The opiomelanotropinergic neuronal and endocrine systems

Carboxyl-terminal tripeptide of alpha-melanocyte-stimulating hormone antagonizes interleukin-1-induced anorexia

Interleukin-1 beta (IL-1), a cytokine released from inflammatory cells, is thought to be involved in the anorexia associated with severe infection. To assess a possible role of the amino acid sequence found in the supposed IL-1 receptor binding sites, we determined the antagonistic effects of alpha-melanocyte-stimulating hormone (MSH) and the carboxyl-terminal tripeptide of alpha-MSH-(11-13) (alpha-MSH-(11-13)) on the anorexia induced by intracerebroventricular (i.c.v.) administration of 0.5 pmol IL-1. The parent alpha-MSH molecule completely prevented the induction of anorexia by IL-1 at both doses tested, 0.5 and 5.0 pmol. In contrast, alpha-MSH-(11-13) prevented the IL-1-induced anorexia only at 5.0 pmol, but not at 0.5 pmol. Intracerebroventricular injection of 5 pmol of the parent alpha-MSH molecule alone temporarily decreased food consumption at 1-2 h; 5.0 pmol of alpha-MSH-(11-13) alone did not affect food consumption. These data indicate that alpha-MSH can antagonize the anorexic effects of IL-1. The carboxyl-terminal tripeptide portion of alpha-MSH may be important for the antagonistic action of alpha-MSH on the anorexia induced by IL-1.

Molecular cloning and expression of the human melanocyte stimulating hormone receptor cDNA

Melanocytes and melanoma cells are known to possess receptors for melanocyte stimulating hormone (MSH). A cDNA clone, designated 11D, has been isolated from human melanoma cells and encodes a MSH receptor. The cloned cDNA encodes a 317 amino acid protein with transmembrane topography characteristics of a G-protein-coupled receptor, but it does not show striking similarity to already published sequences of other G-protein-coupled receptors. When 11D cDNA is expressed in COS-7 cells, it binds an 125I-labelled MSH analogue (NDP-MSH) in a specific manner. The bound ligand could be displaced by melanotropic peptides, alpha-MSH, beta-MSH, gamma-MSH and ACTH (adrenocorticotropic hormone), but not by the non-melanotropic peptide, beta-endorphin. This is the first report of the cloning of the receptor gene of the melanotropin receptor family.

The use of adrenocorticotrophic hormone (4-9) analog ORG 2766 in autistic children: effects on the organization of behavior

In a double-blind placebo-controlled crossover trial, 14 autistic children were treated with the neuropeptide ORG 2766, a synthetic analog of adrenocorticotrophic hormone (ACTH) (4-9). ORG 2766 treatment (20 mg per day during 4 weeks) was associated with an increased amount and an improved quality of the social interaction of the autistic children with a familiar experimenter. These changes in interaction were clinically relevant. Following treatment with ORG 2766 gaze and smile behaviors of child and experimenter showed stronger temporal contingencies. Further, after ORG 2766, stereotypies were temporally disconnected from verbal initiatives. The data supported the notion of a stimulating effect of ORG 2766 on social interaction. The implications of these findings for the endogenous opioid theory of autism are discussed.

Presence of strong glucocorticoid receptor immunoreactivity within hypothalamic and hypophyseal cells containing pro-opiomelanocortic peptides

The presence of nuclear glucocorticoid receptor immunoreactivity (GR IR) was studied in the adrenocorticotropin (ACTH), beta-Endorphin (beta-END) and alpha-melanocyte stimulating hormone (alpha-MSH) IR neuronal populations of the rat hypothalamus and hypophysis using double immunolabelling techniques. All the nuclei of the ACTH/beta-END/alpha-MSH IR neurons of the arcuate and periarcuate nuclei were strongly GR IR in the 48 h colchicine treated animal, but very few alpha-MSH-like IR perikarya located in the dorsal and lateral hypothalamus displayed nuclear GR IR. GR IR was present in the ACTH/beta-END corticotrophs and absent in the intermediate lobe of the hypophysis. The data provide morphological evidence for a glucocorticoid action through a nuclear GR in the arcuate ACTH/beta-END/alpha-MSH IR neurons and the ACTH/beta-END corticotrophs, whereas the alpha-MSH-like IR neurons of the lateral hypothalamus and the melanotropes of the intermediate lobe may not be directly affected by glucocorticoids under normal conditions.

The sites of origin of a-melanocyte-stimulating hormone-containing axonal components in the lateral area of the midbrain periaqueductal gray of the rat

The sites of origin of alpha-melanocyte-stimulating hormone (alpha-MSH)-containing axonal components in the lateral area of the midbrain periaqueductal gray (PAG) were studied in the rat by the retrograde tracing method of horseradish peroxidase, combined with the immunocytochemical technique. The results indicated that alpha-MSH-containing axonal components in the PAG arose not only from the arcuate nucleus of the hypothalamus but also from the ventral zona incerta, the periventricular, perifornical and lateral hypothalamic regions.

Demonstration by in situ hybridization of the proopiomelanocortin gene in the rat heart

A biotinylated oligonucleotide probe was used to demonstrate the presence in the heart of the portion of the proopiomelanocortin messenger RNA which contains the sequence for beta-endorphin. The probe indicated the presence of beta-endorphin messenger RNA in cardiac tissue and specifically in the cardiac muscle cell. The probe also confirmed the well-documented presence of messenger RNA for beta-endorphin in the anterior and neurointermediate lobes of the pituitary. These findings indicate that in addition to the pituitary, beta-endorphin is produced in situ in the heart.

N-acetylation and C-terminal proteolysis of beta-endorphin in the anterior lobe of the horse pituitary

beta-Endorphin is post-translationally processed to both N-acetylated and C-terminally shortened derivatives in the anterior lobe of the horse pituitary, a processing pattern qualitatively different from that of the rat and virtually every other mammalian species. Thus, separation of the molecular forms of beta-endorphin using gel filtration and ion exchange chromatography showed that the horse anterior lobe primarily contains beta-endorphin-1-31 and N-acetyl-beta-endorphin-1-27 along with smaller amounts of beta-lipotropin, beta-endorphin-1-27, and N-acetyl-beta-endorphin-1-31 and -1-26, in contrast to the rat anterior lobe, which contains approximately equal amounts of beta-lipotropin and beta-endorphin-1-31. Immunohistochemical experiments using an antiserum which specifically recognizes N-acetylated beta-endorphin peptides confirmed that N-acetyl-beta-endorphin immunoreactivity is present in the anterior lobe of the horse, but not the rat. The intermediate lobe of both species primarily synthesizes N-acetylated, C-terminally shortened beta-endorphin peptides, and while distinct species differences do occur, they were relatively minor, consisting of quantitative differences in the relative proportion of each peptide. These results are consistent with earlier reports that beta-endorphin processing in the rat pituitary is tissue specific; the anterior and intermediate lobes produce entirely different sets of beta-endorphin peptides. In the equine pituitary, however, both pituitary lobes produce the same multiple beta-endorphin forms, possessing both opioid and nonopioid properties, although their relative amounts differ.

