Page 1. 172 VANDERHOEK AND FEINSTEIN INTRODUCTION Local anesthetics inhibit platelet aggre-gation... more Page 1. 172 VANDERHOEK AND FEINSTEIN INTRODUCTION Local anesthetics inhibit platelet aggre-gation and the secretion of contents of platelet storage granules elicited by ADP, thrombin, collagen and the Ca2-ionophore ...
The mammalian taste system consists of taste buds, which are groups of 50–100 taste cells that ar... more The mammalian taste system consists of taste buds, which are groups of 50–100 taste cells that are found throughout the oral cavity. On the tongue, which is the focus of this chapter, taste buds are located on circumvallate, foliate, and fungiform papillae (Figure 7.1a). Taste cells synapse with afferent fibers from branches of the facial (CN VII), glossopharyngeal (CN IX), and vagus (CN X) cranial nerves (Figure 7.1b) that, in turn, transmit information to the central nervous system (CNS) attributes of tastant quality, intensity, and hedonic nature (Gutierrez and Simon, 2011; Carleton et al., 2010; Vincis and Fontanini, 2016). The list includes several classes of chemical stimuli such as sugars, salts, acids, proteins, and organic compounds that are perceived as bitter tasting (Simon et al., 2006). Taste buds are embedded in a stratified squamous epithelium, which contains somatosensory branches of the trigeminal (CN V), glossopharyngeal (CN IX), and vagus (CN X) cranial nerves. The terminals of these somatosensory fibers often surround taste buds (Figures 7.1b and 7.4), indicating the close association of the taste and somatosensory systems. Information from these general sensory nerves provides information to the CNS about mechanical, thermal, and painful stimuli (Julius, 2013; Kaneko and Szallasi, 2014). The painful stimuli can arise from strong or sharp mechanical stimuli, abnormally high or low temperatures, or chemical stimuli such as capsaicin, which is found in chili peppers and causes a burning taste sensation. As both the peripheral taste and somatosensory systems contain transient receptor potential (TRPs) (Ramsey et al., 2006; Julius, 2013), here we will initially review general properties of TRPs, and then describe their roles in the peripheral taste and somatosensory systems. We do not, however, discuss their presence in keratinocytes, but refer the reader to Chapter 5. Finally, for additional details regarding their roles in taste and as condiments used for cooking, we refer the reader to several excellent reviews on this topic (Vriens et al., 2008; Roper, 2013; Talavera, 2015; Roper, 2014).Since their discovery in 1989, as seen in Figure 7.2, numerous TRP channels have been identified. What they have in common is that they are all cation selective (most for Ca2+), and they are composed of four subunits with six transmembrane spans (S1–S6), with a pore region between S5 and S6 (Morales-Lazaro et al., 2013). Moreover, they often have ankyrin repeats in their N-terminus, exhibit inwardly rectifying current-voltage curves, and are modulated by calmodulin and phospholipases and kinases (Ramsey et al., 2006; Julius, 2013). As seen in Figure 7.2a, TRPs fall into six subfamilies: TRPC for “canonical” (TRPC1–7), TRPM for “melastatin” (TRPM1–8), TRPA for “ankyrin” (TRPA1), TRPV for “vanilloid” (TRPV1–6), TRPML for “mucolipin” (TRPML1–3), and TRPP for “polycystin” (TRPP2, TRPP3, TRPP5). Other interesting properties of many TRP channels, illustrated in Figure 7.2b and elaborated below, are that they are important in gustatory processing, are very sensitive to changes in temperature, and are activated by many compounds found in plants that are often used as spices (Figure 7.2b).
The intensity of sucrose (its perceived concentration) and its palatability (positive hedonic val... more The intensity of sucrose (its perceived concentration) and its palatability (positive hedonic valence associated with ingestion) are two taste attributes that increase its attractiveness and overconsumption. Although both sensory attributes covary, in that increases in sucrose concentration leads to similar increases in its palatability, this covariation does not imply that they are part of the same process or whether they represent separate processes. Both these possibilities are considered in the literature. For this reason, we tested whether sucrose’s perceived intensity could be separated from its hedonically positive palatability. To address this issue, rats were trained in a sucrose intensity task to report the perceived intensity of a range of sucrose concentrations before and after its palatability was changed using a conditioned taste aversion (CTA) protocol. We found that the subjects’ performance remained essentially unchanged, although its palatability was changed from h...
