The vagal motor system is involved in the regulation of cardiorespiratory and gastrointestinal functions. Vagal motor neurons are localized near or adjacent to catecholaminergic neurons, but their co-localisation seems species dependent, present in the cat but absent in the rabbit. In pig, a species commonly used as an experimental model in humans brain disorders (sudden infant death syndrome, hypoxia), the relationship is poorly understood. We aimed at describing the distribution of vagal motor neurons and tyrosine hydroxylase-immunoreactive (-ir) neurons by using a double staining method in combination with retrograde tracing of vagal efferent neurons. After fluorogold impregnation of the central part of the sectioned left cervical vagal trunk, two main vagal motor neuronal populations were located in the dorsal motor nucleus of the vagus nerve (DMX) and in the area of the nucleus ambiguus (Amb). Like in the human, the DMX was composed of different subpopulations of neurons with the same morphological characteristics. Immunohistochemistry of catecholaminergic synthesizing enzymes differentiated two main sites containing vagal motor populations: the dorsomedial and the ventrolateral medulla. TH-ir was rarely seen in vagal motor neurons of the DMX, but TH-ir neurons were present around the two main vagal motor neuronal populations that contained TH-ir fibres. The anatomical organisation of the vagal motor and the catecholaminergic neuronal systems are similar to those described in humans and suggest that the involvement of the catecholamines in the control of the vagal motor system may be similar in pigs and in humans.
"The absence of the somatotopic arrangement of the vagal motor neurons supplying pylorus may be a consequence of the relatively small number of labeled cells in relation to the large dimensions of the whole area of the porcine DMX (Ruggiero et al., 2004) and the fact, that pylorus receives the vagal fibers by hepatic and gastric branches (Keet, 1993; Kressel et al., 1994; Phillips et al., 1997). Other studies on the distribution of the brainstem vagal neurons supplying particular structures in the pig are very sparse and concern the thoracic organs (Hopkins et al., 1984, 1997; Ruggiero et al., 2004; Smith, 1999), swallowing muscles including esophagus (Altschuler 2001; Wu et al., 2003) and whole cervical vagal trunk (Chaillou et al., 2009). In order to elucidate whether the somatotopic arrangement of vagal motor perikarya projecting to the gastrointestinal tract exists in the pig it seems to be reasonable to perform future tracing studies on the larger parts of the digestive tract, e.g. the whole stomach, to verify the higher number of labeled cell bodies in terms of their precise localization within the nuclear area. "
[Show abstract][Hide abstract] ABSTRACT: The goal of the present study was to examine the precise localization of the brainstem motor and primary sensory (nodose ganglion) vagal perikarya supplying the pylorus in the domestic pig. Using the Fast Blue retrograde tracing technique it has been established that all the vagal motor neurons projecting to the pylorus (about 337±59 cells per animal) were localized bilaterally in the dorsal motor nucleus of the vagus nerve (DMX, 171 - left; 167 - right) and all other regions of the porcine brainstem were devoid of labeled neurons. The vagal perikarya supplying the porcine pylorus were dispersed throughout the whole rostro-caudal extent of the DMX and no somatotopic organization of these neurons was observed. The labeled neurons occurred individually or in groups up to five cell bodies per nuclear transverse cross section area (in the middle part of the nucleus). An immunocytochemical staining procedure disclosed that all Fast Blue labeled motor neurons were choline acetyltransferase (ChAT) immunoreactive, however some differences in immunofluorescence intensity occurred. The primary sensory vagal neurons were observed within the left (215±37 cells/animal) and right (148±21 cells/animal) nodose ganglion. The traced neurons were dispersed throughout the ganglia and no characteristic arrangement of these neurons was observed. The present experiment precisely indicates the sources of origin of the vagal motor and primary sensory neurons supplying the pyloric region in the pig, the animal of an increasing significance in biomedical research.
[Show abstract][Hide abstract] ABSTRACT: Combined retrograde tracing (using fluorescent tracer Fast blue) and double-labelling immunofluorescence were used to study the distribution and immunohistochemical characteristics of neurons projecting to the trapezius muscle in mature male rats (n = 9). As revealed by retrograde tracing, Fast blue-positive (FB+) neurons were located within the ambiguous nucleus and accessory nucleus of the grey matter of the spinal cord. Immunohistochemistry revealed that nearly all the neurons were cholinergic in nature [choline acetyltransferase (ChAT)-positive]. Retrogradely labelled neurons displayed also immunoreactivities to calcitonin gene-related peptide (CGRP; approximately 60% of FB+ neurons), nitric oxide synthase (NOS; 50%), substance P (SP; 35%), Leu5-Enkephalin (LEnk; 10%) and vasoactive intestinal polypeptide (VIP; 5%). The analysis of double-stained tissue sections revealed that all CGRP-, VIP- and LEnk-immunoreactive FB+ perikarya were simultaneously ChAT-positive. The vast majority of the neurons expressing SP- or NOS-immunoreactivity were also cholinergic in nature; however, solitary somata were ChAT-negative. FB+ perikarya were surrounded by numerous varicose nerve fibres (often forming basket-like structures) immunoreactive to LEnk or SP. They were also associated with some CGRP-, NOS- and neuropeptide Y-positive nerve terminals.
[Show abstract][Hide abstract] ABSTRACT: Vasopressin (VP)-, neuropeptide FF (NPFF)-, and tyrosine hydroxylase (TH)-expressing neurons were studied by means of single and double immunocytochemistry in the human brainstem of controls who died suddenly due to trauma and of patients who suffered from essential hypertension and died due to acute myocardial infarction, while in one case there was brain hemorrhage. In the control and hypertensive groups VP fibers and NPFF neurons and fibers were the most abundantly present in the dorsal vagal complex, especially in the dorsal motor nucleus of the vagus. Numerous VP and NPFF fibers formed synaptic-like contacts with neuronal profiles in the dorsointermediate, centrointermediate, ventrointermediate, caudointermediate, and caudal parts of the dorsal motor nucleus of vagus as well as adjacent medial and intermediate subnuclei of the solitary nucleus. VP, but not NPFF, positive fibers were found to vastly contact TH-positive neuronal profiles in A2/C2, A2, and ambiguus nucleus (Amb). The density of VP fibers in the dorsal motor nucleus of the vagus and Amb did not differ between hypertensive patients and controls, whereas the density of NPFF fibers in hypertensives was 3.19 times lower in the dorsal motor nucleus of vagus and markedly decreased in the Amb. In both groups, VP and NPFF were scarcely present in the pain pathways, suggesting that these peptides are not crucially involved in nociceptive control in human. The reduction of NPFF release within the dorsal motor nucleus and Amb could serve as a possible cause of the impairment of cardiac vagal control in hypertensive patients.
The Journal of Comparative Neurology 01/2011; 519(1):93-124. DOI:10.1002/cne.22507 · 3.23 Impact Factor
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