Secretin as a Satiation Whisperer With the Potential to Turn into an Obesity-curbing Knight

The obesity pandemic requires effective preventative and therapeutic intervention strategies. Successful and sustained obesity treatment is currently limited to bariatric surgery. Modulating the release of gut hormones is considered promising to mimic bariatric surgery with its beneficial effects on food intake, body weight, and blood glucose levels. The gut peptide secretin was the first molecule to be termed a hormone; nevertheless, only recently has it been established as a legitimate anorexigenic peptide. In contrast to gut hormones that crosstalk with the brain either directly or by afferent neuronal projections, secretin mediates meal-associated brown fat thermogenesis to induce meal termination, thereby qualifying this physiological mechanism as an attractive, peripheral target for the treatment of obesity. In this perspective, it is of pivotal interest to deepen our as yet superficial knowledge on the physiological roles of secretin as well as meal-associated thermogenesis in energy balance and body weight regulation. Of note, the emerging differences between meal-associated thermogenesis and cold-induced thermogenesis must be taken into account. In fact, there is no correlation between these 2 entities. In addition, the investigation of potential effects of secretin in hedonic-driven food intake, bariatric surgery and chronic treatment using suitable application strategies to overcome pharmacokinetic limitations will provide further insight into its potential to influence energy balance. The aim of this article is to review the facts on secretin's metabolic effects, address prevailing gaps in our knowledge, and provide an overview on the opportunities and challenges of the therapeutic potential of secretin in body weight control.

Pleiotropic Effects of Secretin: A Potential Drug Candidate in the Treatment of Obesity?

Secretin is the first hormone that has been discovered, inaugurating the era and the field of endocrinology. Despite the initial focus, the interest in its actions faded away over the decades. However, there is mounting evidence regarding the pleiotropic beneficial effects of secretin on whole-body homeostasis. In this review, we discuss the evidence from preclinical and clinical studies based on which secretin may have a role in the treatment of obesity.

Randomized controlled trial of transdermal secretin on behavior of children with autism

Previous trials of secretin for the treatment of autism have utilized a single or double dose administered intravenously. This is a report of a double-blind, randomized, controlled crossover trial of transdermally applied secretin in 15 children diagnosed with autism or pervasive developmental delay. Secretin or placebo was applied daily, in ointment form, to the backs of the children in randomized, successive 4 week periods with an intermediate 6 week washout period. Behavioral outcomes were measured by parents and teachers using the Autism Treatment Evaluation Checklist. Overall, there were no statistically significant differences in speech, sociability, sensory, and health scores for treatment versus placebo periods. In addition, there were no differences in such scores for children with a history of diarrhea. Severity of autism was significantly greater at baseline in children receiving concomitant medications. Improvement in speech was found during the treatment phase of the trial ( p = 0.0479 for secretin versus placebo) only in children not using other medications.

Intranasal application of secretin, similarly to intracerebroventricular administration, influences the motor behavior of mice probably through specific receptors

Secretin and its receptors show wide distribution in the central nervous system. It was demonstrated previously that intravenous (i.v.) and intracerebroventricular (i.c.v.) application of secretin influenced the behavior of rat, mouse, and human. In our previous experiment, we used a special animal model, Japanese waltzing mice (JWM). These animals run around without stopping (the ambulation distance is very limited) and they do not bother with their environment. The i.c.v. secretin attenuated this hyperactive repetitive movement. In the present work, the effect of i.c.v. and intranasal (i.n.) application of secretin was compared. We have also looked for the presence of secretin receptors in the brain structures related to motor functions. Two micrograms of i.c.v. secretin improved the horizontal movement of JWM, enhancing the ambulation distance. It was nearly threefold higher in treated than in control animals. The i.n. application of secretin to the left nostril once or twice a day or once for 3 days more effectively enhanced the ambulation distance than i.c.v. administration. When secretin was given twice a day for 3 days it had no effect. Secretin did not improve the explorative behavior (the rearing), of JWM. With the use of in situ hybridization, we have found very dense secretin receptor labeling in the cerebellum. In the primary motor cortex and in the striatum, only a few labeled cells were seen. It was supposed that secretin exerted its effect through specific receptors, mainly present in the cerebellum.

Autism

INTRODUCTION

Evidence for the efficacy of treatments for autism has improved in recent years. In this systematic review the evidence for both drug and non-drug treatments is appraised and clinical guidance is provided for their use.

METHODS AND OUTCOMES

We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of early intensive multidisciplinary intervention programmes in children with autism? What are the effects of dietary interventions in children with autism? What are the effects of drug treatments in children with autism? What are the effects of non-drug treatments in children with autism? We searched: Medline, Embase, The Cochrane Library, and other important databases up to May 2009 (Clinical evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

RESULTS

We found 30 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.

CONCLUSIONS

In this systematic review we present information relating to the effectiveness and safety of the following interventions: applied behavioural analysis; auditory integration training; Autism Preschool Programme; casein-free diet; chelation; Child's Talk programme; cognitive behavioural therapy; digestive enzymes; EarlyBird programme; facilitated communication; Floortime therapy; gluten-free diet; immunoglobulins; melatonin; memantine; methylphenidate; More Than Words programme; music therapy; olanzapine; omega-3 fish oil; picture exchange communication system; Portage scheme; probiotics; relationship development interventions; risperidone; secretin; selective serotonin reuptake inhibitors (SSRIs); sensory integration training; social stories; social skills training; Son-Rise programme; TEACCH; vitamin A; vitamin B6 (pyridoxine) plus magnesium; and vitamin C.

Relationship of dietary intake to gastrointestinal symptoms in children with autistic spectrum disorders

BACKGROUND

Gastrointestinal (GI) symptoms and abnormalities in stool consistency are frequently reported by parents of children with autism spectrum disorders (ASD). The purpose of this study was to 1) describe dietary intake of a cohort of children with ASD compared with normative data and 2) determine whether GI symptoms and stool consistency are related to dietary intake.

