Vasoactive intestinal peptide stimulates turkey prolactin gene expression by increasing transcription rate and enhancing mRNA stability

Tong, Zhan; Pitts, Gilbert R.; You, Seungkwon; Foster, D. N.; Halawani, M. E. El

doi:10.1677/jme.0.0210259

Cited by 20 publications

(10 citation statements)

References 52 publications

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“…Consistent with a previous study on turkey pituitary cells (Tong et al 1998), VIP significantly increased PRL mRNA half-life from 26·3 h in control cultures to 53·0 h in VIP-treated cells, an effect that was reversed by pre-incubating the cells with the D 2 AG. This is the first time that the inhibitory effect of DA on PRL mRNA stability has been demonstrated in avian or mammalian species.…”

Section: Discussionsupporting

confidence: 91%

“…Pituitary nuclei were isolated as previously described (Tong et al 1998) with slight modifications. Briefly, pituitary cells were harvested by centrifugation and washed with diethylpyrocarbonate-treated PBS.…”

Section: Pituitary Nuclei Isolationmentioning

confidence: 99%

“…The tripeptide hypothalamic-releasing factor, TRH, and the avian PRF, VIP, produce a stimulation of PRL transcription (Camper et al 1985, Tong et al 1998, and DA effects a transcriptional repression of the PRL gene in cultured rat anterior cell lines (Elsholtz et al 1991, Fischberg & Bancroft 1995. However, the combined effects of these factors on PRL gene (B) Relative quantification of PRL mRNA levels, which were normalized by endogenous β-actin mRNA levels.…”

Section: Introductionmentioning

confidence: 99%

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Dopaminergic regulation of avian prolactin gene transcription

Kahtane

Chaiseha

Halawani

2003

Journal of Molecular Endocrinology

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It is well documented that prolactin (PRL) release and PRL gene expression in birds are controlled by the tonic stimulation of hypothalamic vasoactive intestinal peptide (VIP). However, there is good evidence that dopamine (DA) exerts both stimulatory (at the hypothalamic level) and inhibitory (at the pituitary level) effects on PRL secretion. The interactions between VIP and DA in the regulation of PRL gene transcription are not known. This study was designed to examine the effects of a D 2 DA receptor agonist (D 2 AG; R(−)-propylnorapomorphine HCl) on basal and VIP-stimulated PRL gene transcription rate, PRL mRNA steady-state levels, PRL mRNA stability and PRL release from cultured turkey anterior pituitary cells. The D 2 AG (10 −10 M) completely inhibited the stimulatory effect of VIP (10 −7 M) upon nascent PRL mRNA as determined utilizing a nuclear run-on transcription assay. To examine further the effect of the D 2 AG on PRL mRNA post-transcriptional events, anterior pituitary cells were treated with different concentrations of D 2 AG (10 −12 -10 −4 M). Semi-quantitative RT-PCR and RIA were performed to determine the levels of PRL mRNA and PRL content in the medium respectively. The results show that D 2 AG inhibited VIP-stimulated PRL mRNA steady-state levels as well as basal and VIP-stimulated PRL release, effects which were diminished by the D 2 DA receptor antagonist, S(−)-eticlopride HCl (10 −10 M). Actinomycin D (5 µg/ml), an inhibitor of mRNA synthesis, was used to assess the effect of D 2 AG on PRL mRNA stability in response to VIP. The stimulatory effect of VIP on PRL mRNA stability was completely negated by the D 2 AG (from a half-life of 53·0±2·3 h in VIP-treated cells to 25·5±1·6 h in D 2 AG+VIP-treated cells, P≤0·05). These results support the hypothesis that VIP and DA play a major role in the regulation of PRL gene expression in avian species, at both the transcriptional and post-transcriptional levels. In addition, these findings suggest that the DAergic system inhibits PRL release and synthesis by antagonizing VIP at the pituitary level via D 2 DA receptors.

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Section: Discussionsupporting

confidence: 91%

Section: Pituitary Nuclei Isolationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dopaminergic regulation of avian prolactin gene transcription

Kahtane

Chaiseha

Halawani

2003

Journal of Molecular Endocrinology

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“…In contrast to the inhibitory control mechanism for PRL involving dopamine in mammals [12][13][14], stimulation of the avian anterior pituitary gland by VIP results in increased secretion of PRL [15][16][17][18] and transcription of the gene encoding PRL [19][20][21][22][23]. Vasoactive intestinal polypeptide also enhances PRL mRNA stability [24]. Conversely, if the release of VIP is blocked via active or passive immunization against VIP, circulating levels of PRL as well as PRL mRNA will decrease [16,[24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Molecular Cloning of Chicken Vasoactive Intestinal Polypeptide Receptor Complementary DNA, Tissue Distribution and Chromosomal Localization1

