Nodosities

Inhibition of the Na+/K+-ATPase leads to a loss of potassium and an increase of sodium within the cell. Secondary intracellular calcium is increased via the Na VCa -exchanger. This results in a positive inotropic effect in the myocardium, with an increase of peak force and a decrease in time to peak tension. Besides this, cardiac glycosides increase vagal activity by effects on the central vagal nuclei, the nodose ganglion and increase in sensitivity of the sinus node to acetylcholine. 

Sensory neurons nodose dorsal root neurons... 

Neurotrophin 4/5 is not as well characterized as other members of the neurotrophin family. Much of what is known is derived from analysis of NT4/5 and TrkB knockout mice. Elucidating the actions of NT4/5 is complicated by virtue of the fact that both NT4/5 and BDNF exert their effects via the TrkB receptor. It appears that NT4/5 functions largely overlap with those of other neurotrophin family members, particularly BDNF. NT4/5 knockout mice are essentially normal, in contrast to BDNF knockout mice, which do not live long. NT4/5 is likely to have unique actions on a subpopulation of neurons in the nodose and geniculate ganglia, which are not supported by BDNF. Like BDNF, NT4/5 acts on sensory neurons and retinal ganglion cells, supporting their survival. 

Kelly, K. M., Gross, R. A and Macdonald, R. L. Valproic acid selectively reduces the low-threshold (T) calcium current in rat nodose neurons. Neurosci. Lett. 116 233-238,1990. 

Sutton PM (1981) The interaction between reflex apnoea and bradycardia produced by injecting 5-HT into the nodose ganglion of the cat. Pflugers Arch 389 181-187... 

The mechanism of cannabinoid antiemetic activity is not well understood. As pointed out above, it does not seem to involve CB, or CB2. Fan has shown that anandamide and some synthetic cannabinoid agonists inhibit the activation of 5-HT3 receptors in rat nodose ganglion neurons [61]. These receptors are known to mediate emetic activity. However, we have found that HU-211 does not bind to 5-HT3 receptors (unpublished observations). Hence, although cannabinoids may act, in part at least, through this serotonin receptor, this mode of action does not account for the total activity. 

Figure 1. Diagram of the three cranial nerves and associated sensory ganglia that innervate taste buds. As illustrated, electrical recordings were taken from single neurons in the ganglia. Geniculate ganglion in facial nerve petrosal in glossopharyngeal nodose in vagus.

Histologic evidence shows a close anatomic correspondence between mast cells and G-fibers in peripheral organs (Skofitsch et al., 1985 Stead et al., 1987) and in the nodose ganglia (Undem and Weinrich, 1993). There is both functional and structural evidence for innervation of mast cells by C-fibers. Stimulation of the trigeminal nerve causes mast cells in the rat dura mater to degranu-late. This effect, which is apparent on histologic evaluation, is abolished by treatment with neonatal capsaicin and this may be mediated by C-fibers (Dimitriadou etal., 1991). 

Undem, B.J. and Weinreich, D. (1993). Electrophysiolog cal properties and chemosensitivity of guinea-pig nodose ganglion neurons in vitro. J. Autonon. Nerv. Syst. 44, 17-33. 

Schild JH, Kunze DL 1997 Experimental and modeling study of Na current heterogeneity in rat nodose neurons and its impact on neuronal discharge. J Neurophysiol 78 3198-3209... 

Fan P (1995) Cannabinoid agonists inhibit the activation of 5-HT3 receptors in rat nodose ganglion neurons. J Neurophysiol 73 907-910... 

Eischer, A., McGregor, G. P., Saria, A., Philippin, B., and Kummer, W. (1996). Induction of tachykinin gene and peptide expression in guinea pig nodose primary afferent neurons by allergic airway inflammation. J. Clin. Invest. 98, 2284-2291. 

Lindsay, R.M. and Rohrer, H. (1985) Placodal sensory neurons in culture nodose ganglion neurons are unresponsive to NGF, lack NGF receptors but are supported by a liver-derived neurotrophic factor. Dev. Biol. 112 30-48. 

In contrast to NGF, BDNF is able to support the survival of sensory neurons of neural placode origin. These neurons, which include those of the nodose ganglia, are unresponsive to NGF but show cell survival and neurite outgrowth in re-... 

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