A peptide-containing fraction in the urine of schizophrenic patients which stimulates opiate receptors and inhibits dopamine uptake

The Gut Microbiota and the Emergence of Autoimmunity: Relevance to Major Psychiatric Disorders

BACKGROUND

Autoimmune phenotypes are prevalent in major psychiatric disorders. Disequilibria of cellular processes occurring in the gastrointestinal (GI) tract likely contribute to immune dysfunction in psychiatric disorders. As the venue of a complex community of resident microbes, the gut in a homeostatic state equates with a functional digestive system, cellular barrier stability and properly regulated recognition of self and non-self antigens. When gut processes become disrupted as a result of environmental or genetic factors, autoimmunity may ensue.

METHODS

Here, we review the issues pertinent to autoimmunity and the microbiome in psychiatric disorders and show that many of the reported immune risk factors for the development of these brain disorders are in fact related and consistent with dysfunctions occurring in the gut. We review the few human microbiome studies that have been done in people with psychiatric disorders and supplement this information with mechanistic data gleaned from experimental rodent studies.

RESULTS

These investigations demonstrate changes in behavior and brain biochemistry directly attributable to alterations in the gut microbiome. We present a model by which autoantigens are produced by extrinsicallyderived food and microbial factors bound to intrinsic components of the gut including receptors present in the enteric nervous system.

CONCLUSION

This new focus on examining activities outside of the CNS for relevance to the etiology and pathophysiology of psychiatric disorders may require new modalities or a re-evaluation of pharmaceutical targets found in peripheral systems.

Autism and Schizophrenia: Intestinal Disorders

We examined Dohan's hypothesis that schizophrenia is associated with the absorption of "exorphins" contained in gluten and casein. In addition, because of the work of Reichelt et al. (Reichelt, K.L., Saelid, G., Lindback, J. and Orbeck, H. (1986) Biological Psychiatry 21:1279-1290) and Rodriguez et al. (Rodriguez, Trav, A.L., Barreiro Marin, R, Galvez, Borrero, I.M., del Olmo Romero-Nieva, F. and Diaz Alvarez, A. (1994) Journal of Nervous and Mental Disease Aug; 182(8): 478-479), we carried out similar studies on a group of children with autism. In both syndromes we found similar patterns of peptide containing peaks (Ninhydrin positive) after molecular screening with Sephadex G-15. Immunoglobulin assay of IgA and IgG against gliadin and casein in serum was done. High titer IgG antibodies to gliadin were found in 87% of autistic and 86% of schizophrenic patients and high titer IgG antibodies to bovine casein were found in 90% of autistic and in 93% of schizophrenic patients. High titer IgA antibodies to gluten or casein were found in 30% of children with autism while in schizophrenic patients 86% had elevated IgA antibodies to gluten and 67% to casein; some normal children and adults have these antibodies but only in trace amounts. When schizophrenic patients were treated with dialysis or a gluten-casein free diet, or both (Cade, R., Wagemaker, H., Privette, R.M., Fregly, M., Rogers, J. and Orlando, J. (1990) Psychiatry: A World Prespective 1: 494-500) peptiduria and Brief Psychiatric Rating Scores fell while abnormal behavior diminished. A gluten-casein free diet was accompanied by improvement in 81% of autistic children within 3 months in most of the behavior categories. Our data provide support for the proposal that many patients with schizophrenia or autism suffer due to absorption of exorphins formed in the intestine from incomplete digestion of gluten and casein.

A Peptide Found in Schizophrenia and Autism Causes Behavioral Changes in Rats

In a previous study we showed that β-casomorphin-7 (β-CM7) is taken up by brain regions relevant to schizophrenia and autism. The present experiment was designed to find whether β-CM7 has any behavioral or analgesic effects in rats. About 65 seconds after treatment with different doses of β-CM7, rats became restless and ran violently, with teeth chattering and with rapid respiration. Seven minutes later, the rats became inactive with less walking, distancing themselves from the other rat in the same cage, and sitting in, or putting their head against, the corner of the cage. The sound response was reduced and social interaction was absent. One hour later, the rats showed hyperdefensiveness. The above behavioral effects of β-CM7 did not occur when rats were pretreated with naloxone (2 mg/kg, IP). The rats receiving saline did not show any behavioral changes throughout the 2 hour period of observation. β-CM7 also demonstrated analgesic effects, which could be blocked by naloxone. The results suggest that β-CM7 may play a role in behavioral disorders such as autism and schizophrenia.