Specific effects of beta-endorphin infused into the amygdala on sexual behaviour in the male rat

Bilateral intra-amygdaloid infusions of 0, 20, 60, 120 and 200 pmol beta-endorphin were administered to sexually experienced male rats in a Latin-square design. Sixty, 120 and 200 pmol beta-endorphin significantly decreased preintromission investigation rate and increased intromission latency with an oestrous female. No other effects on the male rats' sexual behaviour were produced. beta-Endorphin-induced effects on preintromission investigation and intromission latency were naloxone reversible (5 mg/kg, i.p.). Similar doses of intra-amygdaloid beta-endorphin had no effect on aggressive interaction with another, strange, male behaviour and similar doses of intra-amygdaloid corticotropin-releasing factor had no effect on sexual behaviour. Thus, there was both behavioural and chemical specificity of intra-amygdaloid beta-endorphin-induced effects on male sexual behaviour. Bilateral 60 pmol beta-endorphin infusions into the caudate-putamen had no effects on male sexual behaviour, demonstrating anatomical specificity of the intra-amygdaloid-induced effects. Basolateral excitotoxic lesions did not prevent the behavioural effects of intra-amygdaloid beta-endorphin infusions. These results demonstrate that intra-amygdaloid beta-endorphin specifically suppresses the precopulatory phase of male rat sexual behaviour but leaves the execution of the copulatory series intact once it has been initiated. This effect appears to be mediated via the corticomedial amygdaloid region. The change in precopulatory behaviour suggests that beta-endorphin may interfere with the processing of sensory information from the female, thus delaying appropriate initiation of the copulatory series.

Endogenous gamma-aminobutyric acid tonically inhibits release of alpha-melanocyte-stimulating hormone from rat hypothalamic slices

Release of immunoreactive alpha-melanocyte-stimulating hormone (alpha-MSH) from superfused slices of rat hypothalamus was stimulated by the gamma-aminobutyric acid (GABA) receptor antagonist, bicuculline, and inhibited by the benzodiasepine, chlordiazepoxide, an allosteric GABA receptor modulator, demonstrating the presence of tonic inhibition of alpha-MSH release by endogenous GABA in hypothalamic tissue. Chlordiazepoxide increased the effect of exogenous GABA which by inhibiting basal release of alpha-MSH demonstrated that the tonic inhibition was not maximal in the resting state.

Distribution of Met5-enkephalin-Arg6-Gly7-Leu8-immunoreactivity in the rat and mouse pituitary gland

The distribution of the octapeptide Met5-enkephalin-Arg6-Gly7-Leu8 (MEAGL), a proenkephalin A-derived opioid peptide, in the rat and mouse pituitary gland was studied using the indirect immunofluorescence technique and immunoelectron microscopy. The anterior lobe contained a few MEAGL-immunoreactive cells but no nerve fibers. A previously unknown enkephalin-immunoreactive nerve fiber system was revealed in the intermediate lobe. These fibers originated in a dense MEAGL-immunoreactive plexus located along the border between the intermediate and posterior lobes and were distributed throughout the lobe. In the posterior lobe, MEAGL immunoreactivity was found in a very dense network of varicose fibers that was evenly distributed over the entire lobe. These results provide a morphological correlate for previous chemical studies and together with them suggest that MEAGL-immunoreactive innervation regulates endocrine functions of the intermediate and posterior lobes directly at the pituitary level.

The posttranslational processing of beta-endorphin in human hypothalamus

beta-Endorphin is posttranslationally processed to six derivatives, which, although structurally similar, produce distinctly different biological effects. beta-Endorphin 1-31 is a potent opioid receptor agonist, but beta-endorphin 1-27 exhibits antagonist properties, and beta-endorphin 1-26 and the alpha-N-acetyl derivatives of all three peptides lack opioid receptor activity. In the present study, we identified the beta-endorphin peptides synthesized in human hypothalamus using cation exchange HPLC. First, we tested whether postmortem changes occur by storing rat hypothalami at 4 degrees C. This demonstrated that relative amounts of the six beta-endorphin forms did not change for up to 24 h, although total beta-endorphin immunoreactivity significantly declined after 6 h. HPLC analysis of human hypothalami revealed that beta-endorphin 1-31 was the principal form, constituting 58.4 +/- 5.4% of total immunoreactivity. Substantial amounts of beta-endorphin 1-27 (13.4 +/- 1.2%) and beta-endorphin 1-26 (13.1 +/- 1.6%) were also present, but alpha-N-acetylated forms were quantitatively minor, each comprising approximately 5% of total beta-endorphin. A similar processing pattern occurred in preoptic and suprachiasmatic areas of the hypothalamus. These results show that, despite differences in primary sequence, beta-endorphin is processed similarly in both rat and human hypothalamus. Opiate-active beta-endorphin 1-31 is the principal form in both species.

Anti-inflammatory activity of alpha-MSH(11-13) analogs: influences of alteration in stereochemistry

D-Amino acid substitutions in the anti-inflammatory/antipyretic Ac-alpha-MSH(11-13)-NH2 tripeptide of Ac-alpha-MSH(1-13)-NH2 were made and the altered peptides were injected in mice treated with picryl chloride. Ear swelling, measured 3 and 6 h after application of the irritant, was reduced by IP injections of Ac-alpha-MSH(11-13)-NH2, in confirmation of previous observations. Ac-[D-Lys11]alpha-MSH(11-13)-NH2 effected similar anti-inflammatory activity but Ac-[D-Pro12]alpha-MSH(11-13)-NH2 was inactive. Ac-[D-Val13]alpha-MSH(11-13)-NH2 and Ac-[D-Lys11,D-Val13]alpha-MSH(11-13)-NH2 generally had greater anti-inflammatory activity than the parent tripeptide molecule; the dose-response relations exhibited the bell-shaped characteristics seen previously with MSH peptides. The results indicate that the L-Pro12 is essential for the anti-inflammatory activity of Ac-alpha-MSH(11-13)-NH2 whereas the L-Lys11 is not. D-Val13 substitution increased anti-inflammatory activity approximately four-fold over Ac-alpha-MSH(11-13)-NH2. These results provide new structure-activity relationships of the anti-inflammatory Ac-alpha-MSH(11-13)-NH2 molecule. The data support the developing idea that alpha-MSH and its COOH-terminal fragments modulate host responses, perhaps by antagonizing the actions of cytokines.