METHODS

Data from diet diaries of children (3-8 years) with ASD (n = 62) were analyzed by a registered pediatric dietician to compare to RDA standards for total calories, protein, carbohydrate, and fat. Dietary intake was correlated with descriptors of stool consistency using cumulative logistic regression methods.

RESULTS

Intake of calories, carbohydrates, and fat were in the average range; protein intake was increased (211% of RDA). Reported frequency of GI abnormalities, including abnormal stool consistency (e.g., bulky or loose), was increased (54%). No statistically significant relationships between stool consistency and dietary intake were observed.

CONCLUSIONS

In this sample, there was a high rate of reported gastrointestinal symptoms, despite lack of medical causes. Intake was adequate for calories and carbohydrates and increased for protein. The children did not exhibit excessive carbohydrate intake. There was no association of nutrient intake to changes in stool consistency.

A case of secretin-responsive insulinoma with low serum C-peptide levels

Insulinoma is the most common cause of fasting hypoglycemia resulting from autonomous insulin hypersecretion. A 59-year-old woman who had previously had an insulinoma and had undergone a partial pancreatectomy was admitted to our hospital because of recurrence of hypoglycemia after 27 years. She had two unusual endocrinological features: 1) the serum insulin response to intravenous secretin injection was not impaired, and 2) the serum C-peptide levels and ratios of serum C-peptide to insulin were relatively low. Two pancreatic tumors were readily detectable by computed tomography (CT) and magnetic resonance imaging (MRI). The selective arterial calcium injection (SACI) test showed a hyperinsulinemic response by calcium administration to the gastroduodenal artery. A partial pancreatectomy was done and her hypoglycemia disappeared. Histology revealed that the tumors were composed of monotonous, small round cells that were positive for both insulin and cathepsin B. As previous in vitro studies have shown that C-peptide can be metabolized within human insulinoma cells by proteolytic cleavage by cathepsin B, our patient's low serum C-peptide levels might have been caused by degradation of C-peptide by cathepsin B. According to the data from the literature, the molar ratio of serum C-peptide to insulin is generally decreased in patients with insulinoma than normal subjects. This case highlights the need for careful interpretation of C-peptide levels and the intravenous secretin injection test in the diagnosis of insulinoma.

Secretin: A Pleiotrophic Hormone

Secretin holds a unique place in the history of endocrinology and gastrointestinal physiology, as it is the first peptide designated as a hormone. During the last century since its first discovery, the hormonal effects of secretin in the gastrointestinal tract were extensively studied, and its principal role in the periphery was found to stimulate exocrine secretion from the pancreas. Recently, a functional role of secretin in the brain has also been substantiated, with evidence suggesting a possible role of secretin in embryonic brain development. Given that secretin and its receptors are widely expressed in multiple tissues, this peptide should therefore exhibit pleiotrophic functions throughout the body. The present article reviews the current knowledge on the central and peripheral effects of secretin as well as its therapeutic uses.

Intravenous secretin for autism spectrum disorder

BACKGROUND

Secretin is a gastro-intestinal hormone which has been presented as an effective treatment for autism based on anecdotal evidence.

OBJECTIVES

To determine if intravenous secretin:1. improves the core features of autism (social interaction, communication and behaviour problems); 2. improves the non-core aspects of behaviour or function such as self injurious behaviour;3. improves the quality of life of affected individuals and their carers; 4. has short term and long term effects on outcome; 5. causes harm.

SEARCH STRATEGY

Results of electronic searches of CENTRAL, MEDLINE, EMBASE, PsycINFO, CINAHL, ERIC, HealthStar and Sociofile (1998 - March 2005) were independently examined by two authors. Reference lists of trials and reviews were searched; experts and trialists were contacted to find unpublished studies.

SELECTION CRITERIA

Randomised controlled trials of intravenous secretin comparing secretin with a placebo treatment in children or adults diagnosed with autism spectrum disorders, where at least one standardised outcome measure was reported.

DATA COLLECTION AND ANALYSIS

Fourteen studies met inclusion criteria. All outcome data were continuous. Where trials used cross-over designs, analysis was conducted on results from first treatment phase, allowing combined analysis with parallel design trials. Where standardised assessment tools generated scores as outcome measures, comparisons were made between means of these scores. Where baseline means were reported, differences between treatment and control were determined to assess possible bias. Where mean change from baseline was reported, this was used in preference to post-treatment scores for meta-analyses or forest plots. As meta-analysis was possible for only one outcome (Childhood Autism Rating Scale), it was impossible to use sensitivity or subgroup analyses to assess impact of study quality, clinical differences in the intervention, or clinically relevant differences between groups, such as age or presence of gastrointestinal symptoms.

MAIN RESULTS

Twenty-five established standardised outcome measures were reported to assess core features of autism, communication, behaviour, visio-spatial skills, affect and adverse events within fourteen included studies. No more than four studies used any one outcome measure similarly. Outcomes were reported between three and six weeks. RCTs of efficacy of secretin in autism have not shown improvements for core features of autism.

AUTHORS' CONCLUSIONS

There is no evidence that single or multiple dose intravenous secretin is effective and as such it should not currently be recommended or administered as a treatment for autism. Further experimental assessment of secretin's effectiveness for autism can only be justified if methodological problems of existing research can be overcome.

Partial reversal of phencyclidine-induced impairment of prepulse inhibition by secretin

BACKGROUND

Secretin is a "gut-brain" peptide whose neural function is as yet poorly understood. Several clinical studies have reported modestly increased social interaction in autistic children following intravenous secretin administration. Very recently secretin also was administered to schizophrenic patients and found to increase social interaction in some individuals.

METHODS

In light of this finding, we assessed the ability of secretin to reverse phencyclidine- (PCP) induced impairment in prepulse inhibition (PPI), a leading animal model of sensorimotor gating deficits in schizophrenia.

