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

## TL;DR

Injecting FGF1 in the brain of diabetic mice leads to long-term diabetes remission by changing the activity of specific brain cells called AgRP neurons.

## Contribution

The study identifies a specific subpopulation of AgRP neurons in diabetic mice and shows how FGF1 induces a transcriptional shift in these neurons to achieve diabetes remission.

## Key findings

- AgRP neurons in diabetic mice form a distinct, hyperactive subpopulation.
- FGF1 injection reduces activity in these neurons, coinciding with increased GABAergic signaling and astrocyte interactions.
- The transcriptional shift involves processes like axonogenesis and perineuronal net assembly.

## Abstract

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 (Lepob/ob) mice treated with FGF1 or vehicle. We found that AgRP neurons from Lepob/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.

•snRNA-seq finds a hyperactive, distinct AgRP neuron subtype in hyperglycemic leptin-deficient mice.•Icv FGF1-induced diabetes remission drives in dorsal AgRP neurons a transcriptional state consistent with reduced activity.•Reduced activity coincides with increased GABAergic signaling, axonogenesis, PNNs, and astro-/oligodendrocyte cues.

snRNA-seq finds a hyperactive, distinct AgRP neuron subtype in hyperglycemic leptin-deficient mice.

Icv FGF1-induced diabetes remission drives in dorsal AgRP neurons a transcriptional state consistent with reduced activity.

Reduced activity coincides with increased GABAergic signaling, axonogenesis, PNNs, and astro-/oligodendrocyte cues.