β-Casomorphin Induces Fos-Like Immunoreactivity in Discrete Brain Regions Relevant to Schizophrenia and Autism

The induction of Fos-like immunoreactivity (FLI) was used to determine the brain localization affected by b-casomorphin-7 (b-CM7). Peripheral administration of human b-CM7 at different doses (5, 10 and 30 mg/kg, IV for 1 hour) to rats induced moderate to strong FLI in discrete brain regions including the nucleus accumbens, caudate putamen, ventral tegmental and median raphe nucleus, and orbitofrontal, prefrontal, parietal, temporal, occipital and entorhinal cortex. All of the above areas have been shown to be altered either functionally or anatomically in patients with schizophrenia, and most have been shown to be functionally abnormal in autism. Some of these brain areas are originators or components of dopaminergic, serotoninergic and GABA-ergic pathways, suggesting that b-CM7 can affect the function of all of these systems. The role of some other affected areas in emotional and motivated behavior, social adaptation, hallucinations and delusions suggests that b-CM7, which was found in high concentration in the CSF, blood and urine of patients with either schizophrenia or autism, may be relevant to schizophrenia and autism. Induction of FLI in the above brain areas by a moderate dose (10 mg/kg) of b-CM7 was attenuated significantly, or blocked, by pretreatment with naloxone (2 mg/kg, IP). It is concluded that human b-CM7 can cross the blood-brain barrier, activate opioid receptors and affect brain regions similar to those affected by schizophrenia and autism.

Regulation of Pain Sensitivity in the Central Nervous System

Nociceptive information may be inhibited by stimulation of opiate receptors located presynaptically on primary afferent neurons. Sensory signals entering the spinal chord inhibit nociceptive signals by a non-opioid “gate” mechanism. Descending systems also modulate pain sensitivity at the spinal level. The descending 5-hydroxytryptamine (5-HT) system has a tonic inhibitory function, with diurnal fluctuations in intensity. The strong analgesic effects of electrical stimulation and morphine microinjections in certain brainstem structures is probably mediated by other descending systems. The ascending 5-HT system may influence the results of some complex tests for pain sensitivity by altering e.g. emotionality and habituation rate. Acupuncture analgesia involves opioid systems. In high frequency electroacupuncture and transcutaneous nerve stimulation, a non-opioid “gate” mechanism may predominate. Acute stress may produce analgesia by opioid as well as non-opioid mechanisms. The control of pain sensitivity is influenced by learning (e.g. biofeedback techniques and social factros), and may be affected in depression, mania and schizophrenia.

Bread and Other Edible Agents of Mental Disease

Perhaps because gastroenterology, immunology, toxicology, and the nutrition and agricultural sciences are outside of their competence and responsibility, psychologists and psychiatrists typically fail to appreciate the impact that food can have on their patients' condition. Here we attempt to help correct this situation by reviewing, in non-technical, plain English, how cereal grains-the world's most abundant food source-can affect human behavior and mental health. We present the implications for the psychological sciences of the findings that, in all of us, bread (1) makes the gut more permeable and can thus encourage the migration of food particles to sites where they are not expected, prompting the immune system to attack both these particles and brain-relevant substances that resemble them, and (2) releases opioid-like compounds, capable of causing mental derangement if they make it to the brain. A grain-free diet, although difficult to maintain (especially for those that need it the most), could improve the mental health of many and be a complete cure for others.

Behavioral effects of food-derived opioid-like peptides in rodents: Implications for schizophrenia?

