Acute Anti-Inflammatory Effects of Neostigmine in the Rat Air Pouch Model of Inflammation

The aim of this study was to evaluate the effects of neostigmine on inflammatory parameters and histopathological changes of granulation tissue.

The Air Pouch model was developed in six groups of male Wistar rats. Briefly, the rats were anesthetized, and then 20 ml and 10 ml of sterile air were injected subcutaneously (SC) on the back of the animals on days 0 and 3, respectively. On day 6, inflammation was induced by injection of 2 ml of carrageenan 1% into pouches. Normal saline as control and neostigmine (35, 70, 140, 200, and 310 µg/kg) was administered intraperitoneally (IP) concurrently with carrageenan. After 6 hours, the rats were sacrificed; pouch fluid was collected to determine exudate volume and the number of accumulated cells. The pouches were dissected out and weighed, and histopathological characteristics were evaluated.

Neostigmine (70 µg/kg) reduced leukocyte accumulation (P < 0.050), exudate volume (P < 0.001), and granulation tissue weight (P < 0.001) compared to the carrageenan control group. Inflammatory parameters were increased by neostigmine 200 μg/kg (P < 0.050). The results of histopathological studies of granulation tissue showed that higher doses of neostigmine provided more anti-inflammatory effects.

From this study, it may be concluded that in the air pouch inflammatory model, neostigmine at different doses has different effects on peripheral inflammation. These effects are likely mediated by regulatory effects of the agent on the immune system.