Molecular cloning and expression analysis of the turkey vasoactive intestinal peptide receptor

Vasoactive intestinal peptide (VIP) is a prolactin (PRL)releasing factor wh ose activity in avian species is believed to be mediated by a specific VIP receptor (VIP-R). Circulating PRL levels are closely related to hypothalami c VIP immunoreactivity, hypothalamic VIP mRNA content, and hypophysial-port al blood VIP concentrations in turkeys. In the present study, a turkey VIP- R (tVIP-R) cDNA was cloned and its mRNA abundance was quantified in various tissues during different reproductive stages. The 2347-bp tVIP-R cDNA enco ded a 457 amino acid protein, with a predicted Mr of 52 kDa. The full-lengt h cDNA shares approximately 55% similarity with the mammalian VIP receptor- 1. Northern blot analysis revealed that a major 2.7-kb transcript was expre ssed in laying hen pituitaries. Furthermore, two minor tVIP-R transcripts o f 3.7 and 3.4 kb were observed. Semiquantitative reverse transcription poly merase chain reaction (RT-PCR) was performed using RNA from various turkey brain and peripheral tissues throughout the reproductive cycle. The steady- state levels of pituitary tVIP-R mRNA changed during the reproductive cycle , whereas mRNA expression in other tissues was not affected. The steady-sta te levels of tVIP-R mRNA were only affected in the pituitary, whereas mRNA expression in any of the other tissues examined following the immunization of turkeys against VIP were not affected. (C) 2001 Academic Press.