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Human placental lactogen (hPL), also called human chorionic somatomammotropin (HCS), is a polypeptide placental hormone. Its structure and function is similar to that of human growth hormone. It modifies the metabolic state of the mother during pregnancy to facilitate the energy supply of the fetus. hPL has anti-insulin properties. hPL is a hormone secreted by the syncytiotrophoblast during pregnancy. Like human growth hormone, hPL is encoded by genes on chromosome 17q22-24. It was identified in 1963.^[2]

Structure

hPL molecular mass is 22,125 and contains single chain consisting of 191 amino acid residues that are linked by two disulfide bonds and the structure contains 8 helices. A crystal structure of hPL was determined by X-ray diffraction to a resolution of 2.0 Å.^[1]

Levels

hPL is present only during pregnancy, with maternal serum levels rising in relation to the growth of the fetus and placenta. Maximum levels are reached near term, typically to 5–7 mg/L. Higher levels are noted in patients with multiple gestation. Little hPL enters the fetal circulation. Its biological half-life is 15 minutes.

Physiologic Function

hPL affects the metabolic system of the maternal organism in the following manners:

In a bioassay hPL mimics the action of prolactin, yet it is unclear whether hPL has any role in human lactation.
Metabolic
- ↓ maternal insulin sensitivity leading to an increase in maternal blood glucose levels.
- ↓ maternal glucose utilization, which helps ensure adequate fetal nutrition (the mother responds by increasing beta cells). Chronic hypoglycemia leads to a rise in hPL.
- ↑ lipolysis with the release of free fatty acids. With fasting and release of hPL, free fatty acids become available for the maternal organism as fuel, so that relatively more glucose can be utilized by the fetus. Also, ketones formed from free fatty acids can cross the placenta and be used by the fetus.

These functions help support fetal nutrition even in the case of maternal malnutrition.

This hormone has weak actions similar to those of growth hormone, causing the formation of protein tissues in the same way that growth hormone, but 100 times more hPL than growth hormone is required to promote growth.^[3] An enhancer for the human placental lactogen gene is found 2 kb downstream of the gene and participates in the cell-specific control gene expression.

Clinical measurement of hPL

While hPL has been used as an indicator of fetal well-being and growth, other fetal testing methods have been found to be more reliable.^{[citation needed]} Also, normal pregnancies have been reported with undetectable maternal levels of hPL.

References

^ ^a ^b PDB 1Z7C; Walsh ST, Kossiakoff AA (May 2006). "Crystal structure and site 1 binding energetics of human placental lactogen". J. Mol. Biol. 358 (3): 773–84. doi:10.1016/j.jmb.2006.02.038. PMID 16546209.
^ Josimovich JB, Atwood BL, Goss DA (October 1963). "Luteotrophic, Immunologic and Electrophoretic Properties of Human Placental Lactogen". Endocrinology 73: 410–20. doi:10.1210/endo-73-4-410. PMID 14068826.
^ Guyton and Hall (2005). Textbook of Medical Physiology (11 ed.). Philadelphia: Saunders. p. 1033. ISBN 81-8147-920-3. "This hormone has weak actions similar to those of growth hormone, causing the formation of protein tissues in the same way that growth hormone."

External links

Human Placental Lactogen at the US National Library of Medicine Medical Subject Headings (MeSH)

"RCSB Protein Data Bank - Structure Summary for 1Z7C - Crystal Structure of Human Placental Lactogen".

"Human Chorionic Somatomammotropin Enhancer Function Is Mediated by Cooperative Binding of TEF-1 and CSEF-1 to Multiple, Low-Affinity Binding Sites".

UpToDate Contents

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1. 妊娠に対する母体の内分泌系および代謝の適応 maternal endocrine and metabolic adaptation to pregnancy
2. Pregestational diabetes mellitus: Glycemic control during pregnancy
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5. 糖尿病および遺伝的糖尿病症候群の分類 classification of diabetes mellitus and genetic diabetic syndromes

English Journal

Implications for the offspring of circulating factors involved in beta cell adaptation in pregnancy.