RESULTS

Similar to atypical antipsychotics, secretin (1, 3, 10, 30, and 100 microg/kg) partially and dose-dependently reversed the PCP-induced deficit in PPI without significantly affecting baseline startle when administered intraperitoneally (IP) 10 minutes following IP administration of PCP (3 mg/kg).

CONCLUSIONS

This finding may be relevant to observations of antipsychotic efficacy of secretin in schizophrenic patients as well as our previous report that systemically administered secretin is capable of modulating conditioned fear, even at quite low doses.

The [pre-] history of the incretin concept

The discoverers of secretin already thought of the existence of a chemical excitant for the internal secretion of the pancreas. Numerous experiments have been performed and published between 1906 and 1935 testing the effect of injected or ingested duodenal ("secretin") extracts on fasting or elevated blood glucose levels of normal or diabetic animals and humans with contradictory results. In 1940, after a series of negative dog experiments performed by an opinion leader, the existence of an incretin was considered questionable and further research stopped for more than 20 years. However, after the development of the radio-immunoassay, the incretin-concept has been revived in 1964, showing that significantly more insulin was released after ingestion of glucose than after intravenous injection. The possibility that nerves or one of the known gut hormones were responsible for the incretin effect could be ruled out. In 1970, glucose dependent insulinotropic polypeptide (GIP), and finally, in 1985 glucagon-like peptide 1 (GLP-1) and its truncated form GLP-1(7-36) were recognized as true incretins. Thereafter, multiple antidiabetic qualities and the therapeutic perspectives of GLP-1(7-36) and its analogues and mimetics have been demonstratred.

The effectiveness of secretin in the management of autism

Autism is a complex neurological disorder that severely impacts a child's ability to communicate and interact socially. Many treatments have attempted to alleviate the symptoms of autism, but with limited success. After reports of improvements in autistic children who received secretin, this hormone became popular as a possible treatment for autism. Since then, the interest in secretin has greatly increased, as well as the demand for secretin by parents of autistic children. However, there is still limited experimental evidence that supports its effectiveness. Many biological studies and clinical trials were conducted to test the effectiveness of secretin in treating autism. This review discusses the autistic disorder, instruments used in the trials, and reports the findings of some of these studies.

Novel treatments for autistic spectrum disorders

In no area of developmental pediatric practice is there more controversy regarding the choice of treatment than related to children with autistic spectrum disorders (ASD). Complementary and alternative medical therapies (CAM) are often elected because they are perceived as treating the cause of symptoms rather than the symptoms themselves. CAM used for autism can be divided by proposed mechanism: immune modulation, gastrointestinal, supplements that affect neurotransmitter function, and nonbiologic intervention. Secretin as a therapy for autism is discussed as an example of how a clinical observation rapidly grew to a widespread treatment before well-designed studies demonstrated absence of effect. The plausibility for behavioral effect was not substantiated by clinical studies. CAM used for treatment of autism is examined in terms of rationale, evidence of efficacy, side effects, and additional commentary. Families and clinicians need access to well-designed clinical evidence to assist them in choice of therapies.

Secretin is an ineffective treatment for pervasive developmental disabilities: a review of 15 double-blind randomized controlled trials

In 1998, Horvath et al. [Horvath, K., Stefanatos, G., Sokolski, K. N., Wachtel, R., Nabors, L., & Tildon, J. T. (1998). Improved social and language skills after secretin administration in patients with autism spectrum disorders. Journal of the Association of the Academy of Minority Physicians, 9, 9-15] reported an uncontrolled trial of secretin with three participants with autism, which apparently resulted in significant behavioral improvement. Subsequently, secretin was widely used. Sandler et al. [Sandler, A. D., Sutton, K. A., SeWeese, J., Girardi, M. A., Sheppard, V., & Bodfish, J. W. (1999). Lack of benefit of a single dose of synthetic human secretin in the treatment of autism and pervasive and developmental disorder. The New England Journal of Medicine, 341, 1801-1806] reported the first double-blind trial of secretin with negative results. This article is a review of 15 double-blind trials of secretin. Almost none of the studies reported any significant effects and none concluded that secretin was effective. Transient effects of secretin, including both minor benefits and behavioral deterioration were reported, probably due to multiple statistical tests. Four papers reported data on differential responding in sub-groups of participants, including those with gastrointestinal symptoms. These effects were not replicable. At this time there is no robust evidence that secretin is an effective treatment for pervasive developmental disorders.

Secretin as a Treatment for Autism: A Review of the Evidence

Secretin is used in the United States for diagnosis of pancreatic gastrointestinal (GI) dysfunction and disease. Repeated therapeutic use has not been approved. Widespread interest in secretin as a treatment for autism followed media reports of behavioral improvements in an autistic child who received the hormone during a GI diagnostic procedure. International demand for secretin soared in the absence of experimental evidence of its efficacy for autism. This review presents a brief history of secretin's rise to popularity and summarizes research on secretin as a treatment for autism. Seventeen studies are reviewed comparing the effects of secretin forms, dosage levels, and dosing intervals on outcome measures with approximately 600 children. Twelve of 13 placebo-controlled studies failed to demonstrate the differential efficacy of secretin. Implications for advocating treatment in the absence of empirical evidence are discussed.

[Efficacy of secretin for the treatment of autism]

We administered secretin intravenously to 14 patients with autism (9 to 14 years, 10 males; 4 females), and evaluated its clinical effect. We also measured cerebrospinal fluid (CSF) levels of homovanillic acid (HVA) and 5-hydroxy-indole-3-acetic acid (5HIAA) before and after 4 weeks treatment, and compared them with the grade of improvement of the clinical symptoms assessed by the scores of Autism Diagnostic Interview-Revised (ADI-R). After injection of secretin, the ADI-R score increased in 8 patients, but declined in 3. Improvement was observed in functions such as sociability (interpersonal relationships), communication and speech improved, whereas in the others. symptoms such as hyperkinesias and stereotyped behavior became worse. The CSF levels of HVA was significantly increased in all of the patients showing an improvement in the ADI-R score. SHIAA levels also tended to increase, although this increase was not significant. These findings suggest that secretin promotes the metabolism of serotonin and dopamine in the central nervous system, which may contribute to improvement in clinical symptoms of autism.

