The significance of olfaction and social cues in milt availability, sexual hormone status, and spawning behavior of male rainbow trout (Oncorhynchus mykiss).
Male rainbow trout orientate to a "releaser" pheromone emitted by an ovulated female. This chemical signal is not necessary for the completion of spawning behavior: anosmic males spawned as readily as intact males when paired with ovulated females. The amount of "strippable" milt and plasma concentrations of testosterone (T) and 17 alpha,20 beta-dihydroxy-4-pregnen-3-one (17,20 beta-P) were greater in males paired for 3 hr with ovulated females than in isolated males, or males placed with nonvitellogenic adult females or in all male groups. Milt and plasma T, 17,20 beta-P, and 11-ketotestosterone (11-KT) were reduced in anosmic males paired with ovulated females, indicating the existence of a priming pheromone. Milt, T, 11-KT, and 17,20 beta-P increased in intact males within 4 hr after injection of salmon gonadotrophin-releasing hormone analogue, lyophilized salmon pituitary extract, or homogenized fresh rainbow trout pituitary material. The results indicate that the priming pheromone acts through the hypothalamus-pituitary-gonad axis.
Olsén
K H
KH
Department of Zoophysiology, Uppsala University, Sweden.
Liley
N R
NR
D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D005260:Female; D012739:Gonadal Steroid Hormones / Q000097:blood*; D006908:Hydroxyprogesterones / Q000097:blood / Q000378:metabolism; D008297:Male; D000857:Olfaction Disorders; D010060:Ovulation; D010675:Pheromones; D012098:Reproduction / Q000502:physiology*; D012661:Semen / Q000502:physiology*; D012903:Smell / Q000502:physiology*; D013094:Spermatozoa / Q000502:physiology; D013739:Testosterone / Q000031:analogs & derivatives / Q000097:blood / Q000378:metabolism; D014337:Trout / Q000502:physiology*
D012739:Gonadal Steroid Hormones; D006908:Hydroxyprogesterones; D010675:Pheromones; C021012:17 alpha,20 beta-dihydroxypregn-4-en-3-one; D013739:Testosterone; C003600:11-ketotestosterone