Fig 2: Hypothalamic overexpression of soluble CX3CL1 reduces weight gain, food intake and improves leptin sensitivity in DIO mice. (A) Schematic diagram of a mouse coronal brain section indicating bilateral administration of AAVs into the mediobasal hypothalamus. (B,C) Representative image of a hypothalamic section from a mouse treated with AAV–CX3CL1-s. CX3CL1-s overexpression in the MBH is indicated by HA staining (red). Higher magnification view in C shows broad expression in the arcuate nucleus (ARC) and ventromedial hypothalamus (VMH). (D,E) Body weight gain (D) and 24 h food intake (E) in HFD-fed mice with hypothalamic overexpression of GFP (AAV–GFP) or the soluble isoform of CX3CL1 (AAV–CX3CL1-s) measured daily over the first week and then bi-weekly until day 25 of HFD. (F) Cumulative food intake over days 1–2 (left panel), 3–7 (middle panel) and 8–24 (right panel). (G) 24 h and 48 h food intake after i.p. saline or leptin injections (2 µg/g/day) in AAV–GFP and AAV–CX3CL1-s mice on HFD. Data are presented as mean ± SEM of at least 6 animals per group. (H) Hypothalamic mRNA expression of Pomc in chow-fed AAV–GFP and AAV–CX3CL1-s mice. Data are expressed as a percentage of AAV–GFP control; n = 6 per group. * p < 0.05; *** p < 0.001.

Fig 3: Central CX3CL1 does not reduce weight gain and food intake in mice treated with MC3R/MC4R antagonist. (A) Time scale of the experimental approach used for acute i.c.v. administration of SHU9119 and CX3CL1. (B,C) Average of cumulative 24 h food intake (A) and body weight gain (B) in mice treated with saline (Sal) or SHU9119 i.c.v. and 30 min later with Sal or CX3CL1 i.c.v. Data are presented as mean ± SEM of at least 5 animals per group. * p < 0.05. (D) Time scale for chronic i.c.v. administration of SHU9119 in mice previously subjected to hypothalamic viral microinjection of AAV–GFP and AAV–CX3CL1. (E,F) Body weight gain (E) and total food intake (F) measured in mice with hypothalamic overexpression of CX3CL1-s or GFP control that received SHU9119 i.c.v. infusion over 2 weeks (compare with Figure 1D). Data are presented as mean ± SEM of 10 animals per group. * p < 0.05.