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Li J, Zumpano KT, Lemon CH. Separation of Oral Cooling and Warming Requires TRPM8. J Neurosci 2024; 44:e1383232024. [PMID: 38316563 PMCID: PMC10941239 DOI: 10.1523/jneurosci.1383-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 01/13/2024] [Accepted: 01/24/2024] [Indexed: 02/07/2024] Open
Abstract
Cooling sensations arise inside the mouth during ingestive and homeostasis behaviors. Oral presence of cooling temperature engages the cold and menthol receptor TRPM8 (transient receptor potential melastatin 8) on trigeminal afferents. Yet, how TRPM8 influences brain and behavioral responses to oral temperature is undefined. Here we used in vivo neurophysiology to record action potentials stimulated by cooling and warming of oral tissues from trigeminal nucleus caudalis neurons in female and male wild-type and TRPM8 gene deficient mice. Using these lines, we also measured orobehavioral licking responses to cool and warm water in a novel, temperature-controlled fluid choice test. Capture of antidromic electrophysiological responses to thalamic stimulation identified that wild-type central trigeminal neurons showed diverse responses to oral cooling. Some neurons displayed relatively strong excitation to cold <10°C (COLD neurons) while others responded to only a segment of mild cool temperatures below 30°C (COOL neurons). Notably, TRPM8 deficient mice retained COLD-type but lacked COOL cells. This deficit impaired population responses to mild cooling temperatures below 30°C and allowed warmth-like (≥35°C) neural activity to pervade the normally innocuous cool temperature range, predicting TRPM8 deficient mice would show anomalously similar orobehavioral responses to warm and cool temperatures. Accordingly, TRPM8 deficient mice avoided both warm (35°C) and mild cool (≤30°C) water and sought colder temperatures in fluid licking tests, whereas control mice avoided warm but were indifferent to mild cool and colder water. Results imply TRPM8 input separates cool from warm temperature sensing and suggest other thermoreceptors also participate in oral cooling sensation.
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Affiliation(s)
- Jinrong Li
- School of Biological Sciences, University of Oklahoma, Norman, OK 73019
| | - Kyle T Zumpano
- School of Biological Sciences, University of Oklahoma, Norman, OK 73019
| | - Christian H Lemon
- School of Biological Sciences, University of Oklahoma, Norman, OK 73019
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2
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Bouaichi CG, Odegaard KE, Neese C, Vincis R. Intraoral thermal processing in the gustatory cortex of awake mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.06.526681. [PMID: 36798208 PMCID: PMC9934522 DOI: 10.1101/2023.02.06.526681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Oral temperature is a sensory cue relevant to food preference and nutrition. To understand how orally-sourced thermal inputs are represented in the gustatory cortex (GC) we recorded neural responses from the GC of male and female mice presented with deionized water at different innocuous temperatures (14 °C, 25 °C, 36 °C) and taste stimuli (room temperature). Our results demonstrate that GC neurons encode orally-sourced thermal information in the absence of classical taste qualities at the single neuron and population levels, as confirmed through additional experiments comparing GC neuron responses to water and artificial saliva. Analysis of thermal-evoked responses showed broadly tuned neurons that responded to temperature in a mostly monotonic manner. Spatial location may play a minor role regarding thermosensory activity; aside from the most ventral GC, neurons reliably responded to and encoded thermal information across the dorso-ventral and antero-postero cortical axes. Additional analysis revealed that more than half of GC neurons that encoded chemosensory taste stimuli also accurately discriminated thermal information, providing additional evidence of the GC's involvement in processing thermosensory information important for ingestive behaviors. In terms of convergence, we found that GC neurons encoding information about both taste and temperature were broadly tuned and carried more information than taste-selective only neurons; both groups encoded similar information about the palatability of stimuli. Altogether, our data reveal new details of the cortical code for the mammalian intraoral thermosensory system in behaving mice and pave the way for future investigations on GC functions and operational principles with respect to thermogustation.
