Transgenic increase in the ß-endorphin concentration in cerebrospinal fluid alleviates morphine-primed relapse behavior through the µ opioid receptor in rats.

BACKGROUND: Opioid-primed relapse is a global burden. Although current strategies have improved, optimal therapy is urgently needed. METHODS: A recombinant adenovirus (Ad-NEP) expressing ß-endorphin (ß-EP) was designed and injected intracerebroventricularly (icv) into the right lateral ventricle in rats. Spatial and temporal ß-EP expression in the lateral ventricle wall, subventricular zone and adjacent choroid plexus and the ß-EP concentration in the cerebrospinal fluid (CSF) were observed during a 21-day period. A morphine priming-induced conditioned place preference (CPP) rat model was established. The ß-EP-ir neuron counts, CSF ß-EP concentration, and CPP score, which were used to evaluate morphine-primed reinstatement following extinction, were recorded 7 days after the icv injection. Additionally, the rats were pretreated with the irreversible µ opioid receptor antagonist ß-funaltrexamine (ß-FNA) and the selective κ opioid receptor antagonist nor-binaltorphimine (nor-BNI) to identify the receptor-dependent mechanism. RESULTS: Both peak ß-EP expression in target neurons and the peak CSF ß-EP concentration occurred 7 to 8 days after Ad-NEP icv injection. The sustainable increase in the CSF ß-EP concentration was correlated with a decrease in the CPP score 7 days after the Ad-NEP icv injection. Furthermore, reinstatement was almost reversed by ß-FNA pretreatment 24 hours before the behavioral test, but nor-BNI had little effect. CONCLUSION: The increasing cerebrospinal fluid ß-endorphin concentrations showed that the therapeutic effect on opioid relapse occurred predominantly through a µ opioid receptor-dependent mechanism. The Ad-NEP adenovirus can be considered an alternative therapy for opioid relapse.

Clinical study of cerebrospinal fluid neuropeptides in patients with primary trigeminal neuralgia.

OBJECTIVES: To investigate the expression levels of calcitonin gene-related peptide (CGRP), substance P (SP), vasoactive intestinal peptide (VIP), and ß-endorphin in the cerebrospinal fluid (CSF) and peripheral blood of patients with primary trigeminal neuralgia (TN). PATIENTS AND METHODS: We included 20 patients with primary TN who underwent percutaneous radiofrequency thermocoagulation and collected four types of samples from all of them: sample A: CSF samples; sample B: peripheral blood samples; sample C: peripheral blood samples collected one day before the operation; sample D: peripheral blood samples withdrawn one day after the operation. Another 20 CSF samples of patients with nervous system disease or gynecological disease were collected as a control (sample E). Samples A and B were obtained at the same time. We also evaluated the expression of CGRP, SP, ß-endorphin, and VIP by visual analog scale (VAS) scores one day before and one day after the operation. In addition, heart rate (HR) at baseline and at the time of sample collection, mean arterial pressure (MAP), and all side effects of the procedure were recorded. RESULTS: Significance were found concerning about CGRP, SP, ß-endorphin, and VIP in TN patients and the controls (P<0.001). The expression of CGRP, SP, and VIP in sample A was higher than that in sample E. However, the ß-endorphin level in sample A was lower than that in sample E. There was a positive correlation between sample A and B regarding the expression of CGRP, SP, ß-endorphin, and VIP (P<0. 01). There was no relationship between the time of disease onset and the expression of CGRP, SP, ß-endorphin, and VIP in sample A and sample B (P>0.05). No difference was detected between the neuropeptides levels in samples B and C (P>0.05). Notably, VAS in sample D was significantly lower than that in sample C (P<0.01). Finally, there was no difference between the intraoperative HR and MAP values in the studied samples. CONCLUSION: In primary TN patients, the blood levels of CGRP, SP, ß-endorphin, and VIP were associated with those in CSF samples. There was a significant difference between the levels of the four neuropeptides in CSF and control samples. Our results also indicated that the levels of neuropeptides in blood samples can be tested for those in CSF. The disease onset and duration exerted insignificant effects on the production and release of CGRP, SP, ß-endorphin, and VIP.

