Effects of melanotropic peptides on fetal adrenal gland.

Rudman, Daniel; Hollins, Bettye; Lewis, Nia C. S.; Chawla, Rajender K.

doi:10.1172/jci109733

Cited by 37 publications

(18 citation statements)

References 27 publications

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“…A similar trophic effect of a-MSH on adrenal gland was also reported in the fetus (22). Considering the negative correlation existing between DHEA-S and a-MSH response to domperidone, the actual study suggests that a role for a-MSH could possibly be hypothesized also for human adrenarche (22).…”

Section: Discussionsupporting

confidence: 74%

“…Confirming the in vitro steroidogenic effects of melanotropic hormones, such a treatment was accompanied by an increase in the ACTH 1-13 pituitary content (21). A similar trophic effect of a-MSH on adrenal gland was also reported in the fetus (22). Considering the negative correlation existing between DHEA-S and a-MSH response to domperidone, the actual study suggests that a role for a-MSH could possibly be hypothesized also for human adrenarche (22).…”

Section: Discussionsupporting

confidence: 72%

See 1 more Smart Citation

Changes in Dopaminergic Control of Circulating Melanocyte-Stimulating Hormone-Related Peptides at Puberty

et al. 1995

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Desacetyl a-melanocyte-stimulating hormone (MSH) (ACTH 1-13) is the main form of immunoreactive a-MSH circulating in human plasma. This study evaluates the possibility that a dopaminergic inhibitory mechanism could be operative during human development. Thus, a-MSH and ACTH 1-13 plasma levels were measured after dopaminergic blockade (domperidone (0.3 m a g body weight, maximum 10 mg, p.0.) in 13 prepubertal (aged 4.5-12.3 y) and 12 pubertal (aged 10.2-16.9 y) children. Both peptides were measured by RIA after plasma extraction on Sep-pak C-18 cartridges and reverse phase HPLC. The chromatographic profile of a-MSH immunoreactivity falls into two main peaks, corresponding to the retention time of a-MSH and ACTH 1-13. Moreover, in prepubertal children domperidone induced a significant increase of a-MSH from 1.7 (median) to 5.0 pmol/L, whereas no changes in a-MSH plasma levels were found in pubertal subjects (from 5.0 to 4.1 pmol/L). Similarly, ACTH 1-13 plasma levels significantly increased from 3.0 to 19.8 pmol/L in prepubertal children remaining stable in pubertal ones (from 7.8 to 4.6 pmol/L). Moreover, a significant negative correlation was found between basal DHEA-S levels and the plasma a-MSH increase after domperidone. These data demonstrate that: 1 ) ACTH 1-13 is the main form of immunoreactive a-MSH in prepubertal life and 2) the dopaminergic inhibition of both ACTH 1-13 and a-MSH plasma levels is apparent only in prepubertal subjects. (Pediatr Res 38: 91-94, 1995) Abbreviations a-MSH, a-melanocyte-stimulating hormone ACTH 1-13, desacetyl a-melanocyte-stimulating hormone POMC, proopiomelanocortin DHEA-S, dehydroepiandrosterone sulfate a-MSH is a peptide deriving from a two steps cleavage of POMC for the formation of which the activity of a-Nacetyltransferase is required (1). In lower mammals, these enzymatic events are absent from the anterior pituitary, whereas they are typical of the neurointermediate lobe, which is well developed in these species (2). In humans, the neurointermediate lobe is virtually absent in adults (3), whereas it has been detected in the fetal pituitary (4) and in a subgroup of patients with Cushing's disease (5).In contrast to the studies of late 1970s, detectable levels of a-MSH plasma have been found in healthy adult volunteers (6, 7), and they have been found higher than normal in patients affected by Cushing disease (8). The results of the abovementioned studies were obtained coupling the classical a-MSH RIA to purification procedures, such as extraction and HPLC, and revealed that the des-acetylated form of a-MSH (i.e. ACTH 1-13 amide) is the main form of plasma immunoreactive a-MSH. This finding also suggests a possible functional activity of neurointermediate lobe in some physiopathologic conditions.We previously demonstrated that, in contrast to ACTH levels, plasma P-endorphin concentrations increased progressively throughout prepuberty, reaching adult levels at the beginning of pubertal development (9). These data were in keeping with the suggested role of POMC-related...

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Section: Discussionsupporting

confidence: 74%

Section: Discussionsupporting

confidence: 72%

Changes in Dopaminergic Control of Circulating Melanocyte-Stimulating Hormone-Related Peptides at Puberty

et al. 1995

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“…In this regard it is noteworthy that recently Coates et al [17] demonstrated that desacetyl-a-MSH is the major form of a-MSH in a-MSH-containing isles located inside human adult anterior hypophysis and, additionally, a-MSH re lease does not seem to need previous acetylation in mammals [18], The functional significance of desacetyla-MSH and of its changes during the menstrual cycle as well, is unknown at present. Like a-MSH, desacetyl-a-MSH might participate in the regulation of the adrenal function [ 19,20] or exert a trophic action on the adrenal tissue [21,22]. Furthermore, a-MSH peptides are con sidered to be endogenous antagonists of opioid peptides [23], Since opioid peptides have profound effects on reproductive functions especially on the ovulatory pro cess [24,25], it is tempting to speculate that the various forms of a-MSH might have the role of counteracting opioid function in this crucial event of the reproductive process.…”

