RESUMEN
The hypocretin/orexin neuropeptide system coordinates the regulation of various physiological processes. Our previous study reported that a reduction in the expression of pleomorphic adenoma genelike 1 (Plagl1), which encodes a C2H2 zincfinger transcription factor, occurs in hypocretin neuronablated transgenic mice, suggesting that PLAGL1 is coexpressed in hypocretin neurons and regulates hypocretin transcription. The present study examined whether canonical preprohypocretin transcription is functionally modulated by PLAGL1. Double immunostaining indicated that the majority of hypocretin neurons were positive for PLAGL1 immunoreactivity in the nucleus. Notably, PLAGL1 immunoreactivity in hypocretin neurons was altered in response to several conditions affecting hypocretin function. An uneven localization of PLAGL1 was detected in the nuclei of hypocretin neurons following sleep deprivation. Chromatin immunoprecipitation revealed that endogenous PLAGL1 may bind to a putative PLAGL1binding site in the proximal region of the hypocretin gene, in the murine hypothalamus. In addition, electroporation of the PLAGL1 expression vector into the fetal hypothalamus promoted hypothalamic hypocretin transcription. These results suggested that PLAGL1 may regulate hypothalamic hypocretin transcription.
Asunto(s)
Proteínas de Ciclo Celular/metabolismo , Orexinas/genética , Factores de Transcripción/metabolismo , Transcripción Genética , Animales , Secuencia de Bases , Embrión de Mamíferos/citología , Genes Supresores de Tumor , Hipotálamo/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Células 3T3 NIH , Regiones Promotoras Genéticas/genética , Unión ProteicaRESUMEN
Study Objectives: Recent findings showed that 16%-26% of narcolepsy patients were positive for anti-tribbles pseudokinase 2 (TRIB2) antibody, and the intracerebroventricular administration of immunoglobulin-G purified from anti-TRIB2 positive narcolepsy patients caused hypocretin/orexin neuron loss. We investigated the pathophysiological role of TRIB2 antibody using TRIB2-immunized rats and hypocretin/ataxin-3 transgenic (ataxin-3) mice. Methods: Plasma, cerebrospinal fluid (CSF), and hypothalamic tissues from TRIB2-immunized rats were collected. Anti-TRIB2 titers, hypocretin contents, mRNA expressions, the cell count of hypocretin neurons, and immunoreactivity of anti-TRIB2 antibodies on hypocretin neurons were investigated. The plasma from ataxin-3 mice was also used to determine the anti-TRIB2 antibody titer changes following the loss of hypocretin neurons. Results: TRIB2 antibody titers increased in the plasma and CSF of TRIB2-immunized rats. The hypothalamic tissue immunostained with the sera from TRIB2-immunized rats revealed positive signals in the cytoplasm of hypcretin neurons. While no changes were found regarding hypothalamic hypocretin contents or cell counts, but there were significant decreases of the hypocretin mRNA level and release into the CSF. The plasma from over 26-week-old ataxin-3 mice, at the advanced stage of hypocretin cell destruction, showed positive reactions against TRIB2 antigen, and positive plasma also reacted with murine hypothalamic hypocretin neurons. Conclusions: Our results suggest that the general activation of the immune system modulates the functions of hypocretin neurons. The absence of a change in hypocretin cell populations suggested that factors other than anti-TRIB2 antibody play a part in the loss of hypocretin neurons in narcolepsy. The increased anti-TRIB2 antibody after the destruction of hypocretin neurons suggest that anti-TRIB2 antibody in narcolepsy patients is the consequence rather than the inciting cause of hypocretin cell destruction.
