Arginine vasotocin regulates social ascent in the African cichlid fish Astatotilapia burtoni Lin S. Huffman a , Flora I. Hinz a , Sophie Wojcik b , Nadia Aubin-Horth b,c , Hans A. Hofmann a,⇑ a The University of Texas at Austin, Department of Integrative Biology, Institute for Cellular and Molecular Biology, Center for Brain, Behavior, and Evolution, Austin, TX 78712, USA b Université de Montréal, Département de Sciences Biologiques, Montréal, Québec H2V 2S9, Canada c Université Laval, Département de Biologie & Institut de Biologie Intégrative et des Systèmes, Québec, Québec G1V 0A6, Canada article info Article history: Available online xxxx Keywords: Nonapeptides Manning compound Aggression Social dominance Plasticity abstract Neuropeptides modulate many aspects of behavior and physiology in a broad range of animals. Arginine vasotocin (AVT) is implicated in mediating social behavior in teleost fish, although its specific role varies between species, sexes, life stages, and social context. To investigate whether the effects of AVT on behav- ior depend on social context, we used the African cichlid fish Astatotilapia burtoni, which is well-known for its remarkable behavioral plasticity. We pharmacologically manipulated the AVT system in estab- lished socially dominant and subordinate A. burtoni males, as well as in males ascending to dominance status in a socially unstable environment. Our results show that exogenous AVT causes a stress response, as evidenced by reduced behavioral activity and increased circulating levels of cortisol in established dominant and subordinate males. Administration of the AVT antagonist Manning compound, on the other hand, did not affect established subordinate or dominant males. However, AVT antagonist-treated males ascending from subordinate to dominant status exhibited reduced aggressive and increased courtship behavior compared to vehicle-treated animals. Finally, we measured circulating cortisol levels and brain gene expression levels of AVT and its behaviorally relevant V1a2 receptor in all three social phenotypes and found that plasma cortisol and mRNA levels of both genes were increased in ascending males com- pared to dominant and subordinate males. Our results provide a more detailed understanding of the role of the AVT system in the regulation of complex behavior in a dynamically changing social environment. Ó 2014 Elsevier Inc. All rights reserved. 1. Introduction Neuropeptide systems such as the nonapeptide arginine vasoto- cin (AVT) and its mammalian homolog arginine vasopressin (AVP) are present in diverse taxa, but their functional roles in behavior can vary widely. In addition to being involved in the regulation of a variety of social behaviors in all vertebrate species studied thus far (reproduction, Salek et al., 2002; pair-bonding, Winslow et al., 1993; Oldfield and Hofmann, 2011; parental care, Wang et al., 1994; Kleszczyn ´ ska et al., 2012; affiliation, Landgraf et al., 2003; Young and Wang, 2004; social approach, Thompson and Walton, 2004; Braida et al., 2012), the AVT/AVP system also regulates cen- tral and peripheral stress responses (Engelmann et al., 2004), although its specific role appears to differ between species, sexes, life stages, and social contexts (for review, see Goodson (2008), Godwin (2010)). This neuropeptide system has also been associated with social status (Ferris et al., 1989; Godwin et al., 2000; Goodson and Bass, 2001; Aubin-Horth et al., 2007; Greenwood et al., 2008; Almeida et al., 2011; Lema et al., 2012) and with aggressive behavior in males (Ferris et al., 1997; Goodson, 1998; Delville et al., 2000). However, the involvement of AVT in male aggression can depend on social context (Semsar et al., 2001; Greenwood et al., 2008; Filby et al., 2010), although a detailed understanding is still lacking. Even though the role of AVT in behavioral regulation appears to be conserved in some manner across vertebrates, it is clear that AVT might play different roles in different social contexts, and it has been suggested that this may be observed even within a single species (Goodson, 2008; Ophir, 2011). To gain a better understand- ing of these processes we need a model system in which differ- ences in social context are associated with differences in behaviors and AVT levels, and in which we can experimentally test the behavioral role of AVT in these different social contexts. The African cichlid fish Astatotilapia burtoni is an established model system in social neuroscience and is well-suited to examine AVT function due to its remarkable behavioral plasticity and ease of experimentation (Hofmann, 2003; Fernald and Maruska, http://dx.doi.org/10.1016/j.ygcen.2014.03.004 0016-6480/Ó 2014 Elsevier Inc. All rights reserved. ⇑ Corresponding author. Address: The University of Texas at Austin, Department of Integrative Biology, 2415 Speedway – C0990, Austin, TX 78712, USA. E-mail address: hans@utexas.edu (H.A. Hofmann). General and Comparative Endocrinology xxx (2014) xxx–xxx Contents lists available at ScienceDirect General and Comparative Endocrinology journal homepage: www.elsevier.com/locate/ygcen Please cite this article in press as: Huffman, L.S., et al. Arginine vasotocin regulates social ascent in the African cichlid fish Astatotilapia burtoni. Gen. Comp. Endocrinol. (2014), http://dx.doi.org/10.1016/j.ygcen.2014.03.004