Sucrose consumption increases naloxone-induced c-Fos immunoreactivity in limbic forebrain.
ABSTRACT Opioids have long been known to have an important role in feeding behavior, particularly related to the rewarding aspects of food. Considerable behavioral evidence suggests that sucrose consumption induces endogenous opioid release, affecting feeding behavior as well as other opioid-mediated behaviors, such as analgesia, dependence, and withdrawal. In the present study, rats were given access to a 10% sucrose solution or water for 3 wk, then they were injected with 10 mg/kg naloxone or saline. Brains were subsequently analyzed for c-Fos immunoreactivity (c-Fos-IR) in limbic and autonomic regions in the forebrain and hindbrain. Main effects of sucrose consumption or naloxone injection were seen in several areas, but a significant interaction was seen only in the central nucleus of the amygdala and in the lateral division of the periaqueductal gray. In the central nucleus of the amygdala, naloxone administration to those rats drinking water significantly increased c-Fos-IR, an effect that was significantly enhanced by sucrose consumption, suggesting an upregulation of endogenous opioid tone in this area. The data from this study indicate that the central nucleus of the amygdala has a key role in the integration of gustatory, hedonic, and autonomic signals as they relate to sucrose consumption, if not to food intake regulation in general. Furthermore, the data from this study lend further support to the hypothesis that sucrose consumption induces the release of endogenous opioids.
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ABSTRACT: Individual differences in taste perception may influence dietary habits, nutritional status, and ultimately nutrition-related chronic disease risk. Individual differences in sweetness intensity perception and the relationship between perceived sweetness intensity, food behaviors, and dietary intake was investigated in 85 adults. Subjects (body mass index [BMI]= 21 ± 3, 21 ± 4 y) completed a food and diet questionnaire, food variety survey, 2 24-h food records, and a perceived sweetness intensity measurement using the general labeled magnitude scale (gLMS). There was interindividual variation in perceived sweetness intensity (0 to 34 gLMS units, mean 10 ± 7). One-way analysis of variance (ANOVA) revealed no difference between perceived sweetness intensity and degree of importance placed on not adding sugar to tea or coffee (P = 0.2) and the degree of importance placed on avoiding sugar-sweetened or fizzy drinks (P = 1.0). Independent t-test analysis revealed no significant association between perceived sweetness intensity and the food variety measure for sugar and confectionary intake (P = 0.6) and selected fruit and vegetable intake (P = 0.1 to 0.9). One-way ANOVA also demonstrated no difference between tertiles of sweetness intensity and BMI (P = 0.1), age (P = 0.3), and food variety score (P = 0.5). No correlation was observed with regards to perceived sweetness intensity and mean total energy (kJ) intake (r = 0.05, P = 0.7), percent energy from total fat, saturated fat, protein, carbohydrate, and grams of fiber (r =-0.1 to 0.1, P = 0.2 to 0.8) and also for intake of the micronutrients: folate, magnesium, calcium, iron, and zinc (r = 0.1 to 0.2, P = 0.1 to 0.4). Only modest correlations were observed between sodium (r = 0.3, P < 0.05), vitamin C (r = 0.3, P < 0.05), and potassium (r = 0.2, P < 0.0) intake and perceived sweetness intensity. Overall, perceived sweetness intensity does not appear to play a role in food behaviors relating to sugar consumption and dietary intake in adults.Journal of Food Science 12/2011; 77(1):H31-5. · 1.78 Impact Factor
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ABSTRACT: Oral gavage is a common route of precise oral dosing for studies in rodents. Complications including tracheal administration, esophageal trauma, and aspiration are common and usually related to animal resistance to the procedure, and the stress induced by oral gavage can be a confounding variable in many studies. The taste of sucrose conveys a pacifying and analgesic effect in newborns, whereas sour solutions can induce the swallow reflex in humans that are dysphagic. We hypothesized that precoating a gavage needle with sucrose or citrate (or both) would pacify mice and induce them to swallow, reducing the stress and complications associated with the technique. To validate this hypothesis, we quantitated time to passage, stress-related behavioral reactions to the procedure, and plasma corticosterone levels in mice after precoating gavage needles with water, sucrose, citrate, sucrose and citrate, or sodium chloride prior to oral gavage. Precoating needles with sucrose reduced the time to passage, decreased observable stress-related reactions to the procedure, and maintained plasma corticosterone levels similar to those in ungavaged control mice. Coating needles with water, sucrose and citrate, or citrate had no beneficial effects on these parameters. Our findings describe a novel, validated technique that measurably decreases signs of stress and thereby improves animal welfare during oral gavage. Furthermore, the use of sucrose may be a valuable tool to refine other minor or nonsurgical procedures in the field of laboratory animal research.Journal of the American Association for Laboratory Animal Science: JAALAS 05/2010; 49(3):329-34. · 1.15 Impact Factor
Article: The many paths to fear.[show abstract] [hide abstract]
ABSTRACT: Fear is an emotion that has powerful effects on behaviour and physiology across animal species. It is accepted that the amygdala has a central role in processing fear. However, it is less widely appreciated that distinct amygdala outputs and downstream circuits are involved in different types of fear. Data show that fear of painful stimuli, predators and aggressive members of the same species are processed in independent neural circuits that involve the amygdala and downstream hypothalamic and brainstem circuits. Here, we discuss data supporting multiple fear pathways and the implications of this distributed system for understanding and treating fear.Nature Reviews Neuroscience 08/2012; 13(9):651-8. · 26.48 Impact Factor