The aim of this project was to clone the gene encoding the catalytic subunit of the rat DNA replication enzyme, DNA polymerase alpha. A strategy was adopted in which cDNA clones expressing the catalytic subunit sequences would be identified using anti-DNA polymerase antibodies. DNA polymerase alpha was partially purified from regenerating rat liver and exponentially growing rat Y3 myeloma cells. The catalytic subunit was identified as a 170-180kD polypeptide by activity gel analysis of partially purified Y3 cell fractions. The catalytic subunit was found to be susceptible to degradation but without loss of polymerase activity. Glycerol gradient analysis indicated a two stage degradation of DNA polymerase in vivo. Sera were collected from mice immunised with partially purified DNA polymerase alpha from regenerated rat liver. These sera cross-reacted with Western-blotted Y3 cell fractions; removed polymerase activity from solution in plate binding assays and bound alpha polymerase activity (140-180kD) on an immuno-adsorption column cDNA was synthesised using size selected mRNA from exponentially growing Y3 cells and cloned into the expression vectors pUC8 and ?gtll, both of which utilise the lac Z gene to express cloned DNA sequences. Immunoscreening of the ?gtll library was frustrated by non-specific binding of the serum. This non-specific binding was overcome by pre-adsorbing the serum against a lysate of E. coli JM 83. Screening of the pUC8 library revealled 27 out of 2.25x104 colonies which bound pre-adsorbed anti-DNA polymerase alpha serum.

The object of this study was to investigate the effects of an aldose reductase inhibitor, sorbinil (Pfizer inc), in relation to some of the biochemical, structural and functional changes associated with diabetic nerves. An animal model, the streptozotocin-induced diabetic rat was used and the following studies were performed: Motor nerve conduction velocity (MNCV) was measured in the tibial nerve over a 6 month period. A group of rats were examined at the onset of the experiment (OC) to provide a baseline for comparison to all other groups. Age matched control (AMC) animals showed a 13% increase in MNCV during the first 3 months of the experiment with little increase thereafter. The diabetic animals (DC) did not significantly differ over the experimental period from the OC animals and were thus slower conducting than the corresponding AMC group. Administration of sorbinil (25 mg/Kg) to rats from the onset of diabetes had no effect on MNCV by 3 months but had normalised values by 6 months. Nerve glucose, sorbitol, fructose and myo-inositol levels were examined by GLC. Sorbinil had no effect on nerve glucose values but prevented the 10-fold increase in nerve sorbitol values observed with the DC animals. Sorbinil partially normalised nerve fructose values after 3 months of treatment and fully normalised them after 6 months. Myo-inositol (MI) levels showed a 45% reduction by 3 months of diabetes but were normal after 6 months. Sorbinil showed a tendency to restore the reduced MI values by 3 months. Morphometric profiles were examined in the tibial nerve. Axon areas demonstrated a 14% reduction at both 3 and 6 months of diabetes while myelin areas were increased by 13 and 22% respectively. Sorbinil treatment allowed normal axon growth and normalised myelin areas. MNCV was examined in the tibial and gastrocnemius nerves. As above, diabetes prevented the normal MNCV maturation in the tibial nerve. Sorbinil administration (25 mg/Kg) to rats initially diabetic for 2 months, was ineffective in restoring MNCV in the tibial nerve though a partial recovery was observed after 4 months of treatment. MNCV in the gastrocnemius nerve of the DC animals continued to fall as the experiment progressed, reaching a 33% reduction below the OC animals by 3 months. A spontaneous recovery was observed thereafter. Sorbinil partially normalised MNCV in the gastrocnemius nerve after 1 month. These changes exactly paralleled the changes in nerve MI levels. Sorbinil reversed the already elevated nerve sorbitol levels after 1 month of treatment though nerve fructose levels were only partially normalised after 4 months. A morphometric evaluation of the triceps surae nerve (containing fibres to gastrocnemius and soleus muscles) after 4 months of the experiment demonstrated an 18% increase of myelin area in the DC animals. Axon areas were unaffected by diabetes. Sorbinil treatment for 2 months partially normalised myelin areas. Sorbinil administration at doses of 7.5, 12.5 and 25 mg/Kg to rats that had been diabetic for 2 months did not normalise MNCV in the tibial nerve. However, 12.5 and 25 mg/Kg produced a significant improvement in MNCV of the gastrocnemius nerve after 1 month of treatment. 7.5 mg/Kg had no effect in this nerve. All doses of sorbinil produced a trend towards reversing the already elevated nerve sorbitol levels, though 25 mg/Kg was effective after 1 month of treatment whereas 12.5 mg/Kg required 2 months. 7.5 mg/Kg did not fully normalise nerve sorbitol levels. Nerve fructose values remained elevated, though treatment with 25 mg/Kg of sorbinil produced a reduction towards normal values. All 3 doses partially normalised MI levels. For all DC groups, sciatic nerve water content was significantly elevated after a 1 month experimental period. Sorbinil treatment, either given from the induction of diabetes or given after rats were initially diabetic for 2 months, had only a small effect on water content and values remained elevated compared with the controls.

