Browsing by Author "Falco, Adriana M."
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Item Individual Differences in Locomotion, Anxiety-like Behavior, and Reward After Nicotine and Baclofen Administration(2012-10-09) Falco, Adriana M.; Falco, Adriana M.; Smith, Robert F.Tobacco use is a significant health problem that began in adolescence for many adult smokers. Anxiety may also be a risk factor in who develops nicotine dependence disorders. This study uses adolescent male Sprague-Dawley rats (n = 160) and splits them into a high anxiety (HA) and low anxiety (LA) group based on the results of pretest day of a conditioned place preference (CPP) protocol with a biased chamber. These rats are further divided into drug groups that receive either saline or 0.6 mg/kg baclofen (i.p.) 30 minutes before testing and then either saline or 0.5 mg/kg nicotine (s.c.) immediately before testing. Open field testing showed a significant difference between HA and LA rats in locomotor activity, as well as significant differences between drug groups when compared to saline. Notably, baclofen administration significantly decreased locomotor behavior from saline levels in HA animals, but did not do so in LA animals. In both HA and LA groups, baclofen and nicotine co-administration significantly decreased locomotor behavior from locomotor activity levels in animals administered nicotine alone. Additionally, the open field was used to examine potential differences in anxiety-like behavior. Baclofen administration failed to produce differences in anxiety-like behavior between HA and LA groups, but nicotine administration and baclofen + nicotine co-administration had slightly more of an effect on anxiety-like behavior in LA than HA animals. Single-trial nicotine CPP testing found that HA rats formed significant CPP to nicotine and baclofen + nicotine, but LA rats did not. This study shows that innate anxiety-like behavior plays a significant factor in formation of locomotor responses to baclofen as well as later anxiety-like responses to nicotine and baclofen administration in adolescent rats. This study also serves to highlight the role that innate anxiety-like behavior plays in nicotine reward in adolescents.Item Individual Variance in Locomotor Behavior and D2 mRNA After Acute Nicotine(2010-01-15T20:37:36Z) Falco, Adriana M.; Falco, Adriana M.Tobacco use is one of the leading health concerns in the world. Of particular concern is the unique vulnerability that adolescents exhibit for nicotine use and addiction which has been examined via animal models. This project examines the effects that a single injection of nicotine has on early adolescent, late adolescent, and adult Long-Evans male rats. Rats were initially tested in the elevated plus maze at P28, P45, and P80 as a screen for anxious behavior. The next day, all animals received a saline injection and were placed in the open field to determine baseline locomotor behaviors. On Day 3, all animals received a single injection of nicotine (0.4 mg/kg, s.c., freebase) and locomotor variables were again determined. Twenty-four hours after nicotine injection, rats were sacrificed and tissue targeting the nucleus accumbens was sliced using a cryostat. In situ hybridization was completed to analyze the expression of D2 mRNA in the core and shell of the nucleus accumbens. When all three age groups were compared to each other, adults in the elevated plus maze spent more time in the center than either early or late adolescents. In the open field, early adolescents traveled more total distance than either late adolescents or adults and traveled more distance in the center than adults. Using the data from these two behavioral tests, simple regression equations could be calculated that were predictive of D2 mRNA expression in the core and shell among early adolescents and adults. Interestingly, elevated plus maze variables were more predictive of D2 expression in early adolescents and open field variables were more predictive of D2 expression in adults. This suggests that a rat’s expression of D2 mRNA in the NAc core and shell may be related to differential behavioral variables at different age points.