Decreased level of beta-endorphin-like immunoreactivity in cerebrospinal fluid of patients with senile dementia of Alzheimer type

Roles of β-Endorphin in Stress, Behavior, Neuroinflammation, and Brain Energy Metabolism

β-Endorphins are peptides that exert a wide variety of effects throughout the body. Produced through the cleavage pro-opiomelanocortin (POMC), β-endorphins are the primarily agonist of mu opioid receptors, which can be found throughout the body, brain, and cells of the immune system that regulate a diverse set of systems. As an agonist of the body's opioid receptors, β-endorphins are most noted for their potent analgesic effects, but they also have their involvement in reward-centric and homeostasis-restoring behaviors, among other effects. These effects have implicated the peptide in psychiatric and neurodegenerative disorders, making it a research target of interest. This review briefly summarizes the basics of endorphin function, goes over the behaviors and regulatory pathways it governs, and examines the variability of β-endorphin levels observed between normal and disease/disorder affected individuals.

Physiologic and neuroendocrine responses to intravenous naloxone in subjects with Alzheimer's disease and age-matched controls

BACKGROUND

Prior work showed that administration of naloxone HCl had different behavioral effects in patients with Alzheimer's disease (AD) than controls. The aim of the present study was to contrast the physiologic and neuroendocrine responses to administration of a wide range of doses of intravenous naloxone of patients with probable Alzheimer's disease to aged-matched controls.

METHODS

This was a double-blind, placebo-controlled, study of 12 patients with probable Alzheimer's disease and 8 age-matched normal controls who each received intravenous infusions of naloxone HCl on 3 different days in doses of 0.1 mg/kg and 2.0 mg/kg preceded by test doses of 0.5 mcg/kg. Order of treatment condition was randomized. Vital signs and plasma cortisol and prolactin were obtained at regular intervals.

RESULTS

Both groups showed increased cortisol after naloxone 0.1 mg/kg and 2.0 mg/kg (p < .0001), but the increase was significantly greater and longer lived in controls than in patients. Patients, but not controls, also experienced a significant hypothermic response after naloxone 2.0 mg/kg (p < .05). Prolactin, heart rate, and blood pressure did not change following naloxone and did not differ between groups.

CONCLUSIONS

These findings support a growing body evidence that HPA axis activity is increased in AD, and further suggest that at least part of this may be due to decreased opiatergic tonic inhibition.

Neuropeptide changes in cortical and deep gray structures in Alzheimer's disease

The alteration of certain neuropeptide levels is a dramatic and consistent finding in the brains of AD patients. Levels of SS, which is normally present in high concentrations in cerebral cortex /75/, are consistently decreased in the neocortex, hippocampus and CSF of AD patients. In addition, decreased levels of SS correlate regionally with the distribution of neurofibrillary tangles in AD /47/. Most available evidence suggests that the subset of SS-containing neurons which lack NADPH diaphorase may be relatively vulnerable to degeneration in AD. CRF is another neuropeptide with frequently observed changes in AD. Levels of CRF, which is normally present in low concentrations in cortical structures /75/, are decreased in the neocortex and hippocampus of AD patients. However, levels of CRF in the CSF of AD patients are not consistently reduced, but this is likely a reflection of the relatively low levels of CRF normally present in cerebral cortex. Studies of deep gray structures in AD brains reveal elevated levels of GAL in the nucleus basalis. The ability of GAL to inhibit cholinergic neurotransmission has generated considerable interest, since degeneration of cholinergic neurons in the basal forebrain consistently occurs in AD. In addition, the presence of NADPH diaphorase in GAL-containing neurons may underlie the relative resistance of these neurons to degeneration. From the aforementioned studies, it appears that the neurons which are relatively resistant to neurodegeneration in AD contain NADPH diaphorase. It is hypothesized that the presence of NADPH diaphorase protects these neurons from neurotoxicity mediated by glutamate or nitric oxide. Although one recent study /147/ has reported an elevation of the microtubule-associated protein tau in the CSF of AD patients (and this could become a useful antemortem diagnostic tool for AD), no similar CSF abnormality has been found for any of the neuropeptides. Thus, the measurement of CSF neuropeptide levels presently remains unhelpful in the diagnosis and treatment of AD. Future research on neuropeptides and their potential roles in the pathogenesis, diagnosis, and treatment of AD will likely involve further development of pharmacological modulators of neuropeptide systems, together with the further study of brain neuropeptidases.

