Immunoreactive Beta-endorphin Research Articles

Metabolic and endocrine responses to cold air in women differing in aerobic capacity.

The purpose of this study was to measure resting metabolic rate, plasma norepinephrine, and plasma immunoreactive beta endorphin during exposures to cold air during two consecutive 5-d periods, separated by 2 weekend days, in two groups of women differing in aerobic fitness. Plasma norepinephrine (NE), plasma immunoreactive beta-endorphin (IBE), and resting metabolic response (RMR) were measured during repeated exposures to 3.5 degrees C air in two groups of women differing in aerobic fitness. Ten women, separated into highly fit (HFW) and less fit (LFW) groups, sat in 22 degrees C air for 45 min followed by 45 min in 3.5 degrees C air each day during two consecutive 5-d periods separated by two weekend days. Norepinephrine was not different between groups during warm air exposure; however, following 45 min of cold air, NE was two times higher in HFW compared with that in LFW (P < 0.001). Plasma IBE was elevated (P < 0.02) in HFW compared with that in LFW but was not affected by exposure to cold on any test day. Warm RMR was not different between groups and remained unchanged during the study period. Cold RMR was significantly higher in LFW compared with that in HFW (P < 0.01). Resting metabolic rate peaked at 30% of VO2peak in LFW by the 5th minute of cold exposure on day 1 before declining to 21% and remaining steady. In contrast, RMR in HFW peaked at about 13% and then fell to 9.4% before slowly increasing to 14% by the end of 45 min. On other test days HFW RMR increased to 14% of VO2peak and rose slowly through 45 min of cold exposure while LFW RMR peaked at 24% of VO2peak before declining to 20% and remaining steady. Our findings suggest that, in women, aerobic fitness alters the endocrine and metabolic responses to acute cold air exposure. The norepinephrine response is exaggerated in highly fit women exposed to cold but not the metabolic response. Immunoreactive beta endorphin was not affected by exposure to cold but was elevated in highly fit women. We further conclude that the temperature threshold for acclimation to cold air by women may be higher than the air temperature used in this study.

Acute Alcohol Effects on Opiomelanocortinergic Regulation

To assess acute effects of alcohol on forebrain and pituitary opiomelanocortinergic regulation, a model was developed in which "experienced" (previously introduced to ethanol administration, so the subjective response was not a novel stimulus) male Sprague-Dawley rats received pulsatile intragastric ethanol infusions during the dark (active) photophase to produce and sustain (for 3 hr) behaviorally relevant (0, 40 to 70, 80 to 110, or 120 to 150 mg/dl) plasma ethanol levels. The effects of alcohol on hypothalamo-pituitary-adrenal (H-P-A) axis function were biphasic with respect to dosage (inhibition with low dosage and stimulation with higher dosages) and time (initial stimulation with higher dosages was followed by rapid return to control levels even though elevated plasma ethanol levels were maintained). The effects of alcohol on H-P-A activation were also inconsistent; some of the animals did not appear to respond even though elevated (i.e., >100 mg/dl) plasma ethanol levels were produced. Induction of moderate (80 to 110 mg/dl) plasma ethanol levels acutely (within 30 min) increased immunoreactive (i) beta-endorphin concentrations in the ventral tegmental area of the brain; higher (120 to 150 mg/dl) plasma ethanol levels increased i beta-endorphin concentrations in both the ventral tegmental area and the nucleus accumbens, whereas i beta3-endorphin concentrations were not significantly altered in other brain areas. High (120 to 150 mg/dl) plasma ethanol levels also increased mediobasohypothalamic pro-opiomelanocortin (biosynthetic precursor of forebrain beta-endorphin) mRNA concentrations at 3 and 6 hr after initiation of ethanol infusions. Results demonstrate that atraumatic induction of physiologically meaningful plasma alcohol levels by gastric ethanol infusion activates the forebrain opiomelanocortinergic opioid system and exerts complex effects on the interrelated H-P-A system, consistent with evidence that these systems may interact to mediate or modulate some responses to alcohol ingestion.

