Taste preference and conditioned taste aversion of the metallothionein-1/2 null mice.

To investigate the effects of metallothionein (MT)-1/2 gene knockout on the taste preference and the conditioned taste aversion (CTA), we performed an experiment comparing the behavior of wild type (WT) mice and MT-1/2 null (KO) mice. The taste preference ratio of saccharin solutions (0.1 or 0.

Discrimination of cellulose microparticles in rats.

Oral perception of food particles is important in mastication and swallowing. However, the mechanism underlying particle perception remains poorly understood because of the lack of suitable experimental systems. We evaluated microparticle perception in rats utilizing insoluble cellulose particles of varying diameters (20-170 μm).

Conditioned nausea induced by cisplatin and emetine identified by a taste reactivity test in rats.

No prior studies have shown that gaping reactions are produced with the avoidance of conditioned taste caused by cisplatin and emetine. Therefore, we tried to demonstrate it using a taste reactivity test in rats and found the gaping reactions induced when saccharin is readministered after gustatory conditioning that paired saccharin with cisplatin or emetine. Since conditioned gaping reactions indicate the aversion to saccharin taste and conditioned nausea, the present study suggest that the taste aversion is induced by cisplatin and emetine.

Chemogenetic inhibition of the bed nucleus of the stria terminalis suppresses the intake of a preferable and learned aversive sweet taste solution in male mice.

Conditioned taste aversion (CTA) is established by pairing a taste solution as a conditioned stimulus (CS) with visceral malaise as an unconditioned stimulus (US). CTA decreases the taste palatability of a CS. The bed nucleus of the stria terminalis (BNST) receives taste inputs from the brainstem.

The Effects of Roux-en-Y Gastric Bypass on Glucose- vs. Fructose-Associated Conditioned Flavor Preference.

In rodents, repeated single-bottle exposures to distinctly flavored isocaloric glucose and fructose solutions, two sugars with different metabolic pathways, eventually lead to a preference for the former. Because Roux-en-Y gastric bypass (RYGB) surgery decreases preference for and intake of sugar solutions in rats, we tested whether RYGB would curtail the conditioning of a preference for a glucose-paired vs. fructose-paired flavor.

Oromotor and somatic taste reactivity during sucrose meals reveals internal state and stimulus palatability after gastric bypass in rats.

After Roux-en-Y gastric bypass (RYGB), rats consume less high-energy foods and fluids, though whether this reflects a concomitant change in palatability remains unclear. By measuring behavior during intraorally delivered liquid meals across days (1 water, 8 sucrose sessions), we showed that RYGB rats (RYGB, = 8/sex) consumed less 1.0 M sucrose than their sham surgery counterparts (SHAM, = 8 males, = 11 females) but displayed similarly high levels of ingestive taste reactivity responses at the start of infusions.

Effects of area postrema lesions and bilateral subdiaphragmatic afferent vagotomy on emetine-induced conditioned taste avoidance in rats.

We investigated the effect of area postrema lesions and selective vagotomy of afferent fibers on emetine-induced nausea in rats. We evaluated the acquisition of the conditioned taste avoidance (CTA) to 0.1% saccharin solution after conditioning with emetine dihydrochloride (5.

Involvement of the area postrema and the nucleus tractus solitarius in the emetogenic action of emetine in rats.

Objectives: The aim of the present study was to demonstrate the effective dose of emetine for inducing nausea and/or emesis, and the effects of emetine on the excitability of central neurons in the area postrema (AP) and the nucleus tractus solitarius (NTS).

Methods: Rats were used as experimental animals. We measured the conditioned taste aversion (CTA) induced by the intraperitoneal administration of emetine solution (0.

Neural Isolation of the Olfactory Bulbs Severely Impairs Taste-Guided Behavior to Normally Preferred, But Not Avoided, Stimuli.

