New insights into neuropeptide modulation of aggression: field studies of arginine vasotocin in a territorial tropical damselfish

Abstract

The neuropeptides arginine vasotocin (AVT) and arginine vasopressin are key modulators of affiliation and aggression among non-mammalian and mammalian vertebrates, respectively. Here, we explored AVT's effect on aggression in a wild population of beaugregory damselfish, Stegastes leucostictus, a highly territorial species. Aggression by territorial males towards 'intruders' (bottled fishes) was assessed before and after each male received intramuscular injections of either AVT, Manning compound (an AVT V1a receptor antagonist), isotocin (the teleost homologue of mammalian oxytocin differing from AVT by two amino acids) or saline (vehicle control). Compared to saline controls, AVTand Manning increased and decreased aggression, respectively, while isotocin had no effect. Response selectivity was further established in a dose-response study that revealed an inverted U-shaped function. Compared to saline controls, aggression levels for low and high AVT doses were similar, while medium dose treatments were significantly greater. This type of behavioural response, the first that we know of for a vertebrate neuropeptide, could depend on the binding of AVT to both V1-type and other AVTor non-AVT receptors. The pattern revealed here for damselfish may be symptomatic of species-and context-dependent specificity of AVT's modulation of aggression across teleosts, as is currently proposed for tetrapods.

Comparative gene expression profiles for highly similar aggressive phenotypes in male and female cichlid fishes (Julidochromis)

“…Isotocin, a paralog of arginine vasotocin (AVT) and a homolog to mammalian oxytocin, is a candidate for the regulation of dominant and aggressive behavior in Julidochromis. Although the few studies that have investigated a role for isotocin in aggressive behavior have found no correlation (Santangelo and Bass, 2006), its expression pattern here suggests otherwise. Parvalbumin, another identified gene in the dominance M. Schumer, K. Krishnakant and S. C. P. Renn module, is expressed in GABAergic neurons (de Almeida et al, 2005), which have been linked to aggressive behavior in a number of mammalian species.…”

Mate choice in response to dynamic presentation of male advertisement signals in túngara frogs

“…Our study shows that this preference hinges critically on the timing of complex call production: females prefer males that produce a complex call. All males are capable of producing complex calls but choose to do so depending on the social environment, with complex calls more commonly produced (1) during bouts of vocal competition between neighbouring males (Bernal et al 2009), (2) in the presence of females (K. L. Akre, personal communication), (3) when predation risk is perceived to be lower (Tuttle et al 1982;Jennions & Backwell 1992;Phelps et al 2007) and (4) when injected with arginine vasotocin (Kime et al 2007), a neuropeptide that modulates social behaviour in many species (Moore & Miller 1983;Boyd 1994;Chu et al 1998;Marler et al 1999;Sanantgelo & Bass 2006). We show that the continued production of complex calls is critical when females are assessing and approaching potential mates, and therefore, males should be under selection to maintain complexity during peak female attendance at the chorus or when females are detected directly.…”

Intra- and interspecific aggression do not modulate androgen levels in dusky gregories, yet male aggression is reduced by an androgen blocker

“…Vasopressinergic neuropeptides like AVP/AVT, and the serotonergic systems have been identified as crucial determinants in the regulation of aggression (Trainor et al, 2009), including coral reef teleosts (Semsar et al, 2001). Indeed, AVT has been shown to increase aggression in a dose dependent manner in Stegastes leucosticus, a tropical year-round territorial damselfish (Santangelo and Bass, 2006). Fluoxetine, a serotonin reuptake inhibitor which enhances serotonergic neurotransmission, caused a decline in aggressive behavior in Thalassoma bifasciatum (Perreault et al, 2003).…”