Cortical and subcortical neuropeptides in Alzheimer's disease

Given the clinical features of AD, the severe atrophy of cerebral cortex that accompanies the disease, and the predominant cortical location of plaques and tangles, it is not surprising to find the most consistent changes in neuropeptides in this disease occurring in the cerebral cortex. The neuropeptide changes that have been reproducibly demonstrated in AD are reduced hippocampal and neocortical SS and CRF concentrations and a reduced CSF level of SS. In cerebral cortex, SS and CRF are found in GABAergic local circuit neurons in layers II, III, and VI. The function of these neurons is not well established, although these cells may act to integrate the flow of incoming and outgoing information in cerebral cortex. If this is true, then dysfunction of this integration could produce widespread failure of cerebrocortical function, resulting in the various neurobehavioral deficits seen in AD. The interpretation of neuropeptide changes in subcortical brain regions, either those that project to cortex, or those that are the efferent targets of cortical projections, is also uncertain. The observed neuropeptide abnormalities in these brain regions in AD are less consistent than are those seen in cerebral cortex. Perhaps the most intriguing result in these regions is the increases in galanin-immunoreactive terminals seen in the nucleus basalis of AD brains. Galanin has been shown to inhibit acetylcholine release and to impair memory function in rats (46,113).(ABSTRACT TRUNCATED AT 250 WORDS)

Alzheimer's disease: improvement of visual memory and visuoconstructive performance by treatment with picotesla range magnetic fields

Impairments in visual memory and visuoconstructive functions commonly occur in patients with Alzheimer's disease (AD). Recently, I reported that external application of electromagnetic fields (EMF) of extremely low intensity (in the picotesla range) and of low frequency (in the range of 5Hz-8Hz) improved visual memory and visuoperceptive functions in patients with Parkinson's disease. Since a subgroup of Parkinsonian patients, specifically those with dementia, have coexisting pathological and clinical features of AD, I investigated in two AD patients the effects of these extremely weak EMF on visual memory and visuoconstructive performance. The Rey-Osterrieth Complex Figure Test as well as sequential drawings from memory of a house, a bicycle, and a man were employed to evaluate the effects of EMF on visual memory and visuoconstructive functions, respectively. In both patients treatment with EMF resulted in a dramatic improvement in visual memory and enhancement of visuoconstructive performance which was associated clinically with improvement in other cognitive functions such as short term memory, calculations, spatial orientation, judgement and reasoning as well as level of energy, social interactions, and mood. The report demonstrates, for the first time, that specific cognitive symptoms of AD are improved by treatment with EMF of a specific intensity and frequency. The rapid improvement in cognitive functions in response to EMF suggests that some of the mental deficits of AD are reversible being caused by a functional (i.e., synaptic transmission) rather than a structural (i.e., neuritic plaques) disruption of neuronal communication in the central nervous system.

kappa-1 Opioid receptors of the temporal cortex are preserved in Alzheimer's disease

The binding of [3H]-U-69593 and [3H]-CI-977 to kappa-1 opioid receptors has been examined in the temporal cortex of postmortem brains from patients with Alzheimer's disease and age-matched controls using quantitative autoradiography. There was no significant difference between Alzheimer and control subjects in the level of [3H]-U-69593 and [3H]-CI-977 binding, but ChAT activity was markedly reduced (by 73% compared to controls). These results are not consistent with a presynaptic localisation of kappa-1 receptors on cholinergic terminals in human temporal cortex.

Dynorphin A-(1-13) attenuates basal forebrain-lesion-induced amnesia in rats

The effects of dynorphin A-(1-13), an endogenous kappa opioid agonist, on basal forebrain (BF)-lesion-induced amnesia in rats were investigated using step-through-type passive avoidance task. The BF was lesioned by injecting the cholinergic neurotoxin ibotenic acid (6 micrograms/side). The number of rats achieving the cut-off time (600 s) of step-through latency (STL) in BF-lesioned group significantly decreased as compared with that in sham-operated group. Dynorphin A-(1-13) (0.3 micrograms) significantly increased the number of rats achieving the cut-off time of STL in BF-lesioned rats. These results suggest that dynorphins play an improving role in the impairment of memory processes in BF-lesioned rats.