Here we systematically tested the hypothesis that motivated behavioral responsiveness to preferred and avoided taste compounds is relatively independent of the olfactory system in mice whose olfactory bulbs (main and accessory) were surgically disconnected from the rest of the brain [bulbotomy (BULBx)]. BULBx was confirmed histologically as well as functionally with the buried food test. In brief access taste tests, animals received 10-s trials of various concentrations of a taste compound delivered quasirandomly.

The Basolateral Nucleus of the Amygdala Executes the Parallel Processes of Avoidance and Palatability in the Retrieval of Conditioned Taste Aversion in Male Rats.

Conditioned taste aversion (CTA) is an essential behavior for animal survival. Conditioned animals show avoidance and decreased palatability to a conditioned stimulus (CS) on CTA retrieval. In this study, we aimed to determine whether the basolateral nucleus of the amygdala (BLA) is involved in CTA retrieval and whether avoidance and palatability in CTA retrieval are processed in the BLA.

Extracellular glucose-dependent IPSC enhancement by leptin in fast-spiking to pyramidal neuron connections via JAK2-PI3K pathway in the rat insular cortex.

Leptin is produced in the adipocytes and plays a pivotal role in regulation of energy balance by controlling appetite and metabolism. Leptin receptors are widely distributed in the brain, especially in the hypothalamus, hippocampus, and neocortex. The insular cortex (IC) processes gustatory and visceral information, which functionally correlate to feeding behavior.

Taste preference changes throughout different life stages in male rats.

Taste preference, a key component of food choice, changes with aging. However, it remains unclear how this occurs. To determine differences in taste preference between rats in different life stages, we examined the consumption of taste solutions and water using a two-bottle test.

Activation of mu-opioid receptors in the ventral pallidum decreases the negative hedonic evaluation of a conditioned aversive taste in rats.

Conditioned taste aversion (CTA) causes a shift in the hedonic evaluation of a conditioned stimulus (CS) from positive to negative, and reduces the CS intake. Mu-opioid receptors (MORs) in the ventral pallidum (VP) are known to be involved in the hedonic evaluation of positive rewarding stimuli; however, their involvement in evaluation of a negative aversive stimulus is still unclear. To explore the neural mechanisms of the negative hedonic evaluation of the CS in CTA, we examined the effects of the activation of VP MORs on the behavioral responses of rats to a CS.

Delta-opioid receptor blockade in the ventral pallidum increases perceived palatability and consumption of saccharin solution in rats.

The ventral pallidum (VP) is involved in ingestive behaviour. It receives dense GABAergic projections from the nucleus accumbens. GABAergic terminals in the VP co-express enkephalin, an endogenous ligand of delta-opioid receptors.

Activation of efferents from the basolateral amygdala during the retrieval of conditioned taste aversion.

The basolateral amygdala (BLA) is critical in the retrieval of conditioned taste aversion (CTA). Although BLA neurons have axonal connections with several brain regions, it is unclear which efferent pathways are functional in CTA. The present study investigated the involvement of efferents from BLA in CTA retrieval with manganese (Mn(2+))-enhanced magnetic resonance imaging (MEMRI).

The odor of Osmanthus fragrans attenuates food intake.

Odors have been shown to exert an influence on various physiological and behavioral activities. However, little is known whether or not odor stimulation directly affects the levels of feeding-related neuropeptides. Here we show that the neural transmission by Osmanthus fragrans (OSM) decreased the mRNA expression of orexigenic neuropeptides, such as agouti-related protein, neuropeptide Y, melanin-concentrating hormone and prepro-orexin, while increased anorexigenic neuropeptides, such as cocaine- and amphetamine-regulated transcript and proopiomelanocortin in rats.

Pressure-sensitive adhesion system using acrylate block copolymers in response to photoirradiation and postbaking as the dual external stimuli for on-demand dismantling.