Section: Discussionmentioning

confidence: 99%

Plasma Alpha-Melanocyte-Stimulating Hormone during the Menstrual Cycle in Women

Mauri

Martellotta²,

Melis³

et al. 1990

Horm Res

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α-Melanocyte-stimulating hormone (α-MSH) and adrenocorticotropin (ACTH) immunoreactivity (IR) was measured in the blood of 22 healthy women with normal ovulatory process in the early and late follicular (near to ovulation) phases and in the early luteal phase of the menstrual cycle. Plasma α-MSH IR ranged from undetectable values to 81.3 pg/ml, the highest levels being found in the late follicular phase (15.52 ± 4.16 pg/ml). In contrast, plasma ACTH IR was always detectable (range: 18.5–63.2 pg/ml), but its concentration did not differ significantly between the 3 phases of the menstrual cycle. High-pressure liquid chromatography fractionation of Sep pak C18-purified α-MSH IR revealed in all 3 phases the presence of 3 major peaks of α-MSH IR, coeluting with desacetyl-α-MSH, α-MSH and diacetyl-α-MSH, respectively. The most abundant peak always coeluted with authentic desacetyl-α-MSH, and the ratio between this deacetylated and the other 2 acetylated forms was similar in the 2 follicular phases (1:1.25 and 1:1.16 in the early and late phase, respectively), but significantly different in the luteal phase (1:0.48). The fluctuations in plasma concentration of the above MSH-related peptides suggest that different rates of α-MSH acetylation and release take place in the pituitary gland depending on the phase of the menstrual cycle.

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“…The tryptic and chymotryptic maps, however, demonstrate that product I is neither a-melanotropin nor des-AcaN-r-melanotropin. It also cannot be the recently described bovine melanotropic peptide [N, O-diacetyl-serine'la-melanotropin [22], as a (c1iymo)tryptic map of this latter peptide would, with the exception of the N-terminal fragment, correspond to that of a-melanotropin. Neither are its mapping characteristics consistent with a /3-melanotropin-like structure.…”

Section: Melanotropin-relaied Pepiidesmentioning

confidence: 83%

Biosynthesis of Pairs of Peptides Related to Melanotropin, Corticotropin and Endorphin in the Pars Intermedia of the Amphibian Pituitary Gland

Martens

Jenks

Overbeeke

1982

European Journal of Biochemistry

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This study concerns the biosynthesis of a number of peptides in the neurointermediate lobe of the pituitary gland of the aquatic toad, Xenopus laevis. Using pulse-chase incubations in virro and high-performknce liquid chromatographic analysis, it could be shown that these peptides are synthesized through processing of a prohormone, pro-opiomelanocortin; all peptides were released into the incubation medium. On the basis of electrophoretic analysis, selective amino acid incorporation and immunoprecipitation, as well as peptide mapping by high-performance liquid chromatography, the peptides were classified into three distinct groups : two related to melanocyte-stimulating hormone (melanotropin), two related to adrenocorticotropic hormone (corticotropin) and two endorphin-like peptides. Using tryptic and chymotryptic maps of synthetic cr-melanotropin and des-AcaNa-melanotropin as references, one of the melanotropin-like peptides was identified as des-AcaN-a-melanotropin; the other one represents neither a-melanotropin nor any other known melanotropic peptide. The two peptides that were immunologically related to corticotropin had characteristics consistent with a structures resembling a peptide previously named 'corticotropin-like intermediate lobe peptide', corticotropin-(18 -39). The two endorphin-like peptides, although highly related, do not have the same primary structure. In view of the apparent structural differences between the two peptides in each group, the possible occurrence of two prohormones is discussed.Many amphibians, when placed on a black background, respond by dispersing the melanin granules in the dermal melanophores of their skin, thus causing the animal to darken. This phenomenon, known as background adaptation, is mediated by melanotropin from the pars intermedia of the pituitary gland. It has been demonstrated by a number of investigators that the amphibian pars intermedia produces not one, but several melanotropic peptides [l -S ] . The pars intermedia from black-background-adapted South African clawed toads, Xenopus luevis, when incubated in vitro, synthesizes a precursor; this precursor is subsequently processed to a number of smaller peptides, including some melanotropic ones [4,5]. Such a precursor-product mode of peptide biosynthesis is also found in mammalian pituitary glands. A common prohormone to corticotropin and P-endorphin has been established in a mouse pituitary tumor cell line [6][7][8], as well as in the pars intermedia and the anterior lobe of the rat pituitary gland [9,10]. The circumstance whereby several products, each with its own specific bioactivity, are derived from a common prohormone raises important questions concerning the regulation of both the biosynthesis and the release of such products. For X . luevis, aspects of the control of product release from the neurointermediate lobe, particularly the effect of dopamine and the possible involveAbbreviations and Trivial Names. Melanotropin, melanocyte-stimulating hormone; corticotropin, adrenocorticotropic hormone; H...

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Effects of melanotropic peptides on fetal adrenal gland.

Cited by 37 publications

References 27 publications

Changes in Dopaminergic Control of Circulating Melanocyte-Stimulating Hormone-Related Peptides at Puberty

Changes in Dopaminergic Control of Circulating Melanocyte-Stimulating Hormone-Related Peptides at Puberty

Plasma Alpha-Melanocyte-Stimulating Hormone during the Menstrual Cycle in Women

Biosynthesis of Pairs of Peptides Related to Melanotropin, Corticotropin and Endorphin in the Pars Intermedia of the Amphibian Pituitary Gland

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