Endocannabinoids, through opioids and prostaglandins, contribute to fever induced by key pyrogenic mediators.

This study aims to explore the contribution of endocannabinoids on the cascade of mediators involved in LPS-induced fever and to verify the participation of prostaglandins and endogenous opioids in fever induced by anandamide (AEA). Body temperature (Tc) of male Wistar rats was recorded over 6h, using a thermistor probe. Cerebrospinal fluid concentration of PGE2 and ß-endorphin were measured by ELISA after the administration of AEA. Intracerebroventricular administration of the CB1 receptor antagonist AM251 (5µg, i.c.v.), reduced the fever induced by IL-1ß (3ng, i.c.v.), TNF-α (250ng, i.c.v.), IL-6 (300ng, i.c.v.), corticotrophin release factor (CRH; 2.5µg, i.c.v.) and endothelin (ET)-1 (1pmol, i.c.v.), but not the fever induced by PGE2 (250ng, i.c.v.) or PGF2α (250ng, i.c.v.). Systemic administration of indomethacin (2mgkg(-1), i.p.) or celecoxib (5mgkg(-1), p.o.) reduced the fever induced by AEA (1µg, i.c.v.), while naloxone (1mgkg(-1), s.c.) abolished it. The increases of PGE2 and ß-endorphin concentration in the CSF induced by AEA were abolished by the pretreatment of rats with AM251. These results suggest that endocannabinoids are intrinsically involved in the pyretic activity of cytokines (IL-1ß, TNF-α, IL-6), CRH and ET-1 but not the PGE2 or PGF2α induced fevers. However, anandamide via CB1 receptor activation induces fever that is dependent on the synthesis of prostaglandin and opioids.

Do low levels of beta-endorphin in the cerebrospinal fluid indicate defective top-down inhibition in patients with chronic neuropathic pain? A cross-sectional, comparative study.

OBJECTIVE: Pain medicine still lacks mechanism-specific biomarkers to guide diagnosis and treatment, and defective top-down modulation is an important factor in the pathophysiology of chronic pain conditions. Using modern analytical tools and advanced multivariate statistical analysis, the aim of this study was to revisit two classical potential biomarkers of pro- and anti-nociception in humans (substance P and beta-endorphin), focusing particularly on the cerebrospinal fluid (CSF). DESIGN: Cross-sectional, comparative, observational study. SUBJECTS: Patients with chronic, post-traumatic and/or post-surgical, neuropathic pain refractory to conventional treatment (N = 15) and healthy controls (N = 19) were included. METHODS: Samples were taken from CSF and blood, and levels of substance P and beta-endorphin were investigated using a Luminex technology kit. RESULTS: We found low levels of beta-endorphin in the CSF of neuropathic pain patients (66 ± 11 pcg/mL) compared with healthy controls (115 ± 14 pcg/mL) (P = 0.017). Substance P levels in the CSF did not differ (20 ± 2 pcg/mL, 26 ± 2, P = 0.08). However, our multivariate data analysis showed that belonging to the patient group was associated with low levels of both substances in the CSF. A higher correlation between the levels of beta-endorphin and substance P in CSF was found in healthy controls than in patients (rs = 0.725, P < 0.001 vs. rs = 0.574, P = 0.032). CONCLUSIONS: Patients with chronic neuropathic pain due to trauma or surgery had low levels of beta-endorphin in the CSF. We speculate that this could indicate a defective top-down modulation of pain in chronic neuropathic pain. Our results also illustrate the importance of taking a system-wide, multivariate approach when searching for biomarkers.

Brain mechanisms of sweetness and palatability of sugars.

Sugars are sweet and palatable. Sweetness is detected by the neural system, whereas palatability may be detected within the neural and chemical systems in the brain. Sweetness is discriminated from other tastes by different receptor sites on taste bud cells, a different subset of fibers in the taste nerves, and different projection zones in the brain. The benzodiazepine and opioid systems are related to palatability, and the dopaminergic system mediates the motivation to consume palatable food.

Release of beta-endorphin immunoreactive material under perioperative conditions into blood or cerebrospinal fluid: significance for postoperative pain?

