RESUMEN
In rodent models of type 2 diabetes (T2D), sustained remission of hyperglycemia can be induced by a single intracerebroventricular (icv) injection of fibroblast growth factor 1 (FGF1), and the mediobasal hypothalamus (MBH) was recently implicated as the brain area responsible for this effect. To better understand the cellular response to FGF1 in the MBH, we sequenced >79,000 single-cell transcriptomes from the hypothalamus of diabetic Lepob/ob mice obtained on Days 1 and 5 after icv injection of either FGF1 or vehicle. A wide range of transcriptional responses to FGF1 was observed across diverse hypothalamic cell types, with glial cell types responding much more robustly than neurons at both time points. Tanycytes and ependymal cells were the most FGF1-responsive cell type at Day 1, but astrocytes and oligodendrocyte lineage cells subsequently became more responsive. Based on histochemical and ultrastructural evidence of enhanced cell-cell interactions between astrocytes and Agrp neurons (key components of the melanocortin system), we performed a series of studies showing that intact melanocortin signaling is required for the sustained antidiabetic action of FGF1. These data collectively suggest that hypothalamic glial cells are leading targets for the effects of FGF1 and that sustained diabetes remission is dependent on intact melanocortin signaling.
Asunto(s)
Diabetes Mellitus Experimental/dietoterapia , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Factor 1 de Crecimiento de Fibroblastos/administración & dosificación , Hipoglucemiantes/administración & dosificación , Hipotálamo/efectos de los fármacos , Proteínas Recombinantes/administración & dosificación , Proteína Relacionada con Agouti/metabolismo , Animales , Astrocitos/efectos de los fármacos , Astrocitos/metabolismo , Glucemia/análisis , Comunicación Celular , Núcleo Celular/efectos de los fármacos , Núcleo Celular/metabolismo , Diabetes Mellitus Experimental/sangre , Diabetes Mellitus Experimental/etiología , Diabetes Mellitus Experimental/patología , Diabetes Mellitus Tipo 2/sangre , Diabetes Mellitus Tipo 2/etiología , Diabetes Mellitus Tipo 2/patología , Dieta Alta en Grasa/efectos adversos , Sacarosa en la Dieta/administración & dosificación , Sacarosa en la Dieta/efectos adversos , Humanos , Hipotálamo/citología , Hipotálamo/patología , Inyecciones Intraventriculares , Leptina/genética , Masculino , Melanocortinas/metabolismo , Hormonas Estimuladoras de los Melanocitos/administración & dosificación , Ratones , Ratones Noqueados , Neuronas/efectos de los fármacos , Neuronas/metabolismo , Oligodendroglía/efectos de los fármacos , Oligodendroglía/metabolismo , RNA-Seq , Receptor de Melanocortina Tipo 4/genética , Receptores de Melanocortina/antagonistas & inhibidores , Receptores de Melanocortina/metabolismo , Inducción de Remisión/métodos , Transducción de Señal/efectos de los fármacos , Análisis de la Célula Individual , Técnicas Estereotáxicas , Transcriptoma/efectos de los fármacosRESUMEN
We recently showed that perineuronal nets (PNNs) enmesh glucoregulatory neurons in the arcuate nucleus (Arc) of the mediobasal hypothalamus (MBH)1, but whether these PNNs play a role in either the pathogenesis of type 2 diabetes (T2D) or its treatment remains unclear. Here we show that PNN abundance within the Arc is markedly reduced in the Zucker diabetic fatty (ZDF) rat model of T2D, compared with normoglycaemic rats, correlating with altered PNN-associated sulfation patterns of chondroitin sulfate glycosaminoglycans in the MBH. Each of these PNN-associated changes is reversed following a single intracerebroventricular (icv) injection of fibroblast growth factor 1 (FGF1) at a dose that induces sustained diabetes remission in male ZDF rats. Combined with previous work localizing this FGF1 effect to the Arc area2-4, our finding that enzymatic digestion of Arc PNNs markedly shortens the duration of diabetes remission following icv FGF1 injection in these animals identifies these extracellular matrix structures as previously unrecognized participants in the mechanism underlying diabetes remission induced by the central action of FGF1.