In rats with sepsis, feeding them through a tube (enteral nutrition) boosted the hormone ghrelin and turned on a brain pathway that reduced the breakdown of muscle and other tissues. When the researchers blocked the ghrelin receptor with a peptide (D‑Lys³‑GHRP‑6) or blocked a cell‑clean‑up process (autophagy), the protective effect disappeared. This shows that ghrelin signaling is needed for the anti‑catabolic benefits of nutrition in this severe illness model.

Sustained hypercatabolism induced by sepsis contributed to serious complications and mortality in the intensive care unit. Enteral nutrition (EN) was required to maintain the energy balance during sepsis. Ghrelin, which was stimulated secretion by EN, had been shown to regulate energy homeostasis. Therefore, we tested whether EN alleviated hypercatabolism through ghrelin/GH secretagogue receptor 1α (GHS-R1α)-proopiomelanocortin (POMC) in endotoxemic rats. Rats in the Sham and lipopolysaccharide (LPS) groups were free access to rodent chow diet and water. Rats in the EN, EN + Lys and EN + 3-MA groups were intracerebroventricularly injected with saline, _D-Lys³-GHRP-6 or 3-MA and then received EN for three days. Hypercatabolism was measured by the change of body weight, insulin resistance, leptin, corticosterone, muscle protein synthesis and atrophy. Serum and hypothalamic total ghrelin, acylated ghrelin, GHS-R1α and AMP-activated protein kinase (AMPK)-autophagy-POMC pathway were also detected. The results showed that EN increased serum and hypothalamic total ghrelin, acylated ghrelin and GHS-R1α, effectively activated the hypothalamic AMPK-autophagy-POMC pathway and alleviated hypercatabolism in endotoxemic rats. The improving effects of EN on hypercatabolism and hypothalamic AMPK-autophagy-POMC pathway were abolished with the central administration of _D-Lys³-GHRP-6 to inhibited hypothalamic GHS-R1α. And with the central administration of 3-MA to inhibited hypothalamic autophagy, the improving effect of EN on hypercatabolism was also abolished in endotoxemic rats. In conclusions, EN could significantly alleviate hypercatabolism through ghrelin/GHS-R1α-POMC in endotoxemic rats.