support. Reduced trophic support contributes importantly to striatal degeneration in human HD. Specifically, brainderived neurotrophic factor (BDNF) expression is reduced in patients with HD. BDNF is also decreased in brain tissue from mice transgenic for mutant Htt. BDNF levels influences the onset and the severity of motor dysfunction in HD mice. In addition to BDNF, levels of the molecular chaperones heat shock proteins (Hsp40 and 70) decrease progressively in HD brain. Hsp70 is a highly stress-inducible member of a chaperone family of proteins that functions to prevent misfolding and aggregation of newly synthesized mutant proteins and stress-denatured proteins. Hsps appear to play a critical role in HD since expression of active heat shock factor HSF1, a transcription factor responsible for the induction of Hsps, markedly reduces polyglutamine aggregate formation in both cell and mouse models. Many efforts have been made to develop preventive treatments for HD because of the strong genetic link and a freely available genetic test to identify individuals at risk. At present, only symptomatic therapy is available and effective therapeutic approaches to slow the disease iv process have yet to be developed. Previous studies have shown that electroconvulsive shock (ECS) induces the production of growth factors including BDNF and the molecular chaperones HSP40 and HSP70. Because ECS can stimulate the production of neuroprotective proteins, we determined whether ECS treatment could slow the progressive nature of the disease process and provide a therapeutic benefit in a mouse model of HD. ECS or sham treatment was administered to male N171-82Q Htt mutant mice. End points measured included motor function, striatal and cortical pathology, and levels of neurotrophic factors, protein chaperones, and proteins involved in synaptic plasticity. ECS treatment delayed the onset of motor symptoms, reduced body weight loss and extended the survival of HD mice. Striatal neurodegeneration was attenuated and levels of neurotrophic factors, protein chaperones and mitochondria-stabilizing protein were elevated in striatal cells of ECS-treated compared to sham-treated HD mice. Our findings suggest that ECS can increase the resistance of neurons to mutant huntingtin resulting in improved functional outcome and extended survival. The potential of ECS as a treatment for HD patients merits further consideration.

Background: Streptozotocin (STZ) induced diabetes leads to various complications including cardiomyopathy. Recent data suggests transplanted bone marrow stem cells improve cardiac function in diabetic cardiomyopathy. However, whether modified ES, iPS cells, or factors released from these cells can inhibit apoptosis and fibrosis remains completely unknown. The present study was designed to determine the effects of transplanted ES cells overexpressing pancreatic transcription factor 1 a (Ptf1a), a propancreatic endodermal transcription factor, iPS cells, or their respective conditioned media (CM) on diabetic cardiomyopathy. Methods: Experimental diabetes was induced in male Sprague Dawley rats (8-10 weeks old) by intraperitoneal STZ injections (65 mg/kg body weight for 2 consecutive days). Animals were divided into six experimental groups including control, treated with sodium citrate buffer IP, STZ, STZ + ES-Ptf1a cells, STZ + iPS cells, STZ + ES-Ptf1a CM and STZ + iPS CM. Following STZ injections, appropriate cells (1 X 106/mL/injection/day) or CM (2 mL injection/day) were given intravenously for 3 consecutive days. Animals were sacrificed and hearts were harvested at day 28. Histology, TUNEL staining, and Caspase-3 activity were used to assess apoptosis and fibrosis. ERK1/2 phosphorylation was quantified using ELISAs. M-mode echocardiography fractional shortening was used to assess cardiac function. Results: Animals transplanted with ES cells, iPS cells, or both CMs showed a significant (p

Sepsis is a life-threatening condition characterized by organ dysfunction due to an uncontrolled response to infection. Despite decades of research, the mortality rate remains high, emphasizing the need for an improved understanding of sepsis pathophysiology and improvements in preclinical animal research. Recently, extracellular histones, major mediators of organ dysfunction and death, have emerged as a potential therapeutic target for sepsis. In this thesis, we reported that the ability of heparin to neutralize the cytotoxic and procoagulant effects of histones is size-dependent but independent of the antithrombin- binding pentasaccharide. In contrast, the ability of heparin to neutralize histone-mediated impairment of activated protein C generation is independent of size and anticoagulant activity. These findings suggest that heparin variants may have differential therapeutic potential in vascular disease states that are associated with elevated levels of histones. Before testing the therapeutic efficacy of the heparin variants in vivo, we aimed to develop and standardize a murine model of sepsis that can be utilized in a multi-center platform. As one of the lead sites for the National Preclinical Sepsis Platform (NPSP), we optimized a 72-hour model of abdominal sepsis using supportive treatments. As sepsis predominately impacts the elderly, we also explored the impact of aging on the host response to sepsis using our fecal induced peritonitis (FIP) model. Aged FIP mice exhibited a higher mortality rate compared to young FIP mice. The worsened organ injury and poor survival in aged mice may be attributed to heightened inflammation in aged mice. We also observed trends in increased bacterial loads, increased coagulation, elevated cell free DNA, and decreased ADAMTS13 activity in aged septic mice. These findings help to improve our understanding of how aging impacts the host response to sepsis, which may be translated into therapeutic strategies that considers advanced age as a risk factor for sepsis. / Thesis / Candidate in Philosophy