Lesioning of the nucleus basalis of Meynert has differential effects on mu, delta and kappa opioid receptor binding in rat brain: a quantitative autoradiographic study

Opioid receptor binding was investigated in rat brain following lesioning of the nucleus basalis of Meynert (nbM). The nbM, which provides cholinergic input to the cortex, was lesioned unilaterally using ibotenic acid. The efficacy of lesioning was confirmed by the observation of a significant decrease in choline acetyltransferase (ChAT) activity in the ipsilateral prefrontal cortex. The specific laminar and regional distribution of mu, delta and kappa opioid receptor binding was quantitated in various cortical and limbic structures in the rat using autoradiography. Distinct medial to lateral gradients of mu and kappa opioid binding were observed in regions of the cerebral cortex. In the lesioned hemisphere the levels of mu, delta and kappa opioid binding were altered in localized areas of the cerebral cortex and the hippocampus. The direction of these binding changes varied with the opioid receptor type being assessed. Delta opioid binding was increased in the lateral portions of the frontal, occipital, perirhinal and retrosplenial granular cortices. Kappa opioid binding was increased in the lateral portion of the occipital cortex and in the CA3 region of the hippocampus. In contrast, mu opioid binding was decreased in the lateral portions of the frontal, entorhinal and forelimb cortices. These opioid receptor changes are discussed with respect to the interactions between the cholinergic and opioid systems, and relevance of the nbM lesion model to Alzheimer's disease.

Neurochemical markers in the cerebrospinal fluid of patients with Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis and normal controls

Several neurotransmitter markers were investigated in the cerebrospinal fluid (CSF) from patients with Alzheimer's disease (AD) (n = 27), Parkinson's disease (PD) (n = 35) and ALS (n = 26) and from control subjects (n = 34) to compare the possible alterations in the biochemical profiles of these different neurodegenerative diseases. The main proportion of the patients represented an early phase of the illness at the time of the diagnosis. Correlations of the degree of dementia and the stage of the disease with CSF measures were evaluated. The CSF levels of somatostatin like-immunoreactivity (SLI) were significantly reduced in AD patients when compared with those of normals and ALS patients. The CSF concentrations of homovanillic acid (HVA) were significantly decreased for PD patients and the decrease focused on the non-demented patients. A trend of decreasing HVA values towards the most advanced stage of Parkinson's disease assessed by Webster's scale was also displayed. The content of 3-methoxy-4-hydroxyphenylglycol (MHPG) in the CSF was higher for ALS patients than for other groups. The lowest 5-hydroxy-indoleacetic acid (5HIAA) levels were observed in the PD group and the lowest acetylcholinesterase (AChE) activities were found in the PD patients with the most severe disease. Changes in CSF measures were too subtle to be beneficial for diagnostic purposes, but adequate for reflecting the different neurochemical profiles of these three degenerative neurological disorders.

The neurotoxic actions of ibotenic acid on cholinergic and opioid peptidergic systems in the central nervous system of the rat

The neurotoxic effects produced by ibotenic acid (IA) induced chemical lesions of the central nervous system (CNS) cholinergic system were examined on the opioid peptidergic system in adult rats. Forebrain cholinergic systems were bilaterally lesioned by the infusion of IA (1 or 5 micrograms/site) into the nucleus basalis magnocellularis (NBM). One week after the injections, the animals were sacrificed, and activities of acetylcholinesterase (AChE), choline acetyltransferase (ChAT) and concentrations of beta-endorphin (beta-End) and Met-enkephalin (Met-Enk) were measured in different brain regions. Animals treated with IA showed a decrease in the activity of ChAT (-24%), AChE (-36%) and beta-End level (-33%) in the frontoparietal cortex (FC). For the first time we report that these changes were associated with a compensatory increase in the activity of ChAT (+27%), AChE (+25%), beta-End level (+66%) in the remaining part of the cortex, i.e. cortex devoid of frontal cortex (C-FC). Met-enkephalin level increased by 59% in the frontoparietal cortex and did not change in the cortex devoid of frontal cortex upon IA treatment. These results suggest that IA treatment results in changes in the activity of cortical ChAT and AChE, and beta-End level in the same direction. Injection of IA in the NBM did not cause a change in the activity of ChAT or AChE in other brain regions such as hippocampus, striatum or midbrain. In addition to cortex devoid of frontal cortex, midbrain also showed a significant increase in the beta-End level in the IA treated animals. However, pituitary beta-End decreased in the neurotoxin treated animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebrospinal fluid markers of Alzheimer's disease

OBJECTIVE

To review studies on cerebrospinal fluid (CSF) in patients with Alzheimer's disease (AD) in order to answer the question whether CSF contains a specific marker which can be used to support a clinical diagnosis of AD.

DATA SOURCES

Studies identified through an English-language literature search using MEDLINE (1966 to 1990) and a review of bibliographies of relevant articles.

STUDY SELECTION

All studies on CSF in AD patients were selected. Double publications on the same original data were not included. Otherwise, no particular selection was made.

