Vasoactive intestinal polypeptide in the chicken anterior pituitary gland

• Main Author: Shale, J. A.
• Published: University of Edinburgh 1998
• Subjects: 571.74
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.661773

Vasoactive intestinal polypeptide was shown to be present in the chicken anterior pituitary gland using high performance liquid chromatography (HPLC), radioimmunoassay (RIA) and immunocytochemistry. The VIP antibodies used for both RIA and immunocytochemistry showed no cross reaction with any known VIP-like peptides, including pituitary adenylate cyclase activating polypeptide (PACAP). VIP mRNA was also shown to be present in anterior pituitary gland. Two VIP-immunoreactive cell (VIP-ir) types were found throughout the cephalic and caudal lobes of the anterior pituitary gland. The morphological features of the VIP-ir cell types were similar to that of the folliculo-stellate cell type (FS-cell). One VIP-cell type contained the Ca2+ binding protein S-100 protein, a specific marker of FS-cells, while the S-100 protein was not detected in the second VIP-cell type. The VIP-cells were closely associated with gonadotrophs, lactrotrophs and unidentified cell types, but VIP-ir was not colocalised with LH or PRL. The VIP-cell characteristically enveloped several adjacent gonadotrophs with cytoplasmic projections, which suggests that intra-pituitary VIP may regulate the gonadotroph in a paracrine manner. VIP receptors were localised immunocytochemically, in the anterior pituitary gland and hypothalamus, using antibodies raised the peptide sequence of the human subtype-I (VIP-RI) and the subtype-II VIP receptors (VIP-RII). The VIP-RI was not present in PRL-, LH- or GH-cells, but was found exclusively in ACTH-cells. The VIP-RII was diffusely distributed through both lobes of the chicken anterior pituitary gland, but the cell type containing VIP-RII immunoreactivity was not identified. In conclusion, VIP is produced in the anterior pituitary gland and occurs in a FS-cell type which is closely associated with gonadotrophs. These observations are consistent with the view that intra-pituitary VIP may act in a paracrine manner to regulate the function of gonadotrophs.