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Affiliation(s)
- Cecilia G Bouaichi
- Florida State University, Department of Biological Science and Programs in Neuroscience, Cell and Molecular Biology, and Biophysics
| | - Katherine E Odegaard
- Florida State University, Department of Biological Science and Programs in Neuroscience, Cell and Molecular Biology, and Biophysics
| | - Camden Neese
- Florida State University, Department of Biological Science and Programs in Neuroscience, Cell and Molecular Biology, and Biophysics
| | - Roberto Vincis
- Florida State University, Department of Biological Science and Programs in Neuroscience, Molecular Biophysics and Cell and Molecular Biology
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3
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Bouaichi CG, Odegaard KE, Neese C, Vincis R. Oral thermal processing in the gustatory cortex of awake mice. Chem Senses 2023; 48:bjad042. [PMID: 37850853 PMCID: PMC10630187 DOI: 10.1093/chemse/bjad042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Indexed: 10/19/2023] Open
Abstract
Oral temperature is a sensory cue relevant to food preference and nutrition. To understand how orally sourced thermal inputs are represented in the gustatory cortex (GC), we recorded neural responses from the GC of male and female mice presented with deionized water at different innocuous temperatures (14 °C, 25 °C, and 36 °C) and taste stimuli (room temperature). Our results demonstrate that GC neurons encode orally sourced thermal information in the absence of classical taste qualities at the single neuron and population levels, as confirmed through additional experiments comparing GC neuron responses to water and artificial saliva. Analysis of thermal-evoked responses showed broadly tuned neurons that responded to temperature in a mostly monotonic manner. Spatial location may play a minor role regarding thermosensory activity; aside from the most ventral GC, neurons reliably responded to and encoded thermal information across the dorso-ventral and antero-postero cortical axes. Additional analysis revealed that more than half of the GC neurons that encoded chemosensory taste stimuli also accurately discriminated thermal information, providing additional evidence of the GC's involvement in processing thermosensory information important for ingestive behaviors. In terms of convergence, we found that GC neurons encoding information about both taste and temperature were broadly tuned and carried more information than taste-selective-only neurons; both groups encoded similar information about the palatability of stimuli. Altogether, our data reveal new details of the cortical code for the mammalian oral thermosensory system in behaving mice and pave the way for future investigations on GC functions and operational principles with respect to thermogustation.
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Affiliation(s)
- Cecilia G Bouaichi
- Department of Biological Science and Programs in Neuroscience, Cell and Molecular Biology, and Biophysics, Florida State University, Tallahassee, FL, United States
| | - Katherine E Odegaard
- Department of Biological Science and Programs in Neuroscience, Cell and Molecular Biology, and Biophysics, Florida State University, Tallahassee, FL, United States
| | - Camden Neese
- Department of Biological Science and Programs in Neuroscience, Cell and Molecular Biology, and Biophysics, Florida State University, Tallahassee, FL, United States
| | - Roberto Vincis
- Department of Biological Science and Programs in Neuroscience, Molecular Biophysics and Cell and Molecular Biology, Florida State University, Tallahassee, FL, United States
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4
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Colbert SE, Triplett CS, Maier JX. The role of viscosity in flavor preference: plasticity and interactions with taste. Chem Senses 2022; 47:bjac018. [PMID: 35972847 PMCID: PMC9380780 DOI: 10.1093/chemse/bjac018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The brain combines gustatory, olfactory, and somatosensory information to create our perception of flavor. Within the somatosensory modality, texture attributes such as viscosity appear to play an important role in flavor preference. However, research into the role of texture in flavor perception is relatively sparse, and the contribution of texture cues to hedonic evaluation of flavor remains largely unknown. Here, we used a rat model to investigate whether viscosity preferences can be manipulated through association with nutrient value, and how viscosity interacts with taste to inform preferences for taste + viscosity mixtures. To address these questions, we measured preferences for moderately viscous solutions prepared with xanthan gum using 2-bottle consumption tests. By experimentally exposing animals to viscous solutions with and without nutrient value, we demonstrate that viscosity preferences are susceptible to appetitive conditioning. By independently varying viscosity and taste content of solutions, we further show that taste and viscosity cues both contribute to preferences for taste + viscosity mixtures. How these 2 modalities are combined depended on relative palatability, with mixture preferences falling in between component preferences, suggesting that hedonic aspects of taste and texture inputs are centrally integrated. Together, these findings provide new insight into how texture aspects of flavor inform hedonic perception and impact food choice behavior.
