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Part 1 - Background: Maternal prenatal adversity often results in changes to the hypothalamic- pituitary-adrenal axis (HPA axis) function, such as greater cortisol secretion. Recent evidence suggests that fetal exposure to elevated cortisol levels may cause structural changes to key limbic regions integral to regulation of the HPA axis such as the amydala and hippocampus in children. In the early postnatal months these same structures are particularly vulnerable to the quality of maternal care and parenting styles. However, the relative impact and interaction of such factors is still underreported. Methods: 24 healthy 7-8 year old children (male:female=13:11) underwent an MRI. Amygdala and hippocampal volumes were assessed and used in multiple regression models to determine the impact of prenatal cortisol and postnatal maternal sensitivity. Results: Larger right hippocampal volumes were associated with increases in late gestation cortisol levels (4.6 mm3/nmol of cortisol; FDR corrected p<0.005). Increases in 6th month maternal sensitivity predicted a decrease in right hippocampal volumes at a trend level (FDR corrected p=0.09). There was no interaction effect between cortisol and sensitivity. There were no significant effects on left hippocampus or bilateral amygdala volumes. No sex differences were noted. Discussion: Given previous work we had expected greater amygdala volume and reduced hippocampal volumes to associate with increases in cortisol and decreases in sensitivity. Our results suggest that there may indeed be a programming effect on children’s hippocampi by prenatal cortisol. Findings may be reflective of a positive adaptive response or resilience to adverse prenatal environments. Part 2 - Introduction: Emotion regulation (ER) is an integral component to mental health. ER is thought to incorporate limbic as well prefrontal regions in several cognitive top-down circuits to utilize higher-order executive functions to adequately monitor and inhibit emotion when necessary. However, only recently has research targeted the developmental trajectories of these circuits from childhood. Methods: 29 healthy children aged 7-8 years (mean 7.34 ± 0.48) underwent functional magnetic resonance imaging (fMRI) with an implicit emotion go/nogo cognitive task to assess the developmental state and interaction between cognitive and emotional circuitry using functional connectivity (FC) in this age group. Results: Central executive networks (CEN) and salience networks (SN) showed more diffuse FC than mature networks, with greater inter-network connectivity. During exposure to fearful stimuli, there was greater connectivity within CEN and SN during go trials. Nogo trials were associated with more limbic-cognitive network interaction during concurrent exposure to fearful stimuli than neutral stimuli, Connectivity with the dACC was found to be common between limbic and CEN seeded networks. Discussion: Results indicate that cognitive networks are present but generally less mature than previous results from adult populations. Particularly, diffuse connectivity between the insula and PCC was negatively correlated indicating a developing switch between resting and salience networks. Additionally, greater connectivity for response inhibition tasks (nogo) during fearful stimuli exposure in the dACC, amygdala, anterior prefrontal, and DLPFC, suggests a maturing emotion regulation network, capable of managing cognitive tasks during emotional stimuli presentation. / Thesis / Master of Science (MSc)

<p>Dairy calves in the preweaning period are exposed to a variety of stressors (e.g. disbudding, castration, etc.) and management practices that have the potential to influence their health and productivity later in life. Proper colostrum management at birth is the first step in ensuring calves can reach their full potential in terms of health, growth, and development, while improper management increases a calf’s risk of failed transfer of passive immunity <strong>(FTPI)</strong> which puts the calf at an increased risk of morbidity and mortality. Previous research has indicated there is a difference in colostrum management practices between dairy bull and heifer calves. Due to the marketing of dairy-beef crossbred calves as surplus animals along with dairy bull calves, there is growing interest in the treatment of these calves on farms. The first study presented here (Chapter 2) investigated the relationship between colostrum management practices on 15 farms and the prevalence of FTPI between purebred dairy and dairy-beef crossbred calves on those farms. The results of this study found no influence of calf breed (purebred dairy or dairy-beef crossbred) on the prevalence of FTPI. However, farm tended to influence FTPI. There was also a significant influence of the reported timing of the first colostrum feeding on FTPI, with calves on farms reporting feeding colostrum within 1 hour of birth having decreased odds of experiencing FTPI. In addition to colostrum management at birth, calves are exposed to several management factors during the preweaning period that can cause stressful experiences and result in negative behavioral and physiological outcomes. Early life stress, especially chronic stress, can negatively impact calves later in life. Short term stress load in calves can be quantified by measuring cortisol in the blood serum or saliva; however, these measures are not reflective of chronic stress load because they only measure circulating cortisol. The second study (Chapter 3) considered the efficacy of utilizing hair cortisol concentration <strong>(HCC)</strong> as a measure of stress load in 27 dairy calves exposed to a weekly saline injection or a weekly or biweekly repeated acute stressor (Cosyntropin injection) during the preweaning period. The results revealed no difference in HCC between the treatment groups, though salivary cortisol was increased in calves injected with Cosyntropin. Additionally, calf behavior and growth were not influenced by the treatments in this study. Overall, these studies provided insights into two areas that have not been extensively researched. First, considering dairy-beef crossbred calf management, and second investigating a method to assess chronic stress that has not been extensively researched in calves.</p>

