Article

Melatonin as modulator of pancreatic enzyme secretion and pancreatoprotector.

Department of Med Physiology, Faculty of Health Sciences, Jagiellonian University Medical College, 16 Grzegorzecka Street, Kraków, Poland.
Journal of physiology and pharmacology: an official journal of the Polish Physiological Society (impact factor: 2.27). 01/2008; 58 Suppl 6:65-80. pp.65-80
Source: PubMed

ABSTRACT Melatonin, the main product of the pineal gland, is also released from the gastrointestinal endocrine-neurocrine (EE) cells. The concentrations of melatonin produced in the gut exceeds that originating from central nervous system. In spite of the presence of melatonin receptors in the pancreatic tissue little is known about the role of this indole in the pancreas. Our experimental studies have shown that exogenous melatonin, as well as this produced endogenously from its precursor; L-tryptophan, strongly stimulates pancreatic amylase secretion when given intraperitoneally, or into the gut lumen. This was accompanied by significant increases of CCK plasma level. Above pancreatostimulatory effects of luminal administration of melatonin, were completely reversed by bilateral vagotomy, capsaicin deactivation of sensory nerves or pretreatment of the rats with CCK1 receptor antagonist; tarazepide as well as serotonin antagonist; ketanserin. Melatonin, as well as its precursor; L-tryptophan, effectively protects the pancreas against the damage induced by caerulein overstimulation or ischemia/reperfusion. The beneficial effects of melatonin or L-tryptophan on acute pancreatitis could be related to the ability of melatonin to scavenge the free radicals, to activate antioxidative enzymes and to modulate the cytokine production.

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Keywords

bilateral vagotomy
 
capsaicin deactivation
 
CCK plasma level
 
CCK1 receptor antagonist
 
central nervous system
 
cytokine production
 
damage induced
 
exogenous melatonin
 
experimental studies
 
free radicals
 
gastrointestinal endocrine-neurocrine
 
indole
 
luminal administration
 
melatonin receptors
 
pancreatic tissue
 
pancreatostimulatory effects
 
pineal gland
 
produced endogenously
 
sensory nerves
 
stimulates pancreatic amylase secretion
 

J Jaworek