title: Neuroendocrine regulation of stress in birds with an emphasis on vasotocin receptors (VTRs).
abstract: The neuroendocrine stress response of vertebrates, particularly mammals, comprises at least two types of neuropeptide containing neurons, corticotropin-releasing hormone (CRH) and vasopressin (VP) neurons, and four receptors [CRH receptor one (CRH-R1) and two (CRH-R2) and VP receptor 1a (V1aR) and 1b (V1bR)]. The avian neuropeptide CRH, a 41-amino acid peptide, has been shown to have the same amino acid sequence as humans while nonapeptide neurohormone arginine-vasotocin (AVT) is regarded as highly conserved having a single amino acid substitution compared to mammalian arginine vasopressin. Similar to mammals, birds have two receptor subtypes (CRH-R1 and CRH-R2) for CRH, however, four vasotocin receptors have been identified. Less is known about the functions of the four avian vasotocin receptors compared to homologous ones found in mammals and other vertebrate classes. Recently, chicken vasotocin receptor two (VT2R) and four (VT4R) have been characterized utilizing immunocytochemistry and an imposed stress test. The purpose of this review is to present evidence that the VT2R and VT4R are involved in the avian stress response and that the cephalic lobe of the anterior pituitary appears specialized for this function as it contains the major population of corticotropes and necessary neuroendocrine receptors to respond to stressors impacting avian species.
authors.affiliation: Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR 72701, USA. wkuenzel@uark.edu
authors.forename: Wayne J
authors.initials: WJ
authors.lastname: Kuenzel
authors.forename: Seong W
authors.initials: SW
authors.lastname: Kang
authors.forename: Alexander
authors.initials: A
authors.lastname: Jurkevich
mesh_terms: D000818:Animals; D001717:Birds; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism; D008954:Models, Biological; D055099:Neuroendocrine Cells / Q000378:metabolism*; D017483:Receptors, Vasopressin / Q000378:metabolism*; D014667:Vasopressins / Q000378:metabolism
chemical_list: D017483:Receptors, Vasopressin; C034862:vasotocin receptor; D014667:Vasopressins; D003346:Corticotropin-Releasing Hormone
keywords: Vasopressin V1b and V1a receptors; Vasotocin two (VT2R) and four (VT4R) receptors