Recently, comparisons of "periodized" strength training methods have become a focus of sport science. Daily undulating periodization (DUP), using daily alterations in repetitions, has been developed and touted as a superior method of training. The purpose of this study is to compare traditional periodization (TRA) to DUP in Division I track and field athletes. Thirty-one athletes were assigned to either a TRA or the DUP group training programs based on sex, year, and event. Training lasted 10 weeks. There were 4 testing sessions focusing on strength characteristics. Although, trends favored the TRA group for strength and rate of force development, no significant differences were found between the groups. Significant differences (p≤0.05) in volume and the amount of improvement per volume load were found to be significantly different (p≤0.05) between the TRA and DUP groups. These data indicate that TRA is more efficient in producing strength gains than DUP.

In social primates, the acquisition and maintenance of social dominance may augment reproductive success while incurring immunological costs. This trade-off is hypothetically facilitated by hormones that modulate both status-enhancing behavior and immune function. In the three studies comprising this dissertation, I investigated hormonal mechanisms by which social dominance may reflect immune health, testing relationships between behavioral correlates of dominance rank, steroid hormone secretion, and immune activity in wild adult male chimpanzees (Pan troglodytes schweinfurthii). Between January 2016 and July 2017, I collected behavioral observations and urine samples from adult males at Ngogo in Kibale National Park, Uganda, home to the largest community of habituated wild chimpanzees yet described. In the first study, I assessed behavioral and anatomical mechanisms that may link dominance rank to the secretion of testosterone, the primary male sex hormone. Testosterone was positively correlated with dominance rank and creatinine, a product of muscle catabolism and noninvasive proxy for lean muscle mass. Contrary to expectations, testosterone was negatively correlated with overall rates of aggression, indicating that aggressiveness does not itself account for positive linear correlations between dominance and testosterone in this species. In the second study, I analyzed reproductively salient correlates of cortisol, a glucocorticoid hormone secreted in response to psychosocial and metabolic demands. Urinary measures of reproductive effort and immune challenge were positively correlated with cortisol, indicating adaptive energy allocation. Furthermore, dominance rank was positively correlated with urinary cortisol when c-peptide of insulin, as a measure of energy intake, was low. This indicates that high ranking males deprioritize energy intake in certain social contexts, including competition for sexually receptive mates. In the third study, I found that although urinary testosterone seemingly diminished immune function, high ranking males were less likely to die from severe acute immune challenge than low ranking conspecifics. My results provide evidence that mating effort increases immune challenge both by increasing testosterone secretion and reallocating energy away from immune function. However, despite the increased mating effort exhibited by high ranking males, social dominance does not incur notable immunological costs. On the contrary, social dominance likely reflects immunocompetence and male quality in nonhuman primates. / 2021-12-06T00:00:00Z

This study examined the effects of carbohydrate supplementation on resistance exercise performance, cortisol levels, and creatine kinase levels in trained males undergoing energy restriction. Sixteen experimental subjects were randomly assigned to a carbohydrate (C, n=8) or placebo group (P, n=8). The remaining six subjects served as controls (N). Performance tests were done before (Trials 1 and 2) and after (Trial 3) energy restriction. Experimental subjects consumed a low calorie formula diet for three days (18 kcal-1 kg-1 d-1). They had blood drawn before and after T2 and T3. For T3, they consumed either a carbohydrate (1g kg-1) or a placebo beverage 30 minutes before exercise. There was a significant increase in resting cortisol levels following energy restriction. CK levels were significantly elevated after exercise, suggestion muscle damage. Carbohydrate supplementation had no effect on blood glucose, cortisol, creatine kinase, or RPE. The number of repetitions performed during the final set of bench press showed significant interaction between groups and time. P and N increased the number of repetitions performed from T2 to T3 (15.0 + 1.4 to 17.3 + 0.8 for P, 15.0 + 2.7 to 16.7 + 2.3 for N). C decreased the number of repetitions performed 17.6 + 0.7 to 17.3 + 1.0). The number of repetitions performed during the final set of leg extensions showed no interaction between groups and time (p=0.801). This study did not support a benefit of consuming carbohydrate prior to resistance exercise for dieting athletes but illustrates that energy restriction increases a catabolic hormone. / Master of Science

Hippocampal neurogenesis is linked to the onset, progression and remission of major mood disorder such as anxiety and depression. Neurogenesis is the process by which new neurons are formed in the brain. Mitochondria mediate cellular adaption and provide energy to support growth of new neurons. Chronic stress and mood disorders have been associated with impairments in mitochondrial function and neuronal growth. Individuals experiencing stress and mood disorders reportedly use cannabis as a means to self-medicate. The impacts of cannabis on stress-related effects on hippocampal neurogenesis and mitochondria are vastly unexplored. To investigate these effects we generated an in vitro model of hippocampal neuron stress by treating HT22 cells with corticosterone, the major effector molecule of stress in rodents. We first characterized the impacts of corticosterone on markers of neurogenesis and mitochondrial function in HT22 hippocampal cells. We found that corticosterone decreased gene markers of neurogenesis, mitochondrial biogenesis, content, dynamics and decreased mitochondrial membrane potential. Corticosterone also decreased levels of antioxidant enzymes but did not alter levels of reactive oxygen species (ROS) or elicit lipid peroxidation. We then investigated with potential impacts of cannabis components, delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), on corticosterone-induced stress. Individually, THC and CBD decreased markers of neurogenesis, dysregulated mitochondrial dynamics and decreased mitochondrial membrane potential. Interestingly, both THC and CBD increased a marker of mitochondrial biogenesis. Finally, we co-treated HT22 cells with corticosterone and THC or CBD to interrogate the impacts of THC and CBD on corticosterone-induced alterations. Our results indicated THC and CBD had no effect on corticosterone-related reductions in neurogenesis markers or mitochondrial membrane potential. However, THC demonstrated a rescuing effect on a marker of mitochondrial biogenesis and CBD normalized a marker of mitochondrial fission; both of which were decreased with individual corticosterone treatments. This thesis ultimately identifies some of the pathways THC and CBD may impact stress response in relation to neurogenesis and mitochondria. / Thesis / Master of Science (MSc) / Neurogenesis is a process that describes the production of new nerve cells in the brain. It mainly occurs during early life, but persists in a central brain structure responsible for learning and memory, known as the hippocampus, throughout our lives. This active brain structure relies on the function of certain organelles called mitochondria, which are the primary cellular energy producers and promote nerve cell production. Mood disorders, such as anxiety and depression, may result as a consequence of impaired hippocampal neurogenesis. Evidently, people suffering from anxiety and depression turn to cannabis use for management and treatment of their mood disorders. Considering cannabis has been shown to affect neurogenesis and mitochondrial function, our primary objective was to explore its effects on hippocampal neurogenesis by focusing on mitochondrial function, in the context of stress. We demonstrate that components found in cannabis, delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), alter the stress-induced changes in mitochondrial functions related to neurogenesis, suggesting that cannabis may play a role in protecting nerve cells.

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