We have demonstrated the validity of a new type of pressure-sensitive adhesion system using block copolymers containing a poly(2-ethylhexyl acrylate) (P2EHA) segment as the low glass transition temperature polymer and a poly(tert-butyl acrylate) (PtBA) or poly(isobornyl acrylate) (PIBoA) segment as the reacting polymer in the presence of a photoacid generator (PAG). This adhesion system can be easily debonded because of a change in the polymer properties of the adhesives by acid-catalyzed deprotection uniquely occurring during the photoirradiation followed by postbaking. We investigated the transformation of PtBA and PIBoA into poly(acrylic acid) using IR spectroscopy and a thermogravimetric analysis in the presence of p-toluenesulfonic acid and the PAGs.

Cannabinoid in the nucleus accumbens enhances the intake of palatable solution.

It has been suggested that the activation of cannabinoid receptors in the nucleus accumbens shell facilitates feeding behavior. However, it remains unclear whether cannabinoid ligands enhance the palatability of food to facilitate feeding. In this study, we examined whether microinjecting an endogenous cannabinoid agonist, anandamide into the nucleus accumbens shell would affect the intake of water, sweet or bitter solutions.

Functional organization of the rodent parabrachial nucleus.

The rodent parabrachial nucleus (PBN) is not merely a sensory relay station but also plays an important role in integrating various ascending and descending inputs together with plastic changes of neuronal responses after learning and experience. The limbic and reward systems receive ingestion-related information via the cortical areas in primates, whereas in rodents the information is sent to these systems mostly via the PBN. To explore how the rat PBN is functionally organized, we detected activation patterns of neurons mainly by means of c-fos immunohistochemistry to show neuronal activation in different situations of ingestive behavior.

Spatial differences in molecular characteristics of the pontine parabrachial nucleus.

Neurons in the pontine parabrachial nucleus (PBN) transduce signals for the general visceral sensory, somatic sensory, gustatory, and autonomic nervous systems, and the various PBN neurons that perform these functions are intermingled. In this study, we analyzed PBN gene expression profiles in male Wistar rats and obtained data on gene expression in the PBN and the principal sensory nucleus of the trigeminal nerve (Pr5). Using these data in combination with in situ hybridization analyses, we identified genes that showed higher expression in the PBN than in Pr5.

GABAergic transmission in the rat ventral pallidum mediates a saccharin palatability shift in conditioned taste aversion.

We previously found that the blockade of gamma-aminobutyric acid (GABA)(A) receptors in the ventral pallidum (VP) alters the taste palatability of a conditioned stimulus (CS) from aversive to ingestive after the establishment of conditioned taste aversion (CTA). Because these results suggest that GABAergic transmission in the VP mediates decreased palatability of the taste in CTA, the present study aimed to examine the effects of taste stimulation on the extracellular release of GABA in the VP using in vivo microdialysis. Initially, rats received a paired presentation of 5 mm saccharin or 0.

The role of the ventral pallidum GABAergic system in conditioned taste aversion: effects of microinjections of a GABAA receptor antagonist on taste palatability of a conditioned stimulus.

When subjects receive a taste stimulus (conditioned stimulus, CS) that is paired with malaise, they acquire conditioned taste aversion (CTA). It is thought that the taste CS changes from appetitive to aversive after acquisition of CTA. Previous studies have suggested that the ventral pallidum (VP) is involved in the hedonics of taste stimuli, therefore the present study investigated whether the VP is a neural substrate for the shift in preference of the CS after CTA acquisition.

Effects of brain lesions on taste-potentiated odor aversion in rats.

Rats failed to acquire aversions to odor stimulus, which was followed 30 min later by an unconditioned stimulus (US). However, when the odor stimulus was accompanied by a taste stimulus, they acquired odor aversions as well as taste aversions. In this phenomenon, referred to as a taste-potentiated odor aversion, lesions of the amygdala disrupted both taste and odor aversions, whereas lesions of the parvicellular part of ventroposteromedial thalamic nucleus (VPMpc) or insular cortex (IC) disrupted taste aversion but attenuated only odor aversion.