Chemical Coding for Cardiovascular Sympathetic Preganglionic Neurons in Rats

Abstract

Cocaine and amphetamine-regulated transcript peptide (CART) is present in a subset of sympathetic preganglionic neurons in the rat. We examined the distribution of CART-immunoreactive terminals in rat stellate and superior cervical ganglia and adrenal gland and found that they surround neuropeptide Y-immunoreactive postganglionic neurons and noradrenergic chromaffin cells. The targets of CARTimmunoreactive preganglionic neurons in the stellate and superior cervical ganglia were shown to be vasoconstrictor neurons supplying muscle and skin and cardiac-projecting postganglionic neurons: they did not target non-vasoconstrictor neurons innervating salivary glands, piloerector muscle, brown fat, or adrenergic chromaffin cells. Transneuronal tracing using pseudorabies virus demonstrated that many, but not all, preganglionic neurons in the vasoconstrictor pathway to forelimb skeletal muscle were CART immunoreactive. Similarly, analysis with the confocal microscope confirmed that 70% of boutons in contact with vasoconstrictor ganglion cells contained CART, whereas 30% did not. Finally, we show that CART-immunoreactive cells represented 69% of the preganglionic neuron population expressing c-Fos after systemic hypoxia. We conclude that CART is present in most, although not all, cardiovascular preganglionic neurons but not thoracic preganglionic neurons with non-cardiovascular targets. We suggest that CART immunoreactivity may identify the postulated "accessory" preganglionic neurons, whose actions may amplify vasomotor ganglionic transmission.

Distribution and immunohistochemical characteristics of cocaine- and amphetamineregulated transcript-positive nerve elements in the pelvic ganglia of the female pig

“…Previously, the presence of CART was visualized in both sympathetic and parasympathetic parts of the autonomic nervous system, albeit the CART distribution patterns described seem to be species-specific and vary between particular autonomic centers/ganglia. The presence of dense pericellular baskets of varicose CART-IR terminals around and between sympathetic neurons of the superior cervical ganglion (Gonsalvez et al 2010), stellate ganglion (Dun et al 2000, Richardson et al 2006, coeliac-superior mesenteric ganglion (Palus and Całka 2016) or male major pelvic ganglion (Fenwick et al 2006) has been previously reported. With the use of the retrograde tracer cholera toxin unit it has been demonstrated that these CART-IR nerve terminals originate from CART-IR sympathetic preganglionic neurons (SPN) of the thoracolumbar medullary intermediolateral cell column and in case of major pelvic ganglia also from the central autonomic area and intercalated nucleus (Fenwick et al 2006).…”

“…However, none of the major pelvic ganglion-projecting SPN was found to express CART (Fenwick et al 2006), which suggests that pelvic splanchnic nerves do not participate in CART-like innervation to the porcine PP. Because in rats, experimental exposure to hypoxia induced the expression of c-fos in CART-IR SPN the concept that CART is exclusively present in vasoconstrictor neurons and mediates cardiovascular functions has been considered (Gonsalvez et al 2010). But in other studies, the treatment with hypotensive hydralazine evoked expression of c-fos in only 40% of CART-IR SPN which led the authors to conclude that CART is not an exclusive marker for cardiovascular SPN and may be also present in a subset of spinal interneurons (Fenwick et al 2006).…”

Autonomic cardiac nerves: literature review

“…Such correlation of chemical phenotype and neuron function is called chemical coding [19]. Many papers have been written on this topic.…”

“…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.…”

“…They also contained ChAT or NOS. Gonsalves et al [19] demonstrated that immunoreactive neurons are found in the stellate ganglion and the superior cervical ganglion and they project to the heart, mostly to vasoconstrictor neurons. Hasan and Smith [23] found that the sympathetic regulation of the parasympathetic neurochemical phenotype and the synthesis of neurotrophins can play a role in cardiac dysregulation and in other pathophysiological circumstances.…”