Effects of Ethanol on Basal and Prostaglandin E1‐Induced Increases in β‐Endorphin Release and Intracellular cAMP Levels in Hypothalamic Cells

Our recent studies determining the effect of cAMP-elevating agents forskolin and dibutyryl cAMP on ethanol-induced immunoreactive beta-endorphin (IR-beta-EP) release from hypothalamic cells in primary cultures suggested the possibility that both stimulatory and adaptive secretory responses of beta-EP neurons after ethanol exposure may involve the cAMP system. To determine further the role of cAMP, the effects of prostaglandin E1 (PGE1) on basal and ethanol-regulated IR-beta-EP secretion and cAMP productions were determined in primary cultures of hypothalamic cells. The results presented in this study show that a 50 mM dose of ethanol, which is within the EC50 dose of ethanol required to elevate IR-beta-EP release from hypothalamic cells, increased cellular levels of cAMP and elevated IR-beta-EP release simultaneously from the cultured neurons for a period of 6 hr. The cAMP and IR-beta-EP secretory responses developed desensitization to ethanol challenge after 24 hr of constant ethanol incubation. The cAMP-elevating agent PGE1 increased the cellular content of cAMP and IR-beta-EP release in a dose-dependent manner. The EC50 dose of PGE1 for elevation of IR-beta-EP and cAMP was approximately 0.5 microM. As with ethanol, chronic treatment with PGE1 desensitized the cAMP and IR-beta-EP responses of hypothalamic neurons to PGE1. Acute exposure to ethanol increased the PGE1-stimulated levels of cAMP and IR-beta-EP, whereas chronic exposure to ethanol resulted in diminished cAMP responses to PGE1. These data provide evidence that the cAMP system may be involved in controlling hypothalamic beta-EP secretion, as well in regulating the stimulatory and adaptive responses of beta-EP neurons to ethanol.

The Role of cAMP in Ethanol‐Regulated β‐Endorphin Release from Hypothalamic Neurons

We have previously shown that ethanol acutely stimulates immunoreactive beta-endorphin (IR-beta-EP) release from hypothalamic neurons, whereas chronic administration of ethanol desensitizes these neurons. In the study reported herein, the role of the intracellular cAMP system in the ethanol-regulated IR-beta-EP release from hypothalamic cells in primary cultures was investigated. Acute treatment with ethanol or with the cAMP analog, dibutyryl cAMP, revealed that both agents stimulate the release of IR-beta-EP from the hypothalamic cells. Combined treatment of ethanol and the cAMP analog produced a synergistic effect on IR-beta-EP release. Treatment with ethanol and a cAMP-elevating agent, forskolin, increased cAMP levels in cultured hypothalamic cells. However, prior exposure to ethanol reduced the cAMP-elevating responses of these neurons to ethanol and forskolin. These results indicate that the stimulatory and adaptive responses of IR-beta-EP neurons to ethanol may involve the cAMP system.

Forskolin Delays the Ethanol-Induced Desensitization of Hypothalamic beta-Endorphin Neurons in Primary Cultures

