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PubMed1976

Possible association of increased rat behavioral effects and increased striatal dopamine and norepinephrine levels during the DOPA-potentiation test.

Previous reports have indicated that alpha-MSH release inhibiting hormone (MIF-1) increased the behavior occurring as a result of the dihydroxyphenylalanine (DOPA) potentiation test [3,7]. This study was undertaken to see whether dopamine (DA) or norepinephrine (NE) levels likewise increased in the test animals. The DOPA potentiation test was performed as follows: 2-4 hr before behavior measurement, 40 mg/kg of the monoamine oxidase inhibitor pargyline HCl was given orally. Two hr later this was followed by the intraperitoneal (IP) injection of MIF-1 at doses of 0.1, 0.3 or 1.0 mg/kg. Behavioral measurement was begun after the IP injection of 200 mg/kg of dl-DOPA 1-2 hr after the MIF-1. The parameters included social interaction, aggressiveness, fighting, ataxia, jumping, defecation, urination and salivation. The animals were beheaded while the behavior was still increased and the striatal area removed, placed in aluminum foil, and kept at -50 degrees C until assayed. In general, especially among the younger animals, a significant correlation (p=0.05 to p=0.01) was found between the increased behavioral responses to MIF-I and the rise in DA. Because of a few exceptions to this correlation the possibility is suggested that MIF-I might also affect behavior by acting directly on the postsynaptic membrane thus bypassing any change in NE or DA which is known to increase cycli AMP in the striatum.

Animals↗

PubMed1976

Neurochemical responses of mice to ACTH and lysine vasopressin.

Subcutaneous administration of ACTH 1-24 to mice increased the incorporation of [3H]lysine into brain and liver proteins, an effect which resembled that due to footshock. Corticosterone administration did not mimic these effects. ACTH 4-10 increased the [3H]lysine incorporation into brain or liver. These results are consistent with ACTH mediating the effects of footshock. However, dexamethasone decreased the brain responses to both footshock and ACTH, but while the liver response to ACTH was blocked, the footshock response was only diminished. This suggests a neural component in the response of the liver and possibly the brain. Intraventricular administration of ACTH 1-24 or ACTH 4-10 (D-phe), but not ACTH 4-10, increased [3H]lysine incorporation into brain protein. These neurochemical responses parallelled a distinctive pattern of behavior characterized by stretching, yawning and excessive grooming. Treatment for 3 days with long-acting preparations of ACTH 4-10, ACTH 4-10 (D-phe) or ACTH 1-24 increased the conversion of [3H]tyrosine into dopamine but not norepinephrine, alpha-MSH, beta-MSH or LVP had no such effect. Similar treatment with ACTH 4-10 or ACTH 1-24 increased striatal tyrosine hydroxylase activity measured in vitro, but did not significantly alter the enzyme activity from other brain regions. We conclude that ACTH peptides can stimulate protein and dopamine metabolism in mouse brain and that LVP has no such effects.

Adrenocorticotropic Hormone↗

PubMed1979

Biosynthesis of MSH and related peptides in the pars intermedia of the mouse: a pulse-chase analysis.

Protein biosynthesis in neurointermediate lobes of mouse pituitaries was investigated using pulse and pulse-chase techniques with [3H]lysine. Electrophoretic analysis of lobe homogenates on acid-urea gels resolved 11 labeled products. One was a large protein which was rapidly synthesized during pulse-incubations and disappeared during chase incubations. Three of the products increased during chase incubations, suggesting a precursor-product mode of biosynthesis for these chasde peptides. One of these three products co-migrated with synthetic alpha-MSH and also corresponds to the major peak of mouse neurointermediate lobe MSH bioactivity and immunoactivity on electrophoretograms. Another case of these peptides has electrophoretic properties similar to those of ACTH.

Animals↗

PubMed1979

Met-enkephaline-like immunoreactivity in a cephalopod neurohemal organ.

Using a highly specific antibody we found Met-enkephalin-like immunoreactivity in large granules of numerous distinct cells that are embedded in a layer of secretory terminals inside the octopus vena cava. Application of antibodies against fragments of the mammalian pro-opiocortin precursor -- alpha-MSH, ACTH, beta-endorphin and 16k-fragment -- and against growth hormone did not produce immunostaining in the octopus enkephalin cells. The vena cava neuropil may represent a favourable system for the examination of the physiological role of the opioid peptide enkephalin.

