Pancreatic neurons receive and integrate synaptic input from a wide variety
of extrinsic nerves while providing the predominant innervation of pancrea
tic acini, ducts, and islets of Langerhans. Here we report the first primar
y cultures of adult rabbit pancreatic neurons, isolated from extrinsic nerv
es and secretory cells, and evaluate the neurochemical and electrical prope
rties of these neurons. Pancreatic cultures consisted of single and cluster
ed neurons, extended varicose processes after 3-4 days in culture, and form
ed interconnecting networks of neurons after 7-10 days. Isolated pancreatic
islet cells, added to established neuron cultures, remained attached and v
iable for several weeks and received innervation by varicose nerve fibers.
Histochemical staining revealed populations of neurons positive for acetylc
holinesterase (75%), NADPH-diaphorase (62%), nitric oxide synthase (73%), a
nd/or vasoactive intestinal peptide (VIP) (65%). Intracellular recordings r
evealed active and passive electrical properties comparable to those of neu
rons from intact ganglia. Several distinct populations of neurons were iden
tified by their firing patterns (phasic vs. tonic) in response to prolonged
depolarizing currents or the amplitude and duration of their after-spike h
yperpolarizations. Low-amplitude, pacemaker-like potentials were observed i
n 25% of the neurons and, in older cultures with extensive networks of fibe
rs, spontaneous fast excitatory postsynaptic potentials (EPSPs) also occurr
ed. Thus these cultures retained the salient neurochemical and electrophysi
ologic properties observed in pancreatic neurons from intact ganglia and of
fer a good model for studies of the intrinsic innervation of the pancreas.