Ethanol and its metabolite acetaldehyde have been shown to stimulate immunoreactive beta-endorphin (IR-beta-EP) secretion from hypothalamic neurons in primary cultures. Also, chronic ethanol and acetal-dehyde have been shown to cause the development of tolerance and desensitization of these neurons. In this study, we determined some of the cellular events leading to desensitization of the function of beta-endorphin (beta-EP) secretory neurons. The fetal hypothalamic cells were treated with various doses of ethanol (25 and 50 mM) or acetaldehyde (6.25, 12.5, and 25 mM) for 6 hr or treated with these drugs at 12 hr intervals for 72 hr. Determination of IR-beta-EP concentrations in the media revealed that ethanol increased IR-beta-EP secretion from these cultures for 12 hr, after this period, the cultured cells did not respond to ethanol. Acetaldehyde stimulated IR-beta-EP secretion from this culture for a period of 48 hr, but the IR-beta-EP secretory response to acetaldehyde reduced gradually with time during the first 48-hr period and reached the basal level at 72 hr. The desensitization of beta-EP neurons 12 hr after treatment with alcohol did not seem to be related to the loss of viable cells, because chronic ethanol exposures did not produce any effect on cell viability. However, reduced IR- beta-EP secretory response to acetaldehyde with time was associated with the time-dependent increase in cell death. Pretreatment of cultures with a cAMP analog, forskolin, increased the activity of functional beta-EP neurons and delayed the ethanol desensitization effects on these neurons. Pretreatment of forskolin did not delay the acetaldehyde desensitization of beta-EP neurons, but protected these cells from acetaldehyde toxicity. These results suggest that (i) chronic treatment with ethanol desensitizes beta-EP-secreting neurons due to reduced cellular functions and (ii) chronic acetaldehyde reduces beta-EP neurotransmission due to cell death. Furthermore, data suggest for the first time that cAMP pretreatments delay the ethanol-induced desensitization of opioid neurons and partly protect against the neurotoxic action of acetaldehyde on opioid neurons.

Thiopental Prevents A Beta-Endorphin Response to Cardiopulmonary Bypass

We studied the effects of adding a single bolus(500 mg) of sodium thiopental to a continuous infusion of low-dose fentanyl on plasma beta-endorphin immunoreactivity(iBE) responses to cardiopulmonary bypass(CPB) in 28 patients undergoing elective coronary artery bypass grafting or valve procedures. Thiopental was injected just prior to the initiation of CPB. The iBE levels and the hemodynamic indices such, as mean arterial pressure, cardiac output and systemic vascular resistance were measured before CPB, at 30 min and again at 60 min after the initiation of the bypass. The results were as follows. After the initiation of CPB, iBE levels increased at 30 min and 60 min(P=0.006, P=0.004 respectively) in the control group, but not in the thiopental group. There were significant differences in the changes of iBE levels between the groups(F=8.7, G-G=0.002, P=0.001). The hemodynamic indices were similar in both groups. In conclusion, pretreatment with thiopental just before the initiation of CPB prevents the stress-induced beta-endorphin response to CPB.

Beta-endorphin immunoreactivity levels in CSF after laryngeal chemoreflex activation correlate with apnoea duration in piglets.

The activation of the laryngeal chemoreflex may be a pathogenic mechanism in apnoea, apparent life threatening events, and SIDS. Infants with apnoea and increased levels of beta-endorphin immunoreactivity in CSF have been successfully treated with naloxone. Beta-endorphin may induce respiratory depression, and naloxone is a beta-endorphin antagonist. We therefore wanted to measure beta-endorphin levels in CSF before and after the chemoreflex induced apnoea. This study includes 13 piglets, 5-10 days of age, treated with and without naloxone. Respiration, blood pressure, and heart rate were monitored. CSF was sampled before and after the laryngeal chemoreflex induced apnoea. We found a shorter duration of apnoea in the piglets which had received naloxone than in those which did not (p = 0.02). The beta-endorphin immunoreactivity levels in CSF increased after apnoea, and the increased levels correlated positively with the duration of the apnoea in the piglets which had not received naloxone (r = 0.94, p = 0.02), but not in those pretreated with naloxone (r = 0.1, p = 0.8). The median amount of beta-endorphin immunoreactivity in CSF after apnoea in the naloxone-treated piglets was not significantly different from that in the non-treated piglets: 615 +/- 589 (n = 7) fmol/ml CSF and 984 +/- 851 (n = 6) fmol/ml CSF, respectively. The beta-endorphin immunoreactivity levels measured before the apnoea were less than 4.3 fmol/ml CSF. The laryngeal chemoreflex induced apnoea may possible be partly mediated by beta-endorphin.