The function of beta-endorphin immunoreactive material (IRM) released under perioperative conditions remains to be clarified. In 17 patients undergoing orthopedic surgery, we determined beta-endorphin IRM in venous blood plasma and in cerebrospinal fluid (CSF) before surgery (t(A)); after termination of surgery and general anesthesia, but still under spinal anesthesia (t(B)); on occurrence of postoperative pain (t(C)); and 1 day after the operation (t(D)). Pain severity was rated by the patients by using a visual analog scale. Patients felt postoperative pain (t(C)), but they felt no pain at times t(A), t(B), and t(D). beta-Endorphin IRM plasma levels before surgery (t(A)) or with postoperative pain (t(C)) proved to be significantly higher than levels determined just after surgery, but still under spinal anesthesia (t(B)), or those determined 1 day after the operation (t(D)); beta-endorphin IRM plasma levels at times t(A) and t(C) correlated positively with postoperative pain severity (t(C)). beta-Endorphin IRM CSF levels after surgery, but still under spinal anesthesia (t(B)), were significantly higher than levels determined at times t(A), t(C), or t(D). No correlation was found between beta-endorphin IRM CSF levels and pain severity. In conclusion, postoperative pain severity appears to be related to beta-endorphin IRM levels in plasma before surgery as well as with postoperative pain; the analgesic significance of this material remains to be elucidated.

Effects of electromagnetic fields on the levels of biogenic amine metabolites, quinolinic acid, and beta-endorphin in the cerebrospinal fluid of dairy cows.

Eight multiparous non-lactating pregnant Holstein cows at 198 +/- 35 d of gestation, weighing 608 +/- 24 kg, were confined to wooden metabolic cages in an electric and magnetic field chamber with a 12:12 h light:dark cycle. Subarachnoidal catheters were installed 5 d before the activation of the electric and magnetic fields. The cows were exposed to electric and magnetic fields (60 Hz, 10 kV/m and 30 microT) continuously except for the feeding and cleaning time for an average of 21.44 +/- 1.4 h per day for a period of 30 d. Cerebrospinal fluid samples were collected on three consecutive days before an exposure period of 30 d, on the last 3 d of the exposure period, and for 3 d starting 5 d after the exposure period. The concentrations of beta-endorphin, tryptophan, 5-hydroxyindoleacetic acid, homovanillic acid, 3-methoxy-4-hydroxyphenylethyleneglycol and quinolinic acid in cerebrospinal fluid were determined. There was a significant increase in quinolinic acid, and a trend towards an increase in tryptophan, findings consistent with a weakening of the blood-brain barrier due to exposure to the electric and magnetic fields.

The influence of preoperative concentrations of beta-endorphin and met-enkephalin on the duration of analgesia after transurethral resection of prostate.

beta-Endorphin (beta-EP) and methionine-enkephalin (M-EK) are endogenous peptides that play a role in the modification of pain perception and analgesia threshold. In order to understand more about pathophysiology of pain in association with neuroaxial blocks, we evaluated cerebrospinal fluid (CSF) concentrations of beta-EP and M-EK prior to spinal anesthesia (SA) in patients undergoing transurethral resection of prostate (TURP) to determine the correlation between preanesthesia concentrations and the duration of postoperative analgesia and opioid requirements. Twenty-five healthy patients undergoing TURP under SA were enrolled. beta-EP and M-EK were measured with a competitive radioimmunoassay. Mean preoperative beta-EP and M-EK concentrations were 153 +/- 44 and 38 +/- 5 pg/mL, respectively. Those with beta-EP concentrations > 153 pg/mL had significantly longer analgesia (P < 0.01), and lower utilization of morphine in the first postoperative day (P < 0.01). Moreover, patients with milder postoperative pain (visual analog scale score < 4/10) had significantly higher beta-EP concentrations (P < 0.01). A similar correlation was not found with M-EK values. These data suggest that preoperative CSF beta-EP, but not M-EK, concentrations correlate with the duration and quality of postoperative analgesia, as well as opioid requirements after spinal anesthesia.