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Affiliation(s)
- Sarah E Colbert
- Department of Neurobiology and Anatomy, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Cody S Triplett
- Department of Neurobiology and Anatomy, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Joost X Maier
- Department of Neurobiology and Anatomy, Wake Forest School of Medicine, Winston-Salem, NC, USA
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5
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Samuelsen CL, Vincis R. Cortical Hub for Flavor Sensation in Rodents. Front Syst Neurosci 2021; 15:772286. [PMID: 34867223 PMCID: PMC8636119 DOI: 10.3389/fnsys.2021.772286] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 10/21/2021] [Indexed: 01/05/2023] Open
Abstract
The experience of eating is inherently multimodal, combining intraoral gustatory, olfactory, and somatosensory signals into a single percept called flavor. As foods and beverages enter the mouth, movements associated with chewing and swallowing activate somatosensory receptors in the oral cavity, dissolve tastants in the saliva to activate taste receptors, and release volatile odorant molecules to retronasally activate olfactory receptors in the nasal epithelium. Human studies indicate that sensory cortical areas are important for intraoral multimodal processing, yet their circuit-level mechanisms remain unclear. Animal models allow for detailed analyses of neural circuits due to the large number of molecular tools available for tracing and neuronal manipulations. In this review, we concentrate on the anatomical and neurophysiological evidence from rodent models toward a better understanding of the circuit-level mechanisms underlying the cortical processing of flavor. While more work is needed, the emerging view pertaining to the multimodal processing of food and beverages is that the piriform, gustatory, and somatosensory cortical regions do not function solely as independent areas. Rather they act as an intraoral cortical hub, simultaneously receiving and processing multimodal sensory information from the mouth to produce the rich and complex flavor experience that guides consummatory behavior.
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Affiliation(s)
- Chad L Samuelsen
- Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, KY, United States
| | - Roberto Vincis
- Department of Biological Science and Program in Neuroscience, Florida State University, Tallahassee, FL, United States
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6
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Martin LJ, Breza JM, Sollars SI. Taste activity in the parabrachial region in adult rats following neonatal chorda tympani transection. J Neurophysiol 2021; 125:2178-2190. [PMID: 33909497 DOI: 10.1152/jn.00552.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The chorda tympani is a gustatory nerve that fails to regenerate if sectioned in rats 10 days of age or younger. This early denervation causes an abnormally high preference for NH4Cl in adult rats, but the impact of neonatal chorda tympani transection on the development of the gustatory hindbrain is unclear. Here, we tested the effect of neonatal chorda tympani transection (CTX) on gustatory responses in the parabrachial nucleus (PbN). We recorded in vivo extracellular spikes in single PbN units of urethane-anesthetized adult rats following CTX at P5 (chronic CTX group) or immediately prior to recording (acute CTX group). Thus, all sampled PbN neurons received indirect input from taste nerves other than the CT. Compared to acute CTX rats, chronic CTX animals had significantly higher responses to stimulation with 0.1 and 0.5 M NH4Cl, 0.1 and 0.5 M NaCl, and 0.01 M citric acid. Activity to 0.5 M sucrose and 0.01 M quinine stimulation was not significantly different between groups. Neurons from chronic CTX animals also had larger interstimulus correlations and significantly higher entropy, suggesting that neurons in this group were more likely to be activated by stimulation with multiple tastants. Although neural responses were higher in the PbN of chronic CTX rats compared to acute-sectioned controls, taste-evoked activity was much lower than observed in previous reports, suggesting permanent deficits in taste signaling. These findings demonstrate that the developing gustatory hindbrain exhibits high functional plasticity following early nerve injury.NEW & NOTEWORTHY Early and chronic loss of taste input from the chorda tympani is associated with abnormal taste behaviors. We found that compared to when the chorda tympani is sectioned acutely, chronic nerve loss leads to amplification of spared inputs in the gustatory pons, with higher response to salty and sour stimuli. Findings point to plasticity that may compensate for sensory loss, but permanent deficits in taste signaling also occur following early denervation.
