title: Corticosterone suppresses vasotocin-enhanced clasping behavior in male rough-skinned newts by novel mechanisms interfering with V1a receptor availability and receptor-mediated endocytosis.
abstract: In rough-skinned newts, Taricha granulosa, exposure to an acute stressor results in the rapid release of corticosterone (CORT), which suppresses the ability of vasotocin (VT) to enhance clasping behavior. CORT also suppresses VT-induced spontaneous activity and sensory responsiveness of clasp-controlling neurons in the rostromedial reticular formation (Rf). The cellular mechanisms underlying this interaction remain unclear. We hypothesized that CORT blocks VT-enhanced clasping by interfering with V1a receptor availability and/or VT-induced endocytosis. We administered a physiologically active fluorescent VT conjugated to Oregon Green (VT-OG) to the fourth ventricle 9 min after an intraperitoneal injection of CORT (0, 10, 40 μg/0.1mL amphibian Ringers). The brains were collected 30 min post-VT-OG, fixed, and imaged with confocal microscopy. CORT diminished the number of endocytosed vesicles, percent area containing VT-OG, sum intensity of VT-OG, and the amount of VT-V1a within each vesicle; indicating that CORT was interfering with V1a receptor availability and VT-V1a receptor-mediated endocytosis. CORT actions were brain location-specific and season-dependent in a manner that is consistent with the natural and context-dependent expression of clasping behavior. Furthermore, the sensitivity of the Rf to CORT was much higher in animals during the breeding season, arguing for ethologically appropriate seasonal variation in CORT's ability to prevent VT-induced endocytosis. Our data are consistent with the time course and interaction effects of CORT and VT on clasping behavior and neurophysiology. CORT interference with VT-induced endocytosis may be a common mechanism employed by hormones across taxa for mediating rapid context- and season-specific behavioral responses.
authors.affiliation: Department of Biology, Willamette University, Salem, OR 97301, USA.
authors.forename: Audrey
authors.initials: A
authors.lastname: Davis
authors.affiliation: Department of Biology, Willamette University, Salem, OR 97301, USA.
authors.forename: Emily
authors.initials: E
authors.lastname: Abraham
authors.affiliation: Department of Biology, Willamette University, Salem, OR 97301, USA.
authors.forename: Erin
authors.initials: E
authors.lastname: McEvoy
authors.affiliation: Department of Biology, Willamette University, Salem, OR 97301, USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Sonnenfeld
authors.affiliation: Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA.
authors.forename: Christine
authors.initials: C
authors.lastname: Lewis
authors.affiliation: Department of Neural & Pain Sciences, School of Dentistry, University of Maryland, Baltimore, MD 21201, USA.
authors.forename: Catherine S
authors.initials: CS
authors.lastname: Hubbard
authors.affiliation: School of Pharmacy, University of Wyoming, Laramie, WY, USA.
authors.forename: E Kurt
authors.initials: EK
authors.lastname: Dolence
authors.affiliation: Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA.
authors.forename: James D
authors.initials: JD
authors.lastname: Rose
authors.affiliation: Department of Biology, Willamette University, Salem, OR 97301, USA. Electronic address: ecodding@willamette.edu.
authors.forename: Emma
authors.initials: E
authors.lastname: Coddington
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D003345:Corticosterone / Q000494:pharmacology*; D015536:Down-Regulation / Q000187:drug effects; D004705:Endocytosis / Q000187:drug effects; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D017483:Receptors, Vasopressin / Q000378:metabolism*; D012154:Reticular Formation; D012455:Salamandridae / Q000502:physiology; D012726:Sexual Behavior, Animal / Q000187:drug effects* / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects; D014668:Vasotocin / Q000378:metabolism / Q000502:physiology*
chemical_list: D017483:Receptors, Vasopressin; D014668:Vasotocin; D003345:Corticosterone
keywords: Acute stress; Confocal microscopy; Context-dependent behavior; Cortisol; Hormone action; Neuroethology; Non-genomic; Receptor-mediated endocytosis; Vasopressin; Vasotocin