NITRERGIC NEURONS IN THE PANCREAS OF NEWBORN GUINEA-PIG - THEIR DISTRIBUTION AND COLOCALIZATION WITH VARIOUS NEUROPEPTIDES AND DOPAMINE-BETA-HYDROXYLASE

The distribution of nitrergic neurons in the pancreas of the newborn g uinea pig was first investigated, using nitric oxide synthase (NOS) im munofluorescence and nicotinamide adenine dinucleotide hydrogen phosph ate-diaphorase (NADPH-d) histochemistry. There was total colocalizatio n of NOS and NADPH-d in the pancreatic ganglion cells. NADPH-d was the n used as a marker for NOS. In the whole mount preparation of the panc reas, most of the nitrergic neurons were located in the head and the b ody region, along the branches of pancreatic blood vessels. Some were also associated with the main pancreatic duct, islets of Langerhans an d pancreatic acini. To investigate whether NADPH-d stained cells were neurons and whether NADPH-d was colocalized with various neuropeptides and dopamine-beta-hydroxylase (D beta H), an enzyme involved in the s ynthesis of noradrenaline, antibodies against neuron specific enolase (NSE), vasoactive intestinal peptide (VIP), neuropeptide Y (NPY), D be ta H, substance P (SP), calcitonin gene-related peptide (CGRP) and bom besin (BOM) were used. Of all NSE positive ganglion cells, 76.8% were NADPH-d positive. NOS, VIP, NPY and D beta H immunoreactivities were f ound in both the neuronal cell bodies and nerve fibres in the pancreas while SP, CORP and BOM immunoreactivities were detected only in the n erve fibres. SP-, CGRP- and BOM-containing nerves were in close contac t with both NADPH-d positive as well as NADPH-d negative neurons. The percentages of NADPH-d/VIP, NADPH-d/NPY, NADPH-d/D beta H neurons in t he total number of pancreatic neurons were 67.4%, 53.5%, 21.5% respect ively. With double labelling in adjacent sections three subpopulations of pancreatic ganglion cells were demonstrated: NADPH-d/VIP/NPY, NADP H-d/VIP/D beta H and NADPH-d/NPY/D beta H.