The protective role of melatonin on L-arginine-induced acute pancreatitis in adult male albino rats.

BACKGROUND

Acute pancreatitis (AP) is an inflammatory disease that has an increasing incidence worldwide. AP is associated with high morbidity and mortality rates ranging 15-40% in its severe form. Oxidative stress plays an important role in pancreatic acinar cell injury in case of AP. Melatonin (Mel) is proven to have both antioxidant and anti-inflammatory effects. The aim of the work was to investigate the protective role of Mel against L-arginine (L-arg)-induced AP in adult male albino rats.

METHODS

Thirty-six adult male albino rats were used in this study. Animals were divided into four groups; Control group (Group A; n = 6), Mel group (Group B; n = 6), L-arg group (Group C; n = 12) receiving two doses of L-arg injection with 1 h interval in-between, and L-arg+Mel group (Group D; n = 12) receiving Mel 1 h after each L-arg injection. 24 h after the second L-arg injection, the serum levels of amylase (AM), lipase (LP), interleukin-6 (IL-6) and tumour necrotic factor-alpha (TNF-α) were determined. Then, pancreatic specimens were processed for histological and immunohistochemical staining with vascular endothelial growth factor (VEGF) and the area percentage of VEGF and collagen content were measured by digital image analysis.

RESULTS

Microscopic examination revealed that animals received L-arg only (Group C) showed loss of the pancreatic lobular architecture with marked fibrosis, acinar degeneration, inflammatory reaction and marked oedema with vascular congestion. Also, L-arg-induced AP caused a significant elevation of the serum levels of AM, LP, IL-6. All these histo-pathological and serological parameters were markedly improved by Mel administration.

CONCLUSIONS

Melatonin exhibits strong therapeutic effects in the course of AP. Hence, the use of Mel as adjuvant treatment in AP is recommended.