Pheromonal activation of vomeronasal neurons in plethodontid salamanders

The evolution of pheromonal communication

“…The protein pheromones secreted by male plethodontid salamanders have been shown to activate vomeronasal receptor neurons, but not olfactory receptor neurons in females of the species [86]. Moreover, application of these peptide pheromones to the snout of females increases expression of the immediate early gene c-Fos in areas of the brain thought to be involved in reproduction and sexual receptivity [54], suggesting a functional link between the VNO and the reproductive brain in these salamanders.…”

Is the vomeronasal system really specialized for detecting pheromones?

“…The vomeronasal system mediates both the acceleration of reproductive maturation in female mice exposed to male pheromones and the increase in circulating luteinizing hormone in male mice exposed to a protein from urine of female mice [19][20][21]. In female salamanders (Cynops pyrrhogaster and Plethodon jordani), attraction pheromones produced by males elicit physiological responses from the vomeronasal organ but not from the olfactory epithelium [22,23]. In some snake species, the male vomeronasal organ detects female pheromones in scent trails, and these cues are used to assess reproductive status [24].…”

Chemical signals and vomeronasal system function in axolotls (Ambystoma mexicanum)

“…To date, the pheromones that have been isolated from amphibians are all peptides and proteins (Kikuyama et al, 1995;Rollmann et al, 1999;Wabnitz et al, 1999;, and the only study demonstrating selective stimulation of the vomeronasal organ used stimuli that were 3 kDa and larger (Wirsig-Wiechmann et al, 2002). Perhaps the vomeronasal system of amphibians detects large molecules, and the olfactory system responds to smaller molecules.…”