DATA EXTRACTION

The diagnostic utility of more than 60 substances, including CSF measures related to classical neurotransmitters, (neuro)peptides, proteins, amino acids, purines, trace elements, and constituents of senile plaques and neurofibrillary tangles, is evaluated. Clinical epidemiological criteria for deciding on the usefulness of new diagnostic methods are emphasized in this analysis.

DATA SYNTHESIS

Concentrations of some CSF constituents are consistently found to be significantly changed in AD. However, overlap with data of control populations and methodological shortcomings in study design, limit the diagnostic value of all CSF measurements reviewed.

CONCLUSIONS

None of the CSF constituents studied so far can be used in support of the diagnosis of AD. However, increased knowledge concerning macromolecular abnormalities in amyloid containing plaques and neurofibrillary tangles makes the outlook for a diagnostic test for AD on CSF promising.

Reduced cerebrospinal fluid dynorphin A1-8 in Alzheimer's disease

Cerebrospinal fluid (CSF) measures of dynorphin A were compared in three groups. Alzheimer patients (n = 9), elderly depressives (n = 9), and age-matched normal controls (n = 9). The Alzheimer patients revealed a 40% decrease in CSF dynorphin compared with controls (36 +/- 15 versus 60 +/- 21 pg/ml, p less than 0.05). In contrast, other peptide measures [Neuropeptide Y (NPY), vasoactive intestinal peptide (VIP), and galanin] remained unchanged across groups. This finding was further supported when an additional 20 Alzheimer patients with similar clinical backgrounds also showed reduced CSF dynorphin (37 +/- 13 pg/ml). CSF dynorphin did not correlate significantly with clinical variables or other CSF measures of monoamine metabolites [i.e., 3-methoxy-4-hydroxyphenylglycol (MHPG), 5-hydroxyindoleacetic acid (5-HIAA), and homovanillic acid (HVA)]. Given the previous report of increased kappa binding of Alzheimer brains at autopsy, the authors speculate about a possible up-regulation of opiate receptors in Alzheimer's disease and suggest ways to test this hypothesis in vivo.

Neurotransmitter markers in the cerebrospinal fluid of normal subjects. Effects of aging and other confounding factors

We have investigated neurotransmitter-related markers of the cerebrospinal fluid (CSF) in a carefully screened series of normally aging subjects in standardized conditions in order to find out the influence of age and other confounding factors on CSF measures. The levels of 3-methoxy-4-hydroxyglycol (MHPG) and the activity of acetylcholinesterase (AChE) also increased with age, while homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5 HIAA) and immunoreactivities of somatostatin (SLI), beta-endorphin (BLI) and adrenocorticotropic hormone (ACTH) were unrelated to age. The gender of subjects had no significant effect on the levels of neurotransmitter markers, while seasonal changes, as well as height and weight of the subjects seemed to cause some variations in the levels of HVA, dopamine-beta-hydroxylase (DBH) and ACTH. The study underscores the importance of standardized conditions and matched patient groups in the CSF studies.

A longitudinal study of cerebrospinal fluid beta-endorphin-like immunoreactivity in delirium: changes at the acute stage and at one-year follow-up

Cerebrospinal fluid beta-endorphin-like immunoreactivity (CSF BLI) was determined on 3 occasions for elderly delirious patients and the BLI levels were compared with age-equivalent controls. Delirious patients showed a significant reduction in the BLI values in the first sample and a declining trend was seen in the follow-up. The results suggest a role for beta-endorphinergic dysfunction in the genesis of some symptoms of delirium, and this dysfunction may be a common phenomenon in various forms of delirium and dementia.

Possible role of pineal melatonin in the mechanisms of aging

The pineal gland has captured man's attention as early in recorded history as the Greeks when philosophers considered it the "seat of the soul". Descartes, in the Middle Ages, furthered this concept naming it "esprits animaux" or, in current language, the psychic and somatic activating principle. These notions about the pineal gland were initially purely speculative and unsupported by scientific facts. However, with the development of a sound knowledge base concerning the pineal gland over the past twenty years, evidence has accumulated to suggest a pivotal role for the pineal in the 'fine tuning' and integrating of various neural and endocrine functions. The secretion of pineal melatonin has been shown to decline progressively with age. Recent hypotheses of aging have suggested that cumulative neuronal insults associated with free radical production may be associated with the process of aging. There is evidence to suggest that melatonin may protect against the age processes in part by attenuating the effects of free radical-induced neuronal damage. Other studies derived mainly from observations on pinealectomized rats also suggest that diminished melatonin secretion may be associated with acceleration of the aging process. Thus, pineal melatonin may be a natural anti-aging hormone.

