@article{semsar_perreault_godwin_2004, title={Fluoxetine-treated male wrasses exhibit low AVT expression}, volume={1029}, ISSN={["1872-6240"]}, DOI={10.1016/j.brainres.2004.09.030}, abstractNote={In many species, increasing serotonergic activity can reduce aggression and reverse dominance relationships. These effects may in part be mediated through interactions with the arginine vasotocin/vasopressin (AVT/AVP) system. We tested this hypothesis in a territorial coral reef fish, the bluehead wrasse (Thalassoma bifasciatum), by experimentally enhancing serotonergic neurotransmission, using the selective serotonin re-uptake inhibitor (SSRI) fluoxetine. Terminal phase (TP) males received 2 weeks of nightly intraperitoneal fluoxetine injections (6 microg/g body weight) and were then tested for their aggressive response to an intruder and killed to examine AVT phenotype in the preoptic area of the hypothalamus (POA), an area important to social behavior in fishes. Our previously published study demonstrated that fluoxetine-treated males are less aggressive [H.A.N. Perreault, K. Semsar, J. Godwin, Fluoxetine treatment decreases territorial aggression in a coral reef fish, Physiol. and Behav. 79 (2003) 719-724.]. Here, further study of these same fluoxetine-treated males shows approximately twofold lower AVT mRNA expression relative to saline-treated controls in all regions of the POA (all p< or =0.05) without any changes in AVT-ir soma size (all p>0.4). This study experimentally supports the hypothesis that behavioral effects of SSRIs may be mediated in part through interactions with the AVT/AVP system. These results parallel findings from rodents and humans and are consistent with an indirect neurosteroidogenic rather than a solely direct serotonergic mechanism for SSRI effects on the AVT/AVP system. Furthermore, they suggest that SSRI effects on neuroendocrine function may be best modeled in animals with sensitive stress responses such as those found in nondomesticated animals.}, number={2}, journal={BRAIN RESEARCH}, author={Semsar, K and Perreault, HA and Godwin, J}, year={2004}, month={Dec}, pages={141–147} }
 @article{semsar_godwin_2004, title={Multiple mechanisms of phenotype development in the bluehead wrasse}, volume={45}, ISSN={["1095-6867"]}, DOI={10.1016/j.yhbeh.2004.01.003}, abstractNote={Despite having detailed information on mechanisms mediating sex-typical behavior in many species, we have little understanding of whether the same mechanisms regulate these behaviors when they are performed in the same species under different social contexts. In the five field experiments of this study of bluehead wrasses (Thalassoma bifasciatum), a sex-changing fish, we examined the roles of arginine vasotocin (AVT) and the potent teleost androgen 11-ketotestosterone (11KT) in mediating sexual and aggressive behaviors typical of dominant males. We demonstrated that AVT appears necessary for the assumption of dominant territorial status in males and females, but is sufficient only in the socially dominant terminal phase (TP) male phenotype. Specifically, an AVP V1 receptor antagonist prevented both TP males and females from gaining dominance over recently vacated territories. However, unlike TP males in a previous study, neither females nor initial phase males responded to AVT treatment with increases in display of TP male typical behaviors when under social conditions that inhibit sex change. Treating females with 11KT did not alter responsiveness to AVT, but did induce male coloration and courtship behavior that was not observed in oil-treated females. Combined with the results of a previous study, these results indicate that the ability of AVT to induce male-typical behavior differs among sexual phenotypes and that this differential responsiveness appears to be dependent on social context and not directly on exposure to 11KT. Furthermore, since 11KT can induce courtship behavior in females that is not affected by AVT, there may be different hormonal mechanisms mediating courtship behavior under different social contexts.}, number={5}, journal={HORMONES AND BEHAVIOR}, author={Semsar, K and Godwin, J}, year={2004}, month={May}, pages={345–353} }
 @article{perreault_semsar_godwin_2003, title={Fluoxetine treatment decreases territorial aggression in a coral reef fish}, volume={79}, ISSN={["0031-9384"]}, DOI={10.1016/S0031-9384(03)00211-7}, abstractNote={Serotonin is an important neurotransmitter in the regulation of social interactions in many animals. Correlative studies in numerous vertebrate species, including fishes, indicate that aggressive males have lower relative serotonergic activity than less aggressive males. We used fluoxetine, a selective serotonin reuptake inhibitor, to experimentally enhance serotonergic neurotransmission in a territorial coral reef fish and test the role of this neurotransmitter in mediating aggressive behavior and dominance interactions. The bluehead wrasse, Thalassoma bifasciatum, has a complex social system in which large males aggressively defend spawning territories from intruders. In separate experiments, we tested the effects of chronic and acute fluoxetine treatments on aggressive behavior using a resident-intruder design. In a laboratory experiment, males treated daily with intraperitoneal fluoxetine injections for 2 weeks (6 microg/g bw) displayed fewer intruder chases than saline-treated controls. Chronically fluoxetine-treated males also showed lower levels of activity than saline controls prior to intruder trials. However, activity was not correlated with chases on an individual level, indicating the lower aggression displayed by fluoxetine-treated males was not due solely to general reductions in behavioral display. A field study exposed males to a confined territorial intruder following single intraperitoneal injections of fluoxetine (10 microg/g bw) or saline given to the same individual on different days. The frequency of aggressive chases following acute fluoxetine treatment was significantly lower than that following saline injections. This study experimentally supports the link between serotonin and aggressive behavior in fishes in both a controlled laboratory testing environment and the animal's natural habitat.}, number={4-5}, journal={PHYSIOLOGY & BEHAVIOR}, author={Perreault, HAN and Semsar, K and Godwin, J}, year={2003}, month={Sep}, pages={719–724} }
 @article{semsar_godwin_2003, title={Social influences on the arginine vasotocin system are independent of gonads in a sex-changing fish}, volume={23}, DOI={10.1523/jneurosci.23-10-04386.2003}, abstractNote={Many neuropeptide systems subserving sex-typical behavior are dependent on sex steroids for both their organization early in life and activation during maturity. The arginine vasopressin/vasotocin (AVP/AVT) system is strongly androgen dependent in many species and critically mediates responses to sociosexual stimuli. The bluehead wrasse is a teleost fish that exhibits a female-to-male sex change in response to social cues, and neither the development nor the maintenance of male-typical behavior depends on the presence of gonads. To examine social and gonadal inputs on the AVP/AVT system in the preoptic area (POA) of the hypothalamus, we conducted three field experiments. In the first experiment, we found that AVT mRNA abundance is higher in sex-changing females that attain social dominance and display dominant male behavior than in subordinate females, regardless of whether the dominant females were intact or ovariectomized. However, AVT-immunoreactive (IR) soma size in the gigantocellular POA (gPOA), but not in the magnocellular or parvocellular POA, increased only when females were displaying both dominant male behavior and had developed testes. In the second experiment, castration of dominant terminal-phase males had no effect on AVT mRNA abundance or any behavior we measured but did increase gPOA AVT-IR soma size compared with sham-operated controls. In the third experiment, 11-ketotestosterone implants in socially subordinate, ovariectomized females had no effect on either AVT mRNA abundance or AVT-IR soma size compared with controls. These results demonstrate that the AVT neural phenotype in the bluehead wrasse can be strongly influenced by social status, and that these social influences can be manifested independent of gonads.}, number={10}, journal={Journal of Neuroscience}, author={Semsar, K. and Godwin, John}, year={2003}, pages={4386–4393} }
 @inproceedings{semsar_godwin_2002, title={Multiple mechanisms for phenotype development}, volume={42}, number={6}, booktitle={Integrative and Comparative Biology}, author={Semsar, K. and Godwin, J.}, year={2002}, pages={1309} }
 @article{semsar_kandel_godwin_2001, title={Manipulations of the AVT system shift social status and related courtship and aggressive behavior in the bluehead wrasse}, volume={40}, ISSN={["1095-6867"]}, DOI={10.1006/hbeh.2001.1663}, abstractNote={Arginine vasotocin (AVT) and its mammalian homologoue arginine vasopressin (AVP) influence male sexual and aggressive behaviors in many species. We tested the effects of AVT and an AVP-V(1a) receptor antagonist on the display of alternative male tactics in a tropical coral reef fish, the bluehead wrasse Thalassoma bifasciatum. We gave AVT injections to territorial and nonterritorial males of the large and colorful phenotype (terminal phase) and an AVP-V(1a) receptor antagonist, Manning compound, to territorial males in the field. AVT increased courtship independent of status, while its effects on territoriality and aggression were dependent upon male status. In territorial males, AVT increased courtship and tended to decrease the number of chases toward initial phase individuals. In nonterritorial males, AVT increased courtship, chases toward initial phase individuals, and territorial behavior while decreasing feeding. These are all behaviors rarely seen in nonterritorial males, so AVT made these males act like territorial TP males. The AVP-V(1a) receptor antagonist had opposite effects. It decreased courtship and territorial defense, making these males act more like nonterritorial males. Manipulations of the AVT system shifted males within a single phenotype from the nonterritorial social status to the territorial social status and vice versa. Since the entire suite of behaviors related to territoriality was affected by AVT system manipulations, our results suggest that the AVT system may play a key role in motivation of behaviors related to mating.}, number={1}, journal={HORMONES AND BEHAVIOR}, author={Semsar, K and Kandel, FLM and Godwin, J}, year={2001}, month={Aug}, pages={21–31} }