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Affiliation(s)
- Louis J Martin
- Department of Psychology, University of Nebraska at Omahagrid.266815.e, Omaha, Nebraska
| | - Joseph M Breza
- Department of Psychology, Eastern Michigan University, Ypsilanti, Michigan
| | - Suzanne I Sollars
- Department of Psychology, University of Nebraska at Omahagrid.266815.e, Omaha, Nebraska
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7
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Boughter JD, Fletcher M. Rethinking the role of taste processing in insular cortex and forebrain circuits. CURRENT OPINION IN PHYSIOLOGY 2021; 20:52-56. [PMID: 33681544 PMCID: PMC7932132 DOI: 10.1016/j.cophys.2020.12.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Over the years, many approaches towards studying the taste-responsive area of insular cortex have focused on how basic taste information is represented, and how lesions or silencing of this area impact taste-focused behaviors. Here, we review and highlight recent studies that imply that insular cortex does not contain a "primary" taste cortex in the traditional sense. Rather, taste is employed in concert with other internal and external sensory modalities by highly interconnected regions of insular cortex to guide ingestive decision-making, especially in context of estimating risk and reward. In rodent models, this may best be seen in context of foraging behaviors, which require flexibility and are dependent on learning and memory processes.
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Affiliation(s)
- John D. Boughter
- Department of Anatomy & Neurobiology, University of Tennessee Health Science Center, 855 Monroe Ave., Memphis TN 38163 USA
| | - Max Fletcher
- Department of Anatomy & Neurobiology, University of Tennessee Health Science Center, 855 Monroe Ave., Memphis TN 38163 USA
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8
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Lemon CH. Tasting temperature: neural and behavioral responses to thermal stimulation of oral mucosa. CURRENT OPINION IN PHYSIOLOGY 2021; 20:16-22. [PMID: 33937598 DOI: 10.1016/j.cophys.2020.12.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Temperature sensation contributes to human enjoyment of foods and beverages. The mouthfeel of warmed foods or drinking ice-cold water on a hot day are respectively pleasant and refreshing. Although historically under-studied for a role in food preference, new data have shed light on how oral temperature sensing and thermoreceptor mechanisms inside the mouth influence ingestive acceptance behaviors in rodent models used in flavor neurobiology. Moreover, recent functional data have uncovered a broad diversity of thermosensory neurons in primary afferents and brain pathways that signal oral temperature. This review will discuss some of the progress made in these areas. Ultimately, unraveling the biological basis of oral temperature sensing will be critical to reveal how thermosensory factors interact with other orosensory modalities to shape ingestive preferences. Elucidating oral thermal processing will also be key for establishing general principles of temperature coding by the nervous system.
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Affiliation(s)
- Christian H Lemon
- Department of Biology, 730 Van Vleet Oval, University of Oklahoma, Norman, OK, 73019 USA.,Institute for Biomedical Engineering, Science, and Technology, University of Oklahoma, Norman, OK, 73019 USA
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9
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Jarvie BC, Chen JY, King HO, Palmiter RD. Satb2 neurons in the parabrachial nucleus mediate taste perception. Nat Commun 2021. [PMID: 33431851 DOI: 10.1038/s41467‐020‐20100‐8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The neural circuitry mediating taste has been mapped out from the periphery to the cortex, but genetic identity of taste-responsive neurons has remained elusive. Here, we describe a population of neurons in the gustatory region of the parabrachial nucleus that express the transcription factor Satb2 and project to taste-associated regions, including the gustatory thalamus and insular cortex. Using calcium imaging in awake, freely licking mice, we show that Satb2 neurons respond to the five basic taste modalities. Optogenetic activation of these neurons enhances taste preferences, whereas chronic inactivation decreases the magnitude of taste preferences in both brief- and long-access taste tests. Simultaneous inactivation of Satb2 and calcitonin gene-related peptide neurons in the PBN abolishes responses to aversive tastes. These data suggest that taste information in the parabrachial nucleus is conveyed by multiple populations of neurons, including both Satb2 and calcitonin gene-related peptide neurons.
