Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The blood-brain barrier is capable of transporting peptides with anti-opiate (Tyr-MIF-1) and opiate (enkephalins) activity out of the central nervous system. The relationship of this transport system to the various actions of opiates remains unexplored. This study examined the relationship between the rate of transport and opiate-induced analgesia. Both restraint, a stress that provokes an opiate-mediated analgesia, and the administration of morphine (12 mg/kg, i.p.) each induced an inhibition in the rate of transport. Such inhibition exhibited specificity, since the saturable, brain to blood transport of iodide remained unaltered. However, it was possible to dissociate analgesia and inhibition of transport. The onset and peak of analgesia, as measured by tail-flick latency induced by morphine, preceded the onset and peak of the inhibition of transport. Naltrexone, which blocks opiate-mediated analgesia, also induced inhibition of transport without any significant effect on tail-flick latency. (-) Naloxone but not (+) naloxone also weakly inhibited transport. Deprivation of food and water, associated with analgesia possibly mediated by the opiate, beta-endorphin, which is not transported out of the brain by this system, did not alter transport. These results suggest that while inhibition of transport and analgesia may occur together, these events probably represent two separate aspects of the action of opiates, that may even be mediated by separate receptor sites or peptides in the opiate family.
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PMID:Analgesia and the blood-brain barrier transport system for Tyr-MIF-1/enkephalins: evidence for a dissociation. 289 31

Acute intraventricular administration of human beta-endorphin (15 microgram) produced analgesia, hypothermia and catalepsy in male Sprague-Dawley rats. Injections of beta-endorphin given every 8 hr for 3 days resulted in the development of tolerance to all of the above mentioned pharmacological effects. Tolerance developed rapidly to the hypothermic effect and less rapidly to the analgesic and cataleptic effects. After the third or the fourth injection of beta-endorphin, pronounced hyperthermia, rather than hypothermia, was observed. After seven or eight injections of beta-endorphin, tolerance to the analgesic effect was complete and the cataleptic effect was reduced to 50% of the original. Daily s.c. administration of Pro-Leu-Gly-NH2 (MIF) or cyclo(Leu-Gly) (2 mg/kg each) blocked the development of tolerance to the analgesic and cataleptic effects of beta-endorphin. The hyperthermic effect of beta-endorphin in beta-endorphin-tolerant rats was partially blocked by both MIF and cyclo(Leu-Gly). Multiple injections of MIF or cyclo(Leu-Gly) did not alter beta-endorphin-induced analgesia, catalepsy and hypothermia in rats which were given repeated intraventricular injections of saline. Since MIF is a naturally occurring peptide of hypothalamic origin, these studies suggest that the hypothalamus may be an important site in regulating the pharmacological effects of chronically administered endogenous opiates.
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PMID:Inhibition of tolerance to the pharmacological effects of human beta-endorphin by prolyl-leucyl-glycinamide and cyclo(leucylglycine) in the rat. 611 70

The effects of intravenously-injected alpha-MSH and MIF-1 (Pro-Leu-Gly-NH2) on the permeability of the blood-brain barrier (BBB) to a large protein and a small anion were studied using radioiodinated serum albumin (RISA) and 99mTc-labeled sodium pertechnetate. The permeability of the BBB to RISA was unaltered by either peptide. Permeability to the inorganic pertechnetate anion, however, was significantly increased by alpha-MSH but not by MIF-1 at doses known to evoke EEG and behavioral responses. The peptides did not cause a change in the systemic blood pressure. It is possible, therefore, that at least some CNS effects of peripherally administered peptides are exerted by alteration of the permeability of the BBB to other substances.
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PMID:Selective effects of alpha-MSH and MIF-1 on the blood-brain barrier. 611 42

A study was made of the effect of the low-molecular neuropeptides, leu- and met-enkephalins, thyroliberin (TRH), the C-end tripeptides, gastrin (MAF) and oxytocin (MIF) on the content of biogenic monoamines and their metabolites and on the production of humoral antibodies to sheep red blood cells. The action of the peptides enumerated was compared to that of the peptide immunostimulant, tuftsin. All the peptides (upon intraventricular administration) with the exception of tuftsin affect the content of brain biogenic monoamines or their metabolites. Moreover, upon intravenous injection the neuropeptides under study except met-enkephalin exert a modulating action on the immune response pattern and intensity Leu-enkephalin, MIF and MAF have immunostimulant activity similar to tuftsin. TRH given in high doses (100 and 150 mg/kg) provokes almost a two-fold decrease in the antibody titer. This peptide has an immunosuppressant effect when administered both intravenously and intracisternally. It is suggested that neuro- and immunomodulator effects have much in common at the level of cell receptors.
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PMID:[Comparison of the neuro- and immunomodulator properties of low-molecular neuropeptides]. 612 28

MIF-1 (Pro-Leu-Gly-NH2), a hypothalamic tripeptide, has been demonstrated to stimulate naloxone in antagonizing the effects of opioid peptides in a number of experimental systems including enkephalin-induced analgesia in the tail-flick assay, beta-endorphin induced hypothermia and hypomotility, deprivation-induced drinking, and analgesia in goldfish. MIF-1, however, has no effect upon the activity of enkephalins in the mouse vas deferens or enkephalin binding in the rat striatum. We have studied the interactions of MIF-1 with Leu5-enkephalin (Leu5-ENK) in the conscious, chronically instrumented dog. Although naloxone inhibits both the elevations of heart rate and blood pressure produced by IV Leu5-ENK in the conscious state and the depressions in these variables produced by Leu5-ENK after pentobarbital anesthesia, MIF-1 has no effect upon the Leu5-ENK response in either state. However, both naloxone and MIF-1 seem to raise mean arterial pressure in the conscious dog. These results indicate that MIF-1 does not act like naloxone in antagonizing the peripheral effects of Leu5-ENK and lend further support to the existence of mechanistic differences among opiate-mediated behavior, analgesia, and cardiovascular activity.
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PMID:MIF-1 does not act like naloxone in antagonizing the cardiovascular activity of leucine-enkephalin in the conscious dog. 613 37

Release of alpha-MSH from male rat hypothalamic slices was studied using a sensitive bioassay (1-2 pg). Addition of 60 mM KCl to superfusion medium resulted in a twofold increase in alpha-MSH release compared to spontaneous release. Both spontaneous and potassium-induced release were inhibited in a dose-response manner by the tripeptide Pro-Leu-Gly-NH2 (PLG, or MIF-1); 0.04 microgram to 1 microgram PLG inhibited the alpha-MSH release but the lowest dose demonstrated a greater inhibitory effect; high concentrations of PLG, on the other hand, did not modify either spontaneous or potassium-evoked alpha-MSH release from the slices. Contrarily, DA did not modify either spontaneous or potassium- induced alpha-MSH release at any of the doses tested. These findings demonstrate that the inhibitory behavior of PLG and DA in the central nervous system (CNS) differs from their behavior towards alpha-MSH release in the pituitary. This suggests differences in the regulation of alpha-MSH release from the pituitary and the CNS.
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PMID:Inhibition by L-prolyl-L-leucyl-glycinamide (PLG) of alpha-melanocyte stimulating hormone release from hypothalamic slices. 613 63

Opioid analgesics influence the function of a number of neurotransmitter systems including classical neurotransmitters, neuropeptides and endogenous opioids. The role of these interactions in analgesia, tolerance and dependence is reviewed. Opioids inhibit the release of substance P from high threshold primary afferents, depress the activity of dorsal horn neurons and increase activity in serotonergic and noradrenergic neurons projecting from brainstem to spinal regions. Chronic administration of opioids modifies the dynamics of classical transmitters and those of endogenous opioid peptides in the brain, spinal cord and the pituitary gland. However, the effects observed are very variable. Several neuropeptides (vasopressin, MIF, alpha-MSH, CCK and dynorphin) have been reported to modify acute and chronic effects of opioids. Tolerance and dependence seen after opiate administration may involve changes in the function of these peptides.
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PMID:Opioid-neurotransmitter interactions: significance in analgesia, tolerance and dependence. 615 40

