A GABAergic habenulo-raphe pathway mediates both serotoninergic and hypnogenic effects of vasotocin in cats.
Extremely small amounts (10(-4) pg) of the pineal nonapeptide arginine vasotocin (AVT), injected into the pineal recess of freely moving cats, decreased the levels of 5-hydroxyindole acetic acid (5-HIAA) in the raphe dorsalis nucleus and induced slow wave sleep. In cats with lesions in the lateral habenula, 10(-4) pg AVT injected into the pineal recess, failed to decrease raphe dorsalis 5-HIAA levels and to induce slow wave sleep. The GABA antagonist picrotoxin (1 ng) injected into the pineal recess 15 min before the administration of AVT (10(-4) pg), completely prevented AVT from decreasing raphe dorsalis 5-HIAA levels and from inducing slow wave sleep. A highly significant correlation could be established between the decrease of raphe dorsalis 5-HIAA levels and the induction of slow wave sleep. No changes in raphe dorsalis 5-HIAA levels could be detected in cats injected with 10(-4) pg AVT into the lateral or into the fourth ventricle. Neither arginine vasopressin nor oxytocin (10(-4) pg) injected into the pineal recess, could alter raphe dorsalis 5-HIAA levels. It is concluded that AVT induces slow-wave sleep in cats by activating an inhibitory GABAergic lateral habenula-raphe dorsalis pathway.
D000818:Animals; D001127:Arginine Vasopressin / Q000502:physiology*; D001931:Brain Mapping; D002415:Cats; D004027:Diencephalon / Q000502:physiology*; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D010852:Picrotoxin / Q000494:pharmacology; D011903:Raphe Nuclei / Q000502:physiology*; D012701:Serotonin / Q000502:physiology*; D012890:Sleep / Q000502:physiology*; D012894:Sleep Stages / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
D001127:Arginine Vasopressin; D010852:Picrotoxin; D012701:Serotonin; D005680:gamma-Aminobutyric Acid