Oral afferents

The taste bud is a polarized structure with a narrow apical opening, termed the taste pore, and basolateral synapses with afferent nerve fibers. Solutes in the oral cavity make contact with the apical membranes of the TRCs via the taste pore. There is a significant amount of lateral connectedness between taste cells within a bud both electrical synapses between TRCs and chemical synapses between TRCs and Merkel-like basal cells have been demonstrated to occur [39]. Furthermore, there are symmetrical synapses between TRCs and Merkel-like basal cells [39]. In addition, these basal cells synapse with the afferent nerve fiber, suggesting that they may function in effect as interneurons [39]. The extensive lateral interconnections... 

Fucile S (2004) Ca + permeability of nicotinic acetylcholine receptors. Cell Calcium 35 1-8 Gaddnas H, Pietila K, Ahtee L (2000) Effects of chronic oral nicotine treatment and its withdrawal on locomotor activity and brain monoamines in mice. Behav Brain Res 113 65-72 Geisler S, Derst C, Veh RW, Zahm DS (2007) Glutamatergic afferents of the ventral tegmental area in the rat. J Neurosci 27 5730-5743... 

Pharmacokinetics Slowly, incompletely absorbed affer oral administration. Food delays or decreases the extent of absorption. Protein binding Negligible. Primarily distributed to intestinal mucosa and salivary glands. Primarily excreted unchanged in urine. Removed by hemodialysis. Half-life 3-6 hr. 

Matsuo R, Shimizu N, Kusano K. 1984. Lateral hypothalamic modulation of oral sensory afferent activity in nucleus tractus solitarius neurons of rats. J Neurosci 4 1201-1207. 

Topical products can be used alone or in combination with oral analgesics or NSAIDs. Capsaicin, isolated from hot peppers, releases and ultimately depletes substance P from afferent nociceptive nerve fibers. Substance P has been implicated in the transmission of pain in arthritis, and capsaicin cream has been shown in four controlled studies to provide pain relief in OA when applied over affected joints. " ... 

K+ in the urine ADH also stimulates thirst resulting in increased oral intake of fluids — decreased serum osmolality the afferent arterioles, increasing the glomerular filtration rate — high urine output —> decreased fluid volume... 

The nervous system of hamsters infected orally with scrapie has been studied extensively for the temporal-spatial course of PrP deposition in the brain (for review see ). After centripetally reaching the spinal cord, subsequent centrifugal spread of PrP deposition proceeds to the corresponding afferent dorsal root ganglia (DRG), where the protein can first be detected 76 days postinfection in half of the examined hamsters (Figure 11.2). The DRG are nodules on a dorsal spinal root that contain the cell bodies of afferent nerve fibers, some of the largest cells in the mammalian body. 

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