Vasoactive-Intestinal-Polypeptide Concentrations in Median Eminence of Hypothalamus

Samson, Willis K.; Said, Sami I.; Graham, Julia; McCann, Samuel M.

doi:10.1016/s0140-6736(78)91618-5

Cited by 31 publications

(10 citation statements)

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“…In conclusion, VIP can now be considered a possible PRF in primates because (1) it acts at the pituitary level to evoke PRL secretion in monkeys; (2) it is found in relatively high concentrations within the median eminence of humans [21 ], and (3) receptors specific for VIP are present in plasma membranes obtained from a human PRL secreting tumor [I]. However, the unequivocal acceptance of VIP as a physi ologic PRF in monkeys requires the demonstration that it is secreted by the median eminence into hypophyseal portal blood in amounts sufficient to evoke PRL secretion.…”

Section: Discussionmentioning

confidence: 99%

“…A possible candidate to fulfill this role is vasoactive intestinal polypeptide (VIP), an octacosapeptide first isolated from porcine duodenum [18], which subsequently has been iden tified in several brain areas of mammals, including the hy pothalamus [4,10,13,21]. This peptide is currently viewed as a putative PRF in rats because it evokes the secretion of prolactin (PRL) when injected either intracerebroventricularly or intravenously [ 12,26], and because it is secreted into hypophyseal portal blood [19].…”

Section: Introductionmentioning

confidence: 99%

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Stimulation of Prolactin Secretion in Rhesus Monkeys by Vasoactive Intestinal Polypeptide

Frawley

Neill

1981

Neuroendocrinology

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Vasoactive intestinal polypeptide (VIP) is a potent stimulus for prolactin (PRL) release in rats. The purpose of this study was to test the effect of VIP on PRL secretion in rhesus monkeys and to identify its site of action. Three experimental models were used: (1) intact monkeys during the follicular phase of the menstrual cycle; (2) female, hypophyseal stalk-transected, ovariectomized monkeys (ST-OVX), and (3) monkey pituitary tissue perifused in vitro. Initial serum concentrations of immunoreactive PRL were more than 10-fold higher for ST-OVX monkeys (52.4 ± 10.4 ng/ml, X ± SEM; n = 6) than for intact monkeys (4.79± 1.0 ng/ml; n = l0). Intravenous administration of VIP(20 μg/kg body weight) induced an elevation of circulating PRL in each of the intact and ST-OVX monkeys tested. On the average, VIP treatment evoked more than a 9-fold rise in serum PRL in intact monkeys (p < 0.01) and more than a 2-fold increase in ST-OVX monkeys (p < 0.01), while injection of vehicle alone did not affect PRL levels in either experimental group. Addition of VIP (5 × 10^–9 – 5 × 10^–6M) to medium perifusing monkey pituitary tissue in vitro stimulated PRL secretion both in the presence and in the absence of dopamine (2.5 × 10^–7M).Furthermore, the in vitro potency of VIP was comparable, on a molar basis, with that of thyrotropin releasing hormone. Collectively, these results indicate that VIP is a potent stimulus for PRL secretion in monkeys which exerts its effect, at least in part, by a direct action at the pituitary level. Therefore, VIP should now be considered as a possible PRL releasing factor in primates.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Stimulation of Prolactin Secretion in Rhesus Monkeys by Vasoactive Intestinal Polypeptide

Frawley

Neill

1981

Neuroendocrinology

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“…It exhibits a broad spectrum o f effects ranging from smooth muscle relaxa tion, vasodilatation, and neurotransmission to neuroendocrine regulation [47,53]. The demonstration ofVIPimmunoreactivity in the hypothalamus, median eminence, anterior pituitary and the hypophyseal-portal blood [ 13,54,58,59,62], suggests that it also regulates anterior pituitary function. …”

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confidence: 99%

“…A significant population o f VIP-containing cell bodies has also been demonstrated in the parvocellular region o f the paraventricular nucleus [10,34] with VIP-positive fibres projecting to the ex ternal zone o f the median eminence. While only a few VIP positive fibres can be identified in the rat median eminence under basal conditions, the human median eminence contains high concentrations o f V IP which can be released into the por tal circulation [59]. Adrenalectomy and lactation combined with colchicine treatment result in a marked increase in VIPimmunopositivity in the paraventriculo-tuberoinfundibular system [34].…”

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confidence: 99%

Vasoactive Intestinal Peptide in the Hypothalamus and Pituitary

Lam¹

1991

Neuroendocrinology

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Data are presented to show that vasoactive intestinal peptide (VIP) is synthesized and secreted by the hypothalamus and anterior pituitary and that it participates in the regulation of pituitary functions. Immunoreactive VIP in the hypothalamus and pituitary is increased following estrogen treatment and adrenalectomy and is reduced in hyperprolactinemic states. The level of VIP mRNA in the hypothalamus is increased during lactation and sexual maturation, while that in the anterior pituitary shows a sexual dimorphism and is increased with estrogen treatment and hypothyroidism. All these findings suggest a physiological regulation of hypothalamic and pituitary VIP gene expression in relation to its potential role as a neuroendocrine hormone. Furthermore, VIP stimulates prolactin (PRL) release at concentrations attainable in the hypophyseal-portal blood. Passive immunoneutralization studies with anti-VIP antisera suggest that endogenous VIP acts at multiple loci in the hypothalamic-pituitary axis to regulate PRL secretion, interacting possibly with other regulators of PRL secretion such as estrogen, serotonin, cholecystokinin, prostaglandins, galanin and oxytocin. Regarding other pituitary functions, although VIP has been shown to release growth hormone, ACTH, and vasopressin in vivo and in vitro, the physiological significance of these findings remains to be determined.

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“…Its potential as a therapeutic agent for type 2 diabetes is now being investigated [21]. 6) VIP is broadly distributed in the central nervous system, especially in the hypothalamus and pituitary anterior lobe [22], and it is associated with the regulation of pituitary hormones. VIP acts in vivo as a prolactin (PRL)-releasing factor that stimulates the release of the growth hormone (GH) [23].…”

Section: Physiological Activitiesmentioning

confidence: 99%

Vasoactive Intestinal Peptide (VIP) and VIP Receptors-Elucidation of Structure and Function for Therapeutic Applications

Igarashi¹,

Fujimori²,

Ito³

et al. 2011

IJCM

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Vasoactive-Intestinal-Polypeptide Concentrations in Median Eminence of Hypothalamus

Cited by 31 publications

References 0 publications

Stimulation of Prolactin Secretion in Rhesus Monkeys by Vasoactive Intestinal Polypeptide

Stimulation of Prolactin Secretion in Rhesus Monkeys by Vasoactive Intestinal Polypeptide

Vasoactive Intestinal Peptide in the Hypothalamus and Pituitary

Vasoactive Intestinal Peptide (VIP) and VIP Receptors-Elucidation of Structure and Function for Therapeutic Applications

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