scholarly journals Adrenocorticotrophic and melanocyte-stimulating peptides in the human pituitary

1974 ◽  
Vol 139 (3) ◽  
pp. 593-602 ◽  
Author(s):  
Alexander P. Scott ◽  
Philip J. Lowry
Keyword(s):  
Pars Intermedia ◽  
Intermediate Lobe ◽  
Human Pituitary ◽  
Melanocyte Stimulating Hormone ◽  
Stimulating Hormone

The adrenocorticotrophic and melanocyte-stimulating peptides of the human pituitary were investigated by means of radioimmunoassay, bioassay and physicochemical procedures. Substantial amounts of adrenocorticotrophin and a peptide resembling β-lipotrophin were identified in pituitary extracts, but α-melanocyte-stimulating hormone, β-melanocyte-stimulating hormone and corticotrophin-like intermediate lobe peptide, which have been identified in the pars intermedia of pituitaries from other vertebrates, were not found. The absence of β-melanocyte-stimulating hormone appears to contradict previous chemical and radioimmunological studies. Our results suggest, however, that it is not a natural pituitary peptide but an artefact formed by enzymic degradation of β-lipotrophin during extraction.

Effect of serotonin on α-melanocyte-stimulating hormone secretion from perifused frog neurointermediate lobe: evidence for the presence of serotonin-containing cells in the frog pars intermedia

1989 ◽  
Vol 122 (1) ◽  
pp. 135-NP ◽  
Author(s):  
M. Lamacz ◽  
M. C. Tonon ◽  
F. Leboulenger ◽  
F. Héry ◽  
S. Idres ◽  
...  
Keyword(s):  
Inhibitory Effect ◽  
Electron Microscopic Level ◽  
Adrenergic Nerve ◽  
Pars Intermedia ◽  
Intermediate Lobe ◽  
Melanocyte Stimulating Hormone ◽  
Neurointermediate Lobe ◽  
Parenchymal Cells ◽  
Ics 205 930 ◽  
Stimulating Hormone

ABSTRACT We have examined the presence of 5-hydroxytryptamine (serotonin; 5-HT) in the intermediate lobe of the frog pituitary and investigated the effect of exogenous 5-HT on α-melanocyte-stimulating hormone (α-MSH) release from the perifused neurointermediate lobe (NIL). Using a specific antiserum against 5-HT, the indirect immunofluorescence technique revealed the presence of 5-HT-like immunoreactivity (5-HT-LI) in discrete cells, generally gathered in small clusters among parenchymal cells, and in numerous neurites surrounding melanotrophic cells. At the electron microscopic level, using a silver-gold intensification procedure, 5-HT-LI was localized in dense-core secretory vesicles within specific pituitary cells which appear to be different from pituitary melanotrophs. Dense accumulation of gold particles was also observed in nerve fibres running between parenchymal cells. A combination of high-performance liquid chromatography analysis and electrochemical detection showed the presence of both 5-HT and its metabolite 5-hydroxyindol acetic acid (5-HIAA) in frog NIL extracts (534 ± 40 and 1245 ± 65 (s.e.m.) pg/mg wet tissue respectively). Administration of graded doses of 5-HT (from 1 to 30 μmol/l) to perifused frog NIL induced a dose-dependent inhibition of α-MSH release. Repeated pulses of 5-HT (10 μmol/l each) induced a reproducible inhibition of α-MSH without any desensitization phenomena. The inhibitory effect of 5-HT was partially blocked by the serotonergic antagonists methysergide and ICS-205-930 (10 μmol/l each). Concomitant administration of methysergide and ICS-205-930 (10 μmol/l each) totally abolished 5-HT-evoked inhibition of α-MSH. Fenfluramine, a releaser of 5-HT, induced a slight but significant reduction of α-MSH secretion. While 5-HT caused a marked inhibition of α-MSH release from intact NIL, 5-HT was devoid of effect on acutely dispersed pars intermedia cells suggesting that 5-HT does not exert a direct action on pituitary melanotrophs. We have examined the effect of specific dopaminergic, GABAergic and α-adrenergic antagonists on 5-HT-induced α-MSH inhibition. We observed that sulpiride and SR 95531 (10 μmol/l each) did not affect the response of NIL to 5-HT while yohimbine (10 μmol/l) suppressed the inhibitory action of 5-HT. Taken together, our results indicate that discrete cells of the frog pars intermedia contain the neurotransmitter 5-HT which may act locally to inhibit α-MSH release. Our data also suggest that the inhibitory effect of 5-HT is mediated via presynaptic stimulation of catecholamine (possibly norepinephrine) release from adrenergic nerve endings terminating in the intermediate lobe of the frog pituitary. Journal of Endocrinology (1989) 122, 135–146

