Sustained diabetes remission induced by FGF1 involves a shift in transcriptionally distinct AgRP neuron...

In rodent models of type 2 diabetes, a single intracerebroventricular (icv) injection of fibroblast growth factor 1 (FGF1) induces sustained remission of hyperglycemia. Overactive agouti-related peptide (AgRP) neurons, located in the hypothalamic arcuate nucleus, are a hallmark of diabetic states, and their long-term inhibition has been linked to FGF1's antidiabetic effects. To investigate the underlying mechanism(s), we performed single-nucleus RNA sequencing of the mediobasal hypothalamus at Days 5 and 14 post-injection in wild-type and diabetic (Lep^ob/ob) mice treated with FGF1 or vehicle. We found that AgRP neurons from Lep^ob/ob mice form a transcriptionally distinct, hyperactive subpopulation. By Day 5, icv FGF1 induced a subset of these neurons to shift toward a less active, wild-type-like state, characterized by reduced activity-linked gene expression that persisted through Day 14. Spatial transcriptomics revealed that this FGF1-responsive AgRP subset is positioned dorsally within the arcuate nucleus. The transcriptional shift was accompanied by transcriptional processes indicative of increased GABAergic signaling, axonogenesis, and astrocyte-AgRP and oligodendrocyte-AgRP interactions. These glial inputs involve astrocytic neurexins and the perineuronal net (PNN) component phosphacan, suggesting both intrinsic and extrinsic mechanisms underlie FGF1-induced AgRP silencing. Combined with evidence that FGF1 increases PNN assembly in the arcuate nucleus, our findings reveal a cell-type-specific model for how FGF1 elicits long-term reprogramming of hypothalamic circuits to achieve diabetes remission.