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Food Pellets (food + pellet)
Selected AbstractsInvolvement of NMDA and AMPA/KA receptors in the nucleus accumbens core in instrumental learning guided by reward-predictive cuesEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2005Christian Giertler Abstract The use of reward-predictive cues to guide behavior critically involves the nucleus accumbens. However, little is known regarding the role of ionotropic glutamate receptors in the core subregion of the nucleus accumbens (AcbC) in instrumental learning guided by reward-predictive cues. Here we examined the effects of an intra-AcbC blockade of NMDA and AMPA/KA receptors on the acquisition of an instrumental response in a reaction time (RT) task in rats. In this task, discriminative cues signaled in advance the upcoming reward magnitude (5 or 1 food pellet) associated with a lever release. During early acquisition (days 1,6) rats received daily bilateral injections of either the NMDA receptor antagonist AP5 (5.0 µg per side, n = 14), the AMPA/KA receptor antagonist CNQX (2.5 µg per side, n = 14) or vehicle (0.5 µL per side, n = 19). No treatment was given during late acquisition (days 7,12). The main result was that rats which received intra-AcbC injections of AP5 or CNQX during early acquisition exhibited a general RT increase of responses to high and low reward. However, treatment with AP5 and CNQX did not interfere with discriminative guidance of RTs by cue-associated reward magnitudes, i.e. during acquisition RTs of responses to expected high reward became significantly faster than RTs of responses to expected low reward. Our findings suggest that NMDA and AMPA/KA receptors in the AcbC play a critical role in invigorating responding during instrumental learning, but seem less important in guiding responding according to reward-predictive cues. [source] Schedule-Induced Ethanol Self-Administration in DBA/2J and C57BL/6J MiceALCOHOLISM, Issue 6 2003Guy Mittleman Background: The purpose of these experiments was to provide an initial investigation into ethanol self-administration elicited in the schedule-induced polydipsia (SIP) paradigm. Methods: Mature male mice were food deprived to between 80 and 85% of their baseline weight and received 20 daily 1 hr SIP test sessions in which a food pellet (20 mg) was delivered on a fixed-time 60 sec schedule. In different groups, the acquisition of drinking 5% (v/v) ethanol solution (experiment 1) or water (experiment 2) was recorded along with other behaviors that occurred in the test chambers. Results: Results indicated that C57BL/6J mice drank significantly more ethanol than DBA/2J mice and that C57 mice achieved blood alcohol concentrations as high as 300 mg/dl. Blood alcohol concentrations were consistently correlated with g/kg ethanol intake. The groups did not differ in consumption of water. SIP test sessions using higher concentrations of ethanol (10,20% v/v, experiment 1) or sucrose solutions (0.1,2% w/v, experiment 2) then were performed. Group differences in ethanol consumption were maintained at all ethanol concentrations. Although DBAs drank more of a low concentration of sucrose (0.1%), when expressed as g/kg, sucrose intake was equivalent in the two strains at all concentrations. Analysis of the time course of drinking clearly showed that this behavior was adjunctive in nature. Conclusion: These results demonstrate the effectiveness of this procedure in inducing ethanol self-administration and its utility for investigating the genetic bases of vulnerability toward excessive ethanol consumption. [source] RESEARCH FOCUS ON COMPULSIVE BEHAVIOUR IN ANIMALS: Pre-exposure to environmental cues predictive of food availability elicits hypothalamic,pituitary,adrenal axis activation and increases operant responding for food in female ratsADDICTION BIOLOGY, Issue 4 2009Carlo Cifani ABSTRACT The present study was undertaken to develop an animal model exploiting food cue-induced increased motivation to obtain food under operant self-administration conditions. To demonstrate the predictive validity of the model, rimonabant, fluoxetine, sibutramine and topiramate, administered 1 hour before the experiment, were tested. For 5 days, female Wistar rats were trained to self-administer standard 45 mg food pellets in one daily session (30 minutes) under FR1 (fixed ratio 1) schedule of reinforcement. Rats were then trained to an FR3 schedule and finally divided into two groups. The first group (control) was subjected to a standard 30 minutes FR3 food self-administration session. The second group was exposed to five presentations of levers and light for 10 seconds each (every 3 minutes in 15 minutes total). At the completion of this pre-session phase, a normal 30-minute session (as in the control group) started. Results showed that pre-exposure to environmental stimuli associated to food deliveries increased response for food when the session started. Corticosterone and adrenocorticotropic hormone plasma levels, measured after the 15-minute pre-exposure, were also significantly increased. No changes were observed for the other measured hormones (growth hormone, prolactin, thyroid-stimulating hormone, luteinizing hormone, insulin, amylin, gastric inhibitor polypeptide, ghrelin, leptin, peptide YY and pancreatic polypeptide). Rimonabant, sibutramine and fluoxetine significantly reduced food intake in both animals pre-exposed and in those not pre-exposed to food-associated cues. Topiramate selectively reduced feeding only in pre-exposed rats. The present study describes the development of a new animal model to investigate cue-induced increased motivation to obtain food. This model shows face and predictive validity, thus, supporting its usefulness in the investigation of new potential treatments of binge-related eating disorders. In addition, the present findings confirm that topiramate may represent an important pharmacotherapeutic approach to binge-related eating. [source] Blockade of NMDA receptors in the dorsomedial striatum prevents action,outcome learning in instrumental conditioningEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2005Henry H. Yin Abstract Although there is consensus that instrumental conditioning depends on the encoding of action,outcome associations, it is not known where this learning process is localized in the brain. Recent research suggests that the posterior dorsomedial striatum (pDMS) may be the critical locus of these associations. We tested this hypothesis by examining the contribution of N -methyl- d -aspartate receptors (NMDARs) in the pDMