RESUMEN
Anorexia nervosa (AN) is a severe eating disorder where caloric restriction, excessive physical activity and metabolic alterations lead to life-threatening situations. Despite weight restoration after treatment, a significant part of patients experience relapses. In this translational study, we combined clinical and preclinical approaches. We describe preliminary data about the effect of weight gain on the symptomatology of patients suffering from acute AN (n = 225) and partially recovered (n = 41). We measured more precisely physical activity with continuous cardiac monitoring in a sub-group (n = 68). Using a mouse model, we investigated whether a long-term food restriction followed by nutritional recovery associated or not with physical activity may differentially impact peripheral and central homeostatic regulation. We assessed the plasma concentration of acyl ghrelin, desacyl ghrelin and leptin and the mRNA expression of hypothalamic neuropeptides and their receptors. Our data show an effect of undernutrition history on the level of physical activity in AN. The preclinical model supports an important role of physical activity in the recovery process and points out the leptin system as one factor that can drive a reliable restoration of metabolic variables through the hypothalamic regulation of neuropeptides involved in feeding behavior.
Asunto(s)
Anorexia Nerviosa/metabolismo , Anorexia Nerviosa/rehabilitación , Ejercicio Físico , Adolescente , Adulto , Animales , Anorexia Nerviosa/sangre , Índice de Masa Corporal , Peso Corporal , Conducta Alimentaria , Femenino , Ghrelina/análogos & derivados , Ghrelina/sangre , Ghrelina/metabolismo , Frecuencia Cardíaca , Humanos , Hipotálamo/metabolismo , Leptina/sangre , Ratones , Ratones Endogámicos C57BL , Modelos Animales , Neuropéptidos/metabolismo , ARN Mensajero/metabolismo , Recurrencia , Aumento de Peso , Adulto JovenRESUMEN
Although the short-term effects of fasting or energy deficit on hypothalamic neuropeptide circuitries are now better understood, the effects of long-term energy deficit and refeeding remain to be elucidated. We showed that after a long-term energy deficit, mice exhibited persistent hypoleptinemia following the refeeding period despite restoration of fat mass, ovarian activity, and feeding behavior. We aimed to examine the hypothalamic adaptations after 10 weeks of energy deficit and after 10 further weeks of nutritional recovery. To do so, we assessed the mRNA levels of the leptin receptor and the main orexigenic and anorexigenic peptides, and their receptors regulated by leptin. Markers of hypothalamic inflammation were assessed as leptin can also participate in this phenomenon. Long-term time-restricted feeding and separation induced significant increase in mRNA levels of hypothalamic orexigenic peptides, while both Y1 and Y5 receptor mRNAs were downregulated. No changes occurred in the mRNA levels of orexin (OX), melanin-concentrating hormone, pro-opiomelanocortin, 26RFa (26-amino acid RF-amide peptide), and their receptors despite an increase in the expression of melanocortin receptors (MC3-R and MC4-R) and OXR1 (OX receptor 1). The refeeding period induced an overexpression of leptin receptor mRNA in the hypothalamus. The other assessed mRNA levels were normalized except for Y2, Y5, MC3-R, and MC4-R, which remained upregulated. No convincing changes were observed in neuroinflammatory markers, even if interleukin-1ß mRNA levels were increased in parallel with those of Iba1 (ionized calcium-binding adaptor molecule 1), a marker of microglial activation. Normalization of leptin-regulated functions and hypothalamic gene expressions in refed mice with low plasma leptin levels could be sustained by recalibration of hypothalamic sensitivity to leptin.
