Hyper-endorphin syndrome in a child with necrotizing encephalomyelopathy

Relation of beta-casomorphin to apnea in sudden infant death syndrome

Sudden infant death syndrome (SIDS) is the most common cause of death in infants and its pathogenesis is complex and multifactorial. The aim of this review is to summarize recent novel findings regarding the possible association of beta-casomorphin (beta-CM) to apnea in SIDS, which has not been widely appreciated by pediatricians and scientists. beta-CM is an exogenous bioactive peptide derived from casein, a major protein in milk and milk products, which has opioid activity. Mechanistically, circulation of this peptide into the infant's immature central nervous system might inhibit the respiratory center in the brainstem leading to apnea and death. This paper will review the possible relationship between beta-CM and SIDS in the context of passage of beta-CM through the gastrointestinal tract and the blood-brain barrier (BBB), permeability of the BBB to peptides in infants, and characterization of the casomorphin system in the brain.

Tritiated-naloxone binding to brainstem opioid receptors in the sudden infant death syndrome

The sudden infant death syndrome (SIDS) is defined as the sudden death of an infant under 1 year of age that remains unexplained after a thorough case investigation, including a complete autopsy. We hypothesized that SIDS is associated with altered 3H - naloxone binding to opioid receptors in brainstem nuclei related to respiratory and autonomic control. We analyzed 3H - naloxone binding in 21 regions in SIDS and control brainstems using quantitative tissue receptor autoradiography. Three groups were analyzed: SIDS (n = 45); acute controls (n = 14); and a chronic group with oxygenation disorders (n = 15). Opioid binding was heavily concentrated in the caudal nucleus of the solitary tract, nucleus parabrachialis medialis, spinal trigeminal nucleus, inferior olive, and interpeduncular nucleus in all cases analyzed (n = 74). The arcuate nucleus on the ventral medullary surface contained negligible binding in all cases (n = 74), and therefore binding was not measurable at this site. We found no significant differences among the three groups in the age-adjusted mean 3H - naloxone binding in 21 brainstem sites analyzed. The only differences we have found to date between SIDS and acute controls are decreases in 3H - quinuclidinyl benzilate binding to muscarinic cholinergic receptors and in 3H - kainate binding to kainate receptors in the arcuate nucleus in alternate sections of this same data set. The present study suggests that there is not a defect in opioid receptor binding in cardiorespiratory nuclei in SIDS brainstems.

Antemortem diagnosis of Leigh's disease: role of magnetic resonance studies

A two-and-a-half-year-old male child presented with recurrent attacks of intractable vomiting, psychomotor retardation since 14 months of age. He had also lower cranial nerve palsy and corticospinal involvement. Magnetic resonance imaging had shown multiple well circumscribed areas of hypointusity in T1 weighted image which were brightly hyperintense in heavily T2-weighted image. The lesions were seen in basal ganglia, thalamii and brainstem and spared mamillary bodies. Magnetic resonance spectroscopy demonstrated lactate peak in the affected areas confirming the diagnosis of Leigh's disease. The child responded well to large dose of vitamin 'B' therapy.

Spontaneous periodic hypothermia

Spontaneous periodic hypothermia is a rare syndrome of recurrent, centrally mediated hypothermia without an identifiable systemic cause or brain lesion. Most patients defend a temporarily lowered temperature "set point" during episodes of hypothermia, despite manifesting many well-known systemic consequences of core temperature hypothermia. No case of death directly attributable to an episode of spontaneous periodic hypothermia has been reported, although many of the serious systemic effects of hypothermia have been documented in these cases, so it is not unlikely that death may occur. The syndrome's cause, and that of Shapiro syndrome, remains unknown. Pharmacologic trials to date have been only modestly successful. Anticonvulsant agents, clonidine, and cyproheptadine appear the most likely to succeed, with cyproheptadine being a reasonable first choice. Given that the term "spontaneous periodic hypothermia" describes a syndrome, and not a pathophysiologic mechanism, it is likely to encompass a common eventuality, arrived at via several different pathways. One can postulate mechanisms such as structural abnormalities, trauma, infection, irritation, and degeneration involving strategic locations which create a focus for epileptic or other periodic dysfunction whose scope involves the centers for thermoregulation. The existence of 2 distinct, oppositional thermoregulatory centers would allow for speculation of similar mechanisms accounting for cases of both periodic hypo- and hyperthermia (61). Postmortem data regarding the hypothalamic and surrounding areas from future cases of Shapiro syndrome and spontaneous periodic hypothermia would be of great interest. Further, more sensitive in vivo testing methods are clearly needed. The role of PET or single photon emission computed tomography (SPECT) with technetium 99m-labeled hexamethylpropylene amine oxime (Tc 99m HMPAO) performed acutely during an episode remains to be characterized (64, 103, 105). The term "diencephalic epilepsy" may in fact be accurate, given the periodic episodes of the case presented here and similar cases resulting from non-generalized seizure activity, with or without an underlying predisposing lesion. The label diencephalic epilepsy has been merely speculative so far, however, as definitive evidence of seizure activity has not been documented. Further, it is expected that the descriptive terms "spontaneous periodic hypothermia" and "episodic spontaneous hypothermia with hyperhidrosis" will outlive their usefulness as researchers gain greater understanding of this syndrome, and be replaced with a more pathophysiologically meaningful nomenclature.

A comprehensive review of naloxone for the emergency physician

Naloxone has enjoyed long-standing success as a safe and effective opioid antagonist and has been invaluable in defining the role of endogenous opioid pathways in the response to pathological states such as sepsis and hypovolemia. We look forward to exciting research to further elucidate these pathways and to improve outcome by modulating the patient's physiological response to these stresses.

Leucine modulates peptide transport system-1 across the blood-brain barrier at the stereospecific site within the central nervous system

Previous results have shown that leucine injected into a cerebral ventricle (i.c.v.) can act as an allosteric regulator of peptide transport system-1 (PTS-1), the system that transports Tyr-Pro-Leu-Gly-NH2 (Tyr-MIF-1) and the enkephalins out of the central nervous system (CNS). D-Leucine appeared more potent than L-leucine. In the current study, dose-response curves were constructed for each compound after both intravenous (i.v.) and i.c.v. injection. Based on ED50 values after i.c.v. injection, D-leucine was about 200 times more potent than L-leucine in its inhibition of PTS-1, thereby confirming stereospecificity of the allosteric site. D- and L-Leucine were also more potent when given i.c.v. than when given i.v., suggesting that the site is located on the CNS side of the blood-brain barrier (BBB). The finding that D-leucine was less potent than L-leucine when given i.v. is also consistent with a CNS site of action because the L-isomer of leucine has been shown to be preferentially transported into the brain. These findings agree with the previous suggestion that some of the neurotoxic effects of leucine may be mediated through PTS-1 and could help explain how D-amino acids can exert opiate-related effects on the CNS.

Neural maturational delay as a link in the chain of events leading to SIDS

Although numerous etiological or triggering factors have been suggested in sudden infant death syndrome (SIDS), the underlying mechanism of death is ultimately cardiac and/or respiratory in nature. As there is no evidence of lung or heart abnormalities, attention has focussed on the neural control of respiration and cardiac function. It is important to appreciate the methodological limitations involved in utilizing autopsy material and the criteria for selection of appropriate controls. This report reviews the pathological evidence for developmental delay in SIDS emphasizing delay of neural maturation of both myelination and synapses. Other abnormalities of the nervous system apparently associated with hypoxia-ischemia such as brainstem astrogliosis are also discussed. The occurrence of SIDS at a precise age together with our preliminary studies indicate that neural development delay is an important link in the chain of events leading to SIDS.

Acute respiratory failure precipitated by general anesthesia in Leigh's syndrome

Three patients with Leigh's syndrome developed respiratory failure following general anesthesia. Although all three had respiratory symptoms prior to the anesthetic, the diagnosis was not suspected at the time of the procedure in two of the children. We reviewed the case notes of 16 other patients with Leigh's syndrome. Eight had received anesthetic agents without incident. Although the majority subsequently developed respiratory abnormalities and died with respiratory failure, this problem was not evident at the time of anesthesia. In the presence of respiratory abnormalities, general anesthesia carries significant risks in Leigh's syndrome.

Naltrexone therapy of apnea in children with elevated cerebrospinal fluid beta-endorphin

Previous studies have indicated increased immunoreactivity of the endogenous opioid peptide beta-endorphin in the cerebrospinal fluid (CSF) of infants under 2 years of age with apnea. To assess the role of endogenous opioids in the pathogenesis of apnea in children, the effect of oral treatment with the opioid antagonist naltrexone was studied in apneic infants, as well as in older apneic children, with demonstrated increases in CSF immunoreactive beta-endorphin (i-BE). In the 8 apneic infants with elevated i-BE in lumbar CSF (range, 55-155 pg/ml; normal, 17-52 pg/ml), no further apnea occurred during naltrexone therapy (1 mg/kg/day, by mouth). Five children (2-8 years old) with apnea of unknown cause had elevated CSF i-BE (range, 74-276 pg/ml) compared to 6 age-matched nonapneic children (range, 15-48 pg/ml). No apneic events occurred during naltrexone therapy, except in 1 child during stressful events, but apnea recurred in some patients after attempts to discontinue naltrexone treatment. Adverse effects of naltrexone included complaints of headaches in 2 children and symptoms of a narcotic withdrawal syndrome during the first 3 days of treatment in 1 child. Three children with Leigh's syndrome had elevated CSF i-BE (range, 104-291 pg/ml) and their apnea also responded to naltrexone. We conclude that elevated endogenous opioids contribute to the pathogenesis of apnea in children and may even result in physical dependence.

The opioid system in neurologic and psychiatric disorders and in their experimental models

Evidence from experimental and clinical studies suggests the involvement of the endogenous opioid system in several neurologic and psychiatric disorders (Alzheimer's, Huntington's and Parkinson's diseases, drug-induced movement disorders, Gilles de la Tourette syndrome, stroke, ischemia, brain and spinal cord injury, epilepsy, schizophrenia and affective disorders). However, its involvement is rather a secondary one, perhaps being a severe consequence of a primary, nonopioid disturbance. Thus, treatment of an opioidergic manifestation of a disorder of nonopioidergic origin is necessarily symptomatic and targets only the restoration of the opioid system; such treatment may be beneficial in ameliorating the clinical symptoms of the disorder.

Three-dimensional distribution of 3H-naloxone binding to opiate receptors in the human fetal and infant brainstem

Despite the putative role of opioids in disorders of the developing human brainstem, little is known about the distribution and ontogeny of opioid-specific perikarya, fibers, terminals, and/or receptors in human fetuses and infants. This study provides baseline information about the quantitative distribution of opiate receptors in the human fetal and infant brainstem. Brainstem sections were analyzed from three fetuses, 19-21 weeks gestation, and seven infants, 45-68 postconceptional weeks, in whom the postmortem interval was less than or equal to 12 hours. Opiate receptors were localized by autoradiographic methods with the radiolabelled antagonist 3H-naloxone. Computer-based methods permitted quantitation of 3H-naloxone binding in specific nuclei, as well as three-dimensional reconstructions of binding patterns. High 3H-naloxone binding corresponds primarily to sensory and limbic nuclei, and to nuclei whose functions are known to be influenced by opioids, e.g., trigeminal nucleus (pain), nucleus tractus solitarii and nucleus parabrachialis medialis (cardio-respiration), and locus coeruleus (arousal). The regional distribution of opiate receptors as determined by 3H-naloxone binding is similar in human infants to that reported in human adults and animals and corresponds most closely to that of mu receptors. We found, however, that opiate receptor binding is high in the fetal and infant inferior olive, in comparison to low binding reported in this site in adult humans, primates, and rodents. In addition, opiate receptors are sparse in the fetal and infant substantia nigra, as in reports of the adult human substantia nigra, compared to moderate densities reported in primates and rodents. By midgestation, the regional distribution of 3H-naloxone binding in human fetuses is similar, but not identical, to that in infants. Highest 3H-naloxone binding occurs in the inferior olive in fetuses at midgestation, compared to the interpeduncular nucleus in infants. Tritiated naloxone binding quantitatively decreases in virtually all nuclei sampled over the last trimester, but not to the same degree. The most substantial binding decrease (two- to fourfold) occurs in the inferior olive and may reflect programmed regressive events, e.g., neuronal loss, during its development. Definitive developmental trends in 3H-naloxone binding are not observed in the postnatal period studied. The heterogeneous distribution of opiate binding in individual brainstem nuclei underscores the need for volumetric sampling in quantitative studies.

Increased CSF opioid activity in sleep apnea syndrome. Regression after successful treatment

The etiology of the SAS is unknown. To test whether endogenous opioids could be pathologically active in SAS, markers of opioid systems were measured in the CSF of 15 patients with SAS and in control subjects. Measured by receptor assay, the concentration of so-called fraction 1 opioid was higher in patients with SAS (3.0 +/- 1.5 pmol/ml; mean +/- SD) than in control subjects (1.1 +/- 0.5 pmol/ml) (p less than 0.01), whereas that of fraction 2 opioid was similar in the two groups. Beta-endorphin-like activity, measured by radioimmunoassay, was somewhat lower in patients with SAS (14.0 +/- 2.8 pmol/ml) than in control subjects (21.8 +/- 7.6 pmol/ml) (p less than 0.05). Six months after surgical treatment of the soft palate, new measurements were made in eight patients. Fraction 2 endorphin and beta-endorphin showed no consistent changes. A decrease in the level of fraction 1 from 4.1 +/- 1.5 pmol/ml to 2.3 +/- 1.0 pmol/ml (p less than 0.02) was noted in those six patients showing a successful clinical course. The data support the hypothesis that in SAS the opioid activity is increased.

Characteristics of beta-endorphin-induced histamine release from rat serosal mast cells. Comparison with neurotensin, dynorphin and compound 48/80

Rat peritoneal mast cells were exposed to the neurohormone and basic opioid peptide beta-endorphin. beta-Endorphin induced a dose-dependent release of histamine from the mast cells. A significant histamine release was found at 5 mumol/l of beta-endorphin and maximal release (35% of total) at 20 mumol/l. The histamine release process was very rapid and terminated within 30 s at 37 C, and in this sense is very similar to the histamine release induced by compound 48/80 or neurotensin. The histamine release was temperature-dependent showing an optimum release around 30 C, and it was independent of available extracellular calcium, but was inhibited in the presence of high extracellular calcium concentrations. Naloxone, only in very high concentrations (10 mmol/l), inhibited the release, and the very same concentration also inhibited the neurotensin - as well as the compound 48/80-induced histamine release. Cromoglycate and benzalkoniumchloride, a 48/80 antagonist, both produced a progressive dose-dependent inhibition of beta-endorphin-, neurotensin- as well as compound 48/80-induced histamine release. Taken together, the findings indicate that the opioid peptide beta-endorphin induces a selective, energy-dependent release of histamine from peritoneal rat mast cells. The pattern of release has much in common with that of compound 48/80 and other basic peptides, such as neurotensin and substance P. In addition this pattern of release is similar to that induced by dynorphin.

Opioid peptides from milk as a possible cause of sudden infant death syndrome

Milk from breast or baby formula is the exclusive source of nutrition for newborn infants. Short chain opioid peptides such as beta-casomorphins have been isolated from breast milk as well as baby formula. These biologically active peptides are absorbed from the gastrointestinal tract. In infants predisposed to respiratory apnea because of abnormal autonomic nervous system development and respiratory control mechanisms, opioid peptides derived from milk might be one of the etiological factors for sudden infant death syndrome and near miss sudden infant death syndrome.

Opiate antagonist nalmefene inhibits ethanol-induced flushing in Asians: a preliminary study

Ethanol-induced flushing (EIF) occurs in up to 80% of Asians and is characterized by facial flushing, tachycardia, and increased cardiac output. Since endogenous opiates and prostaglandins may be mediators of flushing syndromes, we attempted to block EIF in four Asian flushers with single doses of either the opiate antagonist nalmefene, or the prostaglandin synthesis inhibitor indomethacin. Nonflushers (2 Caucasian, 2 Asian) and four Asian flushers were given on separate days water, ethanol (0.4 g/kg p.o.), ethanol plus nalmefene (2 mg i.v.), or ethanol plus indomethacin (50 mg p.o.). Ethanol concentrations of flushers and nonflushers were similar. Mean (+/- SEM) plasma acetaldehyde concentrations of flushers (28.2 +/- 11.8 microM) were significantly greater than nonflushers (1.4 +/- 0.5 microM) following ethanol ingestion (p less than 0.001). Ethanol alone always induced a significant rise in facial skin temperature [mean area under the curve (AUC) = 5142 +/- 648 % delta T x min, p less than 0.01] and of pulse (mean AUC = 1622 +/- 120 bpm x min, p less than 0.001) in flushers compared to water ingestion. A single dose of nalmefene (2 mg i.v.) but not indomethacin (50 mg p.o.), reduced the mean (+/- SEM) ethanol-induced rise in facial skin temperature of flushers by 58 +/- 14% (p less than 0.05) without changing plasma acetaldehyde concentrations. These data are preliminary evidence that the opiate antagonist, nalmefene, blocks some of the vascular manifestations of EIF without altering the elevated plasma concentrations of acetaldehyde.

CSF-endorphines in acute and chronic brain lesions

In order to answer the question of an opioid influence on consciousness, a radio-immuno-assay (n = 852) of beta-endorphin and beta-LPH (beta-lipotropic hormone) in both ventricular CSF and blood plasma was carried out in 101 neurosurgical patients. The following results were obtained: I) beta-END and beta-LPH levels were found to be lower in the CSF than in blood plasma. II) beta-END and beta-LPH in the CSF was the same in both sexes. III) beta-END levels in the CSF decreased with age. IV) beta-END and beta-LPH levels showed a diurnal rhythm with a maximum in the late a. m. hours. V) beta-END levels in the ventricular CSF tend to decrease parallel to a drop in conciousness as well as with longlasting comatous states. VI) beta-END in ventricular CSF becomes higher with increasing systolic arterial blood pressure. VII) beta-END and beta-LPH levels in ventricular CSF are not correlated with the type of the disease, CSF pressure, body temperature or respiratory changes.

beta-Casomorphins induce apnea and irregular breathing in adult rats and newborn rabbits

Bovine beta-casomorphin, beta-casomorphin, morphiceptin or morphine were administered systemically (i.v. or i.p.) and intracerebroventricularly (lateral or IVth ventricles) to anesthetized adult rats and preterm newborn rabbits. All agents caused dose-related depressions of respiratory frequency and tidal volume. Morphiceptin and beta-casomorphin were approximately equipotent to morphine while beta-casomorphin was 10 times as potent after intracerebroventricular injection. The beta-casomorphins decreased inspiratory drive and prolonged the expiratory phase by delaying the setpoint for inspiration. A respiratory depression could be elicited by systemic administration of morphiceptin but not by beta-casomorphin or beta-casomorphin. All ventilatory effects induced by the beta-casomorphins could be readily reversed or prevented by naloxone. Intracerebroventricular but not intraperitoneal injection of beta-casomorphin depressed ventilation in preterm newborn rabbits in a similar pattern with apnoic periods to that seen in the adult rats. In addition, an irregular breathing pattern was elicited. Thus, the bovine beta-casomorphins possess potent central respiratory depressive effects. However, after systemic administration, only morphiceptin which is more metabolically stable induced a shortlasting effect on ventilation in adult rats.

Increased cerebrospinal fluid beta-endorphin immunoreactivity in infants with apnea and in siblings of victims of sudden infant death syndrome

To gain further insight into the possible role of endogenous opioid peptides in the respiratory difficulties associated with the apnea of infancy and other disorders possibly related to apnea, the levels of beta-endorphin immunoreactivity were measured in the cerebrospinal fluid (CSF) of five groups of infants: (1) infants with proved apnea, (2) infants with histories of an apparent life-threatening event (ALTE), (3) siblings of victims of the sudden infant death syndrome (SIDS), (4) infants with suspected but unproved apnea, and (5) infants undergoing investigation for other acute illnesses. Twenty-two infants considered at risk for an ALTE (groups 1 to 3) had significantly higher CSF beta-endorphin equivalents (88 +/- 7 pg/mL) than did the 22 control patients in groups 4 and 5 (31 +/- 3 pg/mL). Plasma beta-endorphin immunoreactivity, which was also measured in some of the infants, did not correlate with levels in CSF and, in fact, was significantly lower in the groups at risk for an ALTE (50 +/- 9 pg/mL; n = 14) than in the control subjects (80 +/- 6 pg/mL; n = 11). These studies indicate that elevated beta-endorphin immunoreactivity in CSF may be a marker in infants who have apnea and who may be considered at risk for an ALTE.