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.

Mechanisms of action of ECT in Parkinson's disease: possible role of pineal melatonin

Recent clinical studies have suggested that electroconvulsive therapy (ECT) may be efficacious in the therapy of Parkinson's disease (PD). However, the mechanisms of action of ECT in PD are largely unknown. PD may be associated with reduction in the secretory activity of pineal melatonin, and the therapeutic efficacy of ECT in PD may be associated with an effect on the secretory activity of pineal melatonin. Further studies involving analysis of plasma melatonin levels and circadian release prior to and following ECT are needed more precisely to determine the role of pineal melatonin in PD and in the therapeutic efficacy of ETC in PD.

CSF beta-endorphin, HVA and 5-HIAA of dementia of the Alzheimer type and Binswanger's disease in the elderly

Cerebrospinal fluid (CSF) concentration of beta-endorphin (beta-Ep), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) was measured in 15 patients with dementia of the Alzheimer type (DAT) and in 16 patients suspected of having Binswanger's disease (BD) by MRI, which sometimes resembles DAT clinically. These were classified into three stages according to severity of dementia, Stage 1 (mild dementia)-Stage 3 (severe dementia). CSF levels of HVA decreased significantly in severe dementia, but the level of 5-HIAA did not correlate with dementia severity in both dementia groups. beta-Ep levels did not differ significantly between any stages of DAT, and among controls. beta-Ep levels, however, in BD Stage 1 (27.5 +/- 5.9 pg/ml) were significantly higher (p less than 0.05), but level in Stage 3 (6.7 +/- 2.0) was significantly lower (p less than 0.001) than in the controls (19.2 +/- 4.5). These results suggest that CSF beta-Ep may depend on the cause of dementia rather than severity of dementia, and could possibly distinguish the closely resembling BD from true DAT.

Reduced cerebrospinal fluid B-endorphin levels in Rett syndrome

Cerebrospinal fluid (CSF) levels of B-endorphin (B-EP), B-lipotropin (B-LPH) and ACTH were measured in nine girls with Rett syndrome with features of autistic behavior (3.7-12.1 years of age) and in ten children with chronic leukemia (control group). The peptides were measured by radioimmunoassay, either directly in the sample (ACTH) or after Sephadex G-75 column chromatography, in order to eliminate interfering substances (B-LPH and B-EP). The CSF B-EP patient levels (20.8 +/- 13.1 fmol/ml, means +/- SD) were significantly lower than in age-matched controls (69.1 +/- 32.6, P less than 0.01), whereas the B-LPH and ACTH levels were in the control range. No correlations were found between the clinical findings and CSF neuropeptide concentrations. These data demonstrate a decrease in central opiate activity in girls with Rett syndrome.

CSF beta-endorphin-like immunoreactivity in delirium

Cerebrospinal fluid beta-endorphin-like immunoreactivity (CSF BLI) was determined for 69 patients who met DSM-III criteria for delirium and for 8 controls. The CSF BLI was significantly lower in the delirious patient group than in the controls (12.5 +/- 3.0 pg/ml versus 15.0 +/- 3.4 pg/ml, p less than 0.05). CSF BLI had no correlation with age or neuroleptic drug dosage, but did have a significant positive correlation with cognitive functioning as evaluated by the Mini-Mental State. Our findings suggest a role for beta-endorphinergic dysfunction in the development of delirium.

High-dose naloxone in older normal subjects: implications for Alzheimer's disease

The behavioral and cognitive effects of naloxone HCl, in doses of 5 micrograms/kg, 0.1 mg/kg, and 2.0 mg/kg administered as an IV bolus, were assessed in a double-blind, placebo-controlled, randomized study of eight normal subjects ranging in age from 44 to 74 years (mean 63). Naloxone produced mild behavioral effects with slight cognitive impairment after the 2.0 mg/kg dose only. The threshold, dose dependency, characteristics, and magnitude of these behavioral effects were similar to what has previously been reported in young normal subjects, but markedly different from those observed in patients with dementia of the Alzheimer type (DAT) matched in age to the current study sample. These data suggest that the metabolic fate of naloxone is not substantially affected by age within the range studied. The findings of this study provide further support for a role for endogenous opiate systems in the modulation of behavior and cognition, and suggest that the unusual behavioral sensitivity of patients with DAT to naloxone cannot be accounted for by the effect of age.

