Double immunocytochemistry of vasoactive intestinal peptide and cGnRH-I in male quail: photoperiodic effects

Abstract

Reproduction in Japanese quail is primarily regulated by photoperiod. Vasoactive intestinal peptide (VIP) has been suggested as a transducer of environmental information, especially photoperiodic cues, to the hypothalamo-pituitary-gonadal axis. To investigate the possible interaction of VIP and the reproductive (gonadotropin-releasing hormone, GnRH) system, double-immunocytochemical staining for VIP and cGnRH-I was conducted in sexually mature male quail held under a long-day photoperiod (16L:8D; LD) and in sexually quiescent males held under a short-day photoperiod (8L:16D; SD). VIP-immunoreactive (ir) cells were found primarily in three locations: lateral septal organ (LSO) in nucleus accumbens (Ac), ventral hypothalamus, and infundibular area. VIP-ir cells in LSO displayed characteristics typical of cerebrospinal fluid (CSF)-contacting cells, and co-existed with cGnRH-I-ir cells and beaded fibers. In contrast, VIP-ir cells in the infundibular area did not co-exist with cGnRH-I-ir structures. The number of visible VIP-ir cells in the infundibular area of SD males was significantly lower than that of LD males, while the number of visible VIP-ir cells in Ac/LSO was not altered by photoperiod. A cluster of cGnRH-I-ir cells in the caudalmost septal area was heavily innervated by VIP-ir fibers, which appeared to contact cGnRH-I-ir cells directly at this location. Both VIP- and cGnRH-I-ir fibers heavily innervated the external layer of the median eminence (ME). These data suggest that Ac/LSO, the caudalmost septal area, and ME are possible sites of interaction between the VIP and the GnRH systems.

Chemoarchitectonic subdivisions of the songbird septum and a comparative overview of septum chemical anatomy in jawed vertebrates

“…The distribution of GnRH-ir neurons described for the septum closely matches the position of our LSc.vl, LSc.l, and CcS. This topographical assignment is corroborated by double-label data showing a close correspondence between GnRH-ir neurons and fibers immunoreactive for VIP and CRF (Teruyama and Beck, 2001;Wang and Millam, 1999). The CRF double-label data are particularly informative, as CRF-ir fibers in the present study were located only to the LSc.vl, LSc.l, and CcS.…”

Fasting differentially regulates expression of agouti-related peptide, pro-opiomelanocortin, prepro-orexin, and vasoactive intestinal polypeptide mRNAs in the hypothalamus of Japanese quail

“…The present study has revealed an identical distribution in the hypothalamus and optic tectum to that reported for VIP mRNA in the chicken (Kuenzel et al 1997), and for VIP-like-immunoreactive neuronal cell bodies in the quail brain (Aste et al 1995;Teruyama and Beck 2001). VIP mRNA was detected in hypothalamic structures implicated in the regulation of food intake, including the lateral hypothalamic area extending into the PVN, and the IN.…”

Reproductive hormones, hepatic deiodinase messenger ribonucleic acid, and vasoactive intestinal polypeptide-immunoreactive cells in hypothalamus in the heat stress-induced or chemically induced hypothyroid laying hen

“…Brains were returned to the same fixative overnight and then transferred to a sucrose solution (30% in 0.1 M sodium phosphate buffer) at 4°C. Fixed brains were placed in a brass mold with 2-mm slots and blocked at A 8.8 and A 0.6 (Kuenzel and Masson, 1988) to obtain the hypothalamic areas identified by Teruyama and Beck (2001) as containing high numbers of VIP-ir cells in sexually mature quails. Blocks were sectioned at 50 µm using a freezing microtome and sections were collected in 0.01 M PBS, pH 7.4.…”