Delta-sleep-inducing peptide sequels in the mechanisms of resistance to emotional stress.

The aim of this study is to investigate time-related changes in substance P (SP), beta-endorphin (BE), and corticosterone (CORT) levels due to DSIP aftereffects in the control and stress rats. Experiments were carried out on male Wistar and August rats. The SP and BE immunoreactivity in the hypothalamus and plasma samples was determined radioimmunologically. Blood CORT level was determined radioimmunologically. The rats were stressed at nighttime in special cages and tied by tails to the back side of the cage. The stress experiments were repeated for 12 hours for 5 days. There were 6 groups: 1. control animals, 2. stress animals, 3. rats that received DSIP in a dose of 60 nmol/kg one hour before decapitation, 4. rats in which DSIP was injected 24 hour before decapitation, 5. stressed rats in which DSIP was injected one hour before decapitation during the 5th exposure to stress, 6. stressed rats to which DSIP was injected 12 hours before the 5th exposure to stress, i.e., 24 hours before decapitation. Our experiments showed that DSIP administration induced marked changes in SP, BE, and CORT levels in hypothalamus and blood plasma. This suggests that the long-term stress-coping effect of DSIP depends on considerable changes in the level of other oligopeptides and hormones induced by DSIP. Evidently, DSIP triggers these processes inducing a cascade of interrelated molecular reactions radically different in animals with different resistance to emotional stress. This cascade of sequential reactions is different in Wistar and August rats differing by their resistance to emotional stress. DSIP administration stimulates the mechanism of resistance in August rats to a lesser extent than in Wistar animals.

Comparison of the effects of immobilization and pressure overload induced cardiac hypertrophy on immunoreactive beta-endorphin

Acute physical stress in the form of immobilization resulted in a decrease in the concentration of immunoreactive beta-endorphin (IR-BE) in the anterior pituitary (AP) and an increase in the concentration of IR-BE in the neurointermediate lobe of the pituitary (NIL) and the plasma. Hypothalamic IR-BE was not influenced by immobilization. In response to chronic cardiovascular (physiological) stress resulting from constriction of the aorta (aortic banding) and subsequent pressure overload, the concentration of IR-BE in the AP was increased as was the concentration of IR-BE in the plasma. The concentration of IR-BE in the NIL and the hypothalamus was not affected. These findings suggest that physical stress and cardiovascular stress have the same affect on IR-BE levels in the plasma but differ in their respective effects on IR-BE in the AP and NIL and do not affect the concentration of IR-BE in the hypothalamus. The difference in the effects of each form of stress on the AP and the NIL respectively, may be attributed to either the type of stress employed (physical versus physiological), the duration of the stress (acute vs chronic), or both.

Release of beta-endorphin immunoreactivity from brain by activation of a hypothalamic N-methyl-D-aspartate receptor.

Lateral ventricle-cisterna magna perfusion in the halothane-anesthetized rat was used as a model to study beta-endorphin release in the brain. Microinjection of N-methyl-D-aspartate into the arcuate nucleus of the hypothalamus released beta-endorphin immunoreactivity into perfusate and the release was blocked by systemic pretreatment with the N-methyl-D-aspartate antagonist dizocilpine (MK-801). N-methyl-D-aspartate microinjections did not increase beta-endorphin immunoreactivity in plasma, and pretreatment with dexamethasone did not prevent release of beta-endorphin immunoreactivity into perfusate, emphasizing that the released beta-endorphin immunoreactivity did not come from plasma. The non-N-methyl-D-aspartate glutamate receptor agonist alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid hydrobromide did not release beta-endorphin immunoreactivity. High-performance liquid chromatography characterization of perfusates collected after N-methyl-D-aspartate microinjection showed that a major part, but not all, of the beta-endorphin immunoreactivity co-eluted with authentic beta-endorphin. Microinjection of N-methyl-D-aspartate provoked an algogenic response in the anesthetized rat, and inhibited the motor and cardiovascular responses to tail immersion in 52.5 degrees C water. This block was reversed by pretreatment with MK-801, but not naloxone. Injection of alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid hydrobromide elicited the same behavioral response and blocked the nociceptive tail-dip reaction, but did not release beta-endorphin immunoreactivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of ethanol, propanol, butanol, and catalase enzyme blockers on beta-endorphin secretion from primary cultures of hypothalamic neurons: evidence for a mediatory role of acetaldehyde in ethanol stimulation of beta-endorphin release.