Throughout the animal kingdom sucrose is one of the most palatable and preferred tastants. From a... more Throughout the animal kingdom sucrose is one of the most palatable and preferred tastants. From an evolutionary perspective, this is not surprising as it is a primary source of energy. However, its overconsumption can result in obesity and an associated cornucopia of maladies, including type 2 diabetes and cardiovascular disease. Here we describe three physiological levels of processing sucrose that are involved in the decision to ingest it: the tongue, gut, and brain. The first section describes the peripheral cellular and molecular mechanisms of sweet taste identification that project to higher brain centers. We argue that stimulation of the tongue with sucrose triggers the formation of three distinct pathways that convey sensory attributes about its quality, palatability, and intensity that results in a perception of sweet taste. We also discuss the coding of sucrose throughout the gustatory pathway. The second section reviews how sucrose, and other palatable foods, interact with the gut–brain axis either through the hepatoportal system and/or vagal pathways in a manner that encodes both the rewarding and of nutritional value of foods. The third section reviews the homeostatic, hedonic, and aversive brain circuits involved in the control of food intake. Finally, we discuss evidence that overconsumption of sugars (or high fat diets) blunts taste perception, the post-ingestive nutritional reward value, and the circuits that control feeding in a manner that can lead to the development of obesity.
When consumed with foods, mint, mustard and chili peppers generate pronounced oral thermosensatio... more When consumed with foods, mint, mustard and chili peppers generate pronounced oral thermosensations. Here we recorded responses in mouse trigeminal ganglion neurons to investigate interactions between thermal sensing and the active ingredients of these plants--menthol, allyl isothiocyanate (AITC), and capsaicin, respectively--at concentrations found in foods and commercial hygiene products. We carried out in vivo confocal calcium imaging of trigeminal ganglia in which neurons express GCaMP3 or GCAMP6s and recorded their responses to oral stimulation with thermal and the above chemesthetic stimuli. In the V3 (oral sensory) region of the ganglion, thermoreceptive neurons accounted for ~10% of imaged neurons. We categorized them into 3 distinct classes: cool-responsive and warm-responsive thermosensors, and nociceptors (responsive only to temperatures ≥43-45o). Menthol, AITC, and capsaicin also elicited robust calcium responses that differed markedly in their latencies and durations. M...
Obesity is a worldwide health problem that has reached epidemic proportions. To ameliorate this p... more Obesity is a worldwide health problem that has reached epidemic proportions. To ameliorate this problem, one approach is the use of appetite suppressants. These compounds are frequently amphetamine congeners such as diethylpropion (DEP), phentermine (PHEN), and bupropion (BUP), whose effects are mediated through serotonin, norepinephrine, and dopaminergic pathways. The nucleus accumbens (NAc) shell receives dopaminergic inputs and is involved in feeding and motor activity. However, little is known about how appetite suppressants modulate its activity. Therefore, we characterized behavioral and neuronal NAc shell responses to short-term treatments of DEP, PHEN, and BUP. These compounds caused a transient decrease in weight and food intake while increasing locomotion, stereotypy, and insomnia. They evoked a large inhibitory imbalance in NAc shell spiking activity that correlated with the onset of locomotion and stereotypy. Analysis of the local field potentials (LFPs) showed that all ...
... the energetic costs of peptide-induced bilayer deformation due to hydrophobic mismatch (origi... more ... the energetic costs of peptide-induced bilayer deformation due to hydrophobic mismatch (originally called the "mattress model"; Mouritsen and Bloom ... This short-range potential has been shown to influence the partitioning of charged hy-drophobic ions (Franklin and Cafiso ...
