Substance P expresses in intrapancreatic ganglia of the rats

Substance P (SP) is an important neuropeptide regulating the functions of the pancreas and might play a vital role in the onset of diabetes. SP has been shown to express in nerve fibers of the pancreas, but whether SP exists in the intrapancreatic ganglia, which are components of a complex autonomous nervous system to co-ordinate the functions of the pancreas, is unsure. The aim of this study was to systematically investigate rat intrapancreatic ganglia and the expression of SP in intrapancreatic ganglia. After surgical denervation of posterior branches of bilateral T₅-L₂ dorsal root ganglia, SP expression remained >60% in the pancreas. Moreover, after high doses of capsaicin were injected to destroy sensory nerves, the remainder of SP protein levels was still >50% in the pancreas. In the intrapancreatic ganglia, for anti-SP polyclonal antibody, the immunoreactivity to SP was found in 34.0±1.2% of PGP 9.5-positive intrapancreatic neurons (47 ganglia from 13 rats); for anti-SP monoclonal antibody, the immunoreactivity to SP was found in 26.6±1.0% of PGP 9.5-positive intrapancreatic neurons (18 ganglia from 6 rats). In summary, the present molecular and immunocytochemistry studies showed that there existed intrinsic SP expression in the neurons of intrapancreatic ganglia, which constituted around half of SP origins in the pancreas suggesting that intrapancreatic ganglia might play an important role on mechanisms involving SP.