Adrenocorticotropic hormone influences the development of adaptive changes in dopamine autoreceptors induced by chronic administration of desipramine

The influence of adrenocorticotropic hormone (ACTH) in the adaptive changes on central dopamine (DA) autoreceptors following chronic administration of desipramine (DMI) has been examined in rats. Dopamine had an inhibitory effect on basal and K(+)-induced release of [3H]DA from slices of striatum and n. accumbens of rats treated chronically (10 days) with ACTH (50 IU/kg, s.c.), DMI (10 mg/kg, i.p.) or the combination of ACTH and DMI. In slices of n. accumbens, but not in slices of striatum of rats exposed to the combined treatment of ACTH and DMI, a significant decrease in the inhibitory effect of exogenous DA on stimulated release of [3H]DA was observed. Chronic administration of ACTH or DMI alone had no effect. The effect of the combined treatment with both agents, on the reactivity of these DA receptors was evaluated by means of apomorphine-induced hypoactivity. The administration of ACTH and DMI (5 mg/kg, i.p.) reduced the hypoactivity induced by apomorphine, as compared to hypoactivity in rats treated with ACTH or DMI alone. Experiments with ACTH4-10 revealed that the peptide modified biochemical and behavioural parameters of dopaminergic function, which may implicate a direct action of the peptide on the brain, rather than on the release of adrenal hormones. These findings suggest that ACTH accelerates the onset of DMI-induced adaptive changes on dopamine in the mesolimbic area. However, because the effect of ACTH4-10 on release of adrenocortical hormone was not investigated, the possibility cannot be disregarded that the effect of the peptide was secondary to an enhancement of release of adrenal hormone.

Changes in opioid receptor selectivity following processing of peptide E: effect on gut motility

Peptide E is a mu-selective opioid peptide derived from proenkephalin A which contains [Met5]-enkephalin at the amino end and [Leu5]-enkephalin at the carboxyl end. Peptide E is further processed both centrally and peripherally to a [Leu5]-enkephalin-containing fragment which was investigated to determine if processing leads to alterations in receptor selectivity. Peptide E-(15-25) inhibited electrically stimulated contractions in both the mouse vas deferens, longitudinal muscle, myenteric (IC50 = 459 nmol/L), and guinea pig ileum (IC50 = 2630 nmol/L), indicating a sixfold delta-receptor selectivity. When administered intracerebroventricularly to mice, peptide E-(15-25) also produced potent analgesia which was completely antagonized by naloxone pretreatment, but the peptide had no effect on intestinal transit as measured by the radiochromium geometric center method. This is consistent with earlier findings that intracerebroventricular delta-opioid-selective agents are analgesic but do not inhibit intestinal transit. In vitro radioligand binding assays were performed using male Sprague-Dawley rat whole brain homogenates. The IC50 for peptide E against [3H]naloxone was 1.8 nmol/L compared with the delta-opioid ligand, [3H] [D-Pen2, D-Pen5]-enkephalin of 38.8 nmol/L. The IC50 for peptide E-(15-25) against [3H]naloxone was 497 nmol/L, but for [3H] [D-Pen2, D-Pen5]-enkephalin it was 50.6 nmol/L. Therefore, peptide E loses mu-opioid receptor affinity (1.8-497 nmol/L) after proteolytic processing and the loss of the amino terminal tyrosine but maintains a high delta-opioid affinity (38.8-50.6 nmol/L). These studies demonstrate that enzymatic peptide processing of peptide E to peptide E-(15-25) leads to a shift from mu- to delta-receptor selectivity and a different spectrum of biological effects on gut motility.

Identification of a Single Melanin-Concentrating Hormone Messenger Ribonucleic Acid in Coho Salmon: Structural Relatedness with 7SL Ribonucleic Acid

Abstract Melanin-concentrating hormone (MCH) is a cyclic neuropeptide possessing antagonistic function to alpha-melanocyte-stimulating hormone and corticotropin-releasing factor in the control of melanosome dispersion within melanophores and adrenocorticotropin release in fish. We have isolated and characterized MCH cDNAs from coho salmon (Oncorhyncus kisutch). The precursor protein predicted by the longest cDNA consists of 132 amino-acids with a characteristic signal peptide at the N-terminus and the biologically active salmon MCH (sMCH) peptide at the C-terminus. The coho sMCH mRNA and protein sequences are very similar but not identical to the previously reported chum or chinook salmon counterparts, suggesting the existence of species polymorphism. Sequence similarities were revealed between alpha-melanocyte-stimulating hormone and part of the C-terminal domain of sMCH precursor. Two sMCH genes were found in coho salmon. By contrast to other salmon species, only one major sMCH mRNA was detected in coho species suggesting that differential MCH gene expression might occur in salmon. In addition, under low stringency oligoprobes complementary to the sMCH RNA recognize a 0.3 kb RNA which was identified as the 7SL RNA. The regions conserved between those RNAs fold in a similar secondary structure. These similarities might reflect common ancestry which may have functional significance.

Mass spectrometric quantification of endogenous beta-endorphin

Fast atom bombardment (FAB) mass spectrometry and multiple reaction monitoring (MRM) in the B/E linked-field scan mode were used to quantify endogenous beta-endorphin (BE) in individual human pituitary extracts. The experimental protocol includes the addition of a stable isotope-labeled internal standard ((2H4-Ile22)BE1-31, human) to the tissue homogenate before extraction, purification of the native BE by a combination of Sep-Pak chromatography and gradient high-performance liquid chromatography (HPLC), trypsin digestion to cleave BE into smaller peptides, and separation of the tryptic fragment BE20-24 (NAIIK) by isocratic reversed-phase HPLC. Mass spectrometric quantification is based upon recording either (a) the [M + H]+ ions of NAIIK and its deuterated analog ((2H4)NAIIK), or (b) the transitions ([NAIIK + H](+)----[NAI]+) and [((2H4)NAIIK + H](+)----[(2H4)NAI]+) using the B/E linked-field scan. Linear calibration curves were obtained using these two mass spectrometric techniques from standard solutions containing 1.25-20 micrograms of BE; each standard solution also contained 10 micrograms of (2H4)BE. The amounts (means +/- s.d.) of endogenous BE in five separate human pituitaries were found to be 156 +/- 84 [( M + H]+ method) and 169 +/- 99 pmol mg-1 protein (MRM method).

Pro-opiomelanocortin mRNA and peptide co-expression in the developing rat pituitary

Pro-opiomelanocortin (POMC) is synthesized in both the pituitary gland and the brain. Various peptide products of this precursor, namely beta-endorphin, ACTH and alpha-MSH are co-localized in the anterior lobe corticotrophs, all intermediate lobe cells and in hypothalamic neurons. Messenger RNA (mRNA) for POMC has further been shown to exist in these tissues. In this study, we have shown that POMC mRNA, and peptide accumulation as detected by in situ hybridization and immunocytochemistry, respectively, occur simultaneously within the rat pituitary gland during ontogeny and that their maturation occurs in parallel during prenatal and early postnatal development.

Central-type benzodiazepines inhibit release of alpha-melanocyte-stimulating hormone from the rat hypothalamus

In a previous work, we have shown that GABA inhibits the release of alpha-melanocyte-stimulating hormone (alpha-melanotropin) from hypothalamic neurons through activation of GABAA receptors [Delbende et al. (1989) Brain Res. 497, 86-93]. Since GABA-gated channel activity can be allosterically modulated by a variety of compounds including benzodiazepines, we have investigated the effect of benzodiazepines in the control of alpha-melanotropin release by the rat basal hypothalamus. This study was conducted in vitro using perifused rat hypothalamic slices and the amount of alpha-melanotropin release was monitored with a sensitive and highly specific radioimmunoassay. Infusion of clonazepam (50 microM), a selective agonist for central-type benzodiazepine binding sites, induced an inhibition of KCl (50 mM)-evoked alpha-melanotropin release. The inhibitory effect of clonazepam was rapid and reversible. Administration of Ro 15-1788 (100 microM), a specific antagonist for central-type benzodiazepine receptors or SR 95531, a GABAA receptor antagonist, completely reversed the inhibitory effect of clonazepam. In addition, Ro 15-1788 and SR 95531 both enhanced the amplitude of the response observed during prolonged KCl infusion on alpha-melanotropin neurons, suggesting the existence of a tonic inhibitory effect of endogenous GABA and/or benzodiazepines in the release of alpha-melanotropin by hypothalamic neurons. To investigate further the effect of benzodiazepines in the regulation of alpha-melanotropin neurons, rats were treated in vivo with clonazepam (5 mg/kg) or the non-selective benzodiazepine receptor agonist diazepam (3 mg/kg). Both compounds caused a significant increase in the content of alpha-melanotropin and beta-endorphin in the rat hypothalamus within 3 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrastructural localization of adrenocorticotrophic hormone and the phosphoprotein B-50/growth-associated protein 43 in freeze-substituted, Lowicryl HM20-embedded mesencephalic central gray substance of the rat

Previous studies have shown that the endogenous phosphorylation of the neuron-specific protein B-50 in isolated synaptic plasma membranes is inhibited by adrenocorticotrophic hormone(1-24). The aim of this study is to examine if there is a specific neuroanatomical interaction of adrenocorticotrophic hormone and B-50 in the mesencephalic central gray substance of the rat. With light microscopy, high B-50 immunoreactivity was detected throughout the mesencephalic central gray substance, overlapping with those areas where adrenocorticotrophic hormone-immunoreactive fibres were present. To study the ultrastructural localization of B-50 and adrenocorticotrophic hormone, we employed a method of immunogold labelling on ultrathin sections of freeze-substituted and Lowicryl HM20-embedded fixed brain tissue. This offered optimal morphological preservation together with high retention of antigenicity. At the electron microscopic level, adrenocorticotrophic hormone immunoreactivity was detected in dense-core secretory granules present in non-junctional regions of axoinal varicosities. This suggests a non-synaptic release of adrenocorticotrophic hormone from the axons. Using double immunolabelling techniques we showed that in adrenocorticotrophic hormone-innervated areas of the mesencephalic central gray substance B-50 immunoreactivity was present at plasma membranes of all unmyelinated axons and axonal varicosities and virtually absent in dendrites. The result on B-50 localization agrees well with previous studies in the hippocampus [Van Lookeren Campagne et al. 1990 J. Neurocytol. 19, 948-961] and in the pyramidal tract [Gorgels et al. 1989 J. Neurosci. 9, 3861-3869] of the rat and suggests that in the mature rat central nervous system, B-50 expression in axons is a general phenomenon. For the adrenocorticotrophic hormone-innervated areas, we discuss the proposal that non-synaptically released adrenocorticotrophic hormone modulates B-50 phosphorylation in axons and axon terminals.

Immunohistochemical distribution of corticotropin-like intermediate lobe peptide (CLIP) immunoreactivity in the human brain

The immunocytochemical distribution of CLIP (corticotropin-like intermediate lobe peptide) or ACTH(18-39), a small biologically active peptide, was examined in the human brain, using a monoclonal antibody against this peptide. Groups of CLIP-immunoreactive cell bodies, small to medium size and bipolar or triangular in shape, were found in the basal hypothalamus extending from the retrochiasmatic region to the premammillary nuclei area. Immunoreactive fibers with varicosities, terminals and "pipe shape" structures, were distributed within the hypothalamus, limbic structures, the brainstem and spinal cord nuclei, forming a particularly rich network in the hypothalamus, the preoptic area, the septal region, the amygdala and the upper brainstem periaqueductal gray matter. The above neuroanatomical observations confirm and extend previous findings in animals, strengthening even more the possibility that this peptide may be involved in numerous behavioral, autonomic and physiological functions such as regulation of sleep-waking cycle, pain control and respiratory and cardiovascular regulation.

Behavioral effects of Org 2766, a synthetic analog of the adrenocorticotrophic hormone (4-9), in 14 outpatient autistic children

Fourteen children (12 infantile autism full syndrome present, 2 atypical pervasive developmental disorder) between 5 and 13 years of age participated in a double-blind placebo-controlled cross-over trial. Each child received 20 mg Org 2766 (synthetic analog of ACTH 4-9)/day during 4 weeks, or placebo in a randomly assigned sequence. Drug effects were monitored by ethological playroom observation and by Aberrant Behavior Checklist ratings by parents and teachers. Data of the playroom observation pointed to an activating influence of Org 2766, as revealed by a significant decrease of stereotypic behavior and significant increases in "change toys," "locomote," and "talk." Checklist ratings did not show significant changes. The clinical implications of these findings are discussed.

