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Neurochemical control of social behavior in male and female prairie voles (Microtus ochrogaster)
Unlike most rodent models, prairie voles, show very few sex differences in social behavior. Despite the similarities in their behavior male and female voles, appear to use different physiological machinery to achieve the same behavioral goals. Therefore, male and female voles are likely to respond differently to pharmacological behavioral modifiers. To test whether the behavioral effects of serotonin potentiation vary by gender and/or reproductive context, I compared the effects of the selective serotonin reuptake inhibitor fluoxetine on parental and aggressive behavior in pairbonded, parentally-experienced male and female voles, and in pairbonded, parentally-inexperienced male and female voles. Because sociosexual experience influences the function of the serotonin system, the target of fluoxetine, I also compared serotonergic function in male and female voles that had mated, remained with a same-sex sibling, or been paired with a novel conspecific of the same sex. Fluoxetine increased the latency to parental behavior in parentally-experienced male and female voles and pairbonded, parentally-inexperienced male voles. Fluoxetine also decreased aggressive behavior in parentally-experienced male voles, but had no effect on the aggressive behavior of parentally-experienced female voles, or pairbonded, parentally-inexperienced voles of either sex. In addition, fluoxetine reduced serotonin turnover in the frontal cortex and hypothalamus/preoptic area of male and female voles. Serotonin turnover was also affected by sociosexual experience. Mating and cohabitation with a mate increased serotonin turnover in the hypothalamus of male and female voles. Furthermore, the levels of serotonin and 5-hydroxy-indoleacetic acid in the frontal cortex and amygdala were sexually dimorphic. Although this thesis focused primarily on the influence of gender and reproductive context on the behavioral effects of fluoxetine, it also revealed important aspects of parental and aggressive behavior that were independent of the effects of fluoxetine. Parentally-inexperienced female voles were infanticidal one week into pregnancy whereas their mates were parental. Furthermore, the aggressive behavior of parentally-inexperienced, pairbonded voles but not parentally-experienced voles was affected by the gender composition of the resident-intruder pair. Parentally-inexperienced, pairbonded voles were more aggressive with opponents of the same sex than opponents of the opposite-sex. The findings described in this thesis suggest that fluoxetine has sexually dimorphic effects on behavior and that sociosexual factors influence the effects of fluoxetine on behavior as well as the function of the serotonin innervation of the brain.
Villalba, Constanza A, "Neurochemical control of social behavior in male and female prairie voles (Microtus ochrogaster)" (2000). Doctoral Dissertations Available from Proquest. AAI9960798.