Dohan proposed that an overload of dietary peptides, such as those derived from wheat gluten and milk casein, could be a factor relevant to the development or maintenance of schizophrenia (SZ) symptoms in at least a subset of vulnerable individuals. Rodent behavioral models may offer insight into the plausibility of Dohan's exorphin hypothesis by providing a means to directly study the effects of such peptides. Accordingly, a review of the literature on the behavioral effects of food-derived opioid-like peptides in rodents was undertaken. Studies using a variety of behavioral tests to examine the effects of several classes of food-derived opioid-like peptides were identified and reviewed. Peptides derived from casein (β-casomorphins; BCMs, n=19), spinach (rubiscolins; RCs, n=4), and soy (soymorphins; SMs, n=1) were behaviorally active in various paradigms assessing nociception, spontaneous behavior, and memory. Surprisingly, only a single study evaluating a gluten-derived peptide (gliadorphin-7; GD-7, n=1) was identified and included in this review. In conclusion, food-derived peptides can affect rodent behavior, but more studies of GDs using diverse behavioral batteries are warranted. Assuming they occur in sufficient quantities during protein digestion and can access central opioid receptors (which entails crossing both the gastrointestinal and blood-brain barriers intact), these peptides may affect human behavior. Although BCMs and GDs may not be directly pathogenic in SZ, documented associations of casein and gluten sensitivity with SZ justify increased patient screening and dietary intervention where necessary.

Peptides' role in autism with emphasis on exorphins

Problem

The nature of the peptides found increased in urine from autism needs verification of their structure, especially those that show opioid activity.

Methods

The peptides were separated on reverse phase C-18 HPLC in Trifluoroacetic acid–acetonitril gradients. Peaks eluting where synthetic opioids appear, and peaks that are common to most autistic children were analyzed by mass spectrometry and fragmentation pattern on a quadropole mass-spectrometer.

Results

We could demonstrate exorphins in the urine from autistic children, and their length varied from one patient to the next.

Conclusion

Exorphins are found in urine of autistic children and may account for their symptoms.

Towards a possible aetiology for depressions?

BACKGROUND

Since a genetic disposition for depression is probable, there ought to be biochemical changes. Increased peptide levels with relevant bioactivities have been found in urine in a previous investigation, which may be such changes.

METHODS

Urine from patients with severe depression according to ICD 10 have been run on reversed phase High Performance Liquid Chromatography, and off line mass spectrometry was performed on some of these peptides.

RESULTS

We find overlapping patterns of peptide peaks in severe depression, but with considerable individuality. Mass spectrometry shows that some of these peptides are probably of dietary origin, because their sequences are found only in certain dietary proteins. Opioids from casein and gliadin are typical examples.

CONCLUSION

Our data show that the disposition must be polygenetic because some peptide peaks with the same bioactivity are of different length in different patients, but with the same diagnosis. However, some of the peaks are common Peptide increase in urine is found when break down is deficient, and the data presented agree with reports on peptidase deficiencies in depression. Antidepressant drugs decrease the peptide level after about 3 weeks.

Can the pathophysiology of autism be explained by the nature of the discovered urine peptides?

Opioid peptides derived from food proteins (exorphins) have been found in urine of autistic patients. Based on the work of several groups, we try to show that exorphins and serotonin uptake stimulating factors may explain many of the signs and symptoms seen in autistic disorders. The individual symptoms ought to be explainable by the properties and behavioural effects of the found peptides. The data presented form the basis of an autism model, where we suggest that exorphins and serotonin uptake modulators are key mediators for the development of autism. This may be due to a genetically based peptidase deficiency in at least two or more peptidases and, or of peptidase regulating proteins made manifest by a dietary overload of exorphin precursors such as by increased gut uptake.

A randomised, controlled study of dietary intervention in autistic syndromes

Impaired social interaction, communication and imaginative skills characterize autistic syndromes. In these syndromes urinary peptide abnormalities, derived from gluten, gliadin, and casein, are reported. They reflect processes with opioid effect. The aim of this single blind study was to evaluate effect of gluten and casein-free diet for children with autistic syndromes and urinary peptide abnormalities. A randomly selected diet and control group with 10 children in each group participated. Observations and tests were done before and after a period of 1 year. The development for the group of children on diet was significantly better than for the controls.

Could schizophrenia be reasonably explained by Dohan's hypothesis on genetic interaction with a dietary peptide overload?

1. Dohan has proposed that schizophrenia is a genetic disposition which interacts with an overload of dietary proteins such as casein and gluten or gliadin. 2. A systematic attempt is made to see if this hypothesis is possible faced with aspects of schizophrenia that must be accounted for. 3. The authors conclusion is that it is possible, but more serious work in this field is urgently needed.

