Narcolepsy: an interface among neurology, immunology, sleep, and genetics.

Narcolepsy is a primary disorder of the central nervous system resulting from genetic, environmental, and immunological interactions defined as excessive daytime sleepiness plus cataplexy, hallucinations, sleep paralysis, and sleep fragmentation. The pathophysiology is not entirely known, but the interaction among genetic predisposition, environmental exposition, and immune component with consequent hypocretin-1 deficiency is the model to explain narcolepsy type I. The mechanism of narcolepsy type II is less understood. There is a delay of over ten years for the diagnosis of narcolepsy around the world. Patients with narcolepsy have many comorbidities with a negative impact on quality of life. The treatment of narcolepsy must contain an educational approach for the family, coworkers, and patients. Scheduled naps and sleep hygiene are essential to minimize the dose of medications. Much progress has been seen in the pharmacological treatment of narcolepsy with new stimulants, different presentations of oxybate, and recent studies with orexin agonists. Narcolepsy is a rare disease that needs to be more understood and highlighted to avoid delayed diagnosis and severe disabilities in patients.

A narcolepsia é um distúrbio primário do sistema nervoso central resultante das interações genéticas, ambientais e imunológicas definidas como sonolência diurna excessiva mais cataplexia, alucinações, paralisia do sono e fragmentação do sono. A fisiopatologia não é completamente conhecida, mas a interação entre predisposição genética, exposição ambiental e componente imunológico com consequente deficiência de hipocretina-1 é o modelo para explicar a narcolepsia tipo I. O mecanismo da narcolepsia tipo II é menos compreendido. Há um atraso de mais de dez anos para o diagnóstico da narcolepsia em todo o mundo. Pacientes com narcolepsia apresentam muitas comorbidades com impacto negativo na qualidade de vida. O tratamento da narcolepsia deve conter uma abordagem educativa para a família, colegas de trabalho e pacientes. Cochilos programados e higiene do sono são importantes para minimizar a dose dos medicamentos. Muito progresso foi observado no tratamento farmacológico da narcolepsia com novos estimulantes, diferentes apresentações de oxibato e estudos recentes com agonistas de orexina. A narcolepsia é uma doença rara que precisa ser mais compreendida e destacada para evitar atrasos no diagnóstico e incapacidades graves nos pacientes.

Validation of the Brazilian Portuguese version of the Stanford cataplexy questionnaire.

INTRODUCTION: Cataplexy is a sudden and involuntary episode of loss of muscle tone during wakefulness. Cataplexy cannot be easily recognized when clinical features are atypical or when the physician is unfamiliar with its characteristics. The unstructured clinical interview is the only standard diagnostic method, but the use of a targeted questionnaire can help in the diagnosis of cataplexy. METHODS: The Stanford cataplexy questionnaire is a self-administered 51-question questionnaire. This validation consisted of an initial translation and back-translation of the questionnaire from English into Brazilian Portuguese, followed by a pilot study with 10 participants for the cultural adaptation of the scale. RESULTS: 155 consecutive patients aged 18-85 completed the questionnaire. The Brazilian version of the Stanford cataplexy questionnaire showed similar results to the original version with good metric properties (area under the curve), high internal consistency (Cronbach's alpha equal to 0.87), good reliability and reproducibility. CONCLUSIONS: The Brazilian Portuguese version of the Stanford Cataplexy questionnaire presented good accuracy satisfactory psychometric properties in identifying cataplexy.

Whole-genome analysis of monozygotic Brazilian twins discordant for type 1 narcolepsy: a case report.