Attention-deficit/hyperactivity disorder (ADHD) is highly comorbid with substance use disorders, particularly cocaine. Preclinical studies using the well-validated Spontaneously Hypertensive Rat (SHR) model of ADHD suggest that adolescent treatment with the stimulant methylphenidate increases cocaine abuse risk in adulthood, highlighting the need to identify alternative medications for teenagers with ADHD. Experiments 1-4 tested the hypothesis that atomoxetine, a non-stimulant that improves prefrontal cortex functioning in adolescent SHR, would not increase cocaine abuse risk. The speed to acquire cocaine self-administration, the efficacy and motivating influence of cocaine reinforcement, and reactivity to cocaine cues in adulthood following discontinuation of adolescent atomoxetine treatment were examined in male SHR and two genetic control strains: inbred Wistar-Kyoto (WKY) and outbred Wistar (WIS). Because atomoxetine is not always as clinically efficacious as methylphenidate, Experiments 5-9 tested the hypothesis that an alternative stimulant, d-amphetamine, would improve cognitive performance in adolescent SHR during a strategy set-shifting task and not increase cocaine abuse risk in adult SHR after adolescent d-amphetamine was discontinued. Across experiments, adult SHR acquired cocaine self-administration faster than control strains and also were more sensitive to cocaine’s reinforcing and motivating influence and more reactive to cocaine cues. As hypothesized, adolescent atomoxetine did not increase any measure of cocaine abuse risk in adult SHR and modestly reduced SHR’s reactivity to cocaine cues. In WKY control, however, adolescent atomoxetine accelerated acquisition of cocaine self-administration. d-Amphetamine improved set-shifting deficits in adolescent SHR, demonstrating pro-cognitive effects as hypothesized. When self-administration was acquired, cocaine intake was lower in adult SHR that received adolescent d-amphetamine compared to vehicle-treated SHR, consistent with the hypothesis. Adolescent d-amphetamine slowed acquisition and reduced the efficacy and motivating influence of cocaine reinforcement in WIS control, but accelerated acquisition in WKY control. Collectively, these results highlight the heuristic value of SHR in evaluating comorbid ADHD and cocaine abuse risk, and suggest that atomoxetine and d-amphetamine may be safer medications than methylphenidate for teenagers with ADHD. However, findings in control strains emphasize the need for accurate ADHD diagnosis, as the long-term consequences of treatment could be favorable (d-amphetamine in WIS) or unfavorable (atomoxetine and d-amphetamine in WKY) in misdiagnosed individuals.

Background: The main aim of the studies in this thesis is to provide insights into the neonatal phencyclidine (PCP) induced deficits in male and female rats as a neurodevelopmental animal model of schizophrenia. Methods: Both male and female rats were treated with neonatal PCP on postnatal days (PNDs) 7,9 and 11 or vehicle, followed by weaning on PND 21-22. The rats were then tested in behavioural paradigms such as novel object recognition, spatial memory and social interaction in their adolescent and adult stages and were also tested with acute treatment of typical and atypical antipsychotic agents. Results: Neonatal PCP treatment (10 & 20 mg/kg in males and 10 mg/kg in females; once a day for 3 days on PND 7,9 and 11) caused novel object recognition and spatial memory impairment in male and female rats both in the adolescent (PND35-56) and in the adult stages (PND>56) (chapter 2) and robust deficits in social interaction behaviours in the adolescent stage. The SI deficits were observed in adulthood in female but not in male rats thereby establishing a sex-specific social behavioural deficit (chapter 3). The object memory and social interaction deficits induced by neonatal PCP treatment were reversed following acute risperidone but not haloperidol. Finally, the temporal profile of this treatment regime was investigated and the male and female animals were tested on PND 190 and PND 365. The animals did not have any challenge dose of PCP during their testing stage. The result showed that there was significant deficit in object and spatial recognition memory in both male and female animals at both time points, thereby establishing enduring deficits. Conclusion: Given the heterogeneity of the schizophrenic disorder and its complex aetiology, it is understandably difficult to find animal models that completely mimic most or all of the symptoms associated with the disorder. However, data from the studies in this thesis support the use of neonatal PCP as a valid animal model of cognitive and negative symptoms, and explores the effect of antipsychotics in understanding the model. Also, in light of the efficacy of neonatal PCP to produce robust object, spatial memory and social interaction deficits in rats, it appears that this model may be a useful tool to investigate the potential of novel therapeutic candidates that may help improve therapy and understand the illness.

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