Asunto(s)
Modelos Animales de Enfermedad , Ingestión de Alimentos/fisiología , Hipolipoproteinemias/patología , Hipotálamo/metabolismo , Leptina/metabolismo , Proteína Relacionada con Agouti/metabolismo , Animales , Peso Corporal/fisiología , Citocinas/genética , Citocinas/metabolismo , Femenino , Hipolipoproteinemias/sangre , Hormonas Hipotalámicas , Melaninas , Ratones , Ratones Endogámicos C57BL , Neuropéptido Y/metabolismo , Neuropéptidos/metabolismo , Orexinas/genética , Orexinas/metabolismo , Hormonas Hipofisarias , ARN Mensajero/metabolismo , Receptores de Leptina/genética , Receptores de Leptina/metabolismo , Receptores de Neuropéptido/genética , Receptores de Neuropéptido/metabolismoRESUMEN
The presence of mycotoxins in food is a major problem of public health as they produce immunosuppressive, hepatotoxic and neurotoxic effects. Mycotoxins also induce mutagenic and carcinogenic effects after long exposure. Among mycotoxins that contaminate food are aflatoxins (AF) such as AFB1, which is the most powerful natural carcinogen. The AF poisoning results in symptoms of depression, anorexia, diarrhea, jaundice or anemia that can lead to death, but very few studies have explored the impact of AF on neuroendocrine regulations. To better understand the neurotoxic effects of AF related to anorexia, we explored in rat the impact of AFB1 on the major hypothalamic neuropeptides regulating feeding behavior, either orexigenic (NPY, Orexin, AgRP, MCH) or anorexigenic (α-MSH, CART, TRH). We also studied the effect of AFB1 on a novel neuropeptide, the secretogranin II (SgII)-derived peptide EM66, which has recently been linked to the control of food intake. For this, adult male rats were orally treated twice a week for 5 weeks with a low dose (150 µg/kg) or a high dose (300 µg/kg) of AFB1 dissolved in corn oil. Repeated exposure to AFB1 resulted in reduced body weight gain, which was highly significant for the high dose of AF. Immunocytochemical and quantitative PCR experiments revealed a dose-related decrease in the expression of all the hypothalamic neuropeptides studied in response to AFB1. Such orexigenic and anorexigenic alterations may underlie appetite disorders as they are correlated to a dose-dependent decrease in body weight gain of treated rats as compared to controls. We also found a decrease in the number of EM66-containing neurons in the arcuate nucleus of AFB1-treated animals, which was associated with a lower expression of its precursor SgII. These findings show for the first time that repeated consumption of AFB1 disrupts the hypothalamic regulation of neuropeptides involved in feeding behavior, which may contribute to the lower body weight gain associated to AF exposure.
Asunto(s)
Aflatoxina B1/farmacología , Conducta Alimentaria/efectos de los fármacos , Hipotálamo/efectos de los fármacos , Neuropéptidos/metabolismo , Venenos/farmacología , Análisis de Varianza , Animales , Peso Corporal/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Regulación de la Expresión Génica/efectos de los fármacos , Masculino , Neuropéptidos/genética , ARN Mensajero/metabolismo , Distribución Aleatoria , Ratas , Ratas WistarRESUMEN
26RFa is a hypothalamic neuropeptide that promotes food intake. 26RFa is upregulated in obese animal models, and its orexigenic activity is accentuated in rodents fed a high-fat diet, suggesting that this neuropeptide might play a role in the development and maintenance of the obese status. As obesity is frequently associated with type 2 diabetes, we investigated whether 26RFa may be involved in the regulation of glucose homeostasis. In the current study, we show a moderate positive correlation between plasma 26RFa levels and plasma insulin in patients with diabetes. Plasma 26RFa concentration also increases in response to an oral glucose tolerance test. In addition, we found that 26RFa and its receptor GPR103 are present in human pancreatic ß-cells as well as in the gut. In mice, 26RFa attenuates the hyperglycemia induced by a glucose load, potentiates insulin sensitivity, and increases plasma insulin concentrations. Consistent with these data, 26RFa stimulates insulin production by MIN6 insulinoma cells. Finally, we show, using in vivo and in vitro approaches, that a glucose load induces a massive secretion of 26RFa by the small intestine. Altogether, the present data indicate that 26RFa acts as an incretin to regulate glucose homeostasis.
