Fig. 4

ICV leptin requires intact vagal innervation to regulate hepatic lipid metabolism. a Study timeline for chronic ICV leptin/vehicle infusion studies after selective hepatic sympathectomy (Sx) or vagotomy (Vx). b, c Hepatic lipid content after selective hepatic sympathectomy (n ≥ 4 per group) (b) and liver vagotomy (n ≥ 4 per group) (c) after 28 days of continuous ICV leptin/vehicle infusion (Leptin: 0.3 µg/day). d Study timeline and protocol for tyloxapol infusion studies in rats with hepatic vagotomy that received a 4 h ICV leptin/vehicle infusion. e Progressive accumulation of plasma TGs after an IV tyloxapol bolus (n ≥ 3 per group). f VLDL secretion rates calculated from the slopes depicted in Fig. 4e. g Plasma increase in TG levels following a tyloxapol bolus after a targeted 4 h leptin/vehicle infusion directly into the mediobasal hypothalamus (MBH; n ≥ 5 per group). h VLDL secretion rates calculated from the slopes in Fig. 4g. i Plasma increase in TG levels following a tyloxapol bolus after a targeted 4 h leptin/vehicle infusion directly into the dorsal vagal complex (DVC). j VLDL secretion rates calculated from the slopes in Fig. 4i (n ≥ 3 per group). All data are mean ± SEM; *p < 0.05; **p < 0.01; vs vehicle group if not otherwise indicated by brackets. n.s. not significant by two-tailed Student’s t test; open circles: vehicle; black squares: leptin; green triangles pointing down: ICV vehicle plus liver Sx; violet triangles pointing up: ICV leptin plus liver Sx; blue triangles pointing down: ICV vehicle plus liver Vx; red triangles pointing up: ICV leptin plus liver Vx