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The experiments reported in this thesis attempted to examine the influence of thirst on the extinction of taste aversions in rats. Differences in the amount of stimulus exposure and deprivation state between groups were controlled for. The first experiment presented two novel flavours twelve times to rats when either thirsty or sated. A preference for the flavour presented when thirsty was established. The next three experiments examined whether this preference would accelerate the extinction of a taste aversion, by first pairing a novel flavour with lithium and then presenting the conditioned flavour when rats were either sated or thirsty. No evidence of accelerated extinction was found. The final two experiments examined whether the associatively-activated representation of sucrose could function to extinguish a taste-aversion to that sucrose without presenting sucrose itself. No evidence of representation-mediated extinction was found despite evidence that the context was associated with sucrose. The results indicate that the extinction of conditioned taste aversions is not influenced by counter-conditioning due to thirst relief, and extinction of such aversions appears to be due to similar processes as other forms of conditioning.

Skeletal muscle proteins are the largest amino acid pool in animal body and are continuously degraded and resynthesized. Dozens of factors have been shown to influence the balance between synthesis and degradation and thereby regulate muscle growth and function. It is now know that one of the major regulatory bases of muscle metabolism is neuron-muscle interaction. A neurogenic factor, ciliary neurotrophic factor (CNTF), is proposed to exert myotrophic actions and could possible be a mediator of neuron-muscle interactions. The goal of this study was to investigate the effects of CNTF on muscle protein turnover in an in vitro system. CNTF was applied to differentiated cultured muscle cells (L8 cell line). Radiochemical labeled amino acids were added to the culture medium to determine the rate of incorporation or release by the cells as indexes of protein synthesis and protein degradation, respectively. Total protein was measured as an index of change in total protein accretion. Twelve hours of CNTF treatment increased myofibrillar protein synthesis by 10%. However, longer CNTF treatment (24 hours) reduced non-myofibrillar protein synthesis. CNTF (1 ng/ml) decreased protein degradation but higher doses (20 ng/ml) accelerated protein degradation. These changes in protein turnover resulted from changes in the myofibrillar protein fraction rather than from changes in turnover of the non-myofibrillar fraction. The change in protein synthesis and protein degradation resulted in an increase in total protein accretion of about 6%. Compared with the myotrophic studies on the effects of CNTF in vivo, the action of CNTF were relatively small. Reverse transcription polymerase chain reaction (RT-PCR) analysis showed that CNTF receptor alpha subunit (CNTFR��) mRNA expression is lower than which is expressed in muscle tissue. This could explain the reason why CNTF exerted smaller effects in vitro compared to those reported in vivo. Overall, CNTF exerts a small but statistically significant anabolic actions in cultured skeletal muscle and the actions were highly dose-dependent. The limited action of CNTF in vitro may be related to its low receptor density in the L8 cell (compared to in vivo). Because actions may be highly dose-dependent, a challenging series of studies are ahead for anyone wishing to identify the signal transduction mechanisms which account for CNTF's actions. / Graduation date: 1998

An examination of the image of the rat in Nineteen Eighty-Four, with a focus on how the rat becomes a metaphor for Winston. Further, an examination of how Winston's rat-like behaviour has affected his early family life and how such behaviour has continued to affect Winston. Families in the novel are examined with a view to understanding Winston's relation to the betrayal exemplified by these families, and finally as a way of understanding the true nature of Julia's betrayal of Winston in the Ministry of Love.

Disuse of a limb has been repeatedly demonstrated to cause pronounced atrophy of skeletal muscle. In animals and humans, disuse of a leg due to immobilization can cause pronounced catabolism of many skeletal muscle proteins. Strength, V02 max, oxidative enzyme activities, protein synthesis, and muscle weight are all diminished due to chronic limb immobilization.Testosterone is classified as an anabolic steroid which has the effect of increasing protein synthesis in many tissues. Recently, testosterone has been shown to have a definite anti-catabolic effect on skeletal muacle by competing with glucocorticoids for binding proteins within the muscle cell. This reduces the effect of the circulating catabolic hormones. By slowing protein breakdown and increasing protein synthesis in the skeletal muscle of an immobilized limb, testosterone could effectively delay the rapid atrophy so often seen.To examine the effects of testosterone on skeletal muscle atrophy during limb immobilization, forty albino, male rats were randomly divided into four groups of ten. Group I served as the non-immobilized control and received daily placebo injections of sesame oil. The rats in group II were castrated and their hindlimbs were immobilized using a plaster cast. The animals in this group also received daily injections of sesame oil. The group III rats were also castrated and casted, but they received a daily injection of 5 mg testosterone propionate. The animals in group IV were not castrated but were casted.These rats also received a daily injection of testosterone. The duration of treatment was two weeks for each rat. Body weights were measured before and after treatment. The gastrocnemius, quadriceps, soleus, and cardiac muscles were weighed after treatment. Oxygen consumption capacity (Q02), citrate synthase activity, total protein, and percentage of water were also measured in the gastrocnemius, quadriceps, and cardiac tissues.The results of this study demonstrate that hindlimb immobilization not only causes severe atrophy in those muscles immobilized, but has an overal catabolic effect on the animal. Along with the effects on muscle and body size, the immobilization also significantly reduced the aerobic capacity of affected muscle groups and cardiac tissue. The study also gave evidence that testosterone, or the lack of it, can affect the rate of muscle atrophy. The greatest reduction in body weight, muscle size, heart size, and QO2 were seen in the castrated group which only received a placebo injection of sesame oil. The anti-catabolic effect of testosterone was evedent in groups III and IV.