Loss of the cortisol response to naltrexone in Alzheimer's disease

The administration of a single dose of the opiate antagonist naltrexone (NT) was accompanied by significant elevations in plasma cortisol in normal elderly subjects; in contrast, the cortisol response to NT was absent in individuals of comparable age with Alzheimer's disease (AD). The differential effect of AD on the cortisol response was not accompanied by a significant group difference in plasma prolactin in response to NT administration. Furthermore, this differential cortisol response to NT was not associated with any evident differences in age, sex ratio, plasma levels of naltrexone or its major metabolite beta-naltrexol, or with differences in measures of nonspecific stress, such as plasma free MHPG, pulse, or blood pressure, between the two groups. The absence of the well-characterized cortisol response to NT in AD, together with other reports of abnormal responses to other pharmacological challenges, suggests that neuroendocrine abnormalities might be an important concomitant and possibly a central contributor to the pathophysiology of Alzheimer's disease.

Detection of antigens in Alzheimer cerebrospinal fluid by monoclonal antibodies

Monoclonal antibodies raised against cerebrospinal fluid (CSF) and human ventral forebrain from patients with Alzheimer's disease were tested against CSF pools derived from patients with Alzheimer's disease and normal controls. Antibodies that appeared to distinguish the two pools were subsequently tested against 58 CSF samples from individual Alzheimer patients, normal controls, and individuals with other neurologic diseases. The mean CSF content of two antigens was decreased in patients with Alzheimer's disease compared with controls; the mean CSF content of one of these antigens was also decreased in patients with other neurologic diseases. Although group differences could be detected, the degree of overlap did not follow for the separation of individual patients within these three groups.

Beta endorphin levels in CSF during methadone maintenance

Recent studies have shown that plasma beta endorphin levels of patients on methadone maintenance are comparable to controls. Furthermore, CSF levels of related peptides in methadone patients also do not differ from controls, although CSF levels of beta endorphin have not been specifically measured. In the current study we compared both CSF and plasma levels of beta endorphin in 11 patients on methadone maintenance for at least 10 months to levels in 13 controls getting spinal anesthesia for surgery. The CSF beta endorphin levels of the methadone maintained patients were significantly higher than the controls (52.3 vs 21.7 pg/ml), while plasma levels of beta endorphin (29.6 vs 31.1 pg/ml) and cortisol (13.8 vs 12.6 micro g/dl) [corrected] did not differ. Covarying for age differences between the samples, slightly increased the magnitude of this difference in CSF beta endorphin levels. Plasma levels of beta endorphin did not correlate with CSF levels, but did correlate with plasma levels of cortisol (r = 0.51, P less than 0.02). These findings supported previous studies of plasma beta endorphin levels. However, the dissociation of beta endorphin levels in plasma and CSF within this patient population was a new finding.

The hypothalamus in Parkinson disease

It is currently believed that Parkinson disease (PD) is due to a degenerative process that independently damages multiple areas of the central and peripheral nervous system. Loss of nigrostriatal dopamine is now widely recognized as being directly related to the motor symptoms in Parkinson's disease. Parkinsonian patients also exhibit symptoms and signs suggestive of hypothalamic dysfunction (e.g. dysautonomia, impaired heat tolerance). The latter clinical features are supported by pathological, biochemical and endocrinological findings. Lewy body formation has been demonstrated in every nucleus of the hypothalamus, specifically the tuberomamillary and posterior hypothalamic. Preferential involvement of the hypothalamus was also noted in patients after post-encephalitic parkinsonism. Loss of dopamine (30-40%) in the hypothalamus of affected patients has been shown in recent studies, and is compatible with the reported abnormalities of growth hormone release in response to L-dopa administration, elevated plasma levels of MSH, and reduced CSF levels of somatostatin and beta-endorphins in these patients. Deranged immunological mechanisms have been found in PD patients including the presence of autoantibodies against sympathetic ganglia neurons, adrenal medulla and caudate nucleus. On the evidence of on pathological studies demonstrating the early vulnerability of the hypothalamus in aging and PD, and the known role of the hypothalamus in immune modulation, we expect that it will be shown that primary damage of the hypothalamus leads to subsequent secondary degeneration of structures receiving direct projections from the hypothalamus. Within this framework, the dopaminergic systems may be damaged, since striatal dopamine synthesis and receptor sensitivity have been shown to be regulated by ACTH and alpha-MSH through direct arcuate nucleus-striatal projections.(ABSTRACT TRUNCATED AT 250 WORDS)

CSF beta-endorphin and leu-enkephalin levels in the acute and chronic stages of cerebral infarction

To investigate the role of endogenous opioid peptides in the pathophysiology of cerebral ischaemia, the CSF levels of immunoreactive beta-endorphin and leu-enkephalin in 16 patients with cerebral infarction were measured. Both the CSF beta-endorphin and leu-enkephalin levels in the acute stage of cerebral infarction were significantly higher than the values in the chronic stage. The CSF concentrations of the two peptides revealed a positive correlation in the acute but not the chronic stage. The increased endogenous opioid peptides in the CSF in the acute stage may modify the evolution of cerebral infarction.