Passage of VIP/PACAP/secretin family across the blood-brain barrier: therapeutic effects

In recent years, VIP/PACAP/secretin family has special interest. Family members are vasoactive intestinal peptide (VIP), pituitary adenylate cyclase-activating polypeptide (PACAP), secretin, glucagon, glucagon like peptide-1 (GLP(1)), GLP(2), gastric inhibitory peptide (GIP), growth hormone releasing hormone (GHRH or GRF), and peptide histidine methionine (PHM). Most of the family members present both in central nervous system (CNS) and in various peripheral tissues. The family members that are released into blood from periphery, especially gut, circulate the brain and they can cross the blood brain barrier. On the other hand, some of the members of this family that present in the brain, can cross from brain to blood and reach the peripheral targets. VIP, secretin, GLP(1), and PACAP 27 are transported into the brain by transmembrane diffusion, a non-saturable mechanism. However, uptake of PACAP 38 into the brain is saturable mechanism. While there is no report for the passage of GIP, GLP(2), and PHM, there is only one report that shows, glucagon and GHRH can cross the BBB. The passage of VIP/PACAP/secretin family members opens up new horizon for understanding of CNS effects of peripherally administrated peptides. There is much hope that those peptides may prove to be useful in the treatment of serious neurological diseases such as Alzheimer's disease, amyotropic lateral sclerosis, Parkinson's disease, AIDS related neuropathy, diabetic neuropathy, autism, stroke and nerve injury. Their benefits in various pathophysiologic conditions undoubtly motivate the development of a novel drug design for future therapeutics.

Secretin in a patient with treatment-resistant schizophrenia and prominent autistic features

Secretin, a gastrointestinal (GI) peptide, may offer therapeutic benefit in autism. Autistic features can also be present in schizophrenia and a recent study suggested a role for adjunctive secretin in treatment-resistant schizophrenia. The current report describes one patient with undifferentiated schizophrenia and prominent autistic features who received a single dose of secretin and demonstrated substantial yet transient improvement. The case illustrates the potential role of secretin as a novel adjunctive treatment strategy in schizophrenic patients with autistic features.

Secretin for refractory schizophrenia

In preliminary uncontrolled studies, intravenous injection of the gastrointestinal peptide secretin produced improvements in the symptoms of autism. Because of the phenotypic overlap between autism and some aspects of schizophrenia, we performed a pilot study of secretin for treatment refractory schizophrenia. Twenty-two patients were randomized to a single intravenous dose of porcine secretin or placebo. Patients were evaluated with the Positive and Negative Symptom Scale for Schizophrenia (PANSS) and the Clinical Global Impression Scale (CGI) at baseline, 2 days after secretin infusion and weekly for 4 weeks. There were no statistically significant differences between drug- and placebo-treated patients with repeated measures analysis of variance (ANOVA). However, several patients treated with secretin experienced clinically meaningful, but transient, reductions in symptoms and a greater percentage of patients treated with secretin were rated as improved with the CGI. Further study of brain hypocretins and molecules affecting this system are warranted in schizophrenia.

Use of complementary and alternative treatments for children with autistic spectrum disorders is increasing

Interventions considered to be CAM are in constant flux. New treatments emerge, older treatments become less popular, and the cycle recurs. Data supporting new treatments should be scrutinized for scientific study design, clinical safety, and scientific validity. Many families approach the clinician armed with brochures, handouts, and printouts from Web sites that are dedicated to the care and support of parents and children with ASD. A recent web search using "autism and detoxification" resulted in almost 8,000 sites. The Defeat Autism Now! (DAN!) Project arose in 1995 from collaboration of members of the Autism Research Institute. The DAN! Project advocates a specific and extensive protocol for diagnosis and treatment and can be viewed at http://www.autism.com/ari/#dan. The scientific validation and support for many interventions is incomplete and disparate from the recommendation in the American Academy of Pediatrics Policy Statement. Families should be encouraged to discuss all proposed investigations or treatments they wish to try with their primary care provider so the practitioner can serve as the medical home (Sidebar, page 688). The clinician should communicate and collaborate with the family and educational professionals to encourage objective identification of what works. With increasing access to health information and societal pressure for families to actively participate in their health management, continued growth of interest in CAM can be anticipated. Clinicians must remember that parents may have different beliefs regarding the effectiveness of treatment and different tolerance for treatment risks. Practitioners must keep avenues of communication open, remain open-minded, and not assume a "don't ask, don't tell" posture in the context of providing a medical home to the increasing number of children diagnosed with autism.

Children with autistic spectrum disorders. II: parents are unable to distinguish secretin from placebo under double-blind conditions

BACKGROUND

Standardised measures of behaviour have failed to detect short term improvement in children with autism following treatment with secretin. However, it is possible that standardised measures are insensitive to dimensions of child behaviour that are nonetheless detectable by parents.

AIM

To determine the ability of parents of children with autism to guess, under double blind conditions, whether their child had received secretin or placebo.

METHODS

2x2 crossover randomised blinded study, comparing the effect of synthetic human secretin 2 U/kg to placebo (saline). Sixty two children with autism (aged 43-103 months) were randomly allocated to two groups: group 1 received placebo, followed six weeks later by secretin, and group 2 received secretin followed by placebo. At the conclusion of the study, parents were asked to guess their child's group assignment.

RESULTS

Twenty seven families guessed their child's group assignment correctly and 27 guessed incorrectly. In 48 instances, parents based their guess on perceived improvement; in six cases, parents based their guess on perceived deterioration. Six families saw no difference after either infusion, and offered no guess. One family dropped out after the first infusion, and one family was lost to follow up after the second infusion.

CONCLUSION

In a controlled setting, parents of young children with autism are unable to distinguish the short term behavioural effects of secretin from placebo.