BACKGROUND: Narcolepsy type 1 (NT1) is a rare and chronic neurological disease characterized by sudden sleep attacks, overwhelming daytime drowsiness, and cataplexy. When associated with a sudden loss of muscle tone (cataplexy) narcolepsy is classified as type 1, while the absence of cataplexy indicates type 2. Genetic, degenerative, and immunological hypotheses to explain the pathophysiology of NT1 are still a matter of debate. To contribute to the understanding of NT1 genetic basis, here we describe, for the first time, a whole genome analysis of a monozygotic twin pair discordant for NT1. CASE PRESENTATION: We present the case of a pair of 17-year-old male, monozygotic twins discordant for NT1. The affected twin had Epworth Sleepiness Scale (ESS) of 20 (can range from 0 to 24), cataplexy, hypnagogic hallucinations, polysomnography without abnormalities, multiple sleep latency tests (MSLT) positive for narcolepsy, a mean sleep latency of 3 min, sleep-onset REM periods SOREMPs of 5, presence of allele HLA-DQB1*06:02, and Hypocretin-1 level of zero pg/mL (normal values are > 200 pg/mL). The other twin had no narcolepsy symptoms (ESS of 4), normal polysomnography, MSLT without abnormalities, presence of allele HLA-DQB1*06:02, and Hypocretin-1 level of 396,74 pg/mL. To describe the genetic background for the NT1 discordant manifestations in this case, we present the whole-genome analysis of this monozygotic twin pair. The whole-genome comparison revealed that both twins have identical NT1 pathogenic mutations in known genes, such as HLA-DQB1*06:02:01, HLA-DRB1*11:01:02/*15:03:01. The affected twin has the expected clinical manifestation while the unaffected twin has an unexpected phenotype. The unaffected twin has significantly more frameshift mutations as compared to the affected twin (108 versus 75) and mutations that affect stop codons (61 versus 5 in stop gain, 26 versus 2 in start lost). CONCLUSIONS: The differences observed in frameshift and stop codon mutations in the unaffected twin are consistent with loss-of-function effects and protective alleles, that are almost always associated with loss-of-function rare alleles. Also, overrepresentation analysis of genes containing variants with potential clinical relevance in the unaffected twin shows that most mutations are in genes related to immune regulation function, Golgi apparatus, MHC, and olfactory receptor. These observations support the hypothesis that NT1 has an immunological basis although protective mutations in non-HLA alleles might interfere with the expression of the NT1 phenotype and consequently, with the clinical manifestation of the disease.

Narcolepsia na infância: a atuação multidisciplinar com a psicologia do sono do diagnóstico ao tratamento em um relato de caso / Child narcolepsy: the multidisciplinary approach with sleep psychology from diagnostics to treatment in a case report / Narcolepsia en la infancia: actuación multidisciplinar con la psicología del sueño desde el diagnóstico hasta el tratamiento en un caso clínico

A narcolepsia, distúrbio neurológico crônico caracterizado pela sonolência diurna excessiva, pode ser associada à cataplexia, fragmentação do sono, alucinações relacionadas ao sono e paralisia do sono. Frequentemente, é confundida com outros transtornos, como Transtorno do Déficit de Atenção com Hiperatividade (TDAH), epilepsia e até esquizofrenia, assim, por vezes, é diagnosticada inadequadamente. Objetiva-se relatar o diagnóstico diferencial bem-sucedido da narcolepsia na infância e suas dificuldades, realizado por uma equipe multidisciplinar, enfocando a atuação da psicologia do sono em avaliação e intervenção. Um menino de 10 anos foi recebido no Ambulatório de Narcolepsia e Apneia do Sono Infantil (AMBNAP), alocado no Hospital Universitário Onofre Lopes da Universidade Federal do Rio Grande do Norte (UFRN) com queixas de sonolência diurna excessiva, sono fragmentado e episódios de perda de tônus muscular. Foi submetido a entrevistas psiquiátrica e psicológica pormenorizadas, a exames, aplicação de escalas específicas para rastreio e diagnóstico de transtornos de sono e diário de sono, solicitação de recursos de mídia e de relatório escolar e avaliação neurológica. A partir da investigação multidisciplinar, o diagnóstico foi de Narcolepsia e Síndrome da Apneia Obstrutiva do Sono (SAOS). O paciente foi submetido a técnicas da Terapia Cognitivo-Comportamental (TCC) e segue em acompanhamento, apresentando resultados satisfatórios. Este estudo evidencia que uma equipe multidisciplinar especializada na área de sono atuando em conjunto com a Psicologia do Sono oportuniza o diagnóstico e intervenções precoces eficazes para o tratamento do distúrbio do sono na infância.(AU)

Narcolepsy is a chronic neurologic disorder characterized by excessive daytime sleepiness which can be associated with cataplexy, sleep fragmentation, sleep-related hallucinations, and sleep paralysis. This sleep disorder is often confused with other disorders such as Attention Deficit Hyperactivity Disorder (ADHD), epilepsy, and even schizophrenia, and is, thus, misdiagnosed. This study aims to report the successful differential diagnosis for childhood narcolepsy carried out by a multidisciplinary team and its challenges, with a focus on the role of sleep psychology in assessment and intervention. A 10-year-old child was received at the Child Narcolepsy and Sleep Apnea Clinic (AMBNAP), located at the Onofre Lopes University Hospital of the Federal University of Rio Grande do Norte (UFRN), with complaints of hypersomnolence, fragmented sleep, and episodes of loss of muscle tone. He underwent detailed psychiatric and psychological interviews, analysis of exams, application of specific scales for screening and diagnosis of sleep disorders and sleep diary, request of media resources and school report, and neurological assessment. From the multidisciplinary investigation, excluding of other neurological diagnoses, the diagnosis was Narcolepsy and Obstructive Sleep Apnea Syndrome (OSAS). The patient was submitted to Cognitive Behavioral Therapy (CBT) techniques, such as psychoeducation, scheduled naps, cognitive therapy for dysfunctional beliefs, and sleep hygiene strategies, and continues to be followed up, with satisfactory results since the first two months of intervention. The findings presented in this study show that a multidisciplinary team specialized in the sleep area, acting alongside Sleep Psychology provides early diagnosis and interventions for the sleep disorder treatment in childhood.(AU)

La narcolepsia es un trastorno neurológico crónico caracterizado por somnolencia diurna excesiva que puede asociarse con cataplejía, fragmentación del sueño, alucinaciones relacionadas con el sueño y parálisis del sueño. El trastorno del sueño a menudo se confunde con otros trastornos como el TDAH, la epilepsia e incluso la esquizofrenia, y se diagnostica erróneamente. El objetivo es presentar el diagnóstico diferencial exitoso de la narcolepsia en la infancia y sus dificultades, realizado por un equipo multidisciplinario, con foco en el papel de la psicología del sueño en la evaluación e intervención. El estudiante de 10 años fue recibido en la Clínica de Narcolepsia Infantil y Apnea del Sueño (AMBNAP), ubicada en el Hospital Universitario Onofre Lopes de la Universidad Federal de Rio Grande do Norte, con quejas de hipersomnolencia, sueño fragmentado y episodios de pérdida de tono muscular. Se sometió a entrevistas psiquiátricas y psicológicas detalladas, análisis de exámenes, aplicación de escalas específicas para la detección y diagnóstico de trastornos del sueño y el diario del sueño, solicite recursos de medios y informe escolar y evaluación neurológica. La investigación multidisciplinaria, el diagnóstico fue Narcolepsia y SAOS. El paciente fue sometido a técnicas de terapia cognitivo-conductual (TCC), como psicoeducación, siestas programadas, terapia cognitiva por creencias disfuncionales y estrategias de higiene del sueño, y se le dio seguimiento con resultados satisfactorios. Los resultados demostraron que un equipo multidisciplinario especializado en el campo del sueño, actuando en conjunto con la psicología del sueño, proporciona el diagnóstico y las intervenciones tempranas para el trastorno del sueño de la narcolepsia en la infância.(AU)

Thinking outside the box: cataplexy without narcolepsy.

Cataplexy is a transient loss of muscle tone that can be triggered by emotions such as laughter, excitement or fear. Other causes of cataplexy include Niemann-Pick type C Disease, Angelman Syndrome, Norrie Disease, Prader-Willi Syndrome. In addition, cataplexy can be a side effect of several drugs (eg, lamotrigine, clozapine, and gamma-hydroxybutyrate). Yet, the most prevalent causes of cataplexy without narcolepsy are rare genetic diseases; which explains why cataplexy is classically linked to narcolepsy. Therefore, it is essential disconnecting cataplexy from narcolepsy especially in pediatric population and after use of a few medications. In this review, we described few conditions of cataplexy not related to narcolepsy. We performed a review of literature (MEDLINE and EMBASE database), without limited date or publication restrictions.

Sleep disorders in NiemannPick disease type C, beyond cataplexy.

PURPOSE: The aim of this study was to clinically characterize sleep disorders in a cohort of Niemann-Pick type C (NPC) patients, correlating these findings with disease features and polysomnographic (PSG) results. METHODS: We evaluated eight consecutive patients with molecular confirmation of NPC followed at the Hospital Geral de Fortaleza. Patients underwent a comprehensive neurological and sleep evaluation. Four participants underwent polysomnography and then performed the multiple sleep latency test. RESULTS: All eight patients evaluated had sleep disorders. Four participants performed polysomnography followed by multiple sleep latency test. Chronic insomnia and Obstructive Sleep Apnea (OSA) were the most frequent sleep disorders (62,5%). Two patients were diagnosed with Restless Legs Syndrome (RLS) (25%) and two with probable REM sleep behavior disorder (RBD) (25%). All the patients who did polysomnography had reduced and/or disorganized sleep, with reduction on sleep efficiency, total sleep time and REM sleep time. CONCLUSION: Our results suggest that sleep abnormalities in Niemann-Pick type C patients may be more prevalent than previously thought.

Narcolepsy, Precocious Puberty and Obesity in the Pediatric Population: a Literature Review.

Narcolepsy is a sleep disorder characterized by excessive daytime sleepiness, cataplexy, sleep paralysis and hypnagogic and hypnopompic hallucinations. The onset of the symptoms usually occurs in childhood, and previous studies have reported an association between narcolepsy and other endocrine diseases in the pediatric population, such as obesity and precocious puberty. The incidence of overweight or obesity ranges from 25% to 74% in patients with narcolepsy type I, while precocious puberty is present in 17% of children with narcolepsy with cataplexy. However, the mechanisms involved in the association of narcolepsy with obesity and precocious puberty have not been fully elucidated yet. In this review, we aimed to discuss narcolepsy in pediatric populations, highlighting the diagnostic difficulties and the complexity of the possible mechanisms that can relate narcolepsy to precocious puberty and obesity. We also emphasized the fact that endocrine diseases must be taken into consideration in children diagnosed with narcolepsy.

Neocortical 40 Hz oscillations during carbachol-induced rapid eye movement sleep and cataplexy.

Higher cognitive functions require the integration and coordination of large populations of neurons in cortical and subcortical regions. Oscillations in the gamma band (30-45 Hz) of the electroencephalogram (EEG) have been involved in these cognitive functions. In previous studies, we analysed the extent of functional connectivity between cortical areas employing the 'mean squared coherence' analysis of the EEG gamma band. We demonstrated that gamma coherence is maximal during alert wakefulness and is almost absent during rapid eye movement (REM) sleep. The nucleus pontis oralis (NPO) is critical for REM sleep generation. The NPO is considered to exert executive control over the initiation and maintenance of REM sleep. In the cat, depending on the previous state of the animal, a single microinjection of carbachol (a cholinergic agonist) into the NPO can produce either REM sleep [REM sleep induced by carbachol (REMc)] or a waking state with muscle atonia, i.e. cataplexy [cataplexy induced by carbachol (CA)]. In the present study, in cats that were implanted with electrodes in different cortical areas to record polysomnographic activity, we compared the degree of gamma (30-45 Hz) coherence during REMc, CA and naturally-occurring behavioural states. Gamma coherence was maximal during CA and alert wakefulness. In contrast, gamma coherence was almost absent during REMc as in naturally-occurring REM sleep. We conclude that, in spite of the presence of somatic muscle paralysis, there are remarkable differences in cortical activity between REMc and CA, which confirm that EEG gamma (≈40 Hz) coherence is a trait that differentiates wakefulness from REM sleep.

Narcolepsia canina / Canine narcolepsy / Narcolepsia canina

A narcolepsia canina é um distúrbio neurológico que afeta o surgimento e a organização do sono, sendo caracterizada por sonolência diurna excessiva, cataplexia e prováveis alucinações hipnagógicas. Em cães das raças dobermann e labrador, a narcolepsia é transmitida de forma hereditária pelo gene recessivo de penetrância completa canarc-1, causando mutação nos receptores de hipocretina-2, um neuropeptídeo que ativa os neurônios que impedem a entrada no sono REM. O diagnóstico pode ser feito por meio da observação dos sintomas, sendo a cataplexia um fator-chave para o diagnóstico da doença. A narcolepsia deve ser cuidadosamente diferenciada de outras enfermidades neurológicas e distúrbios paralíticos reversíveis. O tratamento é paliativo e baseia-se na administração de estimulantes do sistema nervoso central (SNC) e antidepressivos tricíclicos.(AU)

