title: Differential responses of the vasotocin 1a receptor (V1aR) and osmoreceptors to immobilization and osmotic stress in sensory circumventricular organs of the chicken (Gallus gallus) brain.
abstract: Past studies have shown that the avian vasotocin 1a receptor (V1aR) is involved in immobilization stress. It is not known whether the receptor functions in osmotic stress, and if sensory circumventricular organs may be involved. An experiment was designed with four treatment groups including a 1h immobilization acute stress (AS) group, an unstressed acute control (AC), a third given an intraperitoneal (ip) hypertonic saline injection (HS) and isotonic saline controls (IC) administered ip. One set of chick brains was perfused for immunohistochemistry while a second was sampled for quantitative RT-PCR. Plasma corticosterone (CORT) and arginine vasotocin (AVT) concentrations were significantly increased in the immobilized and hypertonic saline groups (p<0.01) compared to controls. Intense staining of the V1aR occurred throughout the organum vasculosum of the lamina terminalis (OVLT) and subseptal organ (SSO)/subfornical organ (SFO). The immunostaining allowed the boundaries of the two circumventricular organs (CVOs) to be described for the first time in avian species. Both treatment groups showed marked morphological changes in glia within the OVLT and SSO/SFO. The avian V1aR, angiotensin II type 1 receptor (AT1R), and transient receptor potential vanilloid receptor 1 (TRPV1) mRNA levels were increased in the SSO/SFO in hypertonic saline treated birds compared to isotonic controls. In contrast, the latter two genes (AT1R and TRPV1) were significantly decreased in the OVLT of birds subjected to hyperosmotic stress, while all three genes were significantly up-regulated after immobilization. Taken together, results show a possible differential function for the same receptors in two anatomically adjacent CVOs.
authors: The Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR, USA.
authors: N Alphonse
authors: NA
authors: Aman
authors: The Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR, USA.
authors: Gurueswar
authors: G
authors: Nagarajan
authors: The Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR, USA.
authors: Seong W
authors: SW
authors: Kang
authors: The Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR, USA.
authors: Megan
authors: M
authors: Hancock
authors: The Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR, USA. Electronic address: wkuenzel@uark.edu.
authors: Wayne J
authors: WJ
authors: Kuenzel
keywords: Avian AT1R; Organum vasculosum of the lamina; Subfornical organ (SFO); TRPV1; Terminalis (OVLT)