Demonstration of desacetyl α-melanocyte-stimulating hormone in fetal and adult human anterior pituitary corticotrophs

1989 ◽  
Vol 120 (3) ◽  
pp. 525-NP ◽  
Author(s):  
P. J. Coates ◽  
I. Doniach ◽  
J. M. P. Holly ◽  
L. H. Rees
Keyword(s):  
Pituitary Gland ◽  
High Performance ◽  
Anterior Lobe ◽  
Pars Intermedia ◽  
Intermediate Lobe ◽  
Human Pituitary ◽  
Human Pituitary Gland ◽  
Melanocyte Stimulating Hormone ◽  
Pars Anterior ◽  
Human Anterior Pituitary

ABSTRACT Immunocytochemistry, radioimmunoassay and high-performance liquid chromatography (HPLC) techniques have been used in combination to investigate the presence of immunoreactive (ir)-α-MSH in the normal human pituitary gland, and to investigate the possible origin of these cells from the fetal pars intermedia. Two separate antisera to α-MSH were employed in immunocytochemistry to distinguish between authentic α-MSH and the desacetyl form. Only desacetyl α-MSH was detected in the pituitary gland of fetal and adult man, in both the pars (zona) intermedia and the pars anterior. In the fetus, a large proportion of the ACTH-containing cells of the anterior lobe also contained ir-α-MSH, while ir-α-MSH containing cells were more sparse in adults. Radioimmunoassay of acid extracts of adult pituitary tissue showed α-MSH levels representing less than 0·05% of the ACTH content of the gland. HPLC analysis of these extracts confirmed that only the desacetyl form was present. These results suggest that α-MSH peptides are synthesized by anterior lobe cells of the human pituitary gland, which are not derived from the fetal pars intermedia. Possible regulatory mechanisms affecting cells which contain ir-α-MSH are discussed, and by comparison with the intermediate lobe of other species it is concluded that there is little evidence for a true intermediate lobe in the human pituitary gland. Journal of Endocrinology (1989) 120, 525–530

INCORPORATION OF 14C-LABELLED AMINO ACIDS INTO CORTICOTROPHIN-LIKE INTERMEDIATE LOBE PEPTIDE AND α-MELANOCYTE-STIMULATING HORMONE BY THE RAT PITUITARY NEUROINTERMEDIATE LOBE IN VITRO, AND THE IDENTIFICATION OF FOUR NEW PARS INTERMEDIA PEPTIDES

1976 ◽  
Vol 70 (2) ◽  
pp. 197-205 ◽  
Author(s):  
A. P. SCOTT ◽  
P. J. LOWRY ◽  
TJ. B. VAN WIMERSMA GREIDANUS
Keyword(s):  
Amino Acids ◽  
The Other ◽  
Pars Intermedia ◽  
Intermediate Lobe ◽  
Melanocyte Stimulating Hormone ◽  
Neurointermediate Lobe ◽  
Rat Pituitary ◽  
Stimulating Hormone

SUMMARY At least seven radioactive peptides, which fractionated on Biogel P6, were found in rat neurointermediate lobes after incubation for 6 h with [14C]proline. Only three of these could be tentatively identified; one as α-melanocyte-stimulating hormone (α-MSH) and two as forms of corticotrophin-like intermediate lobe peptide (CLIP). One other crossreacted partially with a β-melanocyte-stimulating hormone (β-MSH) antiserum, was acidically charged and eluted on Biogel P6 in roughly the same position as ACTH. The other three peptides showed no resemblance to α-MSH, CLIP, β-MSH or ACTH.