Kansaku

Shimada

Ohkubo

et al. 2001

Biology of Reproduction

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Chicken vasoactive intestinal polypeptide receptor (VIPR) cDNA was cloned by the reverse transcription-polymerase chain reaction method using primers designed on the basis of other species of VIPR cDNA. The cDNA obtained was sequenced by the dideoxy-mediated chain-termination method. Of the 2227 nucleotides that were sequenced, 84, 855, and 1338 bases represent the 5'-untranslated region (UTR), the 3'-UTR, and the open reading frame that predicts a peptide of 446 amino acids. The cDNA of the chicken VIPR shows 65% and 60% homologies to human cDNA of VIP1 and VIP2 receptors, respectively. The clone had the expected similarity to highly conserved features of the other G protein-coupled receptors (GPCRs) such as six cysteine residues that are functionally important in the VIPR subfamily. In addition, the seven potential membrane-spanning domains characteristic of the family B group III GPCR superfamily and highly conserved motif within the third cellular loop between transmembrane regions 5 and 6. Northern blot hybridization analysis in this study indicated mRNA expression of VIPRs in the various tissues of the chicken. Strong signal was detected in the brain and anterior pituitary gland. High levels of VIPR mRNA in the brain was consistent with VIP-binding experiments and with the function of VIP in the brain as a neuroendocrine factor or neurotransmitter. Expression of VIPR was detected in the anterior pituitary gland of chick embryos. The expression of VIPR mRNA in the chick anterior pituitary gland may indicate a regulatory function of VIP on prolactin (PRL) production or PRL cell proliferation during embryogenesis. Chicken VIPR shows high homology with mammalian type I VIPR but, in some part, possesses similarity of amino acid sequence. Expression of VIPR in various tissues supports diverse functions for VIP in the chicken.

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“…In addition, these results correspond with VIP binding studies [32] demonstrating that hypoprolactinemic nonphotostimulated birds exhibit the fewest number of VIP high-affinity binding sites and that these sites increase after photostimulation to reach maximal levels in hyperprolactinemic incubating hens and then decrease in number again when the birds become photorefractory. VIP receptor mRNA expression in the anterior pituitary of hens in different prolactinemic states may account for the alterations in PRL gene transcription observed during the reproductive cycle and in response to VIP stimulation [50,51]. These results, present and past, provide additional evidence that VIP is the avian PRL-releasing factor and strongly suggest that VIP receptors at the pituitary level play a prominent role in the regulation of PRL secretion.…”

Section: Discussionmentioning

confidence: 59%

Expression of Vasoactive Intestinal Peptide Receptor Messenger RNA in the Hypothalamus and Pituitary Throughout the Turkey Reproductive Cycle1

Chaiseha

Youngren

Halawani

2004

Biology of Reproduction

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Vasoactive intestinal peptide (VIP) has been implicated in the regulation of avian reproductive activity and appears to act at the level of the hypothalamus and pituitary. This in situ hybridization histochemistry study describes the distribution of VIP receptor mRNA expression in the hypothalamus and the pituitary of reproductively active (laying) and quiescent (nonphotostimulated, incubating, and photorefractory) female turkeys and characterizes the differences observed in VIP receptor gene expression. VIP receptor mRNA, while expressed throughout the hypothalamus, was specifically expressed in areas known to contain GnRH-I neurons in the chicken, i.e., the lateral septum, medial preoptic area, anterior hypothalamus, and paraventricular nucleus. Significant differences in VIP receptor mRNA expression between different reproductive states was observed only within the infundibular nuclear complex. VIP receptor mRNA was markedly less in nonphotostimulated and photorefractory hens as compared with laying and incubating hens. The most dense VIP receptor mRNA was found in the anterior pituitary, where it was 2.4- and 3.0-fold greater in laying and incubating hens, respectively, as compared with that in nonphotostimulated ones. Hens that stopped incubating and became photorefractory displayed pituitary VIP receptor mRNA levels similar to those of nonphotostimulated birds. The changes in pituitary VIP receptor mRNA expression were positively correlated with known changes in pituitary prolactin (PRL) mRNA expression and PRL content and release. These findings indicate that the variations in PRL secretion observed across the turkey reproductive cycle are, in part, regulated by changes in VIP receptors at the pituitary level.

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Vasoactive intestinal peptide stimulates turkey prolactin gene expression by increasing transcription rate and enhancing mRNA stability

Cited by 20 publications

References 52 publications

Dopaminergic regulation of avian prolactin gene transcription

Dopaminergic regulation of avian prolactin gene transcription

Molecular Cloning of Chicken Vasoactive Intestinal Polypeptide Receptor Complementary DNA, Tissue Distribution and Chromosomal Localization1

Expression of Vasoactive Intestinal Peptide Receptor Messenger RNA in the Hypothalamus and Pituitary Throughout the Turkey Reproductive Cycle1

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