Growth promoting effect of head activator in cultured chick embryo brain cells

Kajiwara, Sohei; Satô, Tamotsu

doi:10.1530/acta.0.1130604

Cited by 9 publications

(2 citation statements)

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“…Although its true role in mammals is not yet known, it has been shown to stimulate amylase release in vitro from the pancreas (Feurle, Bodenmuller & Baca, 1983;Bodenmuller & Roberge, 1985). The head activator may function as a growth factor during development as it stimulates DNA, RNA and protein synthesis in cultured chick embryo brain cells, operating via a cAMP mechanism (Kajiwara & Sato, 1986).…”

Section: Platyhelminthsmentioning

confidence: 99%

Neuropeptides in platyhelminths

Fairweather

Halton

1991

Parasitology

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The neuropeptide story began in 1928 with the description by Ernst Scharrer of gland-like nerve cells in the hypothalamus of the minnow, Phoxinus laevis. Because these nerve cells were overwhelmingly specialized for secretory activity, overshadowing other neuronal properties, Scharrer termed them ‘neurosecretory neurons’. What was even more remarkable about the cells was that their products were released into the bloodstream to act as hormones, specifically neurohormones. Neurosecretory cells were identified largely on morphological grounds. That is, they could be stained with special techniques, such as chrome-haematoxylin and paraldehyde-fuchsin, although the techniques are far from specific, staining non-neurosecretory cells as well. However, the basis for the ‘special’ neurosecretory techniques is the demonstration of sulphur-containing proteins – so they are indicative of peptide-producing neurones. An alternative characteristic of neurosecretory cells is the presence of large (> 100 nm), dense-cored vesicles at the electron microscope level; these are the so-called elementary granules of neurosecretion, or ENGs. However, implicit in the concept of neurosecretion is that the prime function of the neurosecretory cell is in endocrine regulation, exerting a hormone-like control over some aspect of the organism's metabolism, by controlling endocrine glands and other effector organs. To satisfy this criterion, evidence had to be obtained of cycles of secretory activity within the cell that could be correlated with a change in the physiological condition of the organism.

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Section: Platyhelminthsmentioning

confidence: 99%

Neuropeptides in platyhelminths

Fairweather

Halton

1991

Parasitology

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“…It was also found in the human hypothalamus, intes¬ tine (2,3), and in human plasma at a concentration of 20-100 pmol/1 (4). The physiological functions reported previously were stimulation of amylase secretion from rat pancreas (5) and the growth pro¬ moting effect of chick embryo brain cells (6).…”

mentioning

confidence: 99%

The neuropeptide, head activator, in human placenta and serum from pregnant women

Sakura

Aoki²,

Ozawa³

et al. 1991

Acta Endocrinologica

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The hydra neuropeptide, head activator, was detected in human placenta using radioimmunoassay. The placenta contained 11-68 fmol/g wet weight of head activator. The slope of the inhibition curve by placental extract in radioimmunoassay was identical to that of synthetic head activator. The molecular weight of the major immunoreactive head activator in placental extract corresponded to the synthetic head activator after Bio-Gel P-2 column chromatography. The peak of immunoreactive head activator in the extract emerged at the same retention time as that of the synthetic head activator on reversed-phase high-performance liquid chromatography. Head activator was localized histologically in trophoblasts of placenta by peroxidase-antiperoxidase staining techniques. The head activator staining was inhibited by the excessive synthetic head activator. The serum head activator level during pregnancy ranged from 9 to 31 pmol/l. A positive linear correlation was found between serum head activator content and gestational weeks.Head activator is an undecapeptide with a molecu¬ lar weight of 1125 daltons and an amino acid se¬ quence of pGlu-Pro-Pro-Gly-Gly-Ser-Lys-Val-lleLeu-Phe. Originally, it was discovered in the hydra and was found to exert a stimulatory effect on head specific growth and differentiation process (1). It was also found in the human hypothalamus, intes¬ tine (2,3), and in human plasma at a concentration of 20-100 pmol/1 (4). The physiological functions reported previously were stimulation of amylase secretion from rat pancreas (5) and the growth pro¬ moting effect of chick embryo brain cells (6).Whether head activator is also a differentiation factor of human fetal growth is unclear. The placenta regulates fetal growth through pregnancy by secreting many steroids and polypeptide hormones such as human chorionic gonadotropin and human placental lactogen. Neuropeptides such as gonadotropin-releasing hormone, somatostatin, thyrotropin-releasing hormone, and corticotropin-releasing hormone have also been found in placenta (7).Using a sensitive and specific radioimmunoas¬ say, we here demonstrate that the neuropeptide, head activator, occurs in human placenta. Materials and MethodsThe five placentas were obtained from both normal term deliveries and abortion in the second month of preg¬ nancy. The tissue was repeatedly washed with cold 0.9% saline to free it of contaminated blood. After the blood vessels were removed it was stored at -20°C. Serum from 16 women, obtained from the second to tenth month of pregnancy, one being a twin and one a triplet pregnancy, serum from 4 non-pregnant women as controls, and um¬ bilical cord blood serum (4 women) were obtained at the Hamamatsu Medical Centre.Bio-Gel P-2 was obtained from Bio-Rad (Richmond, VA). Marker proteins for calibration of molecular weight were cytochrome c (12 500), ci-endorphin (1746), n'langiotensin I (1297) and 125I-triiodothyronine (650). Reversed-phase high-performance liquid chromatography (RP-HPLC) was performed on a Chemcosorb 7-ODS-L column (2 x 25 ...

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