In Syrian hamsters, sexual preference requires integration of chemosensory and steroid cues. Although data suggest that separate pathways within the brain process these two signals, the functional significance of this separation is not well understood. Within the medial amygdala, the anterior region (MEa) receives input from the olfactory bulbs, whereas the posterodorsal region (MEpd) is sensitive to steroid hormones. Lesions of either the MEa or MEpd eliminated preference to investigate female over male odors. Importantly, males with MEpd lesions displayed decreased attraction toward female odors, suggesting a decrease in sexual motivation. In contrast, males with MEa lesions displayed high levels of investigation of both female and male odors, suggesting an inability to categorize the relevance of the odor stimuli. These results suggest that both the MEa and MEpd are critical for the expression of opposite-sex odor preference, although they appear to mediate distinct aspects of this behavior.

Originally developed as an anti-depressant and later available as a ‘party-pill’ in New Zealand, methylone is currently classed as an illegal drug. This is due to findings of its similarity in chemical structure to that of Ecstasy (MDMA). Methylone is a relatively new drug into which little research has been conducted. Consequently, no known study has investigated the long-term effects on behavioural development arising from exposure during adolescence. The present thesis therefore aimed to identify long-term effects of chronic adolescent exposure to methylone on adult anxiety-like behaviours. This was achieved by the use of 80 rats (40 males: 40 females) and exposing them to either a methylone or saline treatment for ten consecutive days. Two different treatment age groups (early versus late adolescence) were examined and to ensure adequate comparisons could be made, two control groups were utilised. All rats were tested during adulthood in four specifically selected anxiety-measure tests; the open-field, preference for the light side of a light-dark box, acoustic startle and responsiveness to the novel arm of a Y-maze. The results suggested methylone-exposed rats displayed more anxiolytic behaviours than saline-treated rats. In the open field methylone exposed rats exhibited less ambulation than controls and those treated in early adolescence defecated more while rats treated in late adolescence occupied the corners of the apparatus more exhibiting higher anxiety-like behaviours. Exploratory behaviours in the Y-maze were decreased in methylone-treated rats, and those exposed in early adolescence entered the novel arm less often. However, acoustic startle results suggested methylone-exposed rats were less anxious as evidenced by a lower startle amplitude than controls. Overall, the results suggested differences in anxiety-like behaviours between methylone-exposed rats and controls. It did not appear that being exposed to methylone in early adolescence resulted in vast differences in anxiety-like behaviours than if exposure began in late adolescence.

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 101-112). Available also in a digital version from Dissertation Abstracts.

Pacific lamprey (Entosphenus tridentatus) are experiencing population declines throughout their range. Xenobiotics could be an important risk factor for lamprey populations. Our goal was to establish if common herbicides, as used in forest management, could affect reproductive fitness. We determined that atrazine was a likely compound of greatest concern to lamprey populations. Using an odorant response behavioral assay we were able to demonstrate that environmentally relevant concentrations of atrazine caused a depressed response to adult lamprey holding tank effluent, likely pheromones. Atrazine also depressed their activity level; the number of times they crossed into the effluent arm after being treated with atrazine was significantly lower than controls. In addition, activity level post exposure to atrazine differed between adult life history stages, something which was not significantly different during control trials. Using an odorant detection assay, based on evaluating ventilation rate, we were able to show that environmentally relevant concentrations of atrazine caused a significant increase in ventilatory response to a repulsive odorant, a conspecific necromone. Through the detection study we also showed that lamprey,exposed to atrazine, had a slight increase in ventilatory response to odor from adult lamprey. If we are concerned about the decline in Pacific lamprey populations, then we should logically be concerned with their exposure to atrazine in the environment. / Graduation date: 2012