Distribution of cocaine‐ and amphetamine‐regulated transcript peptide in the guinea pig intrinsic cardiac nervous system and colocalization with neuropeptides or transmitter synthetic enzymes

Abstract

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.

TRPC6 immunoreactivity is colocalized with neuronal nitric oxide synthase in extrinsic fibers innervating guinea pig intrinsic cardiac ganglia

“…We did not attempt to establish colocalization of NOS and TRPC6 in sections of nodose ganglia doubly labeled using the sheep antiserum directed against NOS. As indicated previously, the sheep antiserum directed against NOS did not consistently label cells above background in sections of nodose ganglia (Calupca et al, 2001).…”

Distribution of cocaine- and amphetamine-regulated transcript (CART), neuropeptide Y (NPY) and galanin (GAL) in the pterygopalatine ganglion of the domestic duck (Anas platyrhynchos f. domestica)

“…CART was found primarily in the brain, but is also present in the plexuses of the stomach muscular layer of mammals, e.g. in pig and wild boar (where it coexists with other biologically active neuropeptides, such as GAL, SP, and NPY) [27], sheep [28], various parts of rat's gastrointestinal [10], intramural ganglia of the pig urinary bladder in colocalization with pituitary adenylate cyclase-activating polypeptide (PACAP) [29] and in cardiac ganglia of a number of animals, including guinea pig and rat [30][31][32]. In the enteric nervous system CART is regarded as a strong neuroprotective factor.…”

Autonomic cardiac nerves: literature review

“…Many studies describing the presence of cocaineand amphetamine-related transcript peptide (CART) proteins in cardiac ganglia have been conducted recently [10,18,19,53,54,58]. The CART neuropeptide is also known as an anorexigen from other areas in the nervous system, mostly the hypothalamus, although there is an increasing number of reports of yet another function as a neurotransmitter in the ANS.…”

“…In guinea pigs, CART was found in vagus nerve endings in the heart and when it was injected in the solitary tract nucleus, baroreflex was impaired and bradycardia ensued [58]. Calupa et al [10] demonstrated that most (but not all) cardiac ganglia in guinea pigs were innervated by nerve fibres immunoreactive to CART. Only few neurocytes in cardiac ganglia were positive to CART.…”