Animals↗

PubMedDate not supplied

Involvement of ACTH and MSH in active and passive avoidance behavior.

Intracerebroventricular injection of antiserum to alpha--MSH induces a weak reduction of passive avoidance latencies after administration prior to retention testing. Administration of antiserum to ACTH 1--24 induces a more marked effect in this respect, whereas injection of a combination of these antisera results in the strongest reduction of passive avoidance retention. No effect of this treatment is observed when these antisera are injected immediately after the learning trial. In active avoidance behavior a facilitation of extinction of the response is observed after intracerebroventricular administration of the antisera prior to each extinction session. This effect is comparable with the one observed in passive avoidance behavior. From these data it is suggested that ACTH and alpha-MSH play an important role in processes related to the retrieval of information stored in the brain.

Adrenocorticotropic Hormone↗

PubMedDate not supplied

Subcellular localization of immunoreactive alpha-melanocyte stimulating hormone in human brain.

The regional and subcellular distribution of immunoreactive alpha-melanocyte stimulating hormone (alpha-MSHi) in the post mortem adult human brain was investigated. alpha-MSHi was highly concentrated in medial basal hypothalamic tissue (1.02 ng/mg protein). Lower levels of alpha-MSHi were present in the optic chiasm and mammillary bodies, 0.08 and 0.11 ng/mg protein, respectively. The concentrations of alpha-MSHi in cerebellum and frontal cerebral cortex were 1/1,000th that of the medial basal hypothalamus. When medial basal hypothalamic homogenates were subjected to discontinuous or continuous sucrose density gradients, alpha-MSHi was found to be associated primarily with subcellular particles which resembled isolated nerve terminals, i.e., synaptosomes. Low to undetectable amounts of alpha-MSHi were found in the cytosol or the myelin/microsome fraction of the gradients. The results of these studies are consistent with the view that alpha-MSH is a neuronal peptide in the human brain.

Brain↗

PubMed1976

Stimulation of growth hormone release by luteinizing hormone-releasing hormone and melanocyte-stimulating hormone-release inhibiting hormone in the hypophysectomized rat bearing an ectopic pituitary.

Intrajugular administration of LHRH (0-6 and 1-2 mug) in hypophysectomized rats which received renal grafts of anterior pituitary induced a small but significant rise in plasma GH 5 and 10 min post-treatment. LHRH, at the same dose levels, was ineffective in weight-matched intact controls. MIF, at the dose of 1-2 mug, induced a slight GH rise 5 min after treatment in hypophysectomized trasnplanted rats, while it was ineffective in intact controls. Unlike the two hypothalamic peptides, alpha-MSH (0-6 and 1-2 mug) was ineffective as a GH-releaser in both transplanted and intact rats.

Animals↗

PubMed1979

The role of the carbohydrate in the stabilization, processing, and packaging of the glycosylated adrenocorticotropin-endorphin common precursor in toad pituitaries.

The neurointermediate lobes of dark adapted toads, Xenopus laevis, were incubated for 30 min in [3H]arginine, [3H]arginine plus [14C]glucosamine, or [3H]glucosamine and then chased for various time periods ranging from 1--3 h. The labeled polypeptides synthesized and secreted by the lobes were analyzed by acid-urea polyacrylamide gel electrophoresis. A glycosylated ACTH-endorphin precursor (32,000 mol wt) was synthesized during the pulse and identified by immunoprecipitation by ACTH-(11--24) antiserum. During the chase, this precursor was processed to various glycopeptides and peptides, including ACTH, beta-lipotropin, and alpha-MSH, which were subsequently secreted into the medium. An immunoprecipitable ACTH-related glycoprotein (approximately 150,000 mol wt) and other nonimmunoprecipitable glycoproteins (approximately 80,000--100,000 mol wt) were also synthesized and secreted by the neurointermediate lobe. The secretion of these glycoproteins and peptides was inhibited by dopamine. The significance of glycosylation of the precursor for the biosynthesis, processing, and secretion of the ACTH, beta-lipotropin-, and MSH-related peptides was examined by using a specific inhibitor of glycosylation, tunicamycin. Tunicamycin treatment did not affect the synthesis of the 32,000 mol wt ACTH-endorphin precursor but did prevent its glycosylation. The absence of carbohydrate on the precursor resulted in its rapid intracellular degradation. Precursors that escaped degradation were processed incompletely, leading to the formation and secretion of an unglycosylated intermediate and various other abnormal peptides. The data indicate that glycosylation of the ACTH-endorphin precursor may not be involved in the processes of intracellular transport, packaging, and secretion per se but, rather, may provide specific conformational stability to the precursor as a signal for directed limited proteolysis.