Melanocyte-stimulating hormone (MSH) has putative adaptive significance in all forms of species where it is present. In mammals the polypeptide chain influences learning, memory and attention. Chemically MSH shares the first 13 (alpha-MSH) or the first 18 or 22 (beta-MSH) amino acids with adrenocorticotropic hormone (ACTH), even though the mechanisms of secretion and behavioral effects are often quite different. The still shorter peptide chain MSH/ACH4-10 demonstrates significant melanotropic and behavioral actions of alpha-MSH without showing any steroidogenic effect. Behaviorally, alpha-MSH and MSH/ACTH analogues (MSH/ACTH4-9 and MSH/ACTH4-10 influence the parameters of learning, attention and memory in both human and infrahuman subjects. Alpha-MSH has also been reported to increase sensitivity and augment arousal mechanisms in the CNS. Alpha-MSH has been observed to increase and sustain novelty-induced defecation, and this behavior was found to be accompanied by a concomitant decrease in whole brain DA and NE levels in both intact and hypophysectomized rats exposed daily to a test box. The behavioral effects of alpha-MSH may be partially modulated by the enhanced cyclic-AMP activity in the CNS observed after MSH administration. MSH also seems to be working in conjunction with the hypothalamic tripeptide MIF-1 and the pineal hormone melatonin, both of which can affect the release of MSH from the pituitary. Recent evidence suggests that MSH is counterbalancing against and complementing with the effects of endorphins, specifically beta-endorphin (61-91 chain of beta-LPH), in maintaining learning and attentive behaviors.
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PMID:Alpha-melanocyte-stimulating hormone and behavior. 629 67

Most neuropeptides are known to occur both in the central nervous system and in blood. This, as well as the occurrence of central nervous peptide effects after peripheral administration, show the importance of studying the relationships between the peptides in the two compartments. For many peptides, such as the enkephalins, TRH, somatostatin and MIF-1, poor penetration of the blood-brain barrier was shown. In other cases, including beta-endorphin and angiotensin, peptides are rapidly degraded during or just after their entry into brain or cerebrospinal fluid. Some peptides, such as insulin, delta-sleep-inducing peptide, and the lipotropin-derived peptides, enter the cerebrospinal fluid to a slight or moderate extent in the intact form. Many peptide hormones, such as insulin, calcitonin and angiotensin, act directly on receptors in the circumventricular organs, where the blood-brain barrier is absent. Oxytocin, vasopressin, MSH, and an MSH-analog alter the properties of the blood-brain barrier, which may result in altered nutritient supply to the brain. In conclusion, the diffusion of most peptides across the brain vascular endothelium seems to be severely restricted. There are, however, several alternative routes for peripheral peptides to act on the central nervous system. The blood-brain barrier is a major obstacle for the development of pharmaceutically useful peptides, as in the case of synthetic enkephalin-analogs.
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PMID:Minireview. Peptides and the blood-brain barrier. 630 42

The transport properties of several peptides across blood-brain barrier (BBB) have been investigated theoretically in terms of simple diffusion and facilitated diffusion processes. Comparison of the calculated results from the simple diffusion and the experimental data reveals the presence of the facilitated diffusion of these substances which we have conceived of as a carrier-mediated process. The values of the partition coefficients f for these peptides were in the range 7 X 10(-4) less than or equal to f less than or equal to 200 X 10(-4). The calculated f values gave permeabilities, Ps, in lipids between 10(-7) less than or equal to Ps less than or equal to 14 X 10(-7) cm/s. These values were then used to estimate the extraction for peptides from simple diffusion alone which vary from 0.3 to 3.5% compared with the experimental extraction (0.4-12%) indicating the inadequacy of the simple diffusion alone to explain the experimental data. As for the carrier-mediated facilitated diffusion process we have used the activated-complex theory. The extraction in this case depends on the maximal rate of transport (Tmax)f and the reciprocal of the affinity constant Kt for the transport of peptides through BBB. We have deduced that (Tmax)f approximately 0.46 X 10(-3) pmol/g X s and Kt approximately 0.35 nM for Met-enkephalin (Met-ENK), Leu-enkephalin (Leu-ENK), glutathione, carnosine, alpha-MSH and MIF and (Tmax)f approximately 10 X 10(-3) pmol/g X s and Kt approximately 7 nM for AVP, beta LT, beta E and alpha E to explain the observed results. We have also obtained the quantitative variation of extraction with concentration of peptides in the brain-capillary and have established that the extraction decreases with increasing concentration of peptides, tending to a small constant value at high concentrations. It has been inferred that carrier-mediated facilitated diffusion is important for the transport of peptides across BBB.
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PMID:Theoretical interpretation of extraction (in brain) of peptides including concentration variations. 643 51


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