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Affiliation(s)
- Brooke C Jarvie
- Departments of Biochemistry and Genome Sciences, University of Washington, Seattle, WA, 98195, USA.,Graduate Program in Neuroscience, University of Washington, Seattle, WA, USA
| | - Jane Y Chen
- Departments of Biochemistry and Genome Sciences, University of Washington, Seattle, WA, 98195, USA.,Graduate Program in Neuroscience, University of Washington, Seattle, WA, USA
| | - Hunter O King
- Departments of Biochemistry and Genome Sciences, University of Washington, Seattle, WA, 98195, USA
| | - Richard D Palmiter
- Departments of Biochemistry and Genome Sciences, University of Washington, Seattle, WA, 98195, USA. .,Graduate Program in Neuroscience, University of Washington, Seattle, WA, USA. .,Howard Hughes Medical Institute, University of Washington, Seattle, WA, USA.
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10
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Jarvie BC, Chen JY, King HO, Palmiter RD. Satb2 neurons in the parabrachial nucleus mediate taste perception. Nat Commun 2021; 12:224. [PMID: 33431851 PMCID: PMC7801645 DOI: 10.1038/s41467-020-20100-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 11/10/2020] [Indexed: 11/09/2022] Open
Abstract
The neural circuitry mediating taste has been mapped out from the periphery to the cortex, but genetic identity of taste-responsive neurons has remained elusive. Here, we describe a population of neurons in the gustatory region of the parabrachial nucleus that express the transcription factor Satb2 and project to taste-associated regions, including the gustatory thalamus and insular cortex. Using calcium imaging in awake, freely licking mice, we show that Satb2 neurons respond to the five basic taste modalities. Optogenetic activation of these neurons enhances taste preferences, whereas chronic inactivation decreases the magnitude of taste preferences in both brief- and long-access taste tests. Simultaneous inactivation of Satb2 and calcitonin gene-related peptide neurons in the PBN abolishes responses to aversive tastes. These data suggest that taste information in the parabrachial nucleus is conveyed by multiple populations of neurons, including both Satb2 and calcitonin gene-related peptide neurons.
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Affiliation(s)
- Brooke C Jarvie
- Departments of Biochemistry and Genome Sciences, University of Washington, Seattle, WA, 98195, USA
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, USA
| | - Jane Y Chen
- Departments of Biochemistry and Genome Sciences, University of Washington, Seattle, WA, 98195, USA
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, USA
| | - Hunter O King
- Departments of Biochemistry and Genome Sciences, University of Washington, Seattle, WA, 98195, USA
| | - Richard D Palmiter
- Departments of Biochemistry and Genome Sciences, University of Washington, Seattle, WA, 98195, USA.
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, USA.
- Howard Hughes Medical Institute, University of Washington, Seattle, WA, USA.