Previously, we have shown that low doses of ethanol (12.5-100 mM) and acetaldehyde (12.5-50 microM), but not salsolinol, enhanced immunoreactive beta-endorphin (IR-beta-EP) secretion from fetal hypothalamic neurons in primary culture. In this study, the effects of ethanol, propanol, and butanol, as well as the effect of catalase inhibitors on IR-beta-EP secretion were studied in vitro to determine the role of membrane fluidization and ethanol metabolism on ethanol-induced IR-beta-EP secretion. The primary cultures of fetal hypothalamic neurons were maintained for 8-9 days in chemically defined medium and treated for 5 hr with ethanol (50 mM), propanol (25 and 50 mM), and butanol (25 and 50 mM). Determination of hourly secretion of IR-beta-EP from the cultures revealed that only 50 mM ethanol caused stimulation of IR-beta-EP secretion, whereas propanol and butanol did not alter IR-beta-EP response at any given concentration. Pretreatment of these cultures with the catalase inhibitors, 3-amino-1,2,4-triazole (3-AT; 1, 5, and 10 mM), caused a dose-dependent inhibition of ethanol-stimulated IR-beta-EP secretion, but did not inhibit dibutyryl cAMP (dcAMP)-stimulated IR-beta-EP secretion. Another catalase inhibitor, sodium azide (5 mM), also inhibited ethanol-stimulated IR-beta-EP secretion. Measurement of acetaldehyde production in cultured cells and media after ethanol or dcAMP treatments revealed that cultured cells produce acetaldehyde only after ethanol treatment and at levels of acetaldehyde (8-24 microM) that are known to evoke IR-beta-EP release. The catalase inhibitor 3-AT (10 mM) treatment reduced ethanol-evoked acetaldehyde production.(ABSTRACT TRUNCATED AT 250 WORDS)

Maintained PC1 and PC2 expression in the AtT-20 variant cell line 6T3 lacking regulated secretion and POMC: restored POMC expression and regulated secretion after cAMP treatment.

Two variant cell lines were recently established from parent AtT-20 cells. Whereas HYA.15.10.T.2 have a reduced level of secretory granules, HYA.15.6.T.3 are completely devoid of both the regulated pathway of secretion and of dense-core secretory granules. AtT-20 cells normally express the processing enzymes PC1, PC2, furin, carboxypeptidase E, and peptidylglycine alpha-amidating monooxygenase, as well as proopiomelanocortin, chromogranin B, and 7B2. We measured the expression of these mRNAs in both variant cell lines. Although some differences in mRNA level were noted, HYA.15.10.T.2 and HYA.15.6.T.3 cell lines maintained their expression of the processing enzymes and of 7B2. Furthermore, PC1 and PC2 were shown to be functionally active in the HYA.15.6.T.3 cells. In contrast, proopiomelanocortin and chromogranin B mRNA levels were no longer detectable in HYA.15.6.T.3 cells. Interestingly, stimulation of the HYA.15.6.T.3 cells with cAMP restored proopiomelanocortin mRNA, beta-endorphin immunoreactivity, and dense-core granules. Furthermore, at the ultrastructural level, beta-lipotropin immunoreactivity was detected in granules of cAMP-induced HYA.15.6.T.3 cells. Finally, depolarization of cAMP-induced HYA.15.6.T.3 cells with 56 mM potassium chloride resulted in a marked increase in the release of beta-endorphin immunoreactivity. These observations demonstrate that cAMP restores the regulated pathway of secretion in HYA.15.6.T.3 cells, which under untreated conditions do not demonstrate regulated release. These variant cell lines are unique models to understand better the relationship of the regulated pathway and the expression of the processing enzymes.