Asunto(s)
Autoanticuerpos/metabolismo , Autoantígenos/metabolismo , Proteínas Quinasas Dependientes de Calcio-Calmodulina/inmunología , Péptidos y Proteínas de Señalización Intracelular/inmunología , Narcolepsia/inmunología , Neuronas/inmunología , Orexinas/metabolismo , Animales , Animales Modificados Genéticamente , Ataxina-3/metabolismo , Biomarcadores/metabolismo , Proteínas Quinasas Dependientes de Calcio-Calmodulina/metabolismo , Femenino , Hipotálamo/metabolismo , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Masculino , Ratones , Ratones Transgénicos , Narcolepsia/metabolismo , Narcolepsia/fisiopatología , Neuronas/metabolismo , Neuropéptidos/metabolismo , Ratas , Ratas Sprague-Dawley , VacunaciónRESUMEN
Patients with bilateral pheochromocytoma often require an adrenalectomy. Autotransplantation of the adrenal cortex is an alternative therapy that could potentially be performed instead of receiving glucocorticoid replacement following adrenalectomy. Adrenal cortex autotransplantation aims to avoid the side effects of longterm steroid treatment and adrenal insufficiency. Although the function of the hypothalamohypophysial system is critical for patients who have undergone adrenal cortex autotransplantation, the details of that system, with the exception of adrenocorticotropic hormone in the subjects with adrenal autotransplantation, have been overlooked for a long time. To clarify the precise effect of adrenal autotransplantation on the pituitary gland and hypothalamus, the current study examined the gene expression of hormones produced from the hypothalamus and pituitary gland. Bilateral adrenalectomy and adrenal autotransplantation were performed in 8 to 9weekold male rats. The hypothalamus and pituitary tissues were collected at 4 weeks after surgery. Transcriptional regulation of hypothalamic and pituitary hormones was subsequently examined by reverse transcriptionquantitative polymerase chain reaction. Proopiomelanocortin, glycoprotein hormone α polypeptide, and thyroid stimulating hormone ß were significantly elevated in the pituitary gland of autotransplanted rats when compared with shamoperated rats. In addition, there were significant differences in the levels of corticotropin releasing hormone receptor 1 (Crhr1), Crhr2, nuclear receptor subfamily 3 group C member 1 and thyrotropin releasing hormone receptor between the shamoperated rats and autotransplanted rats in the pituitary gland. In the hypothalamus, corticotropin releasing hormone and urocortin 2 mRNA was significantly upregulated in autotransplanted rats compared with shamoperated rats. The authors identified significant alterations in the function of not only the hypothalamuspituitaryadrenal axis, but also the adenohypophysis thyrotropes in autotransplanted rats. In the future, it will be important to examine other tissues affected by glucocorticoids following adrenal cortex autotransplantation.
Asunto(s)
Corteza Suprarrenal/trasplante , Sistema Hipotálamo-Hipofisario/metabolismo , Adrenalectomía , Animales , Hormona Liberadora de Corticotropina/genética , Hormona Liberadora de Corticotropina/metabolismo , Hormonas Glicoproteicas de Subunidad alfa/genética , Hormonas Glicoproteicas de Subunidad alfa/metabolismo , Hipotálamo/metabolismo , Masculino , Hipófisis/metabolismo , Proopiomelanocortina/genética , Proopiomelanocortina/metabolismo , ARN Mensajero/metabolismo , Ratas , Ratas Wistar , Receptores de Hormona Liberadora de Corticotropina/genética , Receptores de Hormona Liberadora de Corticotropina/metabolismo , Receptores de Glucocorticoides/genética , Receptores de Glucocorticoides/metabolismo , Receptores de Hormona Liberadora de Tirotropina/genética , Receptores de Hormona Liberadora de Tirotropina/metabolismo , Tirotropina de Subunidad beta/genética , Tirotropina de Subunidad beta/metabolismo , Trasplante Autólogo , Regulación hacia Arriba , Urocortinas/genética , Urocortinas/metabolismoRESUMEN
Hypocretin, also known as orexin, maintains the vigilance state and regulates various physiological processes, such as arousal, sleep, food intake, energy expenditure, and reward. Previously, we found that when wild-type mice and hypocretin/ataxin-3 littermates (which are depleted of hypothalamic hypocretin-expressing neurons postnatally) were administered lipopolysaccharide (LPS), the two genotypes exhibited significant differences in their sleep/wake cycle, including differences in the degree of increase in sleep periods and in recovery from sickness behaviour. In the present study, we examined changes in the hypothalamic vigilance system and in the hypothalamic expression of inflammatory factors in response to LPS in hypocretin/ataxin-3 mice. Peripheral immune challenge with LPS affected the hypothalamic immune response and vigilance states. This response was altered by the loss of hypocretin. Hypocretin expression was inhibited after LPS injection in both hypocretin/ataxin-3 mice and their wild-type littermates, but expression was completely abolished only in hypocretin/ataxin-3 mice. Increases in the number of histidine decarboxylase (HDC)-positive cells and in Hdc mRNA expression were found in hypocretin/ataxin-3 mice, and this increase was suppressed by LPS. Hypocretin loss did not impact the change in expression of hypothalamic inflammatory factors in response to LPS, except for interferon gamma and colony stimulating factor 3. The number of c-Fos-positive/HDC-positive cells in hypocretin/ataxin-3 mice administered LPS injections was elevated, even during the rest period, in all areas, suggesting that there is an increase in the activity of histaminergic neurons in hypocretin/ataxin-3 mice following LPS injection. Taken together, our results suggest a novel role for hypocretin in the hypothalamic response to peripheral immune challenge. Our findings contribute to the understanding of the pathophysiology of narcolepsy.