Nalla A1, Ringholm L, Søstrup B, Højrup P, Thim L, Levery SB, Vakhrushev SY, Billestrup N, Mathiesen ER, Damm P, Nielsen JH.
Acta obstetricia et gynecologica Scandinavica.Acta Obstet Gynecol Scand.2014 Nov;93(11):1181-1189. doi: 10.1111/aogs.12505. Epub 2014 Oct 16.
OBJECTIVE: Several studies have shown an increase in beta cell mass during pregnancy. Somatolactogenic hormones are known to stimulate the proliferation of existing beta cells in rodents whereas the mechanism in humans is still unclear. We hypothesize that in addition to somatolactogenic hormones th
PMID 25223212

Endocrine Disruption in Human Placenta: Expression of the Dioxin-Inducible Enzyme, Cyp1a1, Is Correlated With That of Thyroid Hormone-Regulated Genes.

Wadzinski TL1, Geromini K, McKinley Brewer J, Bansal R, Abdelouahab N, Langlois MF, Takser L, Zoeller RT.
The Journal of clinical endocrinology and metabolism.J Clin Endocrinol Metab.2014 Oct 9:jc20142629. [Epub ahead of print]
Context: Thyroid hormone (TH) is essential for normal development; therefore, disruption of TH action by a number of industrial chemicals is critical to identify. Several chemicals including polychlorinated biphenyls are metabolized by the dioxin-inducible enzyme CYP1A1; some of their metabolites ca
PMID 25299844

Trophoblast-Specific Reduction of VEGFA Alters Placental Gene Expression and Maternal Cardiovascular Function in Mice.

Li H1, Qu D2, McDonald A2, Isaac SM2, Whiteley KJ2, Sung HK2, Nagy A3, Adamson SL4.
Biology of reproduction.Biol Reprod.2014 Oct;91(4):87. doi: 10.1095/biolreprod.114.118299. Epub 2014 Aug 13.
Given the angiogenic function of vascular endothelial growth factor A (VEGFA), the function of its expression by trophoblast in the avascular placental junctional zone is unknown. In mice, cells from the trophoblast-specific protein alpha (Tpbpa) lineage populate this zone and, in late gestation, so
PMID 25122061

Japanese Journal

Similarities and Differences in Reproductive Endocrinology Between Non-Human Primates and Humans

吉田高志
Congenital anomalies 39(4), 209-222, 1999-12-31
NAID 110002786117

Monoclonal Antibodies which Preferentially Bind to 22K Human Growth Hormone Rather than Its 20k Variant.

NAKANISHI TOHRU,MATSUI HIROSHI,NOGUCHI HIROSHI
Endocrinologia Japonica 36(4), 481-490, 1989
… Bl showed a high affinity of 9.8×10<SUP>8</SUP>l/mol, and all McAbs so far tested showed very weak cross-reactivity or none at all with human prolactin (hPRL) and human chorionic somatomammotropin (hCS; …
NAID 130000952673

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★リンクテーブル★

リンク元	「ソマトマンモトロピン」「泌乳刺激ホルモン」
拡張検索	「chorionic somatomammotropin」「human chorionic somatomammotropin」

「ソマトマンモトロピン」

chorionic somatomammotropin hormone 2
Identifiers
Symbol	CSH2
Entrez	1443
HUGO	2441
OMIM	118820
PDB	1Z7C (RCSB PDB PDBe PDBj)
RefSeq	NM_020991
UniProt	P01243
Other data
Locus	Chr. 17 q22-q24

chorionic somatomammotropin hormone 1 (human placental lactogen)
	Crystal Structure of Human Placental Lactogen.
Identifiers
Symbol	CSH1
Entrez	1442
HUGO	2440
OMIM	150200
RefSeq	NM_001317
UniProt	Q6PF11
Other data
Locus	Chr. 17 q22-q24