Children with autistic spectrum disorders. I: comparison of placebo and single dose of human synthetic secretin

AIMS

To examine the effect of a single dose of human synthetic secretin (HSS) on behaviour and communication in children with autism spectrum disorder (ASD) using an objective measure of communication and social reciprocity and standardised rating scales.

METHODS

Randomised, crossover, double blind, and placebo controlled trial of a single intravenous dose of human synthetic secretin (HSS) 2 CU/kg. The 62 subjects (3-8 years) were assigned to group 1 (saline placebo/HSS) or group 2 (HSS/saline placebo). Diagnosis was confirmed by ADI-R (Autism Diagnostic Interview-Revised) algorithm. Severity of symptoms was rated using the CARS (Childhood Autism Rating Scale). Outcome measures included Communication and Symbolic Behavior Scale (CSBS), Ritvo Real-life Rating Scale, weekly Global Rating Scale (GBRS) by parents and teachers, and daily log of gastrointestinal symptoms. The communication subscale of the CSBS, specifying communication function, reciprocity, and social-affective signalling was videotaped and scored by a blinded, trained observer.

RESULTS

Sixty one children completed the study. After randomisation, there were no significant differences in gender, race, age, and parent and teacher GBRS and Ritvo Scale between the two groups. Compared with placebo, secretin treatment was not associated with significant improvement of CSBS standard scores from baseline to 2 or 4 weeks post-infusion. Five children showed clinical improvement in standard scores: two after HSS and three after placebo. There were no significant changes in gastrointestinal symptoms after HSS or saline placebo.

CONCLUSIONS

A single dose of intravenous human secretin is not effective in changing behaviour and communication in children with ASD when compared to placebo.

A new synthetic porcine secretin for facilitation of cannulation of the dorsal pancreatic duct at ERCP in patients with pancreas divisum: a multicenter, randomized, double-blind comparative study

BACKGROUND

Secretin, a 27 amino acid polypeptide released in response to duodenal luminal acidification, stimulates secretion of water and bicarbonate from pancreatic ductal cells. To date the only secretin available for clinical use has been a biologically derived compound extracted from porcine duodenums. Although used to facilitate pancreatic duct cannulation, secretin has not been approved for this indication. In this study, a new synthetic porcine secretin with an identical amino acid composition was compared with saline solution for the facilitation of minor papilla cannulation in patients with pancreas divisum.

METHODS

A multicenter, prospective, randomized, placebo-controlled, double-blind, comparative trial was conducted at 4 centers with expertise in pancreaticobiliary endoscopy. Patients with pancreas divisum in whom minor papilla cannulation initially was unsuccessful were enrolled. Either saline solution (placebo) or synthetic porcine secretin was administered. If the minor papilla orifice and/or pancreatic juice flow was noted, cannulation was attempted and success or failure was documented (phase 1), as well as the time taken for successful cannulation. If cannulation was unsuccessful, no juice flow was noted, or the orifice was not seen, the alternate agent was administered (phase 2).

RESULTS

Twenty-nine patients (7 men, 22 women; mean age 51 years, range 21-76 years) were enrolled. In phase 1, cannulation was achieved in 1 of 13 patients (7.7%) after the placebo was given and in 13 of 16 patients (81.3%) after synthetic porcine secretin was given (p < 0.0001). In phase 2, cannulation was achieved in 12 of 12 patients (100%) after synthetic porcine secretin was given and in 0 of 3 patients (0%) after the placebo was given (p = 0.0022). Overall, cannulation was successful in 25 of 28 patients (89.3%) who received synthetic porcine secretin and in 1 of 16 (6.3%) who received the placebo (p < 0.0001). Mean time to cannulation was significantly greater for the placebo than for the synthetic porcine secretin (4.75 min vs. 2.63 min; p = 0.0001). No adverse events directly attributable to synthetic porcine secretin administration were documented.

CONCLUSIONS

This study confirmed the use and safety of synthetic porcine secretin in facilitating cannulation of the minor papilla in patients with pancreas divisum in whom cannulation was difficult. Use of this agent has the potential to further increase the cannulation success rate in this group of patients.

Multiple doses of secretin in the treatment of autism: a controlled study

Dramatic effects on autistic behaviour after repeated injections of the gastrointestinal hormone secretin have been referred in a number of case reports. In the absence of curative and effective treatments for this disabling condition, this information has created new hope among parents. Although controlled studies on the effect of mainly one single dose have not documented any effect, many children still continue to receive secretin. Six children enrolled in a double-blind, placebo-controlled crossover study in which each child was its own control. Human synthetic secretin, mean dose 3.4 clinical units, and placebo were administered intravenously in randomized order every 4th wk, on three occasions each. The measurement instruments were the visual analogue scale (VAS) and the aberrant behaviour checklist (ABC). Statistically significant differences were found for placebo in 3 out of 6 children and for secretin in one child, using parental ratings only (VAS scores). Differences were small and lacked clinical significance, which was in accordance with the overall impression of the parents and teachers and visual inspection of graphs.

CONCLUSION

In this placebo-controlled study, multiple doses of secretin did not produce any symptomatic improvement.

RG-1068 RepliGen

RG-1068 is a synthetic form of the natural human hormone secretin under development by RepliGen for the potential treatment of autism. RG-1068 received Fast Track designation for the treatment of pediatric autism in September 2001, and in February 2002, it entered phase III clinical trials.