Page 1. 172 VANDERHOEK AND FEINSTEIN INTRODUCTION Local anesthetics inhibit platelet aggre-gation... more Page 1. 172 VANDERHOEK AND FEINSTEIN INTRODUCTION Local anesthetics inhibit platelet aggre-gation and the secretion of contents of platelet storage granules elicited by ADP, thrombin, collagen and the Ca2-ionophore ...
The mammalian taste system consists of taste buds, which are groups of 50–100 taste cells that ar... more The mammalian taste system consists of taste buds, which are groups of 50–100 taste cells that are found throughout the oral cavity. On the tongue, which is the focus of this chapter, taste buds are located on circumvallate, foliate, and fungiform papillae (Figure 7.1a). Taste cells synapse with afferent fibers from branches of the facial (CN VII), glossopharyngeal (CN IX), and vagus (CN X) cranial nerves (Figure 7.1b) that, in turn, transmit information to the central nervous system (CNS) attributes of tastant quality, intensity, and hedonic nature (Gutierrez and Simon, 2011; Carleton et al., 2010; Vincis and Fontanini, 2016). The list includes several classes of chemical stimuli such as sugars, salts, acids, proteins, and organic compounds that are perceived as bitter tasting (Simon et al., 2006). Taste buds are embedded in a stratified squamous epithelium, which contains somatosensory branches of the trigeminal (CN V), glossopharyngeal (CN IX), and vagus (CN X) cranial nerves. The terminals of these somatosensory fibers often surround taste buds (Figures 7.1b and 7.4), indicating the close association of the taste and somatosensory systems. Information from these general sensory nerves provides information to the CNS about mechanical, thermal, and painful stimuli (Julius, 2013; Kaneko and Szallasi, 2014). The painful stimuli can arise from strong or sharp mechanical stimuli, abnormally high or low temperatures, or chemical stimuli such as capsaicin, which is found in chili peppers and causes a burning taste sensation. As both the peripheral taste and somatosensory systems contain transient receptor potential (TRPs) (Ramsey et al., 2006; Julius, 2013), here we will initially review general properties of TRPs, and then describe their roles in the peripheral taste and somatosensory systems. We do not, however, discuss their presence in keratinocytes, but refer the reader to Chapter 5. Finally, for additional details regarding their roles in taste and as condiments used for cooking, we refer the reader to several excellent reviews on this topic (Vriens et al., 2008; Roper, 2013; Talavera, 2015; Roper, 2014).Since their discovery in 1989, as seen in Figure 7.2, numerous TRP channels have been identified. What they have in common is that they are all cation selective (most for Ca2+), and they are composed of four subunits with six transmembrane spans (S1–S6), with a pore region between S5 and S6 (Morales-Lazaro et al., 2013). Moreover, they often have ankyrin repeats in their N-terminus, exhibit inwardly rectifying current-voltage curves, and are modulated by calmodulin and phospholipases and kinases (Ramsey et al., 2006; Julius, 2013). As seen in Figure 7.2a, TRPs fall into six subfamilies: TRPC for “canonical” (TRPC1–7), TRPM for “melastatin” (TRPM1–8), TRPA for “ankyrin” (TRPA1), TRPV for “vanilloid” (TRPV1–6), TRPML for “mucolipin” (TRPML1–3), and TRPP for “polycystin” (TRPP2, TRPP3, TRPP5). Other interesting properties of many TRP channels, illustrated in Figure 7.2b and elaborated below, are that they are important in gustatory processing, are very sensitive to changes in temperature, and are activated by many compounds found in plants that are often used as spices (Figure 7.2b).
The intensity of sucrose (its perceived concentration) and its palatability (positive hedonic val... more The intensity of sucrose (its perceived concentration) and its palatability (positive hedonic valence associated with ingestion) are two taste attributes that increase its attractiveness and overconsumption. Although both sensory attributes covary, in that increases in sucrose concentration leads to similar increases in its palatability, this covariation does not imply that they are part of the same process or whether they represent separate processes. Both these possibilities are considered in the literature. For this reason, we tested whether sucrose’s perceived intensity could be separated from its hedonically positive palatability. To address this issue, rats were trained in a sucrose intensity task to report the perceived intensity of a range of sucrose concentrations before and after its palatability was changed using a conditioned taste aversion (CTA) protocol. We found that the subjects’ performance remained essentially unchanged, although its palatability was changed from h...
