Gonadotropin-releasing hormones modulate electrical activity of vasotocin and isotocin neurons in the brain of rainbow trout.
Gonadotropin-releasing hormone (GnRH) is widely distributed in the vertebrate brains; however, its significance in the brain function is poorly understood. Both GnRH and vasopressin-family hormones are involved in control of reproductive behavior. Anatomical evidence indicated the possible action of GnRH on classical neurosecretory neurons. In the present study, we examined whether GnRH modulates electrical activity of vasotocin (VT) and isotocin (IT) neurons in the brain of rainbow trout (Oncorhynchus mykiss). Two forms of GnRH, salmon GnRH and chicken GnRH II, are present in the rainbow trout brain, and their fibers are localized in the close vicinity of VT and IT neurons. Applications of both GnRH forms elevated the frequency of cell-type-specific synchronous Ca(2+) pulses in VT and IT neurons that are blocked by a GnRH-receptor antagonist. Our results showed facilitatory actions of GnRHs on VT and IT neurons, suggesting that GnRH neurons modulate classical neurosecretory neurons to control reproductive behavior.
Division of Biological Sciences, Hokkaido University Graduate School of Science, Sapporo, Hokkaido 060-0810, Japan. djsaito@sci.hokudai.ac.jp
Daisuke
D
Saito
Yoshihisa
Y
Hasegawa
Akihisa
A
Urano
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001369:Axons / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D001921:Brain / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism* / Q000494:pharmacology; D006065:Gonadotropins, Pituitary / Q000378:metabolism / Q000494:pharmacology; D007030:Hypothalamo-Hypophyseal System / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008636:Mesencephalon / Q000166:cytology / Q000378:metabolism; D009434:Neural Pathways / Q000166:cytology / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D017686:Oncorhynchus mykiss / Q000033:anatomy & histology / Q000502:physiology*; D010121:Oxytocin / Q000031:analogs & derivatives* / Q000378:metabolism*; D016548:Prosencephalon / Q000166:cytology / Q000378:metabolism; D011966:Receptors, LHRH / Q000037:antagonists & inhibitors / Q000378:metabolism; D012726:Sexual Behavior, Animal / Q000502:physiology; D014668:Vasotocin / Q000378:metabolism*
D006065:Gonadotropins, Pituitary; D011966:Receptors, LHRH; D007987:Gonadotropin-Releasing Hormone; D010121:Oxytocin; C008215:isotocin; D014668:Vasotocin