Saturable transport of peptides across the blood-brain barrier

Peptides can be transported across the blood-brain barrier by saturable transport systems. One system, characterized with radioactively labeled Tyr-MIF-1 (Tyr-Pro-Leu-Gly-amide), is specific for some of the small peptides with an N-terminal tyrosine, including Tyr-MIF-1, the enkephalins, beta-casomorphin, and dynorphin (1-8). Another separate system transports vasopressin-like peptides. The choroid plexus has at least one system distinguishable from those above that is capable of uptake and possibly transport of opiate-like peptides. The possibility of saturable transport of other peptides has been investigated to a varying degree. Specificity, stereo-specificity, saturability, allosteric regulation, modulation by physiologic and pharmacologic manipulations, and noncompetitive inhibition have been demonstrated to occur in peptide transport systems and suggest a role for them in physiology and disease.

Leigh syndrome, a mitochondrial encephalo(myo)pathy. A review of the literature

Results of a literature survey of 173 patients with Leigh syndrome are presented, with emphasis on signs and symptoms in relation to age at onset, contributions of technical investigations to the diagnosis, pathophysiology, genetic considerations and therapeutic aspects. Based on this study we are of the opinion that it is possible to come to a diagnosis of "most probable Leigh syndrome" durante vitamin on the combination of clinical signs and symptoms, autosomal recessive mode of inheritance, association with a defect of energy metabolism, and CT or MRI abnormalities.

Carrier-mediated transport of enkephalins and N-Tyr-MIF-1 across blood-brain barrier

The saturable, carrier-mediated system capable of the brain-to-blood transport of small peptides with an N-terminal tyrosine was characterized. The rate of disappearance of intraventricularly injected iodinated peptide in the presence or absence of the inhibitor being tested was determined from formulas based on the residual radioactivity in the brains of mice after decapitation. The injection of 100 nmol/mouse of unlabeled N-Tyr-MIF-1 (TMIF) increased the half-time disappearance of 125I-TMIF (ITMIF) in the central nervous system (CNS) from 14.1 to 88.7 min (P less than 0.00005). Technetium, a substance transported out of the brain by the same system that transports iodine, was used as a control; the half-time disappearance of technetium pertechnetate was unaffected by unlabeled TMIF. With two related but distinct techniques, the maximum transport rate out of the CNS (Vmax) for TMIF was 0.266 nmol X g of brain per min (method 1) and 0.297 nmol X g-1 X min-1 (method 2), while the amount of unlabeled material needed to achieve 50% of Vmax (Km) was 15.2 nmol/g (method 1) and 15.1 nmol/g (method 2). The lack of effect of the tyrosinated fragments of TMIF as inhibitors indicates that TMIF is being transported in intact form. The Vmax for methionine enkephalin determined with labeled and unlabeled methionine enkephalin was 0.630 nmol X g-1 X min-1 and the Km was 24.95 nmol/g. Studies with the metabolic modulators furosemide, acetozolamide, reserpine, ouabain, and theophylline suggest that the system is sodium dependent and probably independent of ATPase.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of dynorphin1-13 on opiate binding and dopamine and GABA uptake in stroked cat brain

We previously reported that the opioid peptide dynorphin1-13 improves survival chances in stroked cats. Some evidence also suggests that changes in dopamine and gamma-aminobutyric acid (GABA) uptake may be associated with stroke. In the present study, therefore, we determined binding of the opiate [3H]ethylketocyclazocine (EKC), as well as dopamine and GABA uptake in various brain regions of control, stroked and dynorphin1-13-treated stroked cats. Cats were stroked by middle cerebral artery occlusion. In the EKC binding study, the Kd of the high-affinity site of the occluded cortex was significantly increased, relative to that of both the unoccluded side and control cortex. Dynorphin1-13 treatment reversed this effect, lowering the Kd to control level. In the dopamine uptake study, the Km was decreased and Vmax was increased significantly in unoccluded cortex, compared with that in the occluded cortex or in control cortex. Again, dynorphin1-13 reversed these effects, raising the Km and lowering the Vmax. However, the Km of occluded cortex was also increased so that it became significantly higher than that of control cortex. The Km of unoccluded subcortex in stroked cats treated with dynorphin1-13 was significantly reduced compared with control. In the GABA uptake study, there was no significant change in any parameter. The change in opioid binding observed here and its reversal by dynorphin1-13 are consistent with the notion that the peptide's beneficial effect on stroke is mediated through opiate receptors. Since opioid systems in the brain are known to have association with dopaminergic ones, the change in dopamine uptake could also be the result of an opioid effect.

Disorders of the pyruvate dehydrogenase complex

Pyruvate dehydrogenase deficiency may be a non-specific consequence of many different neurological degenerative disorders. There are also serious methodological problems in estimating the activity of this enzyme complex.