Canine narcolepsy is a neurological disorder that affects the appearance and organization of sleep. It is characterized by excessive daytime sleepiness, cataplexy and hypnagogic hallucinations. In Dobermann and Labrador breeds, narcolepsy is transmitted hereditarily by the canarc-1recessive gene, which has complete penetrance and causes a mutation in the receptor for hypocretin-2, a neuropeptide that prevents entry into REM sleep by activating specific neurons. Diagnosis can be achieved by observing the symptoms. Cataplexy is a key factor for diagnosis of narcolepsy and must be carefully distinguished from other neurological diseases and reversible paralytic disorders. Treatment is palliative and based on the administration of stimulants of the central nervous system (CNS) and tricyclic antidepressants.(AU)

La narcolepsia canina es una alteración neurológica que afecta la aparición y organización del sueño, que se caracteriza por una excesiva somnolencia diurna, cataplejía y probables alucinaciones hipnagógicas. En perros de las razas Doberman y Labrador, la narcolepsia se transmite de forma hereditaria a través del gen recesivo de penetrancia completa canarc-1, que provoca mutación de los receptores de hipocretina-2, un neuropéptido que activa las neuronas que impiden la entrada en sueño REM. El diagnostico se puede realizar a través de la sintomatología y la cataplejía representa un factor llave para llegar al mismo. La narcolepsia debe ser cuidadosamente diferenciada de otras enfermedades neurológicas y de alteraciones paralíticas reversibles. El tratamiento es paliativo, y se realiza a través de estimulantes del sistema nervioso central y antidepresivos tricíclicos.(AU)

Narcolepsia canina / Canine narcolepsy / Narcolepsia canina

A narcolepsia canina é um distúrbio neurológico que afeta o surgimento e a organização do sono, sendo caracterizada por sonolência diurna excessiva, cataplexia e prováveis alucinações hipnagógicas. Em cães das raças dobermann e labrador, a narcolepsia é transmitida de forma hereditária pelo gene recessivo de penetrância completa canarc-1, causando mutação nos receptores de hipocretina-2, um neuropeptídeo que ativa os neurônios que impedem a entrada no sono REM. O diagnóstico pode ser feito por meio da observação dos sintomas, sendo a cataplexia um fator-chave para o diagnóstico da doença. A narcolepsia deve ser cuidadosamente diferenciada de outras enfermidades neurológicas e distúrbios paralíticos reversíveis. O tratamento é paliativo e baseia-se na administração de estimulantes do sistema nervoso central (SNC) e antidepressivos tricíclicos.

Canine narcolepsy is a neurological disorder that affects the appearance and organization of sleep. It is characterized by excessive daytime sleepiness, cataplexy and hypnagogic hallucinations. In Dobermann and Labrador breeds, narcolepsy is transmitted hereditarily by the canarc-1recessive gene, which has complete penetrance and causes a mutation in the receptor for hypocretin-2, a neuropeptide that prevents entry into REM sleep by activating specific neurons. Diagnosis can be achieved by observing the symptoms. Cataplexy is a key factor for diagnosis of narcolepsy and must be carefully distinguished from other neurological diseases and reversible paralytic disorders. Treatment is palliative and based on the administration of stimulants of the central nervous system (CNS) and tricyclic antidepressants.

La narcolepsia canina es una alteración neurológica que afecta la aparición y organización del sueño, que se caracteriza por una excesiva somnolencia diurna, cataplejía y probables alucinaciones hipnagógicas. En perros de las razas Doberman y Labrador, la narcolepsia se transmite de forma hereditaria a través del gen recesivo de penetrancia completa canarc-1, que provoca mutación de los receptores de hipocretina-2, un neuropéptido que activa las neuronas que impiden la entrada en sueño REM. El diagnostico se puede realizar a través de la sintomatología y la cataplejía representa un factor llave para llegar al mismo. La narcolepsia debe ser cuidadosamente diferenciada de otras enfermedades neurológicas y de alteraciones paralíticas reversibles. El tratamiento es paliativo, y se realiza a través de estimulantes del sistema nervioso central y antidepresivos tricíclicos.

Teaching video neuroimages: gelastic cataplexy as the first neurologic manifestation of Niemann-Pick disease type C.