Peptide-containing fractions in depression

A mixture of peptides and glycoproteins has been found in benzoic acid-precipitable material from urines of psychomotorically agitated and retarded endogenous depressive patients. This complex mixture of compounds is fractionated on a Sephadex G-25 gel, from which the different peaks are further separated on Biogel P2. The G-25 elution profiles ultraviolet absorbance, 280 nm) from depressive patients deviated from the normal pattern. The increase in hydrolyzable ninhydrin-colorable material of the P2 fractionation step encountered in psychotic depression was several-fold that of the normal population. Neurochemically active peptide-containing fractions were found. As explanation of these findings, it is probable that a genetically determined peptidase insufficiency is present, causing a peptide overflow when the secretion outstrips the breakdown. This model could easily combine more psychodynamic models with the genetic-biological models. The variability of the peptide patterns could possibly reflect the considerable clinical variability of the syndrome. Furthermore, the presence of a group of active compounds with different neuropharmacological activities might reflect the composite nature of the depressive syndrome.

Changes in body temperature after administration of amino acids, peptides, dopamine, neuroleptics and related agents: II

This survey begins a second series of compilations of data regarding changes in body temperature induced by drugs and related agents. The information listed includes the species used, the route of administration and dose of drug, the environmental temperature at which experiments were performed, the number of tests, the direction and magnitude of change in body temperature and remarks on the presence of special conditions, such as age or brain lesions. Also indicated is the influence of other drugs, such as antagonists, on the response to the primary agent. Most of the papers were published since 1978, but data from many earlier papers are also tabulated.

Chromatographic profiles at E-280 nm for urinary precipitates in morbus Rett

Previously we have observed different characteristic chromatographic ultraviolet absorbancy profiles at 280 nm for urinary protein precipitates from patients with behavioral disorders. The purpose with this study was to look for similar changes in urinary protein excretion from the grossly disabled patients with the Rett syndrome. Benzoic acid precipitates from the urine from 20 patients were chromatographed on a Sephadex G-25 gel column. There appeared 3 different profiles: 6 as observed in normal controls, 5 like that in compulsive behavior, and 9 were similar to those observed for autistiform-schizophreniform patients. The profiles did not mirror the behavioral observations for the patients, although the first group of 6 patients were the least disabled, whereas the last 9 patients were the most seriously ill. In conclusion the chromatographic profiles suggest a heterogeneous group of patients, but we need more observations for several patients over time, as there may be a change with the exacerbation of the disease.

The isolation and characterization of an insulin-releasing tetrapeptide from urines of patients with lipoatrophic diabetes

The tetrapeptide pyroGlu-Glu-Asp-GlyOH and its gamma-amide have been isolated from the urines of lipodystrophic patients with insulin-resistant diabetes. Both peptides induce insulin release only at high blood glucose levels.

Transport and distribution of homocarnosine after intracerebroventricular and intravenous injection in the rat

Rats were injected intracerebroventricularly (i.c.v.) or i.v. with [14C]homocarnosine (250 nmol). Distribution of the dipeptide in brain structures, transport from the brain to the blood, distribution in peripheral organs, and excretion in the urine were studied by measuring radioactivity in tissue, plasma, and urine samples by liquid scintillation counting 15-120 min after injection. After i.c.v. injection, [14C]homocarnosine was taken up into all parts of the brain investigated (highest uptake in structures close to the site of injection), it was transported to the blood, and radioactive substances were found in low concentration in muscle, spleen, and liver, in high concentration in the kidneys, and very high concentration in the urine. Investigations using high pressure liquid chromatography (HPLC) showed that no degradation took place in the brain, all radioactivity was found in the homocarnosine fraction. In the plasma 86% of the radioactivity was found in the GABA fraction presumed to be formed by cleavage of the peptide.

Is schizophrenia an immunologic receptor disorder?

A model is proposed for an autoimmune etiology for schizophrenia. We propose that schizophrenia is a syndrome (not a disease). We suggest that autoantibodies (and/or cell-mediated immunity) directed against autologous neurotransmitter receptors are responsible for the ebb and flow of psychotic symptomatology. The hypothesis is predicated on autoimmune models in other known receptor diseases as well as on the newly emerging recognition that general immune dysfunction exists in certain schizophreniform psychoses.