A novel biochemical model linking dysfunctions in brain melatonin, proopiomelanocortin peptides, and serotonin in autism

A novel biochemical model for autism is presented, which proposes that a subgroup of autistic individuals may have a hypersecretion of pineal melatonin that produces a cascade of biochemical effects including a corresponding hyposecretion of pituitary proopiomelanocortin (POMC) peptides and a hypersecretion of hypothalamic opioid peptides and serotonin (5-HT). The model is reviewed, and supporting animal and clinical research, is summarized. The first arm of the model suggests that increases in pineal melatonin results in hypersecretion of 5-HT in hypothalamus and blood. The second arm of the model indicates that hypersecretion of melatonin also inhibits the release of hypothalamic corticotrophin-releasing hormone (CRH). Hyposecretion of CRH may result in decreased release of both pituitary B-endorphin (B-E) and adrenocorticotrophin hormone (ACTH); this, in turn, may result in decreased plasma concentrations of B-E, ACTH, and cortisol. In autism, a genetically determined hypersecretion of hypothalamic B-E may further contribute to an inhibition of pituitary B-E because of negative feedback inhibition. Therefore, autism may reflect a dysfunction in the pineal-hypothalamic-pituitary-adrenal axis which, modulates POMC and 5-HT systems of the brain. This model is consistent with numerous clinical investigations implicating hypersecretion of brain 5-HT and opioid peptides in autism. The model may have heuristic importance in guiding future research in the biochemistry of autism.

Alpha-MSH peptides inhibit acute inflammation and contact sensitivity

Alpha-melanocyte stimulating hormone [alpha-MSH(1-13)] occurs within the CNS, skin, circulation and in other body sites. This tridecapeptide and its COOH-terminal tripeptide, alpha-MSH (11-13), have antipyretic and anti-inflammatory actions. Studies of the anti-inflammatory effects of these molecules have been confined mainly to tests of inhibition of histamine and endogenous pyrogen-induced increases in capillary permeability in rabbits and acute inflammation of ear tissue in mice. The aim in the present experiments was to learn if alpha-MSH peptides also antagonize inflammation in two additional models: acute edema induced in the mouse paw and contact sensitivity. Significant anti-inflammatory effects were observed with MSH peptides in both models. These findings converge with previous results to indicate that alpha-MSH peptides modulate inflammation. Because circulating alpha-MSH increases after treatment of animals with endogenous pyrogen or endotoxin, administration of the peptides may simply mimic a naturally occurring modulation of host defense reactions.

Effects of ions and ionic channel activators or blockers on release of alpha-MSH from perifused rat hypothalamic slices

The involvement of sodium and chloride ions in the process of alpha-melanocyte-stimulating hormone (a-MSH) release from hypothalamic neurons was investigated using perifused rat hypothalamic slices. Three different stimuli were found to increase a-MSH release from hypothalamic slices: high K+ concentration (50 mM), veratridine (50 microM), and the Na+/K(+)-ATPase inhibitor ouabain (1 mM). Spontaneous or K(+)-evoked a-MSH release was insensitive to the specific Na+ channel blocker tetrodotoxin (TTX; 1.5 microM) and to the blocker of K+ channels tetraethylammonium (TEA; 30 mM) or 4-aminopyridine (4-AP; 4 mM). In contrast, blockage of ouabain-sensitive Na+/K(+)-ATPase increased the resting level of a-MSH and caused a dramatic potentiation of K(+)-evoked a-MSH release. The Na+ channel activator veratridine (50 microM) triggered a-MSH release. This stimulatory effect was blocked by TTX and prolonged by TEA application, indicating the occurrence of voltage-sensitive Na+ and K+ channels on a-MSH neurons. Replacement of Na+ by impermeant choline ions from 95 to 60 mM did not alter K(+)-evoked a-MSH release. Conversely, dramatic reduction of the external Na+ concentration to 16 mM caused a robust increase of a-MSH secretion from hypothalamic neurons, likely through activation of the Na+/Ca2+ exchange system. These data indicate that the depolarizing effect of K+ results from direct activation of voltage-operated Ca2+ channels. The lack of effect of TEA on basal a-MSH release prompted us to investigate the possible involvement of chloride ions in the regulation of the spontaneous activity of a-MSH neurons. Substitution of Cl- for impermeant acetate ions did not affect basal or K(+)-evoked a-MSH release.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of calcium in the expression of ACTH-induced stretching, yawning and penile erection

The effect of omega-conotoxin GVIA, a potent and selective inhibitor of N-type calcium channels and of the organic calcium channel inhibitors nimodipine, verapamil and flunarizine, on stretching, yawning and penile erection induced by ACTH 1-24 was studied in male rats. omega-Conotoxin (1-10 ng ICV 15 min before ACTH, 10 micrograms ICV), but not carboxymethylated omega-conotoxin, induced a dose-dependent prevention of all ACTH effects. In contrast, organic calcium channel inhibitors (20 mg/kg IP 30-60 min before ACTH) failed to modify ACTH-induced stretching and yawning but induced a 25% decrease in the number of penile erection episodes induced by the peptide, and prevented, like ICV omega-conotoxin, oxytocin- and apomorphine-induced yawning and penile erection. When injected in the paraventricular nucleus of the hypothalamus, omega-conotoxin prevented the above behavioral responses induced by apomorphine and oxytocin but not by ACTH 1-24. The present results suggest that ACTH induces stretching, yawning and penile erection by mobilizing calcium through central omega-conotoxin-sensitive calcium channels in brain sites different from those sensitive to oxytocin and apomorphine.

Synthesis and actions of a melanotropin conjugate, Ac-[Nle4, Glu(gamma-4'-hydroxyanilide)5, D-Phe7]alpha-MSH4-10-NH2, on melanocytes and melanoma cells in vitro

L-Glutamic acid (gamma-4'-hydroxyanilide) (GHB) is oxidized by tyrosinase to a quinone which inhibits DNA polymerase, RNA polymerase, and mitochondrial energy production within mushrooms. It was previously shown that GHB can kill B16 melanoma cells in culture, but lacks cytotoxicity for nontyrosinase-containing cells. We have conjugated this drug to a superpotent melanotropic peptide and examined the bioactivity of this conjugate to melanoma cells. 4'-Hydroxyaniline was attached to glutamic acid at position 5 in the superpotent melanotropin fragment analogue, Ac-[Nle4, D-Phe7]alpha-MSH4-10-NH2. The melanotropin:anilide conjugate, Ac-[Nle4, Glu(gamma-4'-hydroxyanilide)5, D-Phe7]alpha-MSH4-10-NH2, was not cytotoxic to B16 or Cloudman S91 mouse melanoma cells in culture, as determined by cell counts and protein assays. Interestingly, we also found that GHB stimulated melanoma cell tyrosinase above control levels in both melanoma cell lines. In our study, GHB itself also was found not to be cytotoxic to B16 or S91 melanoma cells in culture. In the frog skin bioassay, the melanotropin conjugate was more potent than alpha-MSH or Ac-[Nle4, D-Phe7]alpha-MSH4-10 in stimulating melanosome dispersion. These results demonstrate that putative chemotherapeutic ligands can be incorporated into active-site fragment analogues of MSH without loss of biological activity.

MIF-induced augmentation of melatonin functions: possible relevance to mechanisms of action of MIF-1 in movement disorders

MIF-1, a synthetic tripeptide with MSH-release inhibitory properties, has been reported to improve symptoms of Parkinson's disease, attenuate levodopa-related dyskinesias and diminish the dyskinetic movements of Tardive dyskinesia. More recently, MIF-1 has been reported partially to protect against the nigro-striatal dopamine depleting effects of MPTP in mice, raising the possibility that it may exert protective effects against the development of Parkinson's disease. There is evidence to suggest that MIF-1 increases nigro-striatal dopaminergic activity, but its ability to improve symptoms in patients with Parkinson's disease, levodopa-related dyskinesias and Tardive dyskinesia cannot be explained solely on the basis of the drug's effect on striatal dopaminergic neurons. MIF-1 has been reported to potentiate the melanocyte-lightening effect of melatonin in rats and its effects in patients with Parkinson's disease and Tardive dyskinesia are associated with marked mood elevation. It is, therefore, possible that the effects of MIF-1 in movement disorders are associated with increased melatonin secretion. Thus, hypothalamic MIF may modulate nigro-striatal dopaminergic functions in part via pineal melatonin. Such an interaction represents a novel mechanism by which hypothalamic peptides act to modulate the expression of movement disorders.

Opioids modulate interleukin-1 production and secretion by bone-marrow macrophages

In the present study, we have assessed the effect of opioids (endorphins, enkephalins and neoendorphins) on production of IL-1 activity by bone-marrow-derived macrophages. None of the neuropeptides induced IL-1 production by itself. However, some of the opioids potentiated IL-1 production and release in macrophages concomitantly stimulated by lipopolysaccharide (LPS) or silica. LPS induced predominantly intracellular IL-1 activity, whereas most of the silica-induced IL-1 was released extracellularly. beta-Endorphin, leucine-enkephalin (leu-enkephalin) and beta-neoendorphin all potentiated both intracellular and extracellular release of IL 1 induced by either LPS or silica. In contrast, alpha-endorphin, methionine-enkephalin (metenkephalin) and alpha-neoendorphin did not influence IL-1 production or release. The potentiating effects of beta-endorphin on LPS-induced IL-1 production/secretion were inhibited by naloxone, pointing to an involvement of opioid receptors.

Characterization of alpha-melanocyte-stimulating hormone (alpha-MSH)-like peptides in discrete regions of the rat brain. In vitro release of alpha-MSH from perifused hypothalamus and amygdala

The neuropeptide alpha-melanocyte-stimulating hormone (alpha-MSH) is synthesized by discrete populations of hypothalamic neurons which project in different brain regions including the cerebral cortex, hippocampus and amygdala nuclei. The purpose of the present study was to identify the alpha-MSH-immunoreactive species contained in these different structures and to compare the ionic mechanisms underlaying alpha-MSH release at the proximal and distal levels, i.e. within the hypothalamus and amygdala nuclei, respectively. The molecular forms of alpha-MSH-related peptides stored in discrete areas of the brain were characterized by combining high-performance liquid chromatography (HPLC) separation and radioimmunoassay detection. In mediobasal and dorsolateral hypothalamic extracts, HPLC analysis confirmed the existence of a major immunoreactive peak which co-eluted with the synthetic des-N alpha-acetyl alpha-MSH standard. In contrast, 3 distinct forms of immunoreactive alpha-MSH, which exhibited the same retention times as synthetic des-, mono- and di-acetyl alpha-MSH, were resolved in amygdala nuclei, hippocampus, cortex and medulla oblongata extracts. The proportions of acetylated alpha-MSH (authentic alpha-MSH plus diacetyl alpha-MSH) contained in these extrahypothalamic structures were, respectively, 78, 80, 60 and 92% of the total alpha-MSH immunoreactivity. In order to compare the ionic mechanisms underlaying alpha-MSH release from hypothalamic and extrahypothalamic tissues, we have investigated in vitro the secretion of alpha-MSH by perifused slices of hypothalamus and amygdala nuclei. High potassium concentrations induced a marked increase of alpha-MSH release from both tissue preparations. However, a higher concentration of KCl was required to obtain maximal stimulation of amygdala nuclei (90 mM) than hypothalamic tissue (50 mM).(ABSTRACT TRUNCATED AT 250 WORDS)

Melanocyte-stimulating hormone and persistent tardive dyskinesia: a hypothesis

An increased incidence of abnormal perioral movements has recently been reported in drug-naive pinealectomized rats with further accentuation of these movements following administration of haloperidol. Analysis of the temporal course of the development of the perioral dyskinetic movements revealed that the onset of these movements occurred within 4 days postoperatively and peaked at 3 weeks to plateau over the following 4-6 weeks. Increased pituitary Melanocyte-stimulating hormone (MSH) content has been reported in pinealectomized rats. Elevation of MSH content in the pinealectomized rats occurred within 3 days of surgery and was followed by normalization within 4 weeks. These findings suggest that compensatory mechanisms involving hypothalamic-pituitary MSH release must have been activated to induce normalization of pituitary MSH levels. Moreover, reduction of pituitary MSH levels may have coincided with attenuation in the severity of the perioral dyskinetic movements. It is possible that the development of tardive dyskinesia (TD) may in part be associated with increased brain and plasma MSH levels and that impaired hypothalamic-pituitary regulatory mechanisms of MSH release may be associated with persistent TD. The pineal gland may be implicated in this process as diminished melatonin secretion may be associated with disinhibition of MSH release. Thus, the above hypothesis complements and extends the recently presented "melatonin hypothesis" and suggests that research of pineal-hypothalamic interactions may be crucial to the further understanding of TD.