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11
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Niermann CN, Tate TG, Suto AL, Barajas R, White HA, Guswiler OD, Secor SM, Rowe AH, Rowe MP. Defensive Venoms: Is Pain Sufficient for Predator Deterrence? Toxins (Basel) 2020; 12:toxins12040260. [PMID: 32316477 PMCID: PMC7232307 DOI: 10.3390/toxins12040260] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Revised: 03/26/2020] [Accepted: 04/03/2020] [Indexed: 12/19/2022] Open
Abstract
Pain, though unpleasant, is adaptive in calling an animal’s attention to potential tissue damage. A long list of animals representing diverse taxa possess venom-mediated, pain-inducing bites or stings that work by co-opting the pain-sensing pathways of potential enemies. Typically, such venoms include toxins that cause tissue damage or disrupt neuronal activity, rendering painful stings honest indicators of harm. But could pain alone be sufficient for deterring a hungry predator? Some venomologists have argued “no”; predators, in the absence of injury, would “see through” the bluff of a painful but otherwise benign sting or bite. Because most algogenic venoms are also toxic (although not vice versa), it has been difficult to disentangle the relative contributions of each component to predator deterrence. Southern grasshopper mice (Onychomys torridus) are voracious predators of arthropods, feeding on a diversity of scorpion species whose stings vary in painfulness, including painful Arizona bark scorpions (Centruroides sculpturatus) and essentially painless stripe-tailed scorpions (Paravaejovis spinigerus). Moreover, southern grasshopper mice have evolved resistance to the lethal toxins in bark scorpion venom, rendering a sting from these scorpions painful but harmless. Results from a series of laboratory experiments demonstrate that painful stings matter. Grasshopper mice preferred to prey on stripe-tailed scorpions rather than bark scorpions when both species could sting; the preference disappeared when each species had their stingers blocked. A painful sting therefore appears necessary for a scorpion to deter a hungry grasshopper mouse, but it may not always be sufficient: after first attacking and consuming a painless stripe-tailed scorpion, many grasshopper mice went on to attack, kill, and eat a bark scorpion even when the scorpion was capable of stinging. Defensive venoms that result in tissue damage or neurological dysfunction may, thus, be required to condition greater aversion than venoms causing pain alone.
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Affiliation(s)
- Crystal N. Niermann
- Department of Biology, Sam Houston State University, Huntsville, TX 77340, USA; (C.N.N.); (T.G.T.)
| | - Travis G. Tate
- Department of Biology, Sam Houston State University, Huntsville, TX 77340, USA; (C.N.N.); (T.G.T.)
| | - Amber L. Suto
- Department of Integrative Biology, Michigan State University, East Lansing, MI 48824, USA; (A.L.S.); (O.D.G.)
| | - Rolando Barajas
- Neuroscience Program, Michigan State University, East Lansing, MI 48824, USA; (R.B.); (H.A.W.)
| | - Hope A. White
- Neuroscience Program, Michigan State University, East Lansing, MI 48824, USA; (R.B.); (H.A.W.)
| | - Olivia D. Guswiler
- Department of Integrative Biology, Michigan State University, East Lansing, MI 48824, USA; (A.L.S.); (O.D.G.)
| | - Stephen M. Secor
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487, USA;
| | - Ashlee H. Rowe
- Department of Biology, University of Oklahoma, Norman, OK 73019, USA;
| | - Matthew P. Rowe
- Department of Biology, University of Oklahoma, Norman, OK 73019, USA;
- Correspondence: ; Tel.: +1-405-325-6539
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12
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Wukitsch TJ, Brase EC, Moser TJ, Kiefer SW, Cain ME. Differential rearing alters taste reactivity to ethanol, sucrose, and quinine. Psychopharmacology (Berl) 2020; 237:583-597. [PMID: 31832722 PMCID: PMC7747299 DOI: 10.1007/s00213-019-05394-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 11/08/2019] [Indexed: 12/23/2022]
Abstract
RATIONALE Early-life environment influences reinforcer and drug motivation in adulthood; however, the impact on specific components of motivation, including hedonic value ("liking"), remains unknown. OBJECTIVES The current study determined whether differential rearing alters liking and aversive responding to ethanol, sucrose, and quinine in an ethanol-naïve rat model. METHODS Male and female rats were reared for 30 days starting at postnatal day 21 in either an enriched (EC), isolated (IC), or standard condition (SC). Thereafter, all rats had indwelling intraoral fistulae implanted and their taste reactivity to water, ethanol (5, 10, 20, 30, 40% v/v), sucrose (0.1, 0.25, 0.5 M), and quinine (0.1, 0.5 mM) was recorded and analyzed. RESULTS EC rats had higher amounts of liking responses to ethanol, sucrose, and quinine and higher amounts of aversive responses to ethanol and quinine compared to IC rats. While EC and IC rats' responses were different from each other, they both tended to be similar to SCs, who fell in between the EC and IC groups. CONCLUSIONS These results suggest that environmental enrichment may enhance sensitivity to a variety of tastants, thereby enhancing liking, while isolation may dull sensitivity, thereby dulling liking. Altogether, the evidence suggests that isolated rats have a shift in the allostatic set-point which may, in part, drive increased responding for a variety of rewards including ethanol and sucrose. Enriched rats have enhanced liking of both sucrose and ethanol suggesting that enrichment may offer a unique phenotype with divergent preferences for incentive motivation.