Diencephalic syndrome of emaciation (Russell's syndrome). Long-term survival

Three cases of diencephalic syndrome are reported. Two of them, which have been observed postoperatively for more than 7 years, showed typical clinical and endocrinologic features at the time of their first admission, but showed mass signs uncharacteristic of diencephalic syndrome after recurrence of the tumor. Recent data showed a normal baseline for plasma growth hormone but abnormalities in provocation tests. The significance of age in the manifestation of the syndrome is briefly discussed, especially in relation to the tendency toward normalization in the growth hormone level at a later age.

Post-mortem analyses of neuropeptides in brains from sudden infant death victims

The causative factors underlying SIDS are still unknown, but in recent years much interest has been focused on the central ventilatory control system. In this study, peptides which are known to affect respiration were examined in brains from SIDS victims and controls. The levels of Met-enkephalin and substance P were measured in cortex, medulla oblongata, pons and hypothalamus. Substance P1-7, substance P C-terminal fragments, Met-enkephalin-Lys6 and neuropeptide Y (NPY) were estimated in medulla oblongata. The substance P levels in the medulla oblongata from the SIDS victims were significantly elevated compared with the controls. No change, however, was observed in the Met-enkephalin levels, but a tendency to higher levels in the youngest infants was noticed. As substance P and enkephalins have opposite effects on respiration, their relative concentrations were calculated in each individual sample. The ratio was significantly higher in the medulla oblongata from the SIDS victims. The levels of NPY, substance P1-7, C-terminal fragments of substance P and Met-enkephalin-Lys6 were similar in both groups. A significant correlation between the NPY levels and age was observed, however.

Naloxone exacerbates hypoxic-ischemic brain injury in the neonatal rat

Recent reports suggest that naloxone, an opiate antagonist, may adversely affect the asphyxiated fetus. We found that naloxone exacerbated hypoxic-ischemic brain injury in the 7-day-old rat subjected to unilateral common carotid artery ligation and hypoxia. Moreover, there was no amelioration of systemic acidosis or brain edema in naloxone-treated animals compared to animals treated with saline solution. High doses of naloxone may reduce the resistance of the fetus to hypoxic stress.

Cellular mechanisms of opiate receptor stimulation in cat middle cerebral artery

To determine some of the cellular mechanisms of opiate receptor stimulation in cat middle cerebral arterial muscle, intracellular electrical measurements and force development were monitored before and after addition of morphine. Addition of morphine resulted in a dose-dependent hyperpolarization of the muscle cells in the middle cerebral artery with a concomitant relaxation, indicating a high degree of electromechanical coupling in this preparation. The curve relating membrane potential vs. morphine was shifted to the right and downward by naloxone, demonstrating competitive inhibition at receptor sites. When middle cerebral arteries were studied from animals which had been injected with morphine prior to sacrifice, a significant hyperpolarization of the membrane was recorded when studied in an organ bath. This hyperpolarization was abolished if the animal had been pretreated with naloxone prior to morphine injection, suggesting that morphine may act in vivo as we have observed it to act in vitro. Morphine-induced hyperpolarization could be blocked in the organ bath when potassium conductance (gk) was inhibited. Similarly, the reduction in the slope of the voltage/current curve induced by morphine was blocked by agents which reduced gk. These data suggest the presence of opiate receptors on cat cerebral artery and suggest that morphine relaxes these vessels through a mechanism involving increased gk. These findings suggest a role for opiate-mediated systems in cerebral vascular control.

Possible role of the opioid peptides in sleep

The opioid peptide endorphins, enkephalins, and dynorphins--found in brain, pituitary, and gut--are neurohormones involved in the regulation of a number of seemingly diverse biologic activities, including respiration, mood, pain perception, blood pressure, body temperature, and certain visceral responses. When viewed in integrated fashion, however, the spectrum of activities induced by the administration of both the exogenous opiates (e.g. morphine) and the endogenous opioids resembles a natural physiologic state: the sleep state. We propose that the opioid peptides in conjunction with the peptide neurohormone vasopressin are involved in the induction and maintenance of the sleep state. We also propose that the function of sleep is to protect an animal during periods when it is at a selective disadvantage, and we provide evidence to support and integrate both concepts.

Endogenous opiates and schizophrenia: directions in clinical research

In the past decade both basic and clinical research on endogenous opiates has involved many aspects of medicine. This review focuses on the clinical literature that relates physiology and pathophysiology of the endogenous opiates to schizophrenia. Three major investigative approaches are described and their results evaluated. These approaches are described and their results evaluated. These approaches include assays of endogenous opiates in the context of clinical illness and use of exogenous opiates as well as exogenous opiate antagonists in the treatment of clinical illness. Current understanding at both the basic science and clinical research levels does not allow firm conclusions about the role of endogenous opiates in schizophrenia; however, the evolution of the growing understanding is used by the author to provide a speculative hypothesis.

Implications of neuropeptides in neurological diseases

Neuropeptides are sufficiently stable to allow valid radioimmunoassay of peptide concentrations in post-mortem human nervous tissue and in human cerebrospinal fluid. Studies have now documented abnormalities of peptide concentrations in degenerative diseases of the brain. Somatostatin concentration is reduced in the hippocampus and neocortex of patients dying with Alzheimer's type dementia. In Huntington's disease, there are reduced concentrations of substance P, met-enkephalin and cholecystokinin in the basal ganglia; in contrast the concentrations of somatostatin and TRH are increased. Immunocytochemical and experimental lesion studies are underway in an attempt to localize the peptide-containing cells affected by these disorders; and the potential role of alterations in neuropeptide function in the pathogenesis, clinical manifestations and therapy of these illnesses is of great interest. Although alterations of CSF peptide concentrations have been reported in a variety of human diseases, interpretation of these results requires knowledge of the origin and disposition of CSF peptides. Future research into the pathology of peptidergic systems will depend on the development of specific peptide antagonists to probe dynamic aspects of peptide function and on the application of the tools of molecular biology, such as specific mRNA assays, to human material.