Autism, an extreme challenge to integrative medicine. Part 2: medical management

Autism and allied autistic spectrum disorders (ASD) present myriad behavioral, clinical, and biochemical abnormalities. Parental participation, advanced testing protocols, and eclectic treatment strategies have driven progress toward cure. Behavioral modification and structured education are beneficial but insufficient. Dietary restrictions, including removal of milk and other casein dairy products, wheat and other gluten sources, sugar, chocolate, preservatives, and food coloring are beneficial and prerequisite to benefit from other interventions. Individualized IgG or IgE testing can identify other troublesome foods but not non-immune mediated food sensitivities. Gastrointestinal improvement rests on controlling Candida and other parasites, and using probiotic bacteria and nutrients to correct dysbiosis and decrease gut permeability. Detoxification of mercury and other heavy metals by DMSA/DMPS chelation can have marked benefit. Documented sulfoxidation-sulfation inadequacies call for sulfur-sulfhydryl repletion and other liver p450 support. Many nutrient supplements are beneficial and well tolerated, including dimethylglycine (DMG) and a combination of pyridoxine (vitamin B6) and magnesium, both of which benefit roughly half of ASD cases. Vitamins A, B3, C, and folic acid; the minerals calcium and zinc; cod liver oil; and digestive enzymes, all offer benefit. Secretin, a triggering factor for digestion, is presently under investigation. Immune therapies (pentoxifyllin, intravenous immunoglobulin, transfer factor, and colostrum) benefit selected cases. Long-chain omega-3 fatty acids offer great promise. Current pharmaceuticals fail to benefit the primary symptoms and can have marked adverse effects. Individualized, in-depth clinical and laboratory assessments and integrative parent-physician-scientist cooperation are the keys to successful ASD management.

Lack of benefit of intravenous synthetic human secretin in the treatment of autism

The objective of this study was to determine if an intravenous infusion of synthetic human secretin improves language and behavioral symptoms in children with autism. Forty-two children with the diagnosis of autism were randomized to one of two groups in this double-blind cross-over trial. One group received 2 IU/kg of intravenous synthetic human secretin at the first visit, followed by an equal volume of intravenous saline placebo at week 6. The other group received treatments in the reverse order. All children were evaluated at weeks 1, 3, 6, 9, and 12 with standardized assessments of language, behavior, and autism symptomatology. There were no significant differences in the mean scores on any measure of language, behavior, or autism symptom severity after treatment with secretin compared to treatment with placebo. The results of this study do not support secretin as a treatment for autism.

A randomized, double-blind, placebo-controlled trial of porcine versus synthetic secretin for reducing symptoms of autism

OBJECTIVE

To compare the effects of a single dose of biologic and synthetic porcine secretin to placebo on a variety of autism symptoms.

METHOD

Eighty-five children with autism without other medical conditions and not taking other psychotropic medications participated (ages between 3 and 12 years, mean IQ = 55). Children were grouped into trios matched by age and communication level and then randomly assigned to one of three treatment groups: biologic secretin (2 CU/kg), synthetic secretin (0.4 microg/kg), and placebo. Measures collected 1 week before and 4 weeks after infusion included autism symptoms, language skills, and problem behaviors, gathered from parents, teachers, and investigators, who were all blind to treatment. Two-factor, repeated-measures analyses of variance (3 treatment levels by 2 repeated measures, pre- and postinfusion) were used to examine efficacy.

RESULTS

Direct observation measures did not show change over time related to secretin. Parent reports showed an overall reduction of symptom severity for all treatment groups, including the placebo group. One teacher-report measure showed decreases in autism symptoms in the placebo and synthetic secretin groups.

CONCLUSIONS

No evidence that either biologic or synthetic secretin provided amelioration of symptoms beyond placebo was observed. This held true when children with and without gastrointestinal problems were examined separately.

Facilitation of pancreatic duct cannulation using a new synthetic porcine secretin

OBJECTIVES

Cannulation of the pancreatic duct at ERCP can represent a technical challenge, even to experienced pancreaticobiliary endoscopists. Secretin is a polypeptide hormone that increases the volume and bicarbonate content of pancreatic secretions. We report our single center experience in the use of a new synthetic porcine secretin (sPS) for the facilitation of cannulation of either the major or minor pancreatic orifice during ERCP.

METHODS

Patients presenting for a variety of indications were enrolled. If identification or cannulation of the desired pancreatic duct was difficult, 0.2 microg/kg of sPS was administered i.v. Cannulation success or failure was recorded.

RESULTS

Between March, 1999, and May, 2000, a total of 25 patients (seven men and 18 women) were enrolled. The most frequent indication (15 of 25 cases) was facilitation of dorsal pancreatic duct cannulation in patients with pancreas divisum. The overall rate of successful cannulation secretin administration was 24 of 25 cases (96%). No adverse events directly attributable to secretin were observed.

CONCLUSIONS

The results of this study show that sPS is safe and efficacious in faciliting cannulation of either the major or minor pancreatic orifice at ERCP in the subset of patients who represent cannulation difficulties. Once commercially available, sPS can be added to the armamentarium of techniques to facilitate ERP.

Secretin as a neuropeptide

The role of secretin as a classical hormone in the gastrointestinal system is well-established. The recent debate on the use of secretin as a potential therapeutic treatment for autistic patients urges a better understanding of the neuroactive functions of secretin. Indeed, there is an increasing body of evidence pointing to the direction that, in addition to other peptides in the secretin/glucagon superfamily, secretin is also a neuropeptide. The purpose of this review is to discuss the recent data for supporting the neurocrine roles of secretin in rodents. By in situ hybridization and immunostaining, secretin was found to be expressed in distinct neuronal populations within the cerebellum and cerebral cortex, whereas the receptor transcript was found throughout the brain. In the rat cerebellum, secretin functions as a retrograde messenger to facilitate GABA transmission, indicating that it can modulate motor and other functions. In summary, the recent data support strongly the neuropeptide role of secretin, although the secretin-autism link remains to be clarified in the future.

Secretin treatment for autistic disorder: a critical analysis

We assessed evidence of the effects of secretin on behavior in individuals with autistic disorder. Articles were obtained through a MEDLINE search of the English-language literature from January 1966-November 2001; all investigations and case reports on the topic were included. Press releases obtained from the World Wide Web also were included. Secretin, a gastrointestinal hormone, is suggested to improve autistic symptoms, particularly social function and communication. Two formulations, porcine and synthetic human secretin, were evaluated in humans. A small body of literature and popular belief in autistic disorder communities supported the agent's efficacy. A number of controlled clinical trials did not show improvement in autistic symptoms with secretin compared with placebo, possibly indicating no role for the drug in autistic disorder.

