Fetal hypothalamic neuroprogenitor cell culture: preferential differentiation paths induced by leptin and insulin

In response to temporally orchestrated growth factor stimulation, developing neural stem/progenitor cells undergo extensive self-renewal and then generate neurons and astrocytes. Fetal neonatal leptin and insulin deficiency results in reduced hypothalamic axonal pathways regulating appetite, which may predispose to offspring hyperphagia and obesity. Neural development of the arcuate nucleus, a key target of adiposity signals, leptin and insulin, is immature at birth. Hence, to explore proximate effects of leptin/insulin on hypothalamic development, we determined trophic and differentiation effects on neural stem/progenitor cells using a model of fetal hypothalamic neurospheres (NS). NS cultures were produced from embryonic d 20 fetal rats and passage 1 and passage 2 cells examined for proliferation and differentiation into neurons (neuronal nuclei, class IIIβ-tubulin, and doublecortin) and astrocytes (glial fibrillary acidic protein). Leptin-induced NS proliferation was significantly greater than that induced by insulin, although both effects were blocked by Notch, extracellular signal-regulated kinase, or signal transducer and activator of transcription 3 inhibition. Leptin preferentially induced neuronal, whereas insulin promoted astrocyte differentiation. Extracellular signal-regulated kinase inhibition suppressed both leptin and insulin-mediated differentiation, whereas signal transducer and activator of transcription inhibition only affected leptin-mediated responses. These findings demonstrate preferential and disparate differentiation paths induced by leptin and insulin. Altered fetal exposure to leptin or insulin, resulting from fetal growth restriction, macrosomia, or maternal diabetes, may potentially have marked effects on fetal brain development.