Cerebrospinal fluid and plasma concentrations of SRIH, beta-endorphin, CRH, NPY and GHRH in obese and normal weight subjects.

Numerous hypothalamic peptides are involved in the control of eating behaviour. We assessed plasma and cerebrospinal fluid (CSF) levels of SRIH, beta-endorphin (beta-EP), CRH, NPY and GHRH in a group of massively obese patients and in normal weight subjects. In the obese patients, CSF SRIH and beta-EP levels were significantly reduced and increased, respectively, compared with controls (20.6 +/- 2.62, mean +/- s.e.m., vs 34.5 +/- 2.14 pg/ml, P < 0.05, for SRIH and 111.2 +/- 5.00 vs 80.4 +/- 5.32 pg/ml, P < 0.001, for beta-EP). Considering the data of obese and control subjects altogether, SRIH and beta-EP concentrations correlated negatively and positively, respectively, with BMI values (r = -0.641, P < 0.005 and r = 0.518, P < 0.05). No significant differences were observed in CSF levels of CRH, NPY and GHRH between obese and normal weight subjects, though GHRH levels were close to the assay sensitivity. CSF concentrations of CRH were positively correlated with those of SRIH in obese patients (r = 0.60, P < 0.05) and with those of NPY both in obese (r = 0.69, P < 0.02) and in control subjects (r = 0.83, P < 0.005). Plasma levels of SRIH, beta-EP, NPY and GHRH did not differ significantly in the two groups of subjects; plasma CRH was undetectable. Our results argue against the hypothesis of an enhanced SRIH tone as the cause of impaired GH secretion in obese patients, a primary defect in GHRH or GH release seems more likely. Moreover, they emphasise the importance of an increased tone of endogenous opioids in the pathophysiology of human obesity.

Intraventricular beta-endorphin accumulates in DARPP-32 immunoreactive tanycytes.

Intraventricularly administered beta-endorphin (beta-end) (50-500 pmol) is found to be taken up and accumulated in dopamine and adenosine 3',5'-monophosphate regulated phosphoprotein (DARPP-32) positive tanycytes of the median eminence 15 min after injection as revealed by double immunolabelling procedures in combination with confocal laser microscopy. Exogenous beta-end in the cerebrospinal fluid (CSF) may in this way regulate the hypothalamic hormone release at the nerve terminal level by being released from tanycytes in the external layer or by affecting tanycyte function. The findings open up the possibility that neuronal beta-end via volume transmission in the CSF and internalization into tanycytes may exert in part its actions on hypothalamic hormone secretion by actions in the median eminence.

Decreased cerebrospinal fluid beta-endorphin and increased pain sensitivity in patients with functional abdominal pain.

We investigated whether central pain mechanisms including the endogenous antinociceptive system are involved in functional abdominal pain--that is, abdominal pain without abnormal findings at routine examinations. beta-Endorphin, met-enkephalin immunoreactivity, and dynorphin immunoreactivity were measured in cerebrospinal fluid (CSF) from nine patients with long-lasting functional abdominal pain and nine pain-free controls undergoing minor surgery while under spinal analgesia. Furthermore, pain sensitivity was evaluated with an ischaemic pain test comparing 21 functional abdominal pain patients with two control groups: 1) 24 patients with organic abdominal pain due to duodenal ulcer, gallstone, or urinary tract calculi, and 2) 13 healthy pain-free controls. The CSF beta-endorphin concentration was significantly decreased in the functional abdominal pain group as compared with nine matched controls (P = 0.01). Met-enkephalin and dynorphin immunoreactivities were normal. This part of the investigation was suspended after nine patients had been tested, because of post-lumbar-puncture headache. With regard to pain sensitivity, no significant difference between the three groups was shown, but subdivision of the functional abdominal pain group showed that individuals with pain and no symptoms of irritable bowel syndrome (IBS) were significantly more sensitive to pain than functional abdominal pain patients with IBS and healthy controls (P = 0.04).

Proopiomelanocortin is the predominant adrenocorticotropin-related peptide in human cerebrospinal fluid.

