Leptin protects the pancreas from damage induced by caerulein overstimulation by modulating cytokine production.
BACKGROUND
Recent identification of specific leptin receptors in the pancreas suggests that this peptide may also play some role in this gland.


OBJECTIVE
To examine the effect of intraperitoneal (i.p.) or intracerebroventricular (i.c.v.) administration of leptin in rats on caerulein-induced pancreatitis (CIP), pancreatic gene expression of leptin and inflammatory cytokine production.


METHODS
Caerulein (25 micrograms/kg) was infused subcutaneously into conscious rats over 5 h to produce CIP. Leptin (1, 5, or 10 micrograms/kg) was injected i.p. or i.c.v. 30 min prior to the CIP induction. The plasma level of TNF alpha and IL-4 was determined by ELISA, while plasma leptin was measured by RIA and leptin gene expression in pancreas by RT-PCR.


RESULTS
CIP was characterized by the usual pancreatic edema, reduction in pancreatic blood flow (PBF) and an increase in serum levels of amylase, TNF alpha and IL-4. Pretreatment with i.p. or i.c.v. leptin of the CIP rats partially reversed the harmful effects of CIP on the pancreas, and reduced pancreatic inflammation and the fall in PBF. This was accompanied by a dose-dependent reduction in serum levels of amylase and TNF alpha, while serum IL-4 in the CIP rats pretreated with leptin rose dose-dependently as compared to control rats with CIP alone. Pretreatment with leptin resulted in the dose-dependent rise in plasma leptin level over that observed in vehicle-treated controls. Leptin mRNA expression in the pancreas was dose-dependently increased after infusion of caerulein. Leptin content in isolated pancreatic acini was also increased dose-dependently by caerulein added to the incubation medium bathing these acini.


CONCLUSIONS
(1) Exogenous leptin protects the pancreas against damage by CIP; (2) endogenous leptin seems to limit the extend of pancreatic damage, and (3) these protective effects of leptin could be attributed to the reduction in TNF alpha and to the increase in IL-4 production.
Department of Physiology, Jagiellonian University Medical College, Cracow, Poland.
Jolanta
J
Jaworek
Joanna
J
Bonior
Piotr
P
Pierzchalski
Romana
R
Tomaszewska
Jerzy
J
Stachura
Ryszard
R
Sendur
Anna
A
Leja
Bozena
B
Jachimczak
Peter C
PC
Konturek
Władysław
W
Bielański
Wiesław
W
Pawlik
Stanisław J
SJ
Konturek
D000818:Animals; D002108:Ceruletide / Q000494:pharmacology*; D016207:Cytokines / Q000096:biosynthesis*; D015870:Gene Expression / Q000187:drug effects; D066298:In Vitro Techniques; D007274:Injections, Intraperitoneal; D007276:Injections, Intraventricular; D015847:Interleukin-4 / Q000097:blood; D020738:Leptin / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D008297:Male; D009994:Osmolar Concentration; D010179:Pancreas / Q000187:drug effects* / Q000473:pathology; D010195:Pancreatitis / Q000139:chemically induced / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D016207:Cytokines; D020738:Leptin; D014409:Tumor Necrosis Factor-alpha; D015847:Interleukin-4; D002108:Ceruletide