Cell-Cell Communication in Taste Buds:
Activation of Type II cells by taste stimuli causes the release of ATP through pannexin hemichannels and/or CALMH1 channels. The released ATP or sour stimuli can activate Type III cells and causes release of different hormones such as 5-HT and NE via Ca2+-dependent exocytosis. In some instances NE is co-released with 5-HT (Dvoryanchikov et al., 2007; Huang et al., 2008a).
The ATP released by Type II taste cells acts as a paracrine as well as an autocrine signaling molecule. The ATP activates gustatory nerve fibers and Type III cells by binding to the P2X (on nerve fibers) or P2Y (Type III cells) receptors and also binds to purinergic receptors (P2Y) on Type II cells and promotes further release of ATP, …show more content…
These include: 1) motor nerve fibers arising from the hypoglossal nerve (CN XII), 2) somatosensory nerve fibers projecting through divisions of the trigeminal (CN V3) and glossopharyngeal (CN IX) nerves, and 3) autonomic nerve fibers stemming from inter-medio facial nerve (CN VII), the glossopharyngeal (CN IX) nerve, and the vagus nerve (CN X).
Taste buds are innervated by afferent fibers of three cranial nerves. Taste buds of the fungiform papillae are innervated by chorda tympani (CT) and the greater superficial petrosal branches of the CN VII. Taste buds of the foliate and circumvallate papillae are innervated by lingual-tonsillar branch of CN IX. Taste buds in the pharyngeal and laryngeal epithelium are innervated by CN X. Thus, taste signals are mainly transmitted by the glossopharyngeal, chorda tympani and vagus nerves. Cell bodies of all these fibers are located in three peripheral ganglia, the geniculate ganglion (CN VII), the petrosal (XN IX), and the nodose ganglion (CN X). In adult animals, each taste bud is innervated by 3-14 sensory ganglion neurons (Whitehead et al., 1999). The fibers of ganglionic neurons terminate in a small region in the medulla called the gustatory nucleus, or nucleus of solitary tract (NTS) (Whitehead and Finger, 2008). Information from NTS is transmitted in a descending pathway to …show more content…
Signals in this portion of the ascending lemniscal pathway are proposed to be important for the detection and discrimination of taste stimuli (Roper, 2009; Spector and Glendenning, 2009). In rodents this ascending pathway is relayed in the parabrachial nucleus of the pons. However, in humans and other primates it connects directly to the relay neurons in the parvocellular division of the ventroposteromedial thalamic nucleus, or taste thalamic nucleus (Whitehead and Finger, 2008). Taste information from this nucleus then goes to a region of cerebral cortex, known as gustatory cortex. Human neuroimaging studies show that a small number of neurons in the gustatory cortex represent taste quality (Schoenfield et al., 2004). From gustatory cortex, taste signals are transmitted to the secondary gustatory cortex, also known as orbifrontal cortex. Sensory modalities of taste, vision, and olfaction are proposed to converge in this region and construct the perception of flavor. Neurons of the secondary gustatory cortex are also proposed to be involved in satiety. Taste signal from orbifrontal cortex goes to the amygdala and the lateral hypothalamus, which is proposed to impart hedonic value to taste sensations and integrate taste information in the context of energy need and reward (Hofmann et al., 2011). Finally, cortical taste areas send afferents to the NTS/parabrachial nucleus allowing
Activation of Type II cells by taste stimuli causes the release of ATP through pannexin hemichannels and/or CALMH1 channels. The released ATP or sour stimuli can activate Type III cells and causes release of different hormones such as 5-HT and NE via Ca2+-dependent exocytosis. In some instances NE is co-released with 5-HT (Dvoryanchikov et al., 2007; Huang et al., 2008a).
The ATP released by Type II taste cells acts as a paracrine as well as an autocrine signaling molecule. The ATP activates gustatory nerve fibers and Type III cells by binding to the P2X (on nerve fibers) or P2Y (Type III cells) receptors and also binds to purinergic receptors (P2Y) on Type II cells and promotes further release of ATP, …show more content…
These include: 1) motor nerve fibers arising from the hypoglossal nerve (CN XII), 2) somatosensory nerve fibers projecting through divisions of the trigeminal (CN V3) and glossopharyngeal (CN IX) nerves, and 3) autonomic nerve fibers stemming from inter-medio facial nerve (CN VII), the glossopharyngeal (CN IX) nerve, and the vagus nerve (CN X).
Taste buds are innervated by afferent fibers of three cranial nerves. Taste buds of the fungiform papillae are innervated by chorda tympani (CT) and the greater superficial petrosal branches of the CN VII. Taste buds of the foliate and circumvallate papillae are innervated by lingual-tonsillar branch of CN IX. Taste buds in the pharyngeal and laryngeal epithelium are innervated by CN X. Thus, taste signals are mainly transmitted by the glossopharyngeal, chorda tympani and vagus nerves. Cell bodies of all these fibers are located in three peripheral ganglia, the geniculate ganglion (CN VII), the petrosal (XN IX), and the nodose ganglion (CN X). In adult animals, each taste bud is innervated by 3-14 sensory ganglion neurons (Whitehead et al., 1999). The fibers of ganglionic neurons terminate in a small region in the medulla called the gustatory nucleus, or nucleus of solitary tract (NTS) (Whitehead and Finger, 2008). Information from NTS is transmitted in a descending pathway to …show more content…
Signals in this portion of the ascending lemniscal pathway are proposed to be important for the detection and discrimination of taste stimuli (Roper, 2009; Spector and Glendenning, 2009). In rodents this ascending pathway is relayed in the parabrachial nucleus of the pons. However, in humans and other primates it connects directly to the relay neurons in the parvocellular division of the ventroposteromedial thalamic nucleus, or taste thalamic nucleus (Whitehead and Finger, 2008). Taste information from this nucleus then goes to a region of cerebral cortex, known as gustatory cortex. Human neuroimaging studies show that a small number of neurons in the gustatory cortex represent taste quality (Schoenfield et al., 2004). From gustatory cortex, taste signals are transmitted to the secondary gustatory cortex, also known as orbifrontal cortex. Sensory modalities of taste, vision, and olfaction are proposed to converge in this region and construct the perception of flavor. Neurons of the secondary gustatory cortex are also proposed to be involved in satiety. Taste signal from orbifrontal cortex goes to the amygdala and the lateral hypothalamus, which is proposed to impart hedonic value to taste sensations and integrate taste information in the context of energy need and reward (Hofmann et al., 2011). Finally, cortical taste areas send afferents to the NTS/parabrachial nucleus allowing