Adrenocorticotropic Hormone↗

PubMed1975

A sensitive bioassay for the determination of human plasma ACTH levels.

A sensitive bioassay for the measurement of plasma ACTH is presented. The use of silicic acid adsorption of plasma, with a subsequent acid wash and aqueous acetone desorption, was successful in removing those substances which had interfered with the steroidogenic response of dispersed adrenal cells when unextracted plasma was employed. This extraction procedure extracted 72-76% of ACTH present in plasma. Two pg ACTH1-39 could be consistently detected. Alpha-hACTH1-39 and alpha-pACTH1-39 exhibited equal potencies. Beta-MSH was ineffective at dosage levels up to 2 x 10(8) pg. One x 10(8) pg of ACTH1-10, ACTH4-10, or alpha-MSH had a steroidogenic effect equivalent to that of 40 pg ACTH1-39. ACTH 17-39 and ACTH 11-24 were incapable of stimulating steroid production at doses of 1 x 10(8) pg. Excesses of the latter, but not of the former appeared to be able to antagonize the steroidogenic effect of ACTH1-39. Plasma from normal subjects, bioassayed by this extraction procedure, contained 12-186 pg/ml ACTH at 0400-0800: 14-93 pg/ml ACTH at 1000-1300, and less than 10-34 pg/ml ACTH at 1600-2200. Hypoglycemia and vasopressin administration were followed by increases in plasma ACTH concentratrations. Plasma ACTH concentrations in untreated patients with Cushing's disease (sampled over the period 0900-1300) ranged from 65-220 pg/ml. Three patients with Addison's disease (untreated or 12 h following replacement steroid withdrawal) had ACTH concentrations of 223, 370 and 1226 pg/ml. Markedly elevated ACTH concentrations were observed in a patient with Nelson's syndrome (391 and 835 pg/ml). Bioassayable ACTH was not detected in 2 patients with panhypopituitarism.

Acetone↗

PubMed1979

Adrenocorticotrophin-related peptides in adult and foetal sheep pituitary glands.

Differences in foetal and adult adrenal function may be due to qualitative as well as quantitative changes in the pituitary corticotrophic stimulus. Pituitary glands from adult and foetal sheep were freshly dissected and stored at -70 degrees C until extracted at pH 1.5. The extracts were subjected to chromatography on Sephadex G-100 superfine and fractions were assayed by multiple radioimmunoassays directed against the NH2- and CO2H-terminal sequences of ACTH and lipotrophin (LPH). Peaks corresponding to beta-melanocyte-stimulating hormone (beta-MSH), beta-LHP, gamma-LPH, beta-endorphin and ACTH were identified, with little or no evidence for the presence of alpha-MSH and corticotrophin-like intermediate lobe peptide. Three peaks of large molecular weight material, A. B and C, were identified and their relative proportions shown to be considerably greater in the foetus than in the adult. The immunoassay profile of peaks A and B suggested that they were 'stem hormones' which could give rise to a family of biologically active peptides. Since the 'family tree' which they engender varies according to the stage of development, it is proposed that the changes in the 'trophic family' may explain the different adrenal responses of the foetal and adult sheep.

Adrenocorticotropic Hormone↗

PubMed1976

[Cyto-immunological study of the Pleurodele pituitary gland].