Efficacy of porcine secretin in children with autism and pervasive developmental disorder

Secretin, a gastrointestinal (GI) hormone, was reported in a preliminary study to improve language and behavior in children with autism/pervasive developmental disorder (PDD) and chronic diarrhea. To determine the efficacy of secretin, we completed a double-blind, placebo-controlled, crossover (3 weeks) study in children with autism/PDD and various GI conditions using a single dose of intravenous porcine secretin. Children with chronic, active diarrhea showed a reduction in aberrant behaviors when treated with the secretin but not when treated with the placebo. Children with no GI problems are unaffected by either secretin or placebo. The improvement seen with secretin in children with autism/PDD and chronic diarrhea suggests that there may be a subtype of children with autism/PDD who respond to secretin.

Double-blind placebo-controlled trial of secretin: effects on aberrant behavior in children with autism

Secretin has been proposed as a treatment alternative for autistic spectrum disorders, but empirical support is lacking. A double-blind placebo-controlled study examined the effect of a single dose of synthetic human secretin on aberrant behavior. Parent and teacher data from the Aberrant Behavior Checklist for eight male children were analyzed for reliable change in a clinical replication series. By parent and teacher report, the majority of change occurred either on the placebo trial or reflected deterioration subsequent to secretin infusion. Repeated-measures multivariate analysis of variance results were similar. Results are consistent with other studies, suggesting that secretin may not be an effective treatment option.

Biochemical aspects in autism spectrum disorders: updating the opioid-excess theory and presenting new opportunities for biomedical intervention

Autism is a lifelong condition usually described as affecting social, cognitive and imaginative abilities. For many years, parents and some professionals have observed that in concordance with the behavioural and psychological symptoms of the condition, there are a number of physiological and biochemical correlates which may also be of relevance to the syndrome. One area of interest that encompasses many of these observations is the opioid-excess theory of autism. The main premise of this theory is that autism is the result of a metabolic disorder. Peptides with opioid activity derived from dietary sources, in particular foods that contain gluten and casein, pass through an abnormally permeable intestinal membrane and enter the central nervous system (CNS) to exert an effect on neurotransmission, as well as producing other physiologically-based symptoms. Numerous parents and professionals worldwide have found that removal of these exogenously derived compounds through exclusion diets can produce some amelioration in autistic and related behaviours. There is a surprisingly long history of research accompanying these ideas. The aim of this paper is to review the accompanying evidence in support of this theory and present new directions of intervention as a result of it.

Secretin for the treatment of autism

OBJECTIVE

To evaluate the role of secretin in the treatment of children with autism.

DATA SOURCE

Literature was assessed through MEDLINE, EMBASE, BIOSIS (November 1998-August 2001), and the World Wide Web. Literature included scientific studies, anecdotal reports, and meeting abstracts. Key search terms included autism and secretin.

DATA SYNTHESIS

Autism is a pervasive developmental disorder. Although several treatments exist, no cure has been identified. New information suggests that secretin may be beneficial for this disorder. A critical evaluation of current information about the use of secretin in autism was conducted.

CONCLUSIONS

Currently, several anecdotal reports and a few controlled trials with conflicting results have been published regarding the use of secretin in autism. Further studies should be conducted to determine the safety and efficacy of secretin for autism.

Use of secretin in the treatment of childhood autism

The paper presents current views concerning childhood autism. The authors present the concepts of etiology of this disorder, emphasizing the role of negative psychical stimuli in early childhood and the role of mother's contact with the child. Organic factors, including genetic background, developmental abnormalities of the nervous system, teratogenic factors and perinatal traumas are also taken into consideration. The role of metabolic factors and enterohormones, particularly those belonging to the secretin group and their effect on the function of the gastrointestinal tract and central nervous system is emphasized. We discuss signs which may be indicative of first symptoms of autism in different age groups. A typical symptom of autism is no development of speech, observed from infancy, taking the form of complete mutism at later stages. It has been emphasized that most pathologic symptoms result from altered perception of external stimuli, which arouse fear and anxiety. Autistic patients may suffer from gastrointestinal tract disturbances such as abdominal pains and diarrhea. Methods used hitherto in the therapy of childhood autism, mainly by psychologists and psychiatrists, as well as some attempts of pharmacological treatment, are presented. The structure and function of secretin, as well as its effects on the motor and secretory function of the stomach and the exocrine function of the pancreas are discussed. The role of secretin in diagnostic tests, among others in the diagnosis of gastrinoma, is emphasized. We also present the history of the application of secretin in the therapy of childhood autism.

Secretin and sleep in children with autism

The objectives of this pilot study were 1) to examine possible effects of secretin infusions on sleep-wake state organization in children with autism, and 2) to assess the feasibility of home recordings using time-lapse videosomnography in children with autism. Participants were a subset of subjects from two double blind, placebo-control, multi-center clinical trials. One trial, the UC Irvine study, assessed the effects of porcine secretin vs. saline infusions on children's behavior, language and IQ. The UC Davis trial assessed the effects of synthetic human secretin vs. saline infusions on behavior, language and gastrointestinal function. The sleep study enrolled some of the children from each of the two trials to observe possible secretin effects on sleep. To examine sleep, the UC Irvine trial used the Children's Sleep Habits Questionnaire and daily sleep diaries, whereas the UC Davis study used home-recorded time-lapse videosomnography. Because of the small sample size, the results from both trials are preliminary. They suggest that secretin, porcine or synthetic, does not improve sleep-wake state organization dramatically.