THE EFFECT OF INGESTION OF HYPERTONIC SALINE ON THE MELANOCYTE-STIMULATING HORMONE CONTENT AND HISTOLOGY OF THE PARS INTERMEDIA OF THE RAT PITUITARY GLAND

1970 ◽  
Vol 46 (2) ◽  
pp. 201-NP ◽  
Author(s):  
A. HOWE ◽  
A. J. THODY
Keyword(s):  
Control Level ◽  
Pars Intermedia ◽  
Type I ◽  
Melanocyte Stimulating Hormone ◽  
Level Of Activity ◽  
Numerous Type ◽  
Rat Pituitary ◽  
Stimulating Hormone

SUMMARY The changes in the content of melanocyte-stimulating hormone (MSH) and histology of the neuro-intermediate (n.i.) lobe were followed in rats which drank 2% sodium chloride for periods from 1–15 days. The pars intermedia showed a biphasic response. During the initial phase of 1–4 days there was a rapid rise in the MSH content, by 153% in the first day, falling back to control level by 4 days. These fluctuations were paralleled by an increase in the normally small numbers of Type 2 cells and at the same time numerous Type I cells showed hypertrophy and degranulation. After 4 days on saline there was a second rise in the MSH content, which was still evident at 15 days; during this second period the number of Type 2 cells declined to normal levels. The degranulated Type 1 cells also disappeared, most of Type 1 being smaller in size and intensely PAS-positive. After the ingestion of saline it apparently takes several days before the pars intermedia adapts to a new level of activity. The likely significance of these changes and the possibility of a relationship between the pars intermedia and the neurohypophysis are discussed.

DISTRIBUTION OF RADIOACTIVITY IN THE ORGANS OF THE RAT AND MOUSE AFTER INJECTION OF [125I]α-MELANOCYTE-STIMULATING HORMONE

1975 ◽  
Vol 64 (2) ◽  
pp. 237-241 ◽  
Author(s):  
A. DUPONT ◽  
A. J. KASTIN ◽  
F. LABRIE ◽  
G. PELLETIER ◽  
R. PUVIANI ◽  
...  
Keyword(s):  
Pineal Gland ◽  
Direct Measurement ◽  
Whole Body ◽  
Intermediate Lobe ◽  
High Uptake ◽  
Melanocyte Stimulating Hormone ◽  
Whole Body Autoradiography ◽  
Very High ◽  
Stimulating Hormone

SUMMARY The distribution of radioactivity after intrajugular injection of 125Ilabelled α-melanocyte-stimulating hormone (α-MSH) was studied by whole-body autoradiography of the mouse and by direct measurement of radioactivity in individual organs of the rat. Very high uptake of radioactivity in the pineal gland was measured 5 min after the injection of [125I]α-MSH. Lower levels of accumulation of radioactivity were found in the kidney and in the posterior (including intermediate) lobe of the pituitary. High uptake was also found in the thyroid, stomach, and oesophagus. The specificity of uptake of [125I] α-MSH into the pineal and pituitary is suggested by the very low uptake of Na125I into those tissues.

Radioimmunologic Evidence for α-MSH (Melanocyte Stimulating Hormone) in Human Pituitary and Tumor Tissues

1967 ◽  
Vol 27 (1) ◽  
pp. 46-52 ◽  
Author(s):  
KAORU ABE ◽  
DONALD P. ISLAND ◽  
GRANT W. LIDDLE ◽  
NORMAN FLEISCHER ◽  
WENDELL E. NICHOLSON
Keyword(s):  
Human Pituitary ◽  
Melanocyte Stimulating Hormone ◽  
Tumor Tissues ◽  
Stimulating Hormone
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