Role of Prolactin and Placental Lactogens in Vertebrate Growth and Development

Nicoll, Charles S.

doi:10.1016/b978-0-12-629055-4.50011-8

Cited by 10 publications

(3 citation statements)

References 82 publications

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“…(Endocrinology 141: 2886 -2894, 2000) T HE INSULIN-LIKE growth factors (IGFs), IGF-I and IGF-II, and insulin constitute a family of polypeptides that interact with GH and PRL to regulate cellular proliferation and other physiological processes (1)(2)(3). The total PRL content in the incubations and PRL synthesis, as measured by [ 35 S]methionine incorporation, were not altered by IGF-I.…”

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confidence: 99%

Insulin-Like Growth Factor I Disparately Regulates Prolactin and Growth Hormone Synthesis and Secretion: Studies Using the Teleost Pituitary Model¹

2000

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Although insulin-like growth factor I (IGF-I)'s inhibition of GH release is well documented, little is known of its control of GH synthesis at the posttranscriptional level. The manner by which IGF-I alters PRL synthesis and secretion is also unclear. This study was undertaken to examine the role IGF-I plays in regulating in vitro PRL and GH synthesis and release using the teleost pituitary model system. This model allows for isolation of nearly homogenous populations of distinct pituitary cell types that can be cultured in a completely defined, hormone-free medium. Tissues containing PRL cells and those consisting of GH cells were dissected from pituitaries of hybrid striped bass and exposed to varying concentrations of IGF-I, IGF-II, and insulin for 18-20 h. Exposure to graded doses of IGF-I markedly stimulated fractional, total, and newly synthesized PRL release in a dose-dependent fashion (ED50 for fractional release, 35 ng/ml or 4.6 nM; P < 0.0001). IGF-II and insulin also increased PRL release, but only at 10-fold higher concentrations than the lowest effective IGF-I dose. The total PRL content in the incubations and PRL synthesis, as measured by [35S]methionine incorporation, were not altered by IGF-I. By contrast, IGF-I potently reduced GH release (ED50, 29 ng/ml or 3.8 nM; P < 0.0001) and synthesis. Both 100 and 1000 ng/ml IGF-I decreased newly synthesized GH and total GH content (P < 0.001). Insulin and IGF-II mimicked IGF's action in attenuating GH release, but only at 10- to 11-fold higher concentrations. Taken together, these findings clearly indicate that IGF-I disparately regulates PRL and GH synthesis and secretion. We show that the effects of IGF-I on pituitary hormone release occur in a variety of species, suggesting that its actions are well conserved. The inhibition of GH release and synthesis by IGF-I probably reflects a negative feedback loop for maintaining tight control over GH cell function. These findings further indicate that IGF-I is a potent and specific secretagogue of PRL release in vertebrates.

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Insulin-Like Growth Factor I Disparately Regulates Prolactin and Growth Hormone Synthesis and Secretion: Studies Using the Teleost Pituitary Model¹

2000

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“…However, although PLs have been purified and characterized (Arima & Bremel 1983;Ogilvie et al 1990), their precise mechanism of action remains to be fully elucidated. In humans, accumulating evidence suggests that PL is influential in the regulation of maternal metabolism and foetal growth (Nicoll 1993). Other research, with adult rats, has determined that bovine (b) PLs, like GHs, stimulate body weight gain (Florini et al 1966) and IGF-I production (Byatt et al 1991).…”

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“…For example, hPL does not affect sodium retention in Tilapia mossambicu (Peters) (Clarke et al 1973), urinary bladder permeability in Gillichthys mirubilis (Cooper) (Doneen 1976), or the rate of "SO, incorporation by ceratobranchial cartilage explants of coho salmon, Oncorhynchus kisutch (Walbaum) (Chiang et al 1993). From an evolutionary perspective, the lack of responsiveness of fish to hPL should not be too surprising, because it has been estimated that the ancestral gene that gave rise to the PRL-GH family is old indeed; and that the billion or so years that have passed since its origin (Nicoll 1993) have witnessed frequent duplication events, such that large sequence variations are encountered within the PRL-GH family. This is particularly true of the placental proteins (Rand-Weaver et al Chorionic somatomammotropin, chorionic growth hormone, or placental lactogen (PL), is a member of the prolactin (PRL) -1993).…”

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Bovine placental lactogen invokes rapid growth in chinook salmon

McLean

Devlin²,

Donaldson³

et al. 1996

Aquaculture Nutrition

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The effect of recombinant bovine placenta) lactogen (rbPL) treatment upon growth of juvenile chinook salmon, Oncorhynchus tshawytscha (Walbaum) (14.0 ± 0.31 g wet wt), was examined over a period of 6 weeks. Experimental animals were either injected (5 μg rbPL g−1 week−1), implanted with a cholesterol pellet containing 0.4 mg rbPL (approximately 4 μg g−1 week−1), or orally and rectally intubated with 7.5 μg rbPL g−1 week−1. Control animals were injected with bovine serum albumen (BSA), 5 μg g−1 week−1, implanted with a placebo or orally intubated (7.5 μg BSA g−1 week−1). Significant (P < 0.05) growth acceleration was recorded for rbPL‐injected and pellet‐implanted groups from week 2 onwards when compared against all other groups. Oral or rectal intubation of rbPL (7.5 μg rbPL g−1 week−1), however, was without effect. Condition factor decreased in all groups, but was significantly lower in rbPL‐injected and pellet‐implanted fish at trial end when compared against controls. No differences were recorded between groups for per cent body moisture or relative gut length. Hepatosomatic index was significantly (P < 0.05) higher in rbPL‐injected and rbPL‐implanted chinook salmon versus other fish.

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Hormonal Regulation of Growth and Development of Nonmammalian Vertebrates

Nicoll

Rodgers

Kelley

1999

Comprehensive Physiology

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Role of Prolactin and Placental Lactogens in Vertebrate Growth and Development

Cited by 10 publications

References 82 publications

Insulin-Like Growth Factor I Disparately Regulates Prolactin and Growth Hormone Synthesis and Secretion: Studies Using the Teleost Pituitary Model¹

Insulin-Like Growth Factor I Disparately Regulates Prolactin and Growth Hormone Synthesis and Secretion: Studies Using the Teleost Pituitary Model¹

Bovine placental lactogen invokes rapid growth in chinook salmon

Hormonal Regulation of Growth and Development of Nonmammalian Vertebrates

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Role of Prolactin and Placental Lactogens in Vertebrate Growth and Development

Cited by 10 publications

References 82 publications

Insulin-Like Growth Factor I Disparately Regulates Prolactin and Growth Hormone Synthesis and Secretion: Studies Using the Teleost Pituitary Model1

Insulin-Like Growth Factor I Disparately Regulates Prolactin and Growth Hormone Synthesis and Secretion: Studies Using the Teleost Pituitary Model1

Bovine placental lactogen invokes rapid growth in chinook salmon

Hormonal Regulation of Growth and Development of Nonmammalian Vertebrates

Contact Info

Product

Resources

About

Insulin-Like Growth Factor I Disparately Regulates Prolactin and Growth Hormone Synthesis and Secretion: Studies Using the Teleost Pituitary Model¹

Insulin-Like Growth Factor I Disparately Regulates Prolactin and Growth Hormone Synthesis and Secretion: Studies Using the Teleost Pituitary Model¹