Reduction of elevated CSF beta-endorphin by fenfluramine in infantile autism

Fenfluramine therapy has been reported to improve behavior in infantile autism and has been associated with a decrease in abnormally increased blood serotonin content. The primary central effect has not been proved to be serotonergic. Beta-endorphin is involved in the anorexic effect of fenfluramine and may play a role in autism. Nine children with infantile autism were treated with fenfluramine in double-blind, placebo-crossover design. Transient anorexia was the only adverse effect. Autistic behavior was reported to improve in three patients, but objective psychometric tests were unchanged. Beta-endorphin-like immunoreactivity was determined in lumbar cerebrospinal fluid of patients during and before or after treatment with fenfluramine and then was compared to normal controls. Beta-endorphin was elevated significantly in the baseline autistic group (p less than .005) and was reduced toward control values during fenfluramine treatment. The results are consistent with a role for beta-endorphin in infantile autism and in the mechanism of fenfluramine treatment.

beta-Endorphin-like immunoreactivity in cerebrospinal fluid of patients with Alzheimer's disease and Parkinson's disease

beta-Endorphin-like immunoreactivity (beta-EP-LI) in cerebrospinal fluid (CSF) was measured in 42 patients with Alzheimer's disease (AD), 36 patients with Parkinson's disease (PD), and 35 controls. Values for patients with Alzheimer's disease (10.9 +/- 2.8 pmol/l) seemed to be lower than those for controls (12.9 +/- 2.5 pmol/l) (P less than 0.05). In addition, the severely demented patients had lower values than the moderately demented (P less than 0.01). In patients with Parkinson's disease no significant difference in beta-EP-LI values was observed compared to the controls. The data suggest, that processing of pro-opiomelanocortin, precursor of beta-endorphin, and the mechanism of cognitive impairment may differ in Alzheimer's disease and Parkinson's disease.

Neuropeptides in neurological disease

Neuropeptides are widely distributed in the central nervous system, where they serve as neuroregulators. Recent interest has focused on their role in degenerative neurological diseases. We describe the normal anatomy of neuropeptides in both the cerebral cortex and basal ganglia as a framework for interpreting neuropeptide alterations in Alzheimer's disease (AD), Huntington's disease, and Parkinson's disease. Concentrations of cortical somatostatin are reduced in AD and in dementia associated with Parkinson's disease. Concentrations of neuropeptide Y and corticotropin-releasing factor are also reduced in AD cerebral cortex. The reduced cortical concentrations of somatostatin and neuropeptide Y in AD cerebral cortex may reflect a loss of neurons or terminals in which these two peptides are co-localized. In Huntington's disease, basal ganglia neurons in which somatostatin and neuropeptide Y are co-localized are selectively preserved. Cerebrospinal fluid concentrations of neuropeptides in AD reflect alterations in cortical concentrations. Improved understanding of neuropeptides in degenerative neurological illnesses will help define which neuronal populations are specifically vulnerable to the pathological processes, and this could lead to improved therapy.

Antemortem laboratory diagnosis of Alzheimer's disease

The accuracy of diagnosis for AD by conventional clinical and laboratory means is in the order of 80%. Neurophysiological techniques (EEG, evoked potentials) show abnormalities in AD that could prove to be useful for diagnosis after pharmacological challenges. CSF analysis show a reduction of the concentration of various neuropeptides, reduction shared by other types of dementias. Among the existing imaging techniques PET using 18F-fluorodeoxyglucose is the most diagnostic in AD because of the early and often asymmetrical decrease in parietotemporal metabolic activity. Cortical biopsy with histological and biochemical analysis can provide an accurate in vivo diagnosis of AD.