In the pituitary of an Amphibian (Urodela), various cell types were localized by cytoimmunological techniques: corticotrophs located in a rostral zone near the median eminence, ventral orangeophilic cells secreting a prolactin-like hormone and erythrosinophilic cells in a more dorso-caudal situation secreting growth hormone. Alpha-MSH and beta-MSH produceng cell were identified in the intermediate lobe; these cells were also labelled with antibodies against 1-24 ACTH and 17-39 ACTH. These data are in accordance with results obtained after an experimental study of the prolactin cells.

Adrenocorticotropic Hormone↗

PubMed1977

[Demonstration by immunofluorescence of adenohyphysis corticotropin and melanotropin cells in Erythrocebus patas, Cercopithecus aethiops and Papio hamadryas].

Using antibodies against synthetic corticotropic hormones (1-24 ACTH and 17-39 ACTH), and melanotropic hormones (alpha-MSH and beta-MSH), it is possible to identify corticotropic and melanotropic cells in the adenohypophysis of three species of monkeys : Erythrocebus patas, Cercopithecus aethiops and Papio hamadryas. The corticotropic cells are numerous in the anterior lobe in both the adult and infant male and female monkeys of these three species. The intermediate lobe reacts with antibodies against ACTH and also with antibodies against the two MSH. In the anterior lobe, the corticotropic cells react also with anti-beta MSH antibody but not with the anti-alpha MSH antibody.

Adrenocorticotropic Hormone↗

PubMed1978

Mechanism of alpha-melanotropin action.

A structure-function study of alpha-melanotropin has shown that this tridecapeptide consists of two message sequences, (-Glu)-His-Phe-Arg-Trp- and -Gly-Lys-Pro-Val-NH2, and a potentiator sequence, Ac.Ser-Tyr-Ser-Met-(Glu-), when acting on its melanophore receptors. The key elements of the message, -Phe-Arg- and -Lys-Pro-, do not correspond exactly to those responsible for eliciting the effect in other tissues. It appears that alpha-MSH contains more information than would be necessary to interact with only one complementary receptor site; therefore, the topography of the hormone exposed to the binding site may be different on contact with the receptors of different target cells. To further investigate this aspect, new methods for the isolation and characterization of functional receptors must be developed. We are investigating the use of chemically well-defined, biologically active, covalent hormone-macromolecule complexes for this purpose. Another approach utilizes model receptors with a recognition pattern similar to that of the biological receptor, as described in this communication for certain highly specific antibodies.

Amino Acid Sequence↗

PubMed1978

[Recent data on the group of melanotropic and lipotropic pituitary hormones (MSH-LPH) and on the brain morphinomimetic peptides (endorphins)].

It was admitted that human beta-MSH was responsible for the hyper-pigmentation observed in some syndromes associated with ACTH hypersecretion. beta-LPH was a pituitary polypeptide, containing the entire sequence of beta-MSH in its fragment 37-58, and the physiological role of which remained unknown. alpha-MSH and CLIP (Corticotrophin-like Intermediary Peptide) were thought to be specific of certain species possessing a distinct pituitary pars intermedia. Recent data give new insight upon some of these conceptions. beta-MSH seems not to exist in man; it is almost established now that plasma "Immunoreactive beta-MSH" (IR-beta-MSH) is in fact beta- and/or gamma-LPH. In chronic renal failure plasma IR-beta-MSH is elevated because of a decreased plasma disappearance rate, whereas ACTH is normal. Good evidence suggests that both LPH and ACTH are synthesized in the same pituitary cell within a common polypeptidic precursor. Endogenous peptides with morphinomimetic activity (Endorphins) have been isolated from brain and hypophysis; they are all made up of different fractions of beta-LPH-C-terminal fragment 61-91; It is likely that they represent a new class of brain neurotransmitters involved in some functions of the central nervous system, structural similarities suggest that beta-LPH may be the biosynthetic precursor of Endorphins, however such a hypothesis remains to be clearly demonstrated.

Adrenocorticotropic Hormone↗

PubMed1979

Biosynthesis and characterization of adrenocorticotropic hormone, alpha-melanocyte-stimulating hormone, and an NH2-terminal fragment of the adrenocorticotropic hormone/beta-lipotropin precursor from rat pars intermedia.