A 10-year-old boy presented to our hospital with a 3-year history of fall attacks triggered by laughing, leading to a generalized loss of muscle tone without loss of consciousness (video). One year later, motor delayed skills started. Examination showed ataxia, moderate cognitive impairment, and vertical gaze palsy. EEG revealed diffuse slowing and disorganization of background rhythms. Molecular analysis disclosed heterozygosis p.P1007A and p.A1035V mutations, diagnostic of Niemann-Pick disease type C (NPC).

Traditional biomarkers in narcolepsy: experience of a Brazilian sleep centre.

UNLABELLED: This study was thought to characterized clinical and laboratory findings of a narcoleptic patients in an out patients unit at São Paulo, Brazil. METHOD: 28 patients underwent polysomnographic recordings (PSG) and Multiple Sleep Latency Test (MSLT) were analyzed according to standard criteria. The analysis of HLADQB1*0602 allele was performed by PCR. The Hypocretin-1 in cerebral spinal fluid (CSF) was measured using radioimmunoassay. Patients were divided in two groups according Hypocretin-1 level: Normal (N) - Hypocretin-1 higher than 110 pg/ml and Lower (L) Hypocretin-1 lower than 110 pg/ml. RESULTS: Only 4 patients of the N group had cataplexy when compared with 14 members of the L group (p = 0.0002). DISCUSSION: This results were comparable with other authors, confirming the utility of using specific biomarkers (HLA-DQB1*0602 allele and Hypocretin-1 CSF level) in narcolepsy with cataplexy. However, the HLADQB1*0602 allele and Hypocretin-1 level are insufficient to diagnose of narcolepsy without cataplexy.

Traditional biomarkers in narcolepsy: experience of a Brazilian sleep centre / Biomarcadores tradicionias em narcolepsia: experiência de um centro de sono brasileiro

This study was thought to characterized clinical and laboratory findings of a narcoleptic patients in an out patients unit at São Paulo, Brazil. METHOD: 28 patients underwent polysomnographic recordings (PSG) and Multiple Sleep Latency Test (MSLT) were analyzed according to standard criteria. The analysis of HLADQB1*0602 allele was performed by PCR. The Hypocretin-1 in cerebral spinal fluid (CSF) was measured using radioimmunoassay. Patients were divided in two groups according Hypocretin-1 level: Normal (N) - Hypocretin-1 higher than 110pg/ml and Lower (L) Hypocretin-1 lower than 110 pg/ml. RESULTS: Only 4 patients of the N group had cataplexy when compared with 14 members of the L group (p=0.0002). DISCUSSION: This results were comparable with other authors, confirming the utility of using specific biomarkers (HLA-DQB1*0602 allele and Hypocretin-1 CSF level) in narcolepsy with cataplexy. However, the HLADQB1*0602 allele and Hypocretin-1 level are insufficient to diagnose of narcolepsy without cataplexy.

Este estudo foi idealizado para avaliar as características clinicas e laboratoriais de uma população de narcolépticos atendidos num centro de referência na cidade de São Paulo (Brasil). MÉTODO: 28 pacientes realizaram polissonografia e teste de múltiplas latências do sono segundo critérios internacionais. O alelo HLADQB1*0602 foi identificado por PCR. A Hipocretina-1 no líquido cefalorradiano (LCR) foi mensurada por radioimunoensaio. Os pacientes foram divididos em 2 grupos conforme o nível de Hipocretina-1. Normal (N) - Hypocretin-1 >110pg/ml e baixa (B) - Hypocretina-1 <110pg/ml. RESULTADOS: Somente 4 pacientes do grupo N tinham cataplexia quando comparados com 14 pacientes do grupo B (p=0,0002). DISCUSSÃO: Estes resultados foram comparáveis com outros autores, confirmando a utilidade do uso de biomarcadores específicos (HLA-DQB1*0602 e nível da hipocretina-1 no LCR) em narcolepsia com cataplexia. Porém, o alelo HLADQB1*0602 e a dosagem da Hipocretina-1 são insuficientes para o diagnóstico da narcolepsia sem cataplexia.

Activation of serotonin 5-HT1-receptors decreased gripping-induced immobility episodes in taiep rats.