Effects of chronic ethanol treatment on alpha-MSH concentrations in rat brain and pituitary

Male Sprague-Dawley rats were chronically treated with a liquid diet containing 6.5% (v/v) ethanol or equicaloric sucrose. Rats were killed after 21 days of treatment. alpha-MSH-like immunoreactivity was measured in the intermediate lobe of the pituitary gland and in several brain regions. Chronic ethanol treatment significantly reduced alpha-MSH-like immunoreactivity in the pituitary gland; in the arcuate nucleus of the hypothalamus and in the substantia nigra. The results of this study confirm the earlier findings that chronic ethanol treatment reduces POMC biosynthesis in the pituitary gland and in the central nervous system.

Alpha-melanocyte stimulating hormone message and inhibitory sequences: comparative structure-activity studies on melanocytes

We investigated the structure-activity relationships of alpha-MSH (alpha-melanocyte stimulating hormone) fragment derivatives of the generic formulae Ac-alpha-MSH(x-13)-NH2 and Ac-alpha-MSH(6-x)-NH2. The minimal C-terminal sequences required for melanotropic activity were 8-13 and 7-13, respectively, in the frog and lizard skin bioassays. The Arg8-Trp9 sequence appears to be a fundamental component of the minimal message sequences found to date such as alpha-MSH(6-9), alpha-MSH(8-13) and alpha-MSH(7-13). We discovered that Ac-alpha-MSH(7-10)-NH2 was a weak and selective alpha-MSH antagonist on the lizard skin bioassay. Analysis of alpha-MSH(7-10) analogues of the generic formula Ac-Xaa-Arg-Trp-Yaa-NH2 led to Ac-[D-Trp7,D-Phe10]alpha-MSH(7-10)-NH2, a moderately potent, specific and competitive inhibitor of alpha-MSH in both the frog and the lizard skin bioassays.

Opioid and tachykinin peptides, and their precursors and precursor-processing enzymes, in human cerebrospinal fluid

Opioid and tachykinin neuropeptides, which were derived from two biological sources (intact, and released from their corresponding precursors by the action of human cerebrospinal fluid (CSF) neuropeptidases), were characterized in human CSF by using a combination of post-high-performance liquid chromatographic (HPLC) detection techniques. Peptides were separated using gradient and isocratic reversed-phase HPLC. Radioimmunoassay measured immunoreactivity corresponding to several different individual neuropeptides including methionine enkephalin, leucine enkephalin, substance P and beta-endorphin. Commercial enzymes (trypsin, carboxypeptidase B) were used to release methionine- and leucine-enkephalin from precursors. Human CSF also served as a source of endogenous neuropeptidases. Mass spectrometry produced fragment ions that corroborated the amino acid sequence of methionine enkephalin and of substance P derived from both sources (intact, from precursors). These results demonstrated the presence of endogenous intact neuropeptides, several different neuropeptide-containing precursors and appropriate precursor-processing enzymes in human CSF for precursors of methionine enkephalin, leucine enkephalin, beta-endorphin1-31 and substance P.

Proopiomelanocortin (POMC)-derived peptides and sleep in the rat. Part 2--Aminergic regulatory processes

Apomorphine (Apo), a D1/D2 Dopamine (DA) agonist, at high doses (500 micrograms/kg) induces a short-lasting insomnia, antagonized by a secondary injection of corticotropin-like intermediate lobe peptide (CLIP, 10 ng); these effects are also observed with hypophysectomized (hypoX) rats. The administration of the serotonin (5-HT) agonist 8-hydroxy-2-di-n-propylamino-tetralin (8-OHDPAT, 0.3 mg/kg) induces also an insomnia which, unlike Apo, is followed by a significant PS rebound. CLIP, again, antagonizes the 8-OHDPAT-induced insomnia. Finally, Bromocriptine (5 mg/kg), an agonist for both DA and 5-HT, induces first an insomnia (antagonized by CLIP), followed by a PS rebound; these effects persist in hypoX rats.

Proopiomelanocortin (POMC)-derived peptides and sleep in the rat. Part 1--Hypnogenic properties of ACTH derivatives

The sleep-wake effects of the proopiomelanocortin (POMC)-derived peptides, i.c.v. injected, are reported. Adrenocorticotropic hormone (ACTH, 1 microgram) induces an awakening effect, while its two derivatives, desacetyl-alpha-MSH (des-alpha-MSH, 1ng) and corticotropin-like intermediate lobe peptide (CLIP, 10 ng), are respectively able to increase slow wave sleep (SWS) and paradoxical sleep (PS); the hypnogenic effect of CLIP is also observed in hypophysectomized rats. Furthermore, two hypothalamic factors known to be involved in the control of POMC derivatives were also injected; MSH inhibiting Factor (MIF) does not influence the vigilance states, while Corticotropin Releasing Factor (CRF, 1 microgram) increases the waking state. Finally, some preliminary results, obtained with a restraint stress and suggesting a possible interrelation between stress, sleep and POMC derivatives, are discussed.

Seborrhea and persistent tardive dyskinesia

The following communication concerns two schizophrenic patients with Tardive dyskinesia (TD) in whom fluctuations in the severity of the dyskinesias were accompanied by changes in the severity of the seborrheic skin lesions. Since seborrheic dermatitis may be associated with increased plasma melanocyte-stimulating hormone (MSH) level, these observations suggest an association between the severity of TD and increased pituitary MSH release. In addition, TD may be associated with hypothalamic-pituitary dysfunction of MSH autoregulation.

A possible role of proopiomelanocortin peptides in self-injurious behavior

1. The hypothesis that opioids may be involved in self-injurious behavior is supported by fifteen years of basic animal research suggesting that opioid peptides of the brain and spinal cord participate in the modulation of antinociception in animals, and research of animal models for self-injurious behavior utilizing exogenously administered opiate agonists. 2. Clinical biochemical and pharmacological research conducted over the past five years has also suggested the possibility that opioid peptides may play an important etiological role in the elaboration of self-injurious behavior in some individuals. 3. An opioid overactivity self-injurious hypothesis is supported by results of one study indicating elevated Fraction II opioids (enkephalins) in the lumbar-thecal cerebrospinal fluid of self-injurious children compared to controls, and by the five out of six published studies demonstrating statistically significant decreases in the frequency of self-injurious behavior with the opiate antagonist, naltrexone. 4. A very recent investigation has suggested that some self-injurious individuals show abnormalities in their plasma proopiomelanocortin peptide response to naltrexone, thereby indicating a possible dysfunction in the responsitivity of the proopiomelanocortin system of the hypothalamic-pituitary-adrenal axis of these individuals. 5. These data and results of other investigations have resulted in the elaboration of the original opioid hypothesis to a more comprehensive biochemical model that focuses on this proopiomelanocortin dysregulation. 6. Because of biochemical and functional interrelationships between proopiomelanocortin peptides and certain other neurochemical systems in the brain, it is proposed that pineal melatonin and serotonin may also be involved in this dysregulation. Further basic and clinical research will be needed to test the proposed biochemical model for self-injurious behavior.

