Vasopressin-induced constriction of the isolated rat occipital artery is segment dependent.

BACKGROUND: Circulating factors delivered to the nodose ganglion (NG) by the occipital artery (OA) have been shown to affect vagal afferent activity, and thus the contractile state of the OA may influence blood flow to the NG. METHODS: OA were isolated and bisected into proximal and distal segments relative to the external carotid artery. RESULTS: Bisection highlighted stark differences between maximal contractile responses and OA sensitivity. Specifically, maximum responses to vasopressin and the V1 receptor agonist were significantly higher in distal than proximal segments. Distal segments were significantly more sensitive to 5-hydroxytryptamine (5-HT) and the 5-HT2 receptor agonist than proximal segments. Angiotensin II (AT)2, V2 and 5-HT(1B/1D) receptor agonists did not elicit vascular responses. Additionally, AT1 receptor agonists elicited mild, yet not significantly different maximal responses between segments. CONCLUSION: The results of this study are consistent with contractile properties of rat OA being mediated via AT1, V1 and 5-HT2 receptors and dependent upon the OA segment. Furthermore, vasopressin-induced constriction of the OA, regardless of a bolus dose or a first and second concentration-response curve, retained this unique segmental difference. We hypothesize that these segmental differences may be important in the regulation of blood flow through the OA in health and disease.

New Evidence for Causal Central Mechanism of Hyperglycemia in Subarachnoid Hemorrhage Secondary to Ischemic Degenerative Disruption of Circuitry Among Insular Cortex, Nodose Ganglion, and Pancreas: Experimental Study.

INTRODUCTION: Although hyperglycemia is a serious complication of subarachnoid hemorrhage, its pathophysiologic mechanism based on neural circuitry has not been known. MATERIALS AND METHODS: Twenty-five rabbits were divided into 4 groups, with 5 in the control group. The SHAM and study groups received 1 mL saline and 1 mL autologous arterial blood into the sylvian cisterna, respectively. Blood glucose values (BGVs) of all animals were recorded 3 times weekly. After 2 weeks, animals were decapitated. BGVs, the number of normal and degenerated neuron densities (DNDs) of insular cortex (IC), and nodose ganglia, degenerated islands of Reil's surfaces values, were estimated by stereologically and analyzed statistically. RESULTS: The mean blood glucose values were measured as 101 ± 10 mg/dL in the control group (n = 5), 114 ± 11 mg/dL in the SHAM group (n = 5), and 137 ± 12 mg/dL in the subarachnoid hemorrhage (SAH) group (n = 15). The DND of the nodose ganglion was 10 ± 3/mm3 in the control group, while it was 45 ± 7/mm3 in the SHAM group and 1688 ± 191/mm3 in the SAH group. The DND of the IC was 65 ± 12/mm3 in the control group, 689 ± 112/mm3 in the SHAM group, and 3709 ± 643/mm3 in the SAH group. In addition, the proportion of degenerated surface areas in the islet of Langerhans was 0.3% in the control group, 6% in the SHAM group, and 28% in the SAH group. CONCLUSION: There is an important linear relationship among the blood glucose levels, DND of the IC, and nodose ganglia and degenerated surface areas of IL following experimentally induced sylvian SAH.

Neurons and microvessels of the nodose (vagal sensory) ganglion in young adult and aged rats: morphometric and enzyme histochemical studies.

The neuron cell bodies and microvessels in sections of the nodose (vagal sensory) ganglion (NG) of Wistar rats of 4- and 24-months of age have been examined morphometrically and by quantitative enzyme histochemistry. The range of neuronal somata areas was similar at the two ages and distributed unimodally, ranging approximately from 200-1500 microns 2 with the largest somata occurring in the older age group. The range of microvessel diameters was also comparable but the largest microvessels were seen in the older animals. The histological arrangement of the ganglion permitted analyses to be made of 'neuronal' and 'axonal' areas independently. The number of microvessels per unit area was less in regions of the ganglion occupied by axons at both ages. Random transects indicated that the percentage area occupied by neuron somata decreases and that of axons increases with age. Overall, however, the results suggest that the histological organization, the size of vagal sensory neurons, the ganglionic microvessels, and the relationship between them, does not change greatly in Wistar rats of up to 2 years of age. Ultrastructural features of the aged sensory neurons included the presence of secondary lysosomes, disrupted rough endoplasmic reticulum, swollen Golgi cisternae, and the presence of much filamentous material in the perikaryon similar to that seen in chromatolytic neurons. However, analysis of electron micrographs did not reveal significant changes in the numbers of mitochondria or Golgi bodies. There was an overall increased thickness in the microvascular wall in the older animals with the endothelium and pericyte covering being significantly increased, but the thickness of the basal lamina was unchanged. The activities of neuronal NADH tetrazolium reductase, succinate dehydrogenase and cytochrome oxidase were all increased with age. The results suggest that vagal sensory neurons are not greatly affected by age in the rat.

[Light optical and electron microscopic study of the nodose ganglion neurons in emotional stress]. / Svetoopticheskoe i élektronno-mikroskopicheskoe issledovanie uzlovatogo gangliia pri émotsional'nom stresse,

Cell bodies of cardiovascular receptors localized in the ganglion nodosum of rabbits exposed to experimental emotional stress were studied with the light and electron microscope. Two groups of animals were selected for investigation. Under emotional stress rabbits of one group demonstrated almost unchanged arterial pressure and only a small increase in heart rate, while animals of the other group displayed strongly marked disturbances of their blood circulation leading to the lethal outcome at the end of experiment. In the first group rabbits, the microscopic anatomy and ultrastructure of the nodose ganglion neurons indicated an increased activity in the nerve cell. At the same time, morphological evidences of exhaustion were revealed in neurons of the nodose ganglion of the second group rabbits. A possible role of the distortion of the afferent information in pathogenesis of cardiovascular disorders under emotional stress is discussed.

Alkaline Phosphatase distribution in the inferior vagal ganglion of the cat following vagotomy: a chronological study.

The object of this study was to demonstrate sites of alkaline phosphatase activity within the cellular elements of the inferior vagal (nodosal) ganglion of the cat and chronologically observe and describe alterations in enzyme activity following vagotomy. In control tissues alkaline phosphatase activity was localized to the wall of perineuronal blood vessels and the satellite cell cytoplasm which envelops the neuronal perikarya. In the experimental tissues alkaline phosphatase activity was increased in the above locations during the first 20 days following vagotomy then gradually declined to approximate control levels by 60 days post-operatively. The functional significance of changes in alkaline phosphatase activity occurring within an altered metabolic environment induced by vagotomy is discussed.