Chromatographic analysis of urine and dialysate from schizophrenic patients undergoing hemodialysis

Maladjustments in the central nervous system may result in altered concentrations of neuropeptides in cerebrospinal fluid and urine. Urinary protein-peptide precipitates from psychiatric patients have previously been observed to have different chromatographic profiles with regard to the ultraviolet absorbancy at 280 nm. Hemodialysis has previously been reported to improve some schizophrenic patients and has been recommended in treatment trials. Seven chronic schizophrenic patients were selected for hemodialysis in a double-blind crossover study. Specimens of 24-h urine collections were obtained the day before, the day of, and the day after active and sham dialysis. The chromatographic profiles obtained on Sephadex G-25 gel columns did not change with active dialysis. Materials with ultraviolet absorbancy at 280 nm also precipitated from dialysates and showed the same pattern following active and inactive dialysis. Thus, no biochemical evidence for removal of any pathogenetic humoral substance during hemodialysis could be provided.

Research on mental retardation in Norway 1970-1980: a review

The present paper reviews most of the research on mental retardation in Norway, published in 1970-1980. An important part of this work is represented by Hole's reports of experimental phenylketonuria (PKU) in the rat and studies on peptides and protein-associated peptide complexes in mental disturbances, including experimental studies of effects on brain function and behavior of a peptide fraction (factor 3 b 2). Among studies on diseases with mental retardation, are determinations of arylsulphatase A in cultured amniotic fluid cells and in amniotic fluid as measures of prenatal diagnosis of metachromatic leukodystrophy, reports on screening disorders of tyrosine metabolism and the occurrence of positive dye test in blind children and patients with physical and mental handicaps. Further, studies on the effects of antiepileptics on immunoglobulins are reported. In the fields of social medicine, psychology and psychiatry, only few studies have been published in international journals. Brief reports on Norwegian articles comprise studies on work and disability, social and psychological handicaps in special school pupils, psychosis in mental retardation, and some efforts to design psychological treatment programs for the mentally retarded. The majority of research on mental retardation or with relevance to this field in Norway, has either been supported by the Norwegian Council for Research on Mental Retardation, or the Norwegian Research Council for Science and the Humanities. Based on annual reports of these councils, and correspondence to centers involved in such research, we have collected reports published in the period 1970 to 1980. We have also received unpublished reports, but have chosen not to include most of them in this review, because of the difficulties for the readers to obtain these reports. The institutional and noninstitutional services for the mentally retarded in Norway have no formal connection with university or other research institutes. Nevertheless, most of the research papers have been submitted from such institutes. Most of the reports traced are in the fields of basic neurobiology, medicine, and psychology, and will be dealt with under these headings.

A peptide-containing fraction of plasma from schizophrenic patients which binds to opiate receptors and induces hyper-reactivity in rats

A serum fraction from schizophrenic patients has been investigated for its effect on opiate receptor sites and on behaviour in rats. Serum from schizophrenic patients was ultrafiltered and fractionated on DEAE-Sephadex A-25. The concentration of peptide material eluting under 0.1 M HCl (fraction I) was further purified on Sephadex-G10 and four major peaks were identified (fractions II to V). When injected intracerebroventricularly in rats, fraction II produced a characteristic behavioural syndrome, which included hyperactivity associated with hyperemotionality. The effects were long lasting, bouts of hyperemotionality accompanied by analgesia were recorded over a two-week period. The same fraction from control non-patients produced a transient and much reduced, but qualitatively similar response. There was evidence that fraction III was also active. An in vitro opiate receptor binding test showed that fraction II from schizophrenic patients inhibited [3H]naloxone binding.

Clozapine inhibition of metenkephalin binding to synaptosome-enriched fractions of rat whole brain and hippocampus

Clozapine has been found to inhibit the binding of [3H]met-enkephalin to synaptosome-enriched fractions prepared from rat whole brain and hippocampus in a Tris-buffered media without added ions. The IC50 value for hippocampus is 28.5 microM. The inhibition constant for whole brain (41.0 microM) was found to be slightly larger than the corresponding value for chlorpromazine, which was measured under similar experimental conditions.