Retrovirus-mediated expression of an artificial beta-endorphin precursor in primary fibroblasts.

Peptides are of potential interest in the field of gene therapy but require modification by genetic engineering to facilitate their secretion. Amino terminal addition of a signal peptide is not always sufficient to achieve this goal, as found in this study for beta-endorphin. To overcome this problem, addition of the pre-pro-sequence of mouse nerve growth factor to beta-endorphin was tested. Retrovirus-mediated expression of a hybrid construct of the pre-pro-sequence of nerve growth factor and human beta-endorphin in primary fibroblasts resulted in the secretion of beta-endorphin immunoreactivity at a rate of 620 pg/h/10(6) cells. Analysis of the secreted beta-endorphin immunoreactivity with reverse-phase HPLC, immunoassays using three different antibodies, and an assay for the specific displacement of [3H][D-Ala2,N-MePhe4,Gly-ol5]enkephalin from mu-opioid receptors suggests that the pre-pro-sequence is cleaved off from the pre-pro-sequence/beta-endorphin construct prior to secretion, resulting in bona fide beta-endorphin. Transplantation of beta-endorphin-secreting cells into brain or spinal cord may provide a gene therapy approach for the treatment of chronic, opioid-sensitive pain states.

Treatment of Growth Hormone-Deficient Adults with Recombinant Human Growth Hormone Increases the Concentration of Growth Hormone in the Cerebrospinal Fluid and Affects Neurotransmitters

In a double-blind, placebo-controlled trial, the effects of recombinant human growth hormone were studied on cerebrospinal fluid concentrations of growth hormone, insulin-like growth factor 1 (IGF-1), insulin-like growth factor binding protein-3 (IGFBP-3), monoamine metabolites, neuropeptides and endogenous opioid peptides. Twenty patients, 10 patients in each of 2 groups, with adult-onset, growth hormone deficiency were treated for 1 month with recombinant human growth hormone (0.25 U/kg/week) or placebo. All the patients received the appropriate thyroid, adrenal and gonadal hormone replacement. In cerebrospinal fluid, the mean concentration of growth hormone increased from 13.3 +/- 4.4 to 149.3 +/- 22.2 muU/l (p = 0.002), during recombinant human growth hormone treatment. The cerebrospinal fluid IGF-I concentration increased from 0.67 +/- 0.04 to 0.99 +/- 0.10 micrograms/l (p = 0.005) and the IGFBP-3 concentration rose from 13.4 +/- 1.25 to 17.5 +/- 1.83 micrograms/l (p = 0.002). The dopamine metabolite homovanillic acid decreased from 282.1 +/- 36.0 to 234.3 +/- 26.5 nmol/l (p = 0.02) and the vasoactive intestinal peptide decreased from 4.1 +/- 0.6 to 3.7 +/- 0.4 pmol/l (p = 0.03). Cerebrospinal fluid immunoreactive beta-endorphin increased from 24.4 +/- 1.8 to 29.9 +/- 2.1 pmol/l (p = 0.002). There were no significant changes compared to baseline in the cerebrospinal fluid concentrations of enkephalins, dynorphin A, the norepinephrine metabolite 3-methoxy-4-hydroxyphenyl-ethyleneglycol, the serotonin metabolite 5-hydroxyindoleacetic acid, gamma-aminobutyric acid, somatostatin or corticotropin-releasing factor.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of chronic alcohol on immunoreactive beta-endorphin secretion from hypothalamic neurons in primary cultures: evidence for alcohol tolerance, withdrawal, and sensitization responses.