Beta-endorphin-like and alpha-MSH-like immunoreactivities in human milk

We measured with radioimmunoassay the beta-endorphin-like and alpha-MSH-like immunoreactivities in milk and plasma of 8 lactating women. Mean beta-endorphin concentrations ( +/- SD) were 16.6 +/- 6.7 fmol/ml in milk and 9.9 +/- 4.1 fmol/ml in plasma. alpha-MSH concentrations (mean +/- SD) were 39.4 +/- 15.5 pg/ml in milk and 18.2 +/- 8.4 pg/ml in plasma. The concentrations of both peptides in milk were significantly (p less than 0.05) higher than in plasma. No significant correlation between milk and plasma concentrations of these peptides was found.

Pineal melatonin functions: possible relevance to Parkinson's disease

Barbeau hypothesized that Parkinson's disease is associated with hypothalamic deficiency of the specialized neuroendocrine cell system (A.P.U.D.) and that the degeneration of brainstem monoaminergic neurons is secondary to progressive functional loss of this cell system in the disease. The pineal gland meets criteria of the A.P.U.D. cell system and it is possible that dysfunction of the pineal gland may be associated with the pathophysiology and clinical manifestations of Parkinson's disease. Since the role of pineal melatonin in humans remains enigamatic, it is currently unclear which of the symptoms of Parkinson's disease may be associated with deregulation of the secretory activity of pineal melatonin. This review summarizes evidence linking possible alterations of pineal melatonin functions with the clinical manifestations of Parkinson's disease.

The adrenocorticotropic hormone (ACTH)-induced reversal of hemorrhagic shock

Adrenocorticotropic hormone (ACTH), while having negligible effects on cardiovascular function in the intact animal, induces a potent and sustained reversal of an otherwise invariably, rapidly fatal condition of hemorrhage-induced hypovolemic shock, in rats and dogs. The main site(s) of action are at the peripheral level; however, subsidiary site(s) of action in the CNS cannot be excluded. The studies on the mechanism of action indicate that the ACTH-induced reversal of hemorrhagic shock (a) is an extra-hormonal, adrenal-independent effect, because it is not affected by adrenalectomy and is shared by many ACTH-fragments practically devoid of corticotropic activity; (b) is antagonized by morphine in a surmontable way; (c) needs the functional integrity of the sympathetic nervous system (it is prevented by guanethidine, reserpine, and clonidine) and the availability of peripheral alpha-adrenoceptors (it is antagonized by dibenamine, prazosin and yohimbine, but not by practolol); (d) requires the integrity of afferent vagal fibers (it is almost completely abolished by vagotomy); (e) involves central cholinergic networks (it is antagonized by atropine sulphate, but not by atropine methyl bromide; and it is prevented by the intracerebroventricular injection of hemicholinium-3); (f) is associated with a massive increase in the volume of circulating blood, likely due to a mobilization from peripheral pooling sites (it is largely prevented by splenectomy or by suprahepatic veins ligature, and is associated with a restoration of the venous blood flow in peripheral vascular beds and with a normalization of venous PO2); (g) is associated with a restoration of heart and spleen adrenoceptors, whose number is significantly decreased during hemorrhagic shock. The survival time of hemorrhage-shocked animals, which is 26 +/- 3 min in controls, is greatly prolonged (44 +/- 18 h) by ACTH, provided that the treatment is made within 5-10 min after bleeding. Finally, in animals treated with ACTH within 5-10 min after bleeding, blood reinfusion retains its effectiveness and reverse shock even if performed 2-5 h later.

Proopiomelanocortin (POMC)-related peptides in the brain of the rainbow trout, Salmo gairdneri

We have investigated the presence of ACTH, alpha-MSH and beta-endorphin, three peptides which derive from the multifunctional precursor protein proopiomelanocortin (POMC) in the brain of the rainbow trout Salmo gairdneri. Using both the indirect immunofluorescence and peroxidase-antiperoxidase techniques, a discrete group of positive cells was identified in the hypothalamus, within the anterior part of the nucleus lateralis tuberis. alpha-MSH-containing neurons represented the most abundant immunoreactive subpopulation. Coexistence of alpha-MSH, ACTH and beta-endorphin was observed in the lateral part of the nucleus. ACTH- and beta-endorphin-containing cells were mainly distributed in the rostral and caudal regions of the nucleus. In the medial portion of the nucleus lateralis tuberis, numerous cells were only stained for alpha-MSH. Moderate to dense plexuses of immunoreactive fibers were observed in the ventral thalamus and the floor of the hypothalamus. Some of these fibers projected towards the pituitary. The concentrations of ACTH, alpha-MSH and beta-endorphin-like immunoreactivities were measured in microdissected brain regions by means of specific radioimmunoassays. Diencephalon, mesencephalon and medulla oblongata extracts gave dilution curves which were parallel to standard curves. The highest concentrations of POMC-derived peptides were found in the diencephalon (alpha-MSH: 4.28 +/- 0.43 ng/mg prot.; ACTH: 1.08 +/- 0.09 ng/mg prot.; beta-endorphin: 1.02 +/- 0.1 ng/mg prot.), while lower concentrations were detected in the mesencephalon, medulla oblongata and telencephalon. The present results demonstrate that various peptides derived from POMC coexist within the same cell bodies of the fish hypothalamus. Taken together, these data suggest that expression and processing of POMC in the fish brain is similar to that occurring in pituitary melanotrophs.

Distribution of neuropeptides in the infundibular nucleus of the sheep

The distribution of neurons exhibiting somatostatin (SRIF)-, neuropeptide Y (NPY)-, beta-endorphin- and neurotensin (NT)-like immunoreactivity within the infundibular nucleus (NI) of the sheep, and the extent of coexistence of the above peptides within individual neurons of the NI were investigated with immunocytochemical techniques. Our results show that the above neurochemical types of neurons exhibit specific and largely non-overlapping patterns of distribution within the NI of the sheep. Furthermore, the coexistence of these peptides within neurons of the NI is very limited, as from all possible permutations checked, only SRIF and NPY were found together in a small number of cells.