title: An activation of parvocellular oxytocinergic neurons in the paraventricular nucleus in oxytocin-induced yawning and penile erection.
abstract: Intracerebroventricular (ICV) or PVN local injections of oxytocin induce yawning and penile erection, for which a positive feedback mechanism for the PVN oxytocinergic activation is suggested, but this had not been directly substantiated in vivo. We have assessed the behavioral effects and activity of oxytocinergic neurons with double-staining for c-Fos and oxytocin in the PVN after ICV administration of oxytocin in adult male rats. ICV oxytocin injections (50 and 200 ng) dose-dependently induced yawning and penile erection and significantly increased the percentage of c-Fos positive oxytocin neurons in the medial, dorsal and lateral parvocellular subdivision of the PVN. However, increases in the magnocellular portion were not significant. We also found that lithium chloride (LiCl, 0.5 and l.0 mEq), a compound known to activate oxytocinergic neurons, also significantly increased the percentage of c-Fos positive oxytocin neurons in all PVN portions. However, LiCl did not induce yawning and penile erection, but counteracted the oxytocin-induced yawning and penile erection. These results suggest that if the activation of oxytocinergic neurons in the PVN is important for mediating oxytocin-induced yawning and penile erection, a selective activation of parvocellular oxytocinergic neurons in the PVN is likely to be involved.
authors.affiliation: Sleep and Circadian Neurobiology Laboratory, Center for Narcolepsy, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, CA 94304-5489, USA.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Kita
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Yoshida
authors.forename: Seiji
authors.initials: S
authors.lastname: Nishino
mesh_terms: D000818:Animals; D007150:Immunohistochemistry; D007276:Injections, Intraventricular; D008297:Male; D009474:Neurons / Q000378:metabolism / Q000502:physiology*; D010121:Oxytocin / Q000378:metabolism / Q000494:pharmacology*; D010286:Paraventricular Hypothalamic Nucleus / Q000166:cytology / Q000502:physiology*; D010410:Penile Erection; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015000:Yawning
chemical_list: D016760:Proto-Oncogene Proteins c-fos; D010121:Oxytocin