Asunto(s)
Glucosa/metabolismo , Homeostasis/fisiología , Hipotálamo/metabolismo , Incretinas/metabolismo , Neuropéptidos/metabolismo , Animales , Línea Celular Tumoral , Diabetes Mellitus Tipo 1/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Prueba de Tolerancia a la Glucosa , Humanos , Insulina/metabolismo , Células Secretoras de Insulina/metabolismo , Ratones , Obesidad/metabolismoRESUMEN
26RFa is a hypothalamic RFamide neuropeptide that was identified as the endogenous ligand of the orphan G protein-coupled receptor, GPR103, and that stimulates appetite in mice. Up until now, the mechanism of action of 26RFa in the hypothalamic control of food intake remains unknown. The high density of GPR103 in the arcuate nucleus (Arc) prompted us to investigate, in the present study, the effects of 26RFa on the rat neuropeptide Y (NPY)/proopiomelanocortin (POMC) system. Intracerebroventricular injection of 26RFa stimulated NPY expression and release in the basal hypothalamus, whereas it decreased POMC expression and alpha-MSH release, and these effects were associated with an increase in food intake. A double in situ hybridization procedure indicated that the 26RFa receptor is present in NPY neurons of the Arc, but not in POMC neurons. Central administration of NPY Y1 and Y5 receptor antagonists abolished the inhibitory effects of 26RFa on POMC expression and alpha-MSH release, and reversed 26RFa-induced food consumption. Finally, 26RFa antagonized the effects of leptin on NPY expression and release, POMC expression and alpha-MSH release, and food intake. Altogether, the present data demonstrate for the first time that 26RFa exerts its orexigenic activity by stimulating the release of NPY in the Arc, which in turn inhibits POMC neurons by activating the Y1 and Y5 receptors. It is also suggested that the balance 26RFa/leptin is an important parameter in the maintenance of energy homeostasis.
Asunto(s)
Regulación del Apetito/efectos de los fármacos , Núcleo Arqueado del Hipotálamo/fisiología , Neuropéptido Y/metabolismo , Neuropéptidos/farmacología , Proopiomelanocortina/metabolismo , Animales , Regulación del Apetito/genética , Núcleo Arqueado del Hipotálamo/efectos de los fármacos , Núcleo Arqueado del Hipotálamo/metabolismo , Ingestión de Alimentos/efectos de los fármacos , Ingestión de Alimentos/genética , Metabolismo Energético/efectos de los fármacos , Metabolismo Energético/genética , Regulación de la Expresión Génica/efectos de los fármacos , Hormonas Hipotalámicas/administración & dosificación , Hormonas Hipotalámicas/farmacología , Hipotálamo/efectos de los fármacos , Hipotálamo/metabolismo , Inyecciones Intraventriculares , Leptina/metabolismo , Masculino , Neuronas/efectos de los fármacos , Neuronas/metabolismo , Neuronas/fisiología , Neuropéptido Y/genética , Neuropéptido Y/fisiología , Neuropéptidos/administración & dosificación , Proopiomelanocortina/fisiología , Ratas , Ratas Wistar , alfa-MSH/metabolismoRESUMEN
To determine the possible role of pituitary adenylate cyclase-activating polypeptide (PACAP) in the development of the sympathoadrenal cell lineage, we have examined the effects of this neurotrophic peptide, in comparison to nerve growth factor (NGF), on the morphology, electrophysiological properties, expression of neuronal and neuroendocrine marker genes, and activity of transcription factors during differentiation of sympathoadrenal-derived cells, using the rat pheochromocytoma PC12 cell model. Both PACAP and NGF elicited rapid neurite outgrowth, which was accompanied by induction of cell excitability and the development of both sodium and calcium currents. Concurrently, PACAP and NGF increased the expression of a marker of synaptic vesicles. By contrast, PACAP, but not NGF, regulated the expression of different constituents of neuroendocrine large dense core vesicles in PC12 cells. Furthermore, PACAP and NGF differentially regulated the expression of mammalian achaete-scute homologue and paired homeobox 2b genes, transcription factors instrumental for sympathoadrenal development. To compare downstream effectors activated by PACAP and NGF, we studied the effects of these factors on the binding activity of consensus 12-O-tetradecanoylphorbol-13-acetate- and cAMP-responsive elements to nuclear extracts of differentiating PC12 cells. We found that both PACAP and NGF markedly increase the binding activity of these cis-regulatory sequences and that PACAP preferentially recruits activator protein-1-like transcription factors to these elements. Taken together, these results show that PACAP and NGF exert common as well as different effects on neuronal and neuroendocrine traits in differentiating PC12 cells, strongly suggesting that these two trophic factors could play complementary roles in the development of the sympathoadrenal cell lineage.