Endogenous opioid peptides are known to be involved in the alcohol tolerance and dependence following alcohol abuse. However, the cellular mechanisms involved in the ethanol tolerance and dependence are not well established. We have previously shown that low concentrations of ethanol stimulate immunoreactive beta-endorphin (IR-beta-EP) release from the cultured hypothalamic neurons and that chronic ethanol exposure desensitizes these neurons to ethanol challenges. In this study, we determined the IR-beta-EP response to increasing doses of ethanol during the desensitizing phase of moderate ethanol doses to test whether the cultured IR-beta-EP-secreting neurons develop tolerance to ethanol following constant exposure. We also determined IR-beta-EP responses following withdrawal from chronic ethanol challenge and compared the IR-beta-EP secretory response to various doses of ethanol in ethanol-naive and ethanol-preexposed cultures. The IR-beta-EP responses to increasing doses of ethanol (50-150 mM) were markedly reduced in the cultures preexposed to a 50 mM dose of ethanol when compared with those that were naive to ethanol. The ethanol-exposed cultures showed hypersecretion of IR-beta-EP after removal from 48 hr of constant ethanol, as compared with ethanol-naive cultures. When ethanol-preexposed cultures were challenged with various doses of ethanol 4 days after ethanol withdrawal, the cultures showed higher IR-beta-EP secretory responses than did the ethanol-naive cultures. These data suggest that IR-beta-EP secretory neurons in primary cultures develop tolerance to chronic ethanol, show withdrawal response after removal of chronic ethanol exposure, and develop sensitization following repeated ethanol challenges.

Difference between plasma N- and C-terminally directed beta-endorphin immunoreactivity in infantile autism

The authors investigated whether there is excessive opioid activity in infantile autism by measuring plasma beta-endorphin in patients with autism compared with patients who had Rett's syndrome and normal comparison subjects. Radioimmunoassays for beta-endorphin using C-terminally and N-terminally directed antisera were applied to plasma samples from 67 children who met both DSM-III-R and ICD-10 diagnostic criteria for infantile autism, 22 girls with Rett's syndrome, and 67 normal children matched in age and sex with the children with autism. Median N-terminally directed beta-endorphin immunoreactivity appeared to be slightly lower in subjects with autism (7 pg/ml) and clearly higher in the girls with Rett's syndrome (40 pg/ml) than in the comparison subjects (9 pg/ml). Median C-terminally directed beta-endorphin immunoreactivity was higher in the girls with Rett's syndrome (35 pg/ml) and much higher in patients with autism (70 pg/ml) than in comparison subjects (8 pg/ml). These findings demonstrate the existence of a wide discrepancy between C- and N-terminally directed beta-endorphin immunoreactivity among children with autism. Despite the fact that the nature of the antigen recognized in the plasma of autistic children by the C-terminally directed anti-beta-endorphin serum remains to be characterized, the difference between C- and N-terminally directed beta-endorphin immunoreactivity might suggest an abnormal processing of the pro-opiomelanocortin gene in infantile autism.

Beta-endorphin immunoreactivity in spinal fluid and hypoxanthine in vitreous humour related to brain stem gliosis in sudden infant death victims.

Beta-endorphin may induce respiratory depression and bradycardia. Elevated levels of hypoxanthine (HX) in vitreous humour (VH) may possibly indicate hypoxia before death. Furthermore, gliosis in the brain stem may reflect a previous hypoxic/ischaemic injury in the brain. In the present study we relate beta-endorphin immunoreactivity (BENDI) in the CSF to the presence or absence of reactive astrocytosis in the nucleus olivae inferior (NOI). The relationship between the HX concentration in VH and the number of reactive astrocytes in sudden infant death (SID) cases (n = 17) and controls (n = 23) was also studied. The number of reactive astrocytes was examined in the NOI by immunohistochemical demonstration of glial fibrillary acidic protein (GFAP). The BENDI in CSF and the number of reactive astrocytes in the NOI divided the SID victims into two subpopulations (P < 0.01). One had a median of < 4 fmol/ml BENDI in CSF (range < 4) and 2 reactive astrocytes (range 0-15), and was similar to the controls that died from infections. The other subpopulation had a median of 260 fmol/ml BENDI in CSF (range 160-400) and 13 reactive astrocytes (range 7-33), similar to the control infants with previous hypoxia. In this latter SID subpopulation the number of reactive astrocytes correlated positively with BENDI in CSF (r = 0.7, P < 0.05). All the SID victims had elevated levels of HX in VH. In the SID subpopulation with high level of BENDI in CSF and increased number of activated astrocytes, the correlation factor between HX in VH and activated astrocytes was r = 0.7 (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Interleukin 1 beta and corticotropin-releasing factor inhibit pain by releasing opioids from immune cells in inflamed tissue.