High mol wt forms of immunoreactive ACTH and beta-endorphin (beta EP) are present in cerebrospinal fluid (CSF). We have quantified these peptides directly in the CSF of 26 patients undergoing routine myelography, using a panel of monoclonal antibody-based two-site immunoradiometric assays, specific for ACTH precursors (both POMC and pro-ACTH cross-react 100%), POMC, ACTH, and beta EP. The mean +/- SD levels of POMC in CSF were 530 +/- 150 pmol/L similar to total ACTH precursor immunoreactivity (414 +/- 83 pmol/L). By comparison, the CSF levels of ACTH (3.2 +/- 0.6 pmol/L) and beta EP (6.7 +/- 2.9 pmol/L) were 100-fold lower. POMC, by virtue of its 1% cross-reactivity in the ACTH immunoradiometric assay, could have also accounted for the ACTH immunoreactivity in CSF. Sephadex G-75 chromatography of CSF confirmed the presence of a single major peak of ACTH precursors eluting at the position of POMC (31K), while ACTH immunoreactivity was not detected at the position of ACTH-(1-39) (4.5K). We also studied the effect of exogenous glucocorticoids on CSF POMC peptides by giving 2.5 mg dexamethasone (0.5 mg, orally, every 6 h for 24 h) to a similar group of age-matched patients before lumbar puncture. No significant differences in CSF peptide content were observed between the two groups. These data suggest that the unprocessed precursor molecule POMC is the predominant peptide of the POMC family in human CSF and should always be considered when interpreting data involving ACTH or other component peptide immunoreactivity in this biological fluid.

Radioimmunoassay of beta-endorphin in ventricular and lumbar cerebrospinal fluid.

We describe a sensitive beta-endorphin (beta-EP) radioimmunoassay specific for beta-EP 1-31 applied to human ventricular and lumbar cerebrospinal fluid (CSF). Specificity was documented by reversed-phase HPLC of CSF pools. Simultaneous ventricular and lumbar CSF samples from 13 patients suspected of having normal-pressure hydrocephalus showed median beta-EP values of 2.2 (range 1.7-4.0) and 4.8 (2.8-14.6) pmol/L, respectively. Ventricular and lumbar beta-EP concentrations were positively correlated (Spearman r = 0.72, P = 0.013). The beta-EP rostral-caudal gradient was closely related to the CSF protein gradient. HPLC profiles of beta-EP immunoreactivity were similar in ventricular and lumbar CSF with both C- and N-terminal antisera. beta-EP concentrations did not vary in the first 12 mL of lumbar CSF, tapped in 3-mL portions [F(3,32) = 0.42, P = 0.74]. The beta-EP concentration in lumbar CSF from 15 children in remission from acute leukemia [23.4 (15.0-27.1) pmol/L] was higher than in 54 healthy adults [11.7 (10.9-13.3) pmol/L; P less than 0.01]. There was no effect of sex or age on CSF beta-EP in adults. beta-EP in lumbar human CSF may indicate di- and mesencephalic beta-EP neuronal activity.

[Changes in the concentration of beta-endorphin in the cerebrospinal fluid due to morphine analgesia in incurable oncologic patients]. / Izmeneniia kontsentratsii beta-éndorfina v likvore pod vliianiem spinal'noi analgezii morfinom u inkurabel'nykh onkologicheskikh bol'nykh.

Thirty cancer patients, clinical group IV, have been examined. It has been established that a persistent pain syndrome leads to lowering in beta-endorphin liquor level. Morphine analgesia is followed by beta-endorphin level elevation which directly depends on pain intensity and analgesia efficacy. Determination of changes in beta-endorphin liquor level may serve as a criterion of analgesia efficacy.

Elevated CSF beta-endorphin immunoreactivity in Rett's syndrome: report of 158 cases and comparison with leukemic children.

