Distribution of cocaine- and amphetamine-regulated transcript peptide in the guinea pig intrinsic cardiac nervous system and colocalization with neuropeptides or transmitter synthetic enzymes.
This study was conducted to establish the presence of cocaine- and amphetamine-regulated transcript peptide (CARTp) immunoreactivity in neurons and fibers within guinea pig atrial whole-mount preparations containing the intrinsic cardiac ganglia. Many cardiac ganglia, but not all, in a given whole-mount preparation, were innervated by CARTp-immunoreactive (IR) fibers. Following explant culture of whole mounts for 72 hours, the CARTp-IR fiber networks were absent, but the number of CARTp-IR neurons was increased markedly. These observations suggested that the majority of the CARTp-IR fibers in the intracardiac ganglia were derived from sources extrinsic to the heart. In control whole-mount preparations, very few CARTp-positive neurons were present. The few intrinsic CARTp-IR neurons also exhibited choline acetyltransferase (ChAT) immunoreactivity, indicating that they make up a small subpopulation of cholinergic postganglionic neurons. Some CARTp-IR neurons also exhibited nitric oxide synthase (NOS) immunoreactivity, indicating that they were nitrergic as well. We compared the immunohistochemical staining patterns of CARTp-IR fibers with the staining patterns of a number of other neurotransmitters or neurotransmitter synthetic enzymes that mark specific extrinsic inputs. The CARTp-IR fibers were not immunoreactive for ChAT, tyrosine hydroxylase, calcitonin gene-related peptide, or substance P. However, virtually all CARTp-IR fibers exhibited immunoreactivity to neuronal NOS (a marker for nitric oxide-producing neurons). CARTp-IR cells and NOS-IR cells were present in the nodose ganglia. In addition, CARTp-IR neurons in the nodose also were stained positively for NADPH-diaphorase. Thus, we propose that most CARTp-IR fibers within the guinea pig intrinsic cardiac ganglia are vagal afferent fibers that also contain NOS.
Calupca
M A
MA
Department of Anatomy and Neurobiology, College of Medicine, University of Vermont, Burlington, Vermont 05405, USA.
Locknar
S A
SA
Zhang
L
L
Harrison
T A
TA
Hoover
D B
DB
Parsons
R L
RL
D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D004798:Enzymes / Q000378:metabolism*; D005260:Female; D005724:Ganglia / Q000378:metabolism; D005727:Ganglia, Spinal / Q000378:metabolism; D006168:Guinea Pigs; D006329:Heart Conduction System / Q000378:metabolism*; D008297:Male; D009412:Nerve Fibers / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009479:Neuropeptides / Q000378:metabolism*; D018377:Neurotransmitter Agents / Q000096:biosynthesis*; D009435:Synaptic Transmission / Q000502:physiology; D014018:Tissue Distribution; D014630:Vagus Nerve / Q000502:physiology; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein
D004798:Enzymes; D009419:Nerve Tissue Proteins; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein; D002795:Choline O-Acetyltransferase