Title : Long-term treatment with indomethacin increases the number of SP-immunoreactive porcine duodenal neurons
Gastrointestinal inflammation resulting from prolonged NSAID drugs treatment constitutes a worldwide medical problem. Recently the role of enteric neuroactive substances involved in this process has gained attention. Therefore the aim of the study was to determine the effect of inflammation caused by indomethacin supplementation on substance P (SP) expression in enteric duodenal neurons in domestic pigs.
The study was carried out on eight immature pigs of the Pietrain x Duroc race (approximately 20 kg of body weight). The animals were divided into two groups - a control (C group) and an experimental group (I group). Group C (n=4) was consisted of animals which received empty gelatine capsules. Group I (n=4) was composed of pigs which naproxen were given orally (10 mg/kg) for 4 weeks, approximately 1 h before feeding. After this time, animals from both groups were euthanized. Then, frozen sections (14 μm thickness) were prepared from the collected material and subjected to double immunofluorescence staining. Antibodies against the neuronal marker PGP 9.5 and against the substance P were used as primary antibodies. The secondary antibodies - Alexa Fluor 488 and 546 - were also used for staining. Analysis of the sections was performed using an Olympus BX51 fluorescence microscope equipped with a XM10 monochrome camera.
Analysis of the results obtained with a fluorescence microscope showed significant increase in the number of SP immunoreactive submucosal neurons and a smaller increase in the number of SP positive neurons in the myenteric ganglia of the porcine duodenum.
The obtained results suggest that inflammation caused by the administration of high doses of naproxen increases the expression of substance P in the duodenal neurons in domestic pigs. Increased synthesis of this neurotransmitter may suggest the contribution of SP to the development of the local inflammatory process or the involvement of SP positive neurons in local repair processes.