Because some symptoms of Rett's syndrome are suggestive of excessive endogenous opioid activity, we measured the levels of beta-endorphin-like immunoreactivity in lumbar CSF from 158 affected female patients and from 13 female controls. The mean (+/- SE) control level of beta-endorphin immunoreactivity in CSF was 35.3 +/- 2.8 pg/ml (range, 23 to 48 pg/ml), whereas those with Rett's syndrome had a mean level of 95.3 +/- 3.6 pg/ml (range, 31 to 293 pg/ml). The levels of beta-endorphin immunoreactivity in initial CSF samples exceeded the control range in 90% of the patients with Rett's syndrome. The mean beta-endorphin immunoreactivity was also elevated in CSF from leukemic children (119.2 +/- 16.9 pg/ml; range, 40 to 159 pg/ml), relative to the control group. These results are consistent with the hypothesis that some symptoms of Rett's syndrome may be associated with excessive endogenous opioid levels in the CNS.

Effects of dorsal root entry zone lesions on CSF and plasma neuropeptides and catecholamines.

Effects of dorsal root entry zone lesions (DREZLs) on cerebrospinal fluid (CSF) and plasma concentrations of neuropeptides, catecholamines, and cyclic nucleotides were studied in 9 patients with intractable chronic pain. Contents of beta-endorphin-like-material in CSF decreased in all patients 12-17 days following DREZLs during which complete to good pain relief was achieved. Contents of beta-endorphin-like-material in CSF increased again about one month after DREZLs in two and remained unchanged in one of three patients tested, who complained of partial reappearance of pain. Contents of beta-endorphin-like-materials in plasma showed no significant changes after DREZLs. Substance P, noradrenaline, adrenaline, and cyclic nucleotide levels in both CSF and plasma were variable among the subjects and did not change significantly following the operations. Thus, the results suggest that production of beta-endorphin-like-material in the central nervous system is decreased by DREZL, though the increase in its turn-over might not be neglected. The mechanisms of the decrease in contents of beta-endorphin-like-material in CSF after DREZLs were discussed in terms of our current knowledge of pain and pain inhibitory systems.

CSF and endocrine studies of premenstrual syndrome.

Eight women with prospectively documented premenstrual syndrome (PMS) underwent multiple samplings for estradiol, progesterone, prolactin, cortisol, and plasma 3-methoxy-4-hydroxyphenylglycol (MHPG) during an asymptomatic midcycle (late follicular) and a symptomatic premenstrual (late luteal) phase of the menstrual cycle. Cerebrospinal fluid (CSF) was collected for analysis of MHPG, norepinephrine (NE), 5-hydroxyindoleacetic acid (5-HIAA), dihydroxyphenylacetic acid (DOPAC), gamma-aminobutyric acid (GABA), homovanillic acid (HVA), tyrosine, tryptophan, beta-endorphin, prostaglandins, adrenocorticotropic hormone (ACTH), and arginine vasopressin (AVP). In subsequent months, a dexamethasone suppression test (DST) and a thyrotropin-releasing hormone (TRH) stimulation test were performed during midcycle and premenstrual phases. Significant results included increased CSF concentrations of MHPG in the premenstrual, as compared with the midcycle, phase of the cycle, and increased plasma cortisol concentrations during the midcycle phase. The DST showed a 62% overall rate of nonsuppression, irrespective of menstrual cycle phase. Though there were no abnormalities of thyrotropin-stimulating hormone (TSH) after TRH stimulation, the mean delta maximum prolactin values after TRH stimulation were higher than reported normal values both at midcycle and premenstrually. These pilot data suggest hormonal axes that might be worthy of further systematic investigation in future studies of PMS.

[Antalgic activity of adrenal medulla transplantation into the lumbar subarachnoid space. Experimental study]. / Acción antálgica del trasplante de medula suprarrenal al espacio subaracnoideo lumbar. Estudio experimental.

The possible antalgic effect of autografting the medulla adrenal into the subarachnoid lumbar space has been assessed in an experimental model in rats. There were three experimental groups: normal, sham operated, and transplanted. The electrical stimulation of the tail was used as a test for measuring the analgesic effect. The test was performed two days before the surgery and is was repeated 3, 7, 14, 21, and 28 days thereafter. Beta-endorphin levels in the spinal fluid were measured 30 days after surgery using radioimmunoassay techniques. Graft survival was assessed by pathologic examination. The results show that even though the grafts survived, there were only transient changes in pain threshold and the levels of beta-endorphin in the spinal fluid did not change significantly.