Isolated intermediate lobe cells from 40 rat pituitaries were incubated for 3 h with [35S]methionine + [3H]-phenylalanine, [35S]methionine, [3H]valine, and [3H]leucine. The cell extracts were purified by carboxymethyl-cellulose chromatography (CMC) and the fraction eluting with ovine adrenocorticotropic hormone (ACTH) was further purified either by another CMC under the same conditions or by high performance liquid chromatography (HPLC). Microsequencing of the product from the second CMC allowed the identification of a peptide containing methionine 4 and phenylalanine 7, as expected for the NH2 terminus of ACTH. Purification by HPLC of a similar peptide obtained from the three other incubations gave three main raoactive peaks which were further characterized by their migration rates on polyacrylamide gels, molecular weight, and microsequencing. Results indicated that intact ACTH (residues 1-39) is present in extracts of rat intermediate lobe, but in very small quantities (less than 1% of the beta-endorphin content). ACTH is probably broken down into smaller fragments, e.g. alpha-melanocyte-stimulating hormone (alpha-MSH) (ACTH, 1-13) and corticotropin-like intermediate lobe peptide (CLIP) (ACTH, 18-39). These studies also revealed with existence of a peptide having identical sequence with the (N-1) terminus of the ACTH/lipotropin (LPH) precursor.

Adrenocorticotropic Hormone↗

PubMed1979

[Immunocytologic analysis, in rat hypothalamus, of neurons producing peptides related to endorphin, ACTH, MSH and beta-LPH. Comparison with other peptidergic and monoaminergic neurons].

In rat hypothalamus intraventricularly injected with colchicine, the same neurons of the ventral region are stained with I.S. against alpha and beta-endorphin, (1-24) and (17-39) ACTH, alpha and beta-MSH, and beta-LPH. They are distinct from those producing LH-RH, somatostatin, neurophysin, and dopamine. These results suggest that the same neurons elaborate peptides identical with or immunologically related to endorphins, ACTH, alpha-MSH and beta-LPH, probably issued from a common precursor.

Adrenocorticotropic Hormone↗

PubMed1978

[Evaluation of the reflectometric method using the skin of the toad Bufo arenarum in vitro for the determination of plasma MSH].

The aim of the present paper was to investigate the following points, by using the reflectometric bioassay for melanocyte-stimulating hormone (MSH) with skin of the toad Bufo arenarum: (1) To study if solutions of alpha-MSH prepared in rat plasma and amphibian Ringer, or dilutions of plasma overloaded with endogenous MSH, could render in acceptable dose-response lines. 2) To investigate if ACTH at a very high level of plasma concentration could interfere in the bioassay 3) Observing if the storage of plasma could inactivate the inherent MSH activity. 4) Searching for the response of the skins along the 12 months of the year. The results showed that: Acceptable dose-response lines were obtained with the three types of dilutions and parallelism was found among the three lines. ACTH does not interfere in the assay. Almost a total inactivation of MSH was detected after storing the plasma at room temperature for 4 hours; Trasylol or low temperature preserved the hormone activity. Maximal response of the skin corresponded to the minimal concentration of 1 562 pgr/ml, during the whole year. Minimum detectable concentration varied within the range 24-390 pgr/ml, depending on the month when the study was performed.

Adrenocorticotropic Hormone↗

PubMed1977

New evidence that demonstrates that L-pro-L-leu-L-gly-NH2 might be the natural MIF.

A wide range of doses was used to study the effect of Pro-Leu-Gly-NH2 (MIF) on the MSH release in rat pituitaries incubated in vitro. The Pro-Leu-Gly-NH2 was added to one half of the gland, and the other was used as control. The MSH released into the medium was measured by a bioassay and the activity of the samples referred to a standard of synthetic alpha-MSH. Pro-Leu-Gly-NH2 in doses of 10 to 30 ng/ml inhibited the MSH release in about 60%. Doses between 10(3) to 10(4) ng/ml induced neither release nor inhibition of the release of MSH. Dose of 10(5) ng/ml clearly induced release of MSH. The results of the additional experiments presented, although they represent no proof, are in line with the contention that Pro-Ley-Gly-NH2 in the natural MIF.

Animals↗