Guinea pig pancreatic neurons: morphology, neurochemistry, electrical properties, and response to 5-HT

MT Liu, AL Kirchgessner - American Journal of Physiology …, 1997 - journals.physiology.org
MT Liu, AL Kirchgessner
American Journal of Physiology-Gastrointestinal and Liver …, 1997journals.physiology.org
The morphology, neurochemistry, and electrical properties of guinea pig pancreatic neurons
were determined. The majority of neurons expressed choline acetyltransferase (ChAT)
immunoreactivity; however, ChAT-negative neurons were also found. Both cholinergic and
noncholinergic neurons expressed nitric oxide synthase (NOS) immunoreactivity. Three
types of pancreatic neurons were distinguished. Phasic neurons fired action potentials (APs)
at the onset of depolarizing current pulse, tonic neurons spiked throughout the duration of a …
The morphology, neurochemistry, and electrical properties of guinea pig pancreatic neurons were determined. The majority of neurons expressed choline acetyltransferase (ChAT) immunoreactivity; however, ChAT-negative neurons were also found. Both cholinergic and noncholinergic neurons expressed nitric oxide synthase (NOS) immunoreactivity. Three types of pancreatic neurons were distinguished. Phasic neurons fired action potentials (APs) at the onset of depolarizing current pulse, tonic neurons spiked throughout the duration of a suprathreshold depolarizing pulse, and APs could not be generated in nonspiking neurons, even though they did receive synaptic input. APs were tetrodotoxin sensitive, and all types of neurons received fast and slow excitatory postsynaptic potentials (EPSPs). Fast EPSPs had cholinergic and noncholinergic components. The majority of pancreatic neurons appeared to innervate the acini. NOS- and/or neuropeptide Y-immunoreactive phasic and tonic neurons were found. Microejection of 5-hydroxytryptamine (5-HT) caused a slow depolarization that was inhibited by the 5-HT1P antagonistN-acetyl-5-hydroxytryptophyl-5-hydroxytryptophan amide and mimicked by the 5-HT1Pagonist 6-hydroxyindalpine. A pancreatic 5-HT transporter was located, and inhibition of 5-HT uptake by fluoxetine blocked slow EPSPs in 5-HT-responsive neurons by receptor desensitization.
American Physiological Society