Throughout the animal kingdom sucrose is one of the most palatable and preferred tastants. From a... more Throughout the animal kingdom sucrose is one of the most palatable and preferred tastants. From an evolutionary perspective, this is not surprising as it is a primary source of energy. However, its overconsumption can result in obesity and an associated cornucopia of maladies, including type 2 diabetes and cardiovascular disease. Here we describe three physiological levels of processing sucrose that are involved in the decision to ingest it: the tongue, gut, and brain. The first section describes the peripheral cellular and molecular mechanisms of sweet taste identification that project to higher brain centers. We argue that stimulation of the tongue with sucrose triggers the formation of three distinct pathways that convey sensory attributes about its quality, palatability, and intensity that results in a perception of sweet taste. We also discuss the coding of sucrose throughout the gustatory pathway. The second section reviews how sucrose, and other palatable foods, interact with the gut–brain axis either through the hepatoportal system and/or vagal pathways in a manner that encodes both the rewarding and of nutritional value of foods. The third section reviews the homeostatic, hedonic, and aversive brain circuits involved in the control of food intake. Finally, we discuss evidence that overconsumption of sugars (or high fat diets) blunts taste perception, the post-ingestive nutritional reward value, and the circuits that control feeding in a manner that can lead to the development of obesity.
When consumed with foods, mint, mustard and chili peppers generate pronounced oral thermosensatio... more When consumed with foods, mint, mustard and chili peppers generate pronounced oral thermosensations. Here we recorded responses in mouse trigeminal ganglion neurons to investigate interactions between thermal sensing and the active ingredients of these plants--menthol, allyl isothiocyanate (AITC), and capsaicin, respectively--at concentrations found in foods and commercial hygiene products. We carried out in vivo confocal calcium imaging of trigeminal ganglia in which neurons express GCaMP3 or GCAMP6s and recorded their responses to oral stimulation with thermal and the above chemesthetic stimuli. In the V3 (oral sensory) region of the ganglion, thermoreceptive neurons accounted for ~10% of imaged neurons. We categorized them into 3 distinct classes: cool-responsive and warm-responsive thermosensors, and nociceptors (responsive only to temperatures ≥43-45o). Menthol, AITC, and capsaicin also elicited robust calcium responses that differed markedly in their latencies and durations. M...
Obesity is a worldwide health problem that has reached epidemic proportions. To ameliorate this p... more Obesity is a worldwide health problem that has reached epidemic proportions. To ameliorate this problem, one approach is the use of appetite suppressants. These compounds are frequently amphetamine congeners such as diethylpropion (DEP), phentermine (PHEN), and bupropion (BUP), whose effects are mediated through serotonin, norepinephrine, and dopaminergic pathways. The nucleus accumbens (NAc) shell receives dopaminergic inputs and is involved in feeding and motor activity. However, little is known about how appetite suppressants modulate its activity. Therefore, we characterized behavioral and neuronal NAc shell responses to short-term treatments of DEP, PHEN, and BUP. These compounds caused a transient decrease in weight and food intake while increasing locomotion, stereotypy, and insomnia. They evoked a large inhibitory imbalance in NAc shell spiking activity that correlated with the onset of locomotion and stereotypy. Analysis of the local field potentials (LFPs) showed that all ...
... the energetic costs of peptide-induced bilayer deformation due to hydrophobic mismatch (origi... more ... the energetic costs of peptide-induced bilayer deformation due to hydrophobic mismatch (originally called the "mattress model"; Mouritsen and Bloom ... This short-range potential has been shown to influence the partitioning of charged hy-drophobic ions (Franklin and Cafiso ...
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Papers by Sidney Simon