The taiep rat is a myelin mutant that shows a disorganized sleep-wake cycle and immobility episodes (IEs) when the animals are gripped at the base of the tail. During IEs electroencephalographic recordings show a rapid eye movement (REM) sleep-like pattern. These alterations are quite similar to those reported in narcolepsy-cataplexy. Pharmacologically, systemic administration of alpha(2) adrenoceptor agonists increases gripping-induced IEs, whereas alpha(2) antagonists decrease them. However prazosin, an alpha(1) antagonist, increases gripping-induced IEs. In male 8-month-old taiep rats we have studied the effect of systemic administration of serotonergic autoreceptor agonists and antagonists on gripping-induced IEs. 8-Hydroxy-2-(di-n-propylamino) tetraline hydrobromide (8-OH-DPAT), a 5-HT(1A) agonist, and 3-trifluoromethylphenylpiperazine hydrochloride (TFMPP), a 5-HT(1B) agonist, produce a significant decrease in the frequency and mean duration of IEs. Systemic administration of spiperone and 1-(2-methoxyphenyl)-4[4-(2-phthalimido) butyl]piperazine hydrobromide (NAN-190), 5-HT(1) antagonists, increase IEs and their mean duration. When the specific serotonin antagonist N-[2[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinyl-cyclohexanecarboxamide maleate (WAY 100635, 100 microg/kg) was injected 15 min before 8-OH-DPAT, this specific antagonist reverses the effects caused by the 5-HT(1A) agonist. These results show that serotonergic 5-HT(1)-receptors are involved in the susceptibility of gripping-induced IEs in taiep rats. Similar results have been reported in the food-elicited cataplexy test in narcoleptic dogs.

Association of narcolepsy-cataplexy with HLA-DRB1 and DQB1 in Mexican patients: a relationship between HLA and gender is suggested.

BACKGROUND: Narcolepsy-cataplexy is characterized by excessive daytime sleepiness with recurrent episodes of irresistible sleep, cataplexy, hallucinations and sleep paralysis. Its aetiology is unknown, but it is positively associated with the human leukocyte antigens (HLA) in all studied populations. The purpose of the present study was to investigate the association of HLA class II DRB1/DQB1 alleles with narcolepsy-cataplexy in Mexican Mestizo patients. METHODS: This is a case-control study of consecutive patients and ethnically matched controls. We included 32 patients diagnosed with typical narcolepsy-cataplexy, of the National Institute of Neurology, of the Institute of Psychiatry and at the Center of Narcolepsy at Stanford University. As healthy controls, 203 Mexican Mestizos were included. DRB1 alleles were identified using sequence based typing. A PCR-SSOP reverse dot blot was used for DQB1 typing. Allele frequency was calculated by direct counting and the significance of the differences was assessed using the Yates Chi square. Odds ratio and confidence intervals were evaluated. RESULTS: HLA-DRB1*1501 (OR = 8.2; pc < 0.0001) and DQB1*0602 (OR = 8.4; pc < 0.0001) were found positively associated with narcolepsy. When deleting DQB1*0602+ patients from the analysis, DQB1*0301 was also found increased (OR = 2.7; p = 0.035; pc = NS). DQB1*0602/DQB1*0301 genotype was present in 15.6% of the cases (OR = 11.5; p = 0.00035), conferring a high risk. DRB1*0407 (OR = 0.2; p = 0.016 pc = NS) and DQB1*0302(OR = 0.4; p = 0.017, pc = NS) were found decreased in the patients. The gender stratification analysis showed a higher risk in females carrying DRB1*1501 (OR = 15.8, pc < 0.0001) and DQB1*0602 (OR = 19.8, pc < 0.0001) than in males (OR = 5.0 for both alleles; p = 0.012, pc = NS for DRB1 & p = 0.0012, pc = 0.017 for DQB1). The susceptibility alleles found in Mexicans with narcolepsy are also present in Japanese and Caucasians; DRB1*04 linked protection has also been shown in Koreans. A stronger HLA association is suggested in females, in accordance with the sexual dimorphism claimed previously. CONCLUSION: This knowledge may contribute to a better understanding of the disease pathogenesis in different populations. The evaluation of the risk to develop narcolepsy-cataplexy in carriers of the described alleles/genotypes may also be possible. A larger sample should be analysed in Mexican and in other Hispanic patients to confirm these results.