Brainstem ischaemia presenting as naloxone-reversible coma followed by downward gaze paralysis

A 65-year-old man showed naloxone-reversible unconsciousness followed by downward gaze paralysis. CT scan suggested an ischaemic lesion in the mesodiencephalic region. This observation represents the first case of naloxone-reversible coma related to brainstem ischaemia.

Brain peptides: what, where, and why?

Within the past decade, a large number of peptides have been described within the vertebrate central nervous system. Some of these peptides were previously known to be present in nonneural vertebrate tissues, as well as in lower species, in which they may serve as primitive elements of intercellular communication prior to the development of neuronal or endocrine systems. In vertebrates, these peptides are thought to have neurotransmitter or neuromodulatory roles and appear to be involved in the regulation of a number of homeostatic systems, although the mechanisms of their actions are still unclear.

Enkephalins and Endorphins. Clinical, pharmacological and therapeutic implications

During the past 8 years there has been substantial progress in our understanding of the structure, distribution and action of endogenous opioid peptides. Currently, there appear to be 2 groups of peptides; those derived from beta-lipotropin and an enkephalin-related group. Some of these peptides have been shown to be distributed widely in the central nervous system and in endocrine tissues. The activity of the peptides probably occurs at several receptors but only 1 relatively specific (mu-receptor) antagonist, naloxone, is well studies. Although there have been many clinical studies of the action of opioids in man, no novel therapeutic applications have yet been established in clinical practice. Of the many areas of involvement attributed to opioids, those of analgesia, reproductive endocrinology, opiate dependence, and certain as yet undefined subtypes of major psychoses seem reasonably promising. Speculation surround opioid involvement in other disorders such as spinal trauma, septic shock, alcohol dependence, "functional' gastrointestinal disease, diabetes and asthma is of considerable interest but is supported by less clinical evidence. It seems that as research in opioids advances, the putative physiological opioid "spheres of influence' widen. At the same time, opioid mechanisms of action are being revealed to be more subtle and complex than previously thought. As a consequence, the expectations of rapid therapeutic application of opioid peptides and their antagonists are being modified and refined and realistic research strategies applied. In view of the work reviewed in this paper it seems reasonable to expect that such work will pay dividends in the not too distant future.

Failure of naloxone to affect focal incomplete cerebral ischemia and collateral blood flow in cats

Focal incomplete cerebral ischemia was created in 20 adult cats by retro-orbital middle cerebral artery (MCA) occlusion under halothane anesthesia. Arterial blood flow (CBF), bilateral electroencephalographic (EEG) recordings, and systemic arterial blood pressure (SABP) were monitored for the 1st hour of occlusion. Ten animals were treated with 10 mg/kg of naloxone within 10 minutes of MCA clipping, followed by a continuous infusion of naloxone at 2 mg/kg/hr for the duration of the occlusion (8 hours). Ten animals were treated in a similar fashion with physiological saline (control). Blood flow was restored after 8 hours. The brains were examined at the time of death or 7 days after the occlusion period. There was no difference between the two groups regarding cerebral infarction size or distribution, neurological outcome, SABP, PaCO2, or CBF. Minor changes in EEG amplitude observed in the naloxone-treated group appear to represent interaction of the drug with halothane after prolonged administration. The authors conclude that naloxone did not modify the outcome of focal cerebral ischemia in the cat.

Non-familial hemiplegic migraine responsive to naloxone

Two cases of non-familial hemiplegic migraine are described. Naloxone reversed the neurological deficits accompanying attacks, whereas the pain was uninfluenced. The possibility that the opiate-antagonist naloxone facilitates regression of neurological symptoms associated with migraine attacks in general is voiced.

A study of the endogenous opioid system in the sudden infant death syndrome

To investigate the possible role of the endogenous opioid system in the pathogenesis of the sudden infant death syndrome (SIDS), we measured met-enkephalin immunoreactivity by radioimmunoassay in brain, lung, and adrenal glands of SIDS victims and of infants (controls) dying of nonneurologic causes. Met-enkephalin was stable in brain tissue up to 24 hours after death. On inspection, met-enkephalin levels in the cerebral cortex of SIDS victims were similar to those in controls. Levels in the caudate nucleus were lower in infants than in adults. In the medulla, the levels in SIDS cases and controls were not found to differ significantly. The linear relationship between the levels in the medulla and age was not detectably different in SIDS and controls. However, as a subset, levels in the control group significantly decreased with increasing age (P = 0.005), whereas levels in the SIDS group showed no correlation with age (P = 0.33). Levels of met-enkephalin in the adrenal gland of SIDS victims were similar to those in controls and were considerably lower than adult values. Lung tissue was assayed for beta-endorphin immunoreactivity and met-enkephalin: for both peptides the values in SIDS cases were low (femtomolar range) and similar to those in controls. These data suggest that met-enkephalin is not markedly overproduced in brains of SIDS victims. Future postmortem studies should focus on more subtle evidence of endogenous opioid overactivity such as differences in age related changes, receptor number, and levels of other endogenous opioid peptides.