Design and interpretation of opiate antagonist trials in dementia

In view of the reports of possible beneficial effects of naloxone in dementia, rationales and strategies for studying endogenous opiate systems are reviewed. Important considerations in the design and interpretation of clinical investigations using naloxone are also reviewed. The nature and distribution of endogenous opiate systems are summarized from an historical perspective. Endogenous opiate systems are distributed throughout the central nervous system and play important roles in a variety of brain functions, including memory and learning. In view of this, several rationales are evident for studying endogenous opiate systems in dementia, since it is a syndrome in which structures known to contain opiate systems are disturbed, functions modulated by opiate systems are disturbed, and other neurotransmitter systems (functionally linked to endogenous opiate systems) are disturbed. Different strategies for studying endogenous opiate systems are reviewed, including examination of body fluids and pharmacologic challenge studies. Naloxone hydrochloride, a competitive opiate receptor antagonist, is a commonly used pharmacologic agent. The design of a multidose naloxone study of 12 dementia patients is discussed, with reference to the pharmacokinetics, pharmacodynamics, and specificity of naloxone as well as to the nature of the dependent measures selected for this study. No cognitive benefit was observed in this study. Behavioral arousal was observed at naloxone doses, with more evident psychomotor retardation at higher doses. These findings are contrasted with the results of naloxone challenges in other studies. The varying effects of naloxone within and across populations can be conceptualized in terms of the basic and clinical considerations previously discussed. The importance of dose-finding studies is stressed for this and other drug trials.

Plasma endorphins in Rett syndrome: preliminary data

Plasma levels of beta-endorphin (beta-EP) and prolactin (PRL) were measured in 5 girls with Rett syndrome and in a control group before and after giving 10 mg metoclopramide i.v. beta-lipotropin (beta-LPH) was only measured in basal conditions. Basal values of beta-EP and beta-LPH were lower than in control individuals. The responses of plasma beta-EP to metoclopramide in Rett syndrome patients were less intense than in control individuals, while the PRL increase in girls with Rett syndrome was significantly higher than in control subjects. These preliminary data suggest a derangement of the dopaminergic system.

CSF neurotransmitter markers in Alzheimer's disease

CSF neurotransmitter markers may reflect neurochemical alterations in Alzheimer's disease (AD). The best studied neurochemical deficit in AD is that of acetylcholine. Both acetylcholinesterase and butyrylcholinesterase activity have been reported to be reduced in some but not all studies of AD CSF. Studies of monoamine metabolites have also been controversial but most authors have found reduced concentrations of CSF HVA, lesser reductions in HIAA and no change in MHPG. CSF GABA concentrations have been found to be reduced in AD. Studies of CSF neuropeptides in AD have shown reduced concentrations of somatostatin and vasopressin, normal concentrations of vasoactive intestinal polypeptide and either normal or decreased concentrations of beta-endorphin and corticotropin releasing factor. Although no individual CSF neurochemical markers are specific for AD it may be possible to develop a profile of several neurochemical markers which will have enhanced specificity.

Central ACTH deficit in degenerative and vascular dementia

Cerebrospinal fluid (CSF) concentrations of ACTH, beta-lipotropin (beta-LPH) and beta-endorphin (beta-EP) were measured in 15 patients affected by dementia, who underwent also a brain computerized tomography (CT), and in 13 age-matched healthy volunteers. ACTH CSF levels of patients (4.0 +/- 2.4 fmol/ml, M +/- SD) were significantly lower than in controls (9.8 +/- 5.0, P less than 0.01) the lowest values being found in Alzheimer type of dementia (ATD: 3.1 +/- 2.5) and in patients with radiological evidence of cortical atrophy (2.5 +/- 1.2), independently of the probable origin of dementia. Although beta-LPH and beta-EP levels of patients fell within normal range, they were lower in ATD than in dementia sustained on a vascular origin. There was no variation of either peptides concentration in relation to CT findings. These data indicate the ACTH impairment as typical of dementia, supporting in humans the positive role of this peptide on learning and mnesic functions. Moreover, the maintained CSF levels of both beta-LPH and beta-EP in the dementia sustained on a vascular origin, while lower values were found in ATD, could represent a differentiation between vascular and degenerative diseases of the Central Nervous System (CNS).

Endogenous opiates: 1983

This paper is the sixth in an annual series of reviews of research involving the endogenous opiates, each installment being restricted to work published during the previous year. Although the early articles in the series attempted to be comprehensive and cover the complete range of research with the opiate peptides, in the last two years we have limited our coverage to non-analgesic and behavioral work due to the enormous number of articles published in the field. The specific areas discussed here include stress, tolerance and dependence, consummatory responses, other gastrointestinal functions, interactions with alcohol, mental illness, learning and memory, cardiovascular responses, respiratory effects, thermoregulation, neurological disorders, activity, and miscellaneous other topics. As in previous years, we have attempted to present a relatively complete review of the subjects covered only for the previous year and generally have not tried to evaluate their contributions relative to those of past years.