In male golden hamsters, puberty is marked by dramatic changes in agonistic behavior. Attack frequency gradually decreases as agonistic behavior evolves from play fighting to adult aggression. Attack types change as targets of attack mature from play fighting to adult attacks. In adult hamsters, serotonin plays an inhibitory role in aggression. Thus, the decline in attack frequency during puberty could be associated with an up-regulation of the activity of the serotonergic system. In adults, acute Fluoxetine treatment inhibited aggressive behavior at all doses. In juveniles, only the highest dose reduced attack frequency. Interestingly, juveniles treated with the lowest dose showed an increase in aggressive behavior. Attack type was also affected as treatment with Fluoxetine accelerated the maturation of attack targets. This same effect had been observed in previous studies in response to chronic social stress and dexamethasone treatment. Consequently, the role of cortisol on the development of the serotonergic system was also investigated. Furthermore, the density of serotonin innervation in the anterior hypothalamus and medial amygdala was found to be higher in adults than juveniles and consistent with the inhibition of attacks by the high dose of Fluoxetine. However, the differential effects of Fluoxetine at the lower doses were investigated through analysis of different serotonin receptor subtypes. In adult hamsters, aggression can be facilitated by activation of 5-HT₃ receptors and inhibited by 5-HT[subscript 1A] receptors. During puberty, the density of immunoreactive 5-HT1A receptors increased in the anterior hypothalamus and medial amydala while 5-HT₃ receptor immunoreactivity did not change. Thus, it is possible that in these areas the ratio of 5-HT₃ to 5-HT[subscript 1A] receptors decreases during puberty. This change is consistent with the decline in the frequency of offensive responses during puberty. The functionality of 5-HT[subscript 1A] and 5-HT₃ receptors on offensive aggression in juveniles was tested via peripheral injections of a 5-HT[subscript 1A] receptor agonist and a 5-HT₃ receptors antagonist. At the high dose, both drug treatments inhibited attack frequency and attack repetition. Together, these data examine the role of the serotonergic system on the development of agonistic behavior. / text

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

No description available.

Dissertation (Ph.D.)--Auburn University, 2006. / Abstract. Includes bibliographic references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1968. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Agonistic behavior and dominance are described for captive Townsend's chipmunks (Eutamias townsendii). A total of 10,739 encounters was recorded; 644l (59.9%) were agonistic. Chases (58.5%) and displacements (30.8%) were the predominant agonistic behaviors; threats (6.8%) and fights (4.l%) were relatively rare. Stable, non-triangular hierarchies were rapidly established in 11 of the 12 groups of chipmunks observed; the presence of individuals of equal rank in some groups precluded strict linearity. Dominance positions did not change within a group, but reversals in rank and changes from equal to dominant-subordinate reltionships occurred when the mebership of groups was changed. One hierarchy existed for both sexes; neither sex was consistently dominant. Experience and individual differences in activity and aggresiveness were more important determinants of an animal's position than were sex or size. No correlation was found between rank and encounter frequency, nor was closeness of rank strongly correlated with high numbers of agonistic encounters between any two chipmunks. The frequencies of recognitory and sexual behavior were inversely related to the frequency of agonistic behavior between the pairs of animals. Ritualized throats and appeasement behaviors did not replace overt aggression in established hierarchies. Members of hierarchies showed neither a reduction in numbers of asonistic encounters, nor temporal changes in froquency of the different types of agonistic behavior. Agonistic encounters increased in frequency from August to December, but seasonal variations wore much smaller than variations among the groups. Although dominance reduced neither the frequency of agonistic behavior nor the time and energy spent in chasing, it nay be advantageous in curtailing harmful confrontations and enhancing the establishment of tolerance among some individuals.

Title from title page of PDF (University of Missouri--St. Louis, viewed March 8, 2010). Includes bibliographical references.

Thesis (M.S.)--Florida State University, 2006. / Advisor:Thomas A. Houpt, Florida State University, College of Arts and Sciences, Dept. of Biological Science. Title and description from dissertation home page (viewed June 7, 2006). Document formatted into pages; contains vi, 37 pages. Includes bibliographical references.

M. S.