Tripeptidyl peptidase I activity in porcine lumbar spinal ganglia - a histochemical study

Distribution of tripeptidyl peptidase I (TPPI) activity in the structures of porcine lumbar spinal ganglia (LSG) was studied by enzyme histochemistry on cryostat sections from all the ganglia using the substrate glycyl-L-prolyl-L-methionyl-5-chloro-1-anthraquinonyl hydrazide (GPM-CAH) and 4-nitrobenzaldehyde (NBA) as visualization factor. Light microscopic observations showed TPPI activity in almost all the LSG structures. The enzyme reaction in different cell types was compared semi-quantitatively. Strong reaction was observed in the small neurons, satellite ganglia cells and some nerve fibers. Weak reactivity was found in the large sensory somatic neurons, whereas moderate reaction for TPPI was determined in the middle sensory somatic neurons and some nerve fibers. Statistical analysis by one-way ANOVA showed no significance of difference (when p⟨0.05) for the number of TPPI positive neurons per mm2. The original data obtained by the enzyme histochemistry method give us a reason to presume that TPPI actively participates in the functions of all the neuronal structures in porcine LSG. According to our results, it could be suggested that TPPI activity is important for the functions of autonomic and somatic sensory neurons.