Effects of intravenous secretin on language and behavior of children with autism and gastrointestinal symptoms: a single-blinded, open-label pilot study

BACKGROUND

Autism is a severe developmental disorder with poorly understood etiology. A recently published case series describes 3 autistic children with gastrointestinal symptoms who underwent endoscopy and intravenous administration of secretin and were subsequently noted by their parents to demonstrate improved language skills over a 5-week period. This report sparked tremendous public interest, and investigators at several sites moved quickly to design controlled trials to test the efficacy of secretin as a therapy for autistic children. However, this is the first effort specifically designed to replicate the initial reported findings in terms of patient age, presenting symptoms, and drug administration.

OBJECTIVE

To rigorously apply the scientific method by assessing the reproducibility of the reported effects of intravenous secretin on the language of young children with autism and gastrointestinal symptoms.

METHODS

We performed a single-blinded, prospective, open-label trial by conducting formal language testing and blinded behavioral rating both before and repeatedly after a standardized infusion of secretin. We selected autistic children who were similar in age and profile to those described in the published retrospective case review. Inclusion criteria for study participation included age (3-6 years), confirmed diagnosis of autism, and reported gastrointestinal symptoms (16 had chronic diarrhea, 2 had gastroesophageal reflux, and 2 had chronic constipation). Twenty children (18 male) were admitted to the Pediatric Clinical Research Center at the University of California, San Francisco after administration of the Preschool Language Scale-3 (PLS-3). A 3 CU/kg dose of secretin (Secretin-Ferring) was administered intravenously (upper endoscopy was not performed). Behavioral ratings were derived using the Autism Observation Scale applied to a 30-minute time sample of the child's behavior consisting of a videotape of the PLS-3 (structured setting) and a second free play session with a standard set of developmentally appropriate toys. Participants then returned for follow-up evaluations, with readministrations of the PLS-3 at 1, 2, 3, and 5 weeks' postinfusion, and videotaping of each session for later blinded review by 2 independent observers using the Autism Observation Scale, uninformed about week of posttreatment. We also surveyed parents of our study children about their impressions of the effects of secretin using a 5-point Likert scale for parents to rate changes seen in their child.

RESULTS

With a total study completion rate across all participants of 96%, repeated measures analyses of variance revealed no significant increases in children's language skills from baseline across all 5 study time periods after a single infusion of secretin. Similarly, neither significant decreases in atypical behaviors nor increases in prosocial behaviors and developmentally appropriate play skills emerged. Furthermore, no relationship was found between parental reports of change and observable improvement in the sample. Despite the objective lack of drug effect, 70% of parents in our study reported moderate to high change in their child's language and behavior. Furthermore, 85% of parents reported that they felt that their child would obtain at least some additional benefits from another infusion of secretin.

CONCLUSIONS

The results of our pilot study indicate that intravenous secretin had no effects in a 5-week period on the language and behavior of 20 children with autism and gastrointestinal symptoms. The open-label, prospective design of our study with blinded reviews of patients both before and after secretin administration follows the scientific method by seeking to reproduce an observed phenomenon using validating and reliable outcome measures. Pilot studies remain a mandatory step for the design of future randomized, clinical trials investigating potential treatments for children with autism.

A double-blind, placebo-controlled crossover study investigating the effect of porcine secretin in children with autism

A recent patient series reported the incidental findings of improved social and language skills in 3 children with autistic spectrum disorders after the administration of secretin, a peptide hormone. However, a subsequent study did not find evidence for a drug effect. Parents are seeking treatment with secretin despite the absence of empirical investigations demonstrating amelioration in autism symptomology. In order to more precisely measure the effects of secretin, this study investigated the effect of a single intravenous dose of porcine secretin on 12 autistic children through a randomized, double-blind, placebo-controlled, crossover study. Children were assessed on objective language and on social, neuropsychological, and gastrointestinal measures to evaluate drug effects. The study was conducted over a 16-week trial. The results indicated that significant differences were not observed on the majority of the dependent variables. Statistically significant differences were observed on measures of positive affect and activity level following secretin infusion. In general, the autistic children did not demonstrate the improvements described in the initial retrospective report.

Transdermal secretin for autism - a case report

Secretin hormone given daily in transdermal cream was associated with marked and sustained developmental progress in an aphasic two-and-a-half year old child diagnosed with autism.

A randomized controlled crossover study comparing synthetic porcine and human secretins with biologically derived porcine secretin to diagnose Zollinger-Ellison Syndrome

BACKGROUND

Although biologically-derived porcine secretin is approved for the diagnosis of Zollinger-Ellison Syndrome, it is no longer available in the United States. Pure human and porcine secretins have now been synthesized and new drug applications have been filed with the Federal Drug Administration (FDA).

METHODS

In the current study we compared secretin testing results in six confirmed Zollinger-Ellison Syndrome patients using the biologically-derived product and both synthetic products (human and porcine) in a three-way, randomized, single-blind Latin-squares crossover study.

RESULTS

Using the FDA-approved criterion for positive secretin testing (i.e. a serum gastrin concentration increase of > 110 pg/mL), there was complete agreement between all three agents for all patients. With the more stringent NIH criterion (i.e. a serum gastrin concentration increase of > 200 pg/mL), positive results persisted in five out of six, six out of six and four out of six patients using biologically-derived secretin, synthetic porcine secretin, and synthetic human secretin, respectively (six out of six, six out of six and four out of six if a positive test was defined as a 50% increase in serum gastrin concentration). The time to peak serum gastrin concentration after secretin injection occurred within 15 min in all studies (in 94% by 10 min and in 77% by 5 min). Three-way comparisons of serum gastrin concentrations showed a single statistically significant difference (the change from baseline at 15 min between synthetic human and synthetic porcine secretin, P=0.0274). Statistically significant changes from baseline occurred at 1, 2 and 5 min for biologically-derived porcine secretin and at 2 and 5 min for both synthetic porcine and synthetic human secretin, in keeping with the expected time curve for positive tests. All three agents were well-tolerated.

CONCLUSIONS

These data suggest that either synthetic secretin product, when released onto the United States market, can be used to confirm Zollinger-Ellison Syndrome.