Neurodegenerative diseases of infancy and childhood

The neurodegenerative diseases of infancy and childhood include disorders in which there is progressive loss of neurological function due to structural abnormalities of the central nervous system. Well over six hundred disorders, many of which are rarely seen, can be included in this category. Yet, the conditions represent collectively over one-fourth of all admissions to pediatric neurology services. Five-year samples of admission characteristics of 1218 patients from two medical centers over twenty-two years permit an estimate of the frequency of the neurodegenerative diseases. The six most-encountered diagnoses, in declining order, were: subacute sclerosing panencephalitis; neuronal ceroid lipofuscinosis; tuberous sclerosis with degeneration; West disease, or idiopathic degenerative encephalopathy associated with infantile spasms; Werdnig-Hoffmann disease, and hereditary spastic paraplegia. A classification is offered grouping the neurodegenerative disorders into five major categories: polioencephalopathies, leukoencephalopathies, corencephalopathies, spinocerebellopathies, and diffuse encephalopathies. Disorders in each subgroup may be either genetic or nongenetic. Neurodegenerative diseases have multiple causes, including metabolic, viral, immunopathic, environmental, and epileptogenic. The cause of many remains unknown.

Opiate receptors: enkephalins and endorphins

Opiate receptors in the central nervous system may be classified according to pharmacological, behavioural, or binding studies. Classical mu-receptors probably have beta-endorphin as an endogenous ligand, and seem to be involved in the modulation of pain perception, low-frequency acupuncture analgesia, and the stimulation of prolactin, growth hormone and thyroid-stimulating hormone release. Met-enkephalin is likely to be an endogenous ligand for the delta-receptors, which predominate in the basal ganglia and limbic systems; such receptors may tonically inhibit the release of corticotrophin-releasing factor. It has been suggested that the newly-described kappa-receptors may inhibit the release of vasopressin and gonadotrophin-releasing factor; dynorphin may be their endogenous ligand. Endogenous opiates controlling cardiovascular and respiratory reflexes are likely to activate mu-receptors, while high-frequency acupuncture may alleviate the symptoms of opiate withdrawal by allowing an increase in Met-enkephalin to activate delta-receptors. In the periphery, beta-endorphin is concentrated in the corticotrophs of the anterior pituitary, and is cosecreted with ACTH and related peptides. Circulating Met-enkephalin originates in the gut, sympathetic nervous system and adrenal medulla. Met-enkephalin may also be extracted from carcinoid tumours and phaeochromocytomas. Elevations in circulating Met-enkephalin may occur in certain disease states with cardiovascular and psychiatric manifestations. However, manipulation of endogenous or exogenous opiates has as yet no certain place in any clinical situation.

Neuroendocrine effects of endogenous opioid peptides in human subjects: a review

In the decade since the discovery of specific opioid receptors in the brain, there have been rapid advances in our understanding of the physiological and pathological roles of the endogenous opioid systems in humans. Endogenous opioid peptides have been demonstrated to play a role as modulators of a number of hormonal functions in humans. In particular they appear to inhibit luteinizing hormone and ACTH release, and the response of arginine vasopressin to osmotic stimuli. They appear to participate in the modulation of carbohydrate homeostasis. In pathophysiological states, they appear to play a role in the decreased pulsatile luteinizing hormone release seen in patients with prolactinomas. Circulating beta-endorphin appears to be an important regulator of immune function. Preliminary studies in humans have suggested a role for endogenous opioid peptides in appetite regulation. In the last few years, a few case reports have suggested the possibility of a series of syndromes due to endogenous opioid excess. Within the next decade, we can expect to see the routine use of opioid antagonists in a variety of pathophysiological states.

Opiates, endorphins and the developing organism: a comprehensive bibliography

A comprehensive bibliography of the literature concerned with opiates, endorphins, and the developing organism is presented. A total of 1378 clinical and laboratory references, with citations beginning in 1875, are recorded. A series of indexed accompanies the citations in order to make the literature more accessible. These indexes are divided into clinical and laboratory topics. The clinical section is subdivided into: age of subject examined; maternal aspects; effects on the fetus; pharmacology, physiology, and the withdrawal syndrome; and "other" effects on the offspring. The laboratory section is subdivided into: type of opiate/endorphin studied; species utilized; and major subject areas explored.

X-linked Leigh's syndrome

Two male half siblings developed rapid progression of neurologic symptoms at 11/2 and 21/2 years of age. Neither boy had a metabolic acidosis. Characteristic features of subacute necrotizing encephalomyelopathy, the neuropathologic basis of Leigh's syndrome, were demonstrated at autopsy. X-linkage of the disorder was considered because the boys had different fathers. An X-linked form of Leigh's syndrome was supported by a review of the literature, which showed an unexplained male/female ratio in Leigh's syndrome of 1.83/1, and a significant excess of male-male siblings. An X-linked form of Leigh's syndrome would explain the excess of males, and may account for some of the clinical and biochemical heterogeneity.