Local analgesic effects of exogenous opioid agonists are particularly prominent in painful inflammatory conditions and are mediated by opioid receptors on peripheral sensory nerves. The endogenous ligands of these receptors, opioid peptides, have been demonstrated in resident immune cells within inflamed tissue of animals and humans. Here we examine in vivo and in vitro whether interleukin 1 beta (IL-1) or corticotropin-releasing factor (CRF) is capable of releasing these endogenous opioids and inhibiting pain. When injected into inflamed rat paws (but not intravenously), IL-1 and CRF produce antinociception, which is reversible by IL-1 receptor antagonist and alpha-helical CRF, respectively, and by the immunosuppressant cyclosporine A. In vivo administration of antibodies against opioid peptides indicates that the effects of IL-1 and CRF are mediated by beta-endorphin and, in addition, by dynorphin A and [Met]enkephalin, respectively. Correspondingly, IL-1 effects are inhibited by mu-, delta-, and kappa-opioid antagonists, whereas CRF effects are attenuated by all except a kappa-antagonist. Finally, IL-1 and CRF produce acute release of immunoreactive beta-endorphin in cell suspensions freshly prepared from inflamed lymph nodes. This effect is reversible by IL-1 receptor antagonist and alpha-helical CRF, respectively. These findings suggest that IL-1 and CRF activate their receptors on immune cells to release opioids that subsequently occupy multiple opioid receptors on sensory nerves and result in antinociception. beta-Endorphin, mu- and delta-opioid receptors play a major role, but IL-1 and CRF appear to differentially release additional opioid peptides.

Inverse relationship between beta-endorphin immunoreactivity in cerebrospinal fluid and nucleus tractus solitarius in sudden infant death

In nucleus tractus solitarius (NTS) beta-endorphin (BEND) induces bradycardia and respiratory depression which have been reported to precede death in sudden infant death (SID). Of SID victims, 50% have elevated levels of beta-endorphin immunoreactivity (BENDI) in the cerebrospinal fluid (CSF), and 50% had undetectable levels. We therefore investigated the relationship of BENDI in the CSF to BENDI levels in the NTS area. This study included SID victims (CSF from n = 47, brain stem from n = 16), borderline SID victims (CSF and brain stem from n = 2), sudden death in childhood (CSF and brain stem from n = 1), and controls (CSF from n = 32, brain stem from n = 11). BEND in CSF and NTS area, after extraction, was measured by radioimmunoassay. High performance liquid chromatography was used for closer identification of BENDI. We found that the SID victims divided into two subpopulations, one having a relatively high BENDI level in CSF and one having no detectable level (P < 0.01). Furthermore, an inverse relationship was found between BENDI level in CSF and BENDI level in NTS area in the SID victims (P < 0.05). We conclude that increased BENDI level in CSF is associated with low BENDI level in the NTS area in 50% of SID victims. The low BENDI level in the NTS area may be due to increased release of BEND.

Inverse relationship between beta-endorphin immunoreactivity in cerebrospinal fluid and nucleus tractus solitarius in sudden infant death

Inverse relationship between beta-endorphin immunoreactivity in cerebrospinal fluid and nucleus tractus solitarius in sudden infant death