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Postnatal development of the rat intrinsic cardiac nervous system: a confocal laser scanning microscopy study in whole-mount atria.
- Source :
-
Tissue & cell [Tissue Cell] 2000 Oct; Vol. 32 (5), pp. 377-88. - Publication Year :
- 2000
-
Abstract
- We used confocal laser scanning microscopy and fluorescent immunohistochemistry to study the developmental pattern and distribution of specific neuronal phenotypes within the intrinsic cardiac nervous system in whole-mount atrial preparations from newborn to 5 week old rats. Individual ganglia and neuronal cell bodies were localized by means of two general neuronal markers: protein gene product 9.5 (PGP) and microtubule-associated protein two (MAP). In rats < or =2 weeks old there were two main subpopulations of intrinsic neurons located in the intraatrial septum and around the origin of the superior vena cava. The more abundant was a population of strongly tyrosine hydroxylase (TH) immunoreactive (IR) neurons (10-40 microm in diameter) most of which were also PGP-IR. The second, less numerous (approximately 60-70% than the TH-IR group) type of neurons exhibited ChAT-IR which colocalized with MAP-IR. Towards the end of the second postnatal week and during the third, the ganglia containing these neurons became more numerous and their localization also included tissues around the origins of the inferior vena cava and the pulmonary veins, as well as both atrial walls close to the AV junction. During the second and third postnatal weeks, when the extrinsic innervation of the adrenergic and cholinergic phenotypes largely increases, the intrinsic innervation also changed greatly, and around the 21st postnatal day it appeared to acquire mature characteristics. The TH-IR neurons changed their characteristics and formed two types of ganglia. The larger ganglia containing large cells (20-40 microm in diameter) expressed TH-IR mostly close to their inner body surface (approximately 80-90% of identified neurons). Most of these neurons also expressed neuropeptide Y (NPY)-IR, specifically around their nuclei. The second type of small strongly TH-IR neurons (approximately 10% of all identified neurons) were contained in smaller groups (20-50 cells) which were usually embedded into much larger ganglia (100-400 cells), containing large (20-50 microm) neurons. Unlike all other intrinsic neurons, these small TH-IR cells did not exhibit any PGP-IR or MAP-IR. The number of ChAT-IR neurons increased at this stage, reaching approximately 90% of the neurons identified by the general neuronal markers. These neurons were surrounded by a rich network of cholinergic varicose nerve fibers, some of which were likely of an extrinsic origin. We have also identified relatively small ganglia expressing immunoreactivity to vasoactive intestinal polypeptide (VIP), and to substance P (SP). The presented data indicate that the phenotypes of intrinsic neurons in the rat heart change greatly during the first month of postnatal development. This may be at least partially related to the development and maturation of functional extrinsic nervous control of the heart.
- Subjects :
- Age Factors
Animals
Animals, Newborn
Antigens, Differentiation biosynthesis
Heart growth & development
Heart Atria growth & development
Heart Atria innervation
Heart Septum metabolism
Immunohistochemistry
Microscopy, Confocal
Microtubule-Associated Proteins biosynthesis
Nervous System growth & development
Neuropeptide Y biosynthesis
Phenotype
Rats
Substance P biosynthesis
Time Factors
Tyrosine 3-Monooxygenase metabolism
Ubiquitin Thiolesterase
Vasoactive Intestinal Peptide biosynthesis
Vena Cava, Superior metabolism
Heart innervation
Heart Atria ultrastructure
Myocardium ultrastructure
Nervous System ultrastructure
Subjects
Details
- Language :
- English
- ISSN :
- 0040-8166
- Volume :
- 32
- Issue :
- 5
- Database :
- MEDLINE
- Journal :
- Tissue & cell
- Publication Type :
- Academic Journal
- Accession number :
- 11201277
- Full Text :
- https://doi.org/10.1054/tice.2000.0126