Physiology & behavior
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Physiology & behavior · Jun 2014
Experimental manipulation of breakfast in normal and overweight/obese participants is associated with changes to nutrient and energy intake consumption patterns.
The effect of breakfast and breakfast omission on daily food intake in normal and overweight participants was investigated. 37 participants were recruited for this experimental study and assigned to one of four groups on the basis of their body mass index (BMI) (normal weight BMI <25 kg/m(2) or overweight/obese BMI >25 kg/m(2)) and breakfast habits (breakfast eater or breakfast omitter). All participants were requested to eat breakfast for an entire week, and then following a washout period, omit breakfast for an entire week, or vice versa. Seven-day food diaries reporting what was consumed and the timing of consumption were completed for each breakfast condition. ⋯ All groups consumed significantly less energy, carbohydrate and fibre in the no breakfast week; however, overweight participants increased their sugar intakes. Consumption of the micronutrients iron and folate was reduced in the no breakfast week. The findings highlight that the timing of food intake and habitual breakfast eating behaviour are important factors when investigating why breakfast consumption may be associated with BMI.
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Physiology & behavior · Jun 2014
Naloxone treatment alters gene expression in the mesolimbic reward system in 'junk food' exposed offspring in a sex-specific manner but does not affect food preferences in adulthood.
We have previously reported that the opioid receptor blocker, naloxone, is less effective in reducing palatable food intake in offspring exposed to a maternal cafeteria diet during the perinatal period, implicating a desensitization of the central opioid pathway in the programming of food preferences. The present study aimed to investigate the effect of a maternal cafeteria diet and naloxone treatment on the development of the mesolimbic reward pathway and food choices in adulthood. We measured mRNA expression of key components of the reward pathway (mu-opioid receptor, proenkephalin, tyrosine hydroxylase, D1 and D2 receptors and the dopamine active transporter (DAT)) in the nucleus accumbens (NAc) and ventral tegmental area (VTA) of the offspring of control and cafeteria fed (JF) dams at weaning and after a 10-day naloxone treatment post-weaning and determined food preferences in adulthood in the remaining offspring. ⋯ Proenkephalin mRNA expression was higher in the NAc of female JF offspring compared to controls, independent of naloxone treatment (P<0.05). There was no effect of naloxone treatment on food preferences in adulthood in either control or JF offspring. These data indicate that prenatal exposure to a cafeteria diet alters the impact of opioid signaling blockade in the early post-weaning period on gene expression in the central reward pathway in a sex specific manner, but that these changes in gene expression do not appear to have any persistent impact on food preferences in adulthood.
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Physiology & behavior · May 2014
Acid-induced hyperalgesia and anxio-depressive comorbidity in rats.
Fibromyalgia is a prevalent disorder characterized by chronic widespread pain (CWP) and complex comorbid symptoms. A CWP model is developed through repeated unilateral intramuscular injections of acid saline resulting in bilateral mechanical hyperalgesia in rats. The present study aims to evaluate whether both anxious and depressive comorbidities exist in this acid-induced pain model, similarly to patients with CWP syndromes. ⋯ Moreover, rats with chronic pain showed significantly longer immobility than the vehicle group in the forced swimming test. The results indicate that psychiatric behaviors are exacerbated in the CWP model. This study provides evidence for the validity of the acid-induced pain model analogous to patients with CWP syndromes.
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Possible interactions of melatonin with concurrently administered drugs were investigated in in vitro studies utilising human hepatic post-mitochondrial preparations; similar studies were conducted with rat preparations to ascertain whether rat is a suitable surrogate for human. Drugs were selected based not only on the knowledge that the 6-hydroxylation of exogenous melatonin, its principal pathway of metabolism, is mainly mediated by hepatic CYP1A2, but also on the likelihood of the drug being concurrently administered with melatonin. ⋯ Of the drugs screened, only the potent CYP1A2 inhibitor 5-methoxypsoralen impaired the 6-melatonin hydroxylation at pharmacologically relevant concentrations, and is likely to lead to clinical interactions; diazepam, tamoxifen and acetaminophen (paracetamol) did not impair the metabolic conversion of melatonin to 6-sulphatoxymelatonin at concentrations attained following therapeutic administration. 17-Ethinhyloestradiol appeared not to suppress the 6-hydroxylation of melatonin but inhibited the sulphation of 6-hydroxymelatonin, but this is unlikely to result in an interaction following therapeutic intake of the steroid. Species differences in the inhibition of melatonin metabolism in human and rat hepatic post-mitochondrial preparations were evident implying that the rat may not be an appropriate surrogate of human in such studies.
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Physiology & behavior · May 2014
If it makes you feel bad, don't do it! Egoistic rather than altruistic empathy modulates neural and behavioral responses in moral dilemmas.
According to Greene et al.'s dual-process theory, the differential involvement of emotional processes would explain the different patterns of moral judgments people typically produce when faced with Trolley- and Footbridge-type dilemmas. As a relevant factor, dispositional empathy is known to motivate prosocial behaviors, thus playing a central role in moral judgment and behavior. The present study was aimed at investigating how behavioral and neural correlates of moral decision-making are modulated by the cognitive and affective dimensions of empathy. ⋯ Scores on the Empathic Concern affective subscale of the IRI positively predicted unpleasantness experienced during decision-making for all dilemmas. On the other hand, for Footbridge-type dilemmas only, scores on the Personal Distress affective subscale predicted negatively the mean percentages of utilitarian choices and positively the mean amplitudes of the P260, an ERP component reflecting an immediate emotional reaction during decision-making. It is concluded that "self-oriented" feelings of anxiety and unease, rather than "other-oriented" feelings of concern, affect behavioral choices and emotion-related cortical activity in Footbridge-type moral dilemmas.