Hormonally derived sex pheromones in fish: exogenous cues and signals from gonad to brain

Abstract

Living in a medium that can limit visual information but readily exposes the olfactory organ to hormonal compounds released by conspecifics, fish throughout their long evolutionary history have had both clear cause and ample opportunity to evolve olfactory responsiveness to these potentially important chemical cues (hormonal pheromones). Indeed, water-borne steroids, prostaglandins, and their metabolites are detected with great sensitivity and specificity by the olfactory organs of diverse fishes, and exert important effects on reproductive behavior and physiology in major taxa including carps (goldfish), catfishes, salmon, and gobies. Best understood are goldfish, where periovulatory females sequentially release a preovulatory steroid pheromone and a postovulatory prostaglandin pheromone that dramatically affect male behavior, physiology, and reproductive fitness. Although the diverse array of hormonal products released and detected by fish indicates clear potential for species-specific hormonal pheromones, olfactory recordings showing similar patterns of hormone detection among closely related species provide little evidence of selection for specificity. By demonstrating that the actions of sex hormones and related products are not limited to reproductive synchrony within the individual, the relatively recent discovery of hormonal pheromones has considerably expanded our understanding of fish reproductive function, while providing valuable model systems for future study of olfactory function and pheromone evolution.

Hypothalamic progesterone receptor-A mediates gonadotropin surges, self priming and receptivity in estrogen-primed female mice

“…Mating behavior is a symphony of interactions between males and females predominantly influenced by female steroids and pheromones, some of which are Prog metabolites (Schwende et al 1984, Pling et al 2001, Poling et al 2001, Stacey et al 2003. In turn, activation of the male vomeronasal-accessory olfactory system generates electrophysiological changes in the forebrain circuitry for precopulatory behaviors (Pfaff 1999, Holy et al 2000, Luo & Katz 2004.…”

Tilapia male urinary pheromone stimulates female reproductive axis

“…Among this group of chemicals, sex pheromones are involved in reproduction by mediating location of suitable partners, evoking appropriate behavioural and endocrine responses, and improving synchronisation of gametogenesis, spawning, fertility and paternity (see reviews by Burnard et al, 2008;Stacey et al, 2003). The identification and characterisation of these compounds is important for understanding fish reproductive physiology (Stacey, 2011) and as a potential tool for population management (e.g., aquaculture and species invasions) (Johnson and Li, 2010;Sorensen and Stacey, 2004).…”

The elusive crypt olfactory receptor neuron: evidence for its stimulation by amino acids and cAMP pathway agonists

“…Although a large number of chemicals released by fish may act as reproductive pheromones (Stacey et al, 2003), it is possible that crypt ORNs of T. symmetricus are tuned to detect only few specific compounds not tested here, or that their group comprises a variety of odorant receptors responsive to multiple substances acting as conspecific chemosignals, but were under sampled in our experiments. The only odorant class that consistently triggered responses were amino acids, which confirms previous observations (Schmachtenberg, 2006).…”