Evidence that vasoactive intestinal polypeptide is a physiological prolactin-releasing factor in the bantam hen

Macnamee, M.C.; Sharp, P. J.; Lea, Robert; Sterling, R. J.; Harvey, Steven

doi:10.1016/0016-6480(86)90057-2

Cited by 152 publications

(74 citation statements)

References 32 publications

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“…The avian PRF, VIP, is a potent stimulator of PRL release and PRL gene expression, both in vivo and in vitro (Macnamee et al 1986, Opel & Proudman 1988, El Halawani et al 1990a,b, Xu et al 1996. Conversely, as in the present study, D 2 AGs have been shown to inhibit VIP-stimulated PRL mRNA steady-state levels and PRL secretion by turkey pituitary cells (Xu et al 1996).…”

Section: Discussionmentioning

confidence: 99%

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: Discussionmentioning

confidence: 99%

Dopaminergic regulation of avian prolactin gene transcription

Kahtane

Chaiseha

Halawani

2003

Journal of Molecular Endocrinology

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“…Chicken VIP (cVIP) is different in its amino acid sequence from that of mammalian VIP at positions 11, 13, 26, and 28, although the total number of amino acid residues is the same [2]. Abundant VIP immunoreactive neurons are found in the hypothalamus of the quail [3], bantam [4], pigeon [5], and turkey [6] with axons that extend to the external layer of the median eminence, suggesting physiological relevance in neuroendocrine regulation. The presence of VIP receptors in the brain of guinea pigs [7] and rats [8,9] has been reported, Received …”

Section: Vasoactivementioning

confidence: 99%

Presence of Vasoactive Intestinal Peptide Receptor in the Hen Hypothalamus.

et al. 1995

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“…DA inhibits PRL release from anterior pituitary cells in vitro in chicken, pigeon and turkey (Harvey et al, 1982;Chadwick, 1983 andFehrer, 1984) and also in vivo in turkeys (El Halawani et al, 1991). DA-binding sites in the anterior pituitary of bantam hens decrease during incubation, when PRL is high (Macnamee et al, 1986). The dopaminergic D 2 receptor agonist quinpirole inhibits VIP-induced PRL secretion and PRL mRNA level when incubated with turkey anterior pituitary cells (Xu et al, 1996), suggesting the presence of inhibitory D 2 DA receptors within the pituitary.…”

Section: Introductionmentioning

confidence: 99%

Mucuna pruriens seed powder feeding influences reproductive conditions and development in Japanese quail Coturnix coturnix japonica

Prasad

Qureshi

2009

Animal

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This study was designed to test whether Mucuna pruriens, a natural source of L-dihydroxyphenylalanine (L-DOPA, a dopamine precursor) feeding, can influence development and reproductive conditions in the high food value bird, Japanese quail, Coturnix coturnix japonica. Experiments were performed in both male and female Japanese quail. One-week-old quail chicks were divided into three groups of 36 birds each. Group I was provided with normal diet and served as control. Group II was provided with food mixed with L-DOPA (50 mg/15 g food) and Group III was provided with food mixed with M. pruriens seed powder (480 g/kg food). At the age of 3 weeks (when birds were sexually distinguished) Group I was divided into two subgroups IA (male) and IB (female) of six birds each. Similarly, Groups II and III were sub-divided into IIA (male), IIB (female) and IIIA (male), IIIB (female), respectively, of six birds each. Observations were made up to the age of 5 weeks. Male experimental groups (IIA and IIIA) showed significantly increased testicular activity, cloacal gland volume, body weight (BW), plasma testosterone and LH level in comparison to control (IA). Similarly female experimental groups (IIB and IIIB) showed significantly greater weight of reproductive organs (uterus, ovary, oviduct and ovarian follicle), BW, egg weight and size and number of follicles. On the other hand, plasma prolactin level was significantly low in comparison to control (IB). Results suggest that M. pruriens is a rich natural source of L-DOPA and the development and reproduction in Japanese quail might be associated with the dopaminergic system of the brain.Keywords: reproduction, Mucuna pruriens, L-DOPA, nutrition, Japanese quail IntroductionAccording to our present knowledge, neuropeptides and biogenic amines are the most important secretions of neuroendocrine cells. The role of the central nervous system (CNS) neurotransmitters, which appear to be the mediator of many control mechanisms in mammals (Weiner and Ganong, 1978), is little understood in other vertebrate groups except for mammals. The neuroendocrine system is an integral component of the neuronal apparatus of the brain, a major portion of which is concentrated in the hypothalamus. The hypothalamic monoamines dopamine (3,4-dihydroxyphenylalanine), noradrenalin and serotonin have profound effects on the release of mammalian pituitary hormones, presumably in most cases by modulating the release of the hypothalamic hormone . The hypothalamus is of paramount importance as an 'integration center' for the various influences on pituitary function. The hypothalamus apparently responds to the exteroceptive and interoceptive stimuli by altering the secretion of certain neurotransmitters and release hormones. Ideally, a study of the control of pituitary function should not only show the effects of any particular influence on hormone secretion but also demonstrate the changes in the metabolism of neurotransmitters and release of inhibiting hormones. Dopamine (DA) is reported to be synthesized large...

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Evidence that vasoactive intestinal polypeptide is a physiological prolactin-releasing factor in the bantam hen

Cited by 152 publications

References 32 publications

Dopaminergic regulation of avian prolactin gene transcription

Dopaminergic regulation of avian prolactin gene transcription

Presence of Vasoactive Intestinal Peptide Receptor in the Hen Hypothalamus.

Mucuna pruriens seed powder feeding influences reproductive conditions and development in Japanese quail Coturnix coturnix japonica

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