Hormonal protection in acute pancreatitis by ghrelin, leptin and melatonin

Abstract

Acute pancreatitis is a nonbacterial disease of the pancreas. The severe form of this ailment is characterized by high mortality. Whether acute pancreatitis develops as the severe type or resolves depends on the intensity of the inflammatory process which is counteracted by the recruitment of innate defense mechanisms. It has been shown that the hormones ghrelin, leptin and melatonin are able to modulate the immune function of the organism and to protect the pancreas against inflammatory damage. Experimental studies have demonstrated that the application of these substances prior to the induction of acute pancreatitis significantly attenuated the intensity of the inflammation and reduced pancreatic tissue damage. The pancreatic protective mechanisms of the above hormones have been related to the mobilization of non-specific immune defense, to the inhibition of nuclear factor kappa B and modulation of cytokine production, to the stimulation of heat shock proteins and changes of apoptotic processes in the acinar cells, as well as to the activation of antioxidant system of the pancreatic tissue. The protective effect of ghrelin seems to be indirect and perhaps dependent on the release of growth hormone and insulin-like growth factor 1. Leptin and ghrelin, but not melatonin, employ sensory nerves in their beneficial action on acute pancreatitis. It is very likely that ghrelin, leptin and melatonin could be implicated in the natural protection of the pancreatic gland against inflammatory damage because the blood levels of these substances increase in the initial phase of pancreatic inflammation. The above hormones could be a part of the innate resistance system which might remove noxious factors and could suppress or attenuate the inflammatory process in the pancreas.

Keywords: Acute pancreatitis; Ghrelin; Leptin; Melatonin; Protection.

Figure 1

Hypothetical mechanisms of the protective action of ghrelin, leptin and melatonin on acute pancreatitis. GH: Growth hormone; IGF-1: Insulin-like growth factor; NF-κB: Nuclear factor kappa B; HSP60: Heat shock protein 60; nNOS: Neural nitric oxide synthase; NO: Nitric oxide; TNFα: Tumor necrosis factor α; IL: Interleukin; MPO: Myeloperoxidase; SOD: Superoxide dismutase; CAT: Catalase; GPx: Glutathione peroxidase; GR: Glutathione reductase; ROS: Reactive oxygen species; RNS: Reactive nitrogen species.