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Affiliation(s)
- Thomas J. Wukitsch
- Department of Psychological Sciences, Kansas State University, 492 Bluemont Hall, 1114 Mid-Campus Dr N, Manhattan, KS 66506-5302, USA
| | - Emma C. Brase
- Department of Psychological Sciences, Kansas State University, 492 Bluemont Hall, 1114 Mid-Campus Dr N, Manhattan, KS 66506-5302, USA
| | - Theodore J. Moser
- Department of Psychological Sciences, Kansas State University, 492 Bluemont Hall, 1114 Mid-Campus Dr N, Manhattan, KS 66506-5302, USA
| | - Stephen W. Kiefer
- Department of Psychological Sciences, Kansas State University, 492 Bluemont Hall, 1114 Mid-Campus Dr N, Manhattan, KS 66506-5302, USA
| | - Mary E. Cain
- Department of Psychological Sciences, Kansas State University, 492 Bluemont Hall, 1114 Mid-Campus Dr N, Manhattan, KS 66506-5302, USA
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13
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Sweet and bitter taste stimuli activate VTA projection neurons in the parabrachial nucleus. Brain Res 2019; 1714:99-110. [PMID: 30807736 DOI: 10.1016/j.brainres.2019.02.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 02/19/2019] [Accepted: 02/22/2019] [Indexed: 01/22/2023]
Abstract
This study investigated neural projections from the parabrachial nucleus (PBN), a gustatory and visceral processing area in the brainstem, to the ventral tegmental area (VTA) in the midbrain. The VTA contains a large population of dopaminergic neurons that have been shown to play a role in reward processing. Anterograde neural tracing methods were first used to confirm that a robust projection from the caudal PBN terminates in the dorsal VTA; this projection was larger on the contralateral side. In the next experiment, we combined dual retrograde tracing from the VTA and the gustatory ventral posteromedial thalamus (VPMpc) with taste-evoked Fos protein expression, which labels activated neurons. Mice were stimulated through an intraoral cannula with sucrose, quinine, or water, and PBN sections were processed for immunofluorescent detection of Fos and retrograde tracers. The distribution of tracer-labeled PBN neurons demonstrated that the populations of cells projecting to the VTA or VPMpc are largely independent. Quantification of cells double labeled for Fos and either tracer demonstrated that sucrose and quinine were effective in activating both pathways. These results indicate that information about both appetitive and aversive tastes is delivered to a key midbrain reward interface via direct projections from the PBN.
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14
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Abstract
The gustatory system contributes to the flavor of foods and beverages and communicates information about nutrients and poisons. This system has evolved to detect and ultimately respond to hydrophilic molecules dissolved in saliva. Taste receptor cells, located in taste buds and distributed throughout the oral cavity, activate nerve afferents that project to the brainstem. From here, information propagates to thalamic, subcortical, and cortical areas, where it is integrated with information from other sensory systems and with homeostatic, visceral, and affective processes. There is considerable divergence, as well as convergence, of information between multiple regions of the central nervous system that interact with the taste pathways, with reciprocal connections occurring between the involved regions. These widespread interactions among multiple systems are crucial for the perception of food. For example, memory, hunger, satiety, and visceral changes can directly affect and can be affected by the experience of tasting. In this chapter, we review the literature on the central processing of taste with a specific focus on the anatomic and physiologic responses of single neurons. Emphasis is placed on how information is distributed along multiple systems with the goal of better understanding how the rich and complex sensations associated with flavor emerge from large-scale, systems-wide, interactions.
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