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The vascularly and luminally perfused rat jejunum has been developed as a useful experimental model for the study of intestinal function. However there are discrepancies in the reported results on the fate of luminally absorbed glucose in different versions of this system. In the present work, the vascularly and luminally perfused rat jejunum in vitro was established and thorough investigation was made of the dissection procedure and other experimental variables thought to be important in the functioning of the model. Special attention was paid to the preparation of the erythrocytes for the vascular perfusion medium to ensure their ability to pass through the vascular bed and to deliver oxygen to the intestinal tissues. Measurements of the respiration of the perfused intestine were made routinely in view of the paucity of such observations in the literature. Glucose absorption, translocation and metabolism by the intestine were measured using recirculation and once-through perfusion modes and, in the latter system, analysis of these functions was followed using both enzymatic and radiochemical assay techniques. Glucose and water absorption was also studied using a lumen-only recirculation perfusion of rat jejunum in vivo. The experiments were performed over a wide range of luminal glucose concentrations and osmolarities, and using proprietary glucose-electrolyte solutions intended for use in the oral rehydration of patients. In consequence of this work, it has been possible for the first time to realise why literature reports on the fate of luminally absorbed glucose differ so widely, and the present results appear to give the most accurate record so far on the distribution of this glucose (in the absence of other metabolisable substrates, and using this particular experimental system). It is concluded that the vascularly and luminally perfused rat jejunum in vitro appears to be the best available preparation for the study of the absorptive, translocation and metabolic functions of the small intestine.

Thesis advisor: Alexa Veenema / Thesis advisor: Gorica Petrovich / Sex differences in the regulation of social behavior as well as sex biases in prevalence of social disorders such as autism are likely due to sex differences in brain function. An important candidate for investigating sex-specific regulation of social behavior is the neuropeptide arginine vasopressin (AVP). AVP shows sex differences in synthesis and fiber innervation in the brain, regulates a wide variety of social behaviors, and has been implicated in the etiology of autism. However, a systematic analysis of potential sex differences in AVP receptors in the brain and linking such parameters to sex differences in social behavior is lacking thus far. Therefore, we determined whether there are sex differences in AVP V1a receptor (V1aR) in the rat brain. We then targeted specific brain regions to determine the functional significance of such sex differences. We found that males showed higher V1aR binding densities compared to females in 6 out of 15 forebrain regions analyzed, including the anteroventral thalamic nucleus, hippocampal dentate gyrus, lateral hypothalamus, tuberal lateral hypothalamus, anterior piriform cortex, and stigmoid hypothalamic nucleus. Because of hormonal regulation of the AVP system, we also analyzed differences in V1aR binding due to estrus phase and maternal experience. Since the most robust sex difference in V1aR binding was found in the hippocampal dentate gyrus, we targeted this region to study its functional significance. Surprisingly, not only rats given an injection with a V1aR antagonist, but also vehicle-treated rats failed to show social and object recognition memory. However, social and object investigation times were normal. We therefore hypothesize that the specific impairments in memory function are likely the result of damage to other hippocampal regions due to the cannula placement. Overall, these findings demonstrate that there are significant sex differences in the V1aR in brain regions implicated in social behavior. The functional significance of these sex differences remains to be determined. / Thesis (BS) — Boston College, 2014. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: College Honors Program. / Discipline: Psychology Honors Program. / Discipline: Psychology.

Avec le développement des nouvelles technologies, l'exposition aux champs électromagnétiques est de plus en plus importante. En marge de ce développement, nos sociétés ont vu émerger des personnes présentant des symptômes qu'ils attribuent à une exposition aux champs électromagnétiques. Les résultats des études expérimentales antérieurs restant à controverse, l'objectif de ce travail est de voir si une exposition conjointe entre les champs électromagnétiques et le bruit conduit à une apparition ou une exacerbation des symptômes des champs électromagnétiques. Cette étude s'est portée sur différentes fonctions physiologiques chez une population juvénile : le sommeil, le système immunitaire, la prise alimentaire, la respiration et le comportement. Nos résultats montrent un comportement anxieux, une diminution de la locomotion ainsi qu'une augmentation du poids des animaux, associé à des variations dans le pattern alimentaire. Le sommeil et la respiration sont peu modifiés chez les animaux exposés aux champs électromagnétiques. Le système immunitaire des animaux exposés aux champs électromagnétiques présente des altérations au niveau du système immunitaire acquis avec une redistribution des sous-populations lymphocytaires en faveur d'une activation des cellules et de l'immunité humorale, mais sans variation du système immunitaire inné. L'altération de ce dernier système est observée lors de la co-exposition mais est différente de celle d'une exposition au bruit. Ce travail de thèse a permis de mettre en évidence différents effets des CEM, notamment un comportement anxieux et des variations immunitaire / With the development of wireless technologies, electromagnetic fields became an important environmental constraint. However, some people attribute symptoms to electromagnetic fields exposure. The results of experimental studies remain controversial due to contradictory results. The aim of this work is to evaluate the effects of a co-exposure between electromagnetic fields and noise. The hypothesis is that co-exposure led to an exacerbation of the electromagnetic fields effects. This work focused on different physiological functions in a juvenile population: sleep, immune system, food intake, respiratory parameters and behavior. The results showed a higher anxious behavior, a decrease of locomotor parameters and an increase in the weight of the animals, associated with variations in the food intake pattern. Sleep is slightly altered in animals exposed to electromagnetic fields. The immune system of animals exposed to electromagnetic fields exhibits alterations in the adaptive immune system by a redistribution of lymphocyte subpopulations in favor of cell activation and humoral immunity, but without variation of the innate immune system. The alteration of immune system was observed during the co-exposure with a different way than noise exposure. This work was the first study to show a variation of immune parameters in juveniles chronically exposed to electromagnetic fields

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The behavioural and neurological effects of excessive sucrose intake overlap with those of abused drugs, suggesting that sucrose bingeing should be categorized with addictive disorders. Behaviorally, a primary characteristic of drug addiction is compulsive responding, manifested as an inability to inhibit drug intake despite negative consequences. We examined whether excessive sucrose self-administration produces these behavioural patterns using a validated rat model of sucrose bingeing (Avena et al., 2008) and investigated potential neurophysiological correlates with brain slice electrophysiology. Rats (n = 8-16 per group) received 12 or 24 hour access to a 10% sucrose solution and food, while control groups received food only or a 0.1% saccharin solution with food, each day for 28 days. Sucrose/saccharin/food consumption and weight were recorded daily. Compulsive responding for sucrose was assessed one or 28 days after the final self-administration session using a conditioned suppression paradigm. Persistent responding in the presence of a cue (tone) predicting a negative outcome (0.5 mA footshock) was used as a measure of compulsive responding. Only rats given 12-hour access to sucrose developed a binge pattern of intake, in which solution consumption increased dramatically during the first hour of each session. This group also developed compulsive responding for sucrose, exhibiting a reduced conditioned suppression effect following both one day and 28 days of abstinence. At a neural level, there was a switch in direction (from reduction to enhancement) in dopaminergic (DA) modulation of GABA synaptic transmission in the oval bed nucleus of the stria terminalis (ovBNST) of rats that developed a binge pattern of sucrose intake. This switch was similar to that recently observed in rats displaying enhanced motivation to self-administer cocaine. Therefore, excessive intermittent sucrose consumption produces compulsive responding and this shift from controlled to compulsive intake may involve the same neural mechanisms that underlie excessive cocaine self-administration. / Thesis (Master, Psychology) -- Queen's University, 2012-09-28 09:28:10.705

Methamphetamine is a widely abused psychostimulant often associated with aggressive, violent, and criminal behaviour. Research into the effects of adolescent methamphetamine use on aggressive behaviour is limited. This study aimed to establish whether methamphetamine would induce aggressive behaviour following an acute dosing regimen and a chronic dosing regimen. It also aimed to establish a teratological or delayed effect on adult behaviour. To investigate this 20 male and 20 female adolescent rats were equally divided into treatment and control conditions. The treatment condition received a single dose of methamphetamine (2mg/kg) on postnatal day (PND) 35 followed by twice daily doses of methamphetamine (2mg/kg) from PND 36-46. This was done via intraperitoneal injection. The control condition received comparable doses of saline. Animals were tested using the resident intruder test following the single dose, after the completion of the final dose, and again in early adulthood (PND 90). Results found an acute dosing regimen significantly reduced aggressive-like behaviour. A chronic dosing regimen increased aggressive-like behaviour however, this relationship was less clear. Finally, the results found increased aggressive behaviour in adult animals following methamphetamine use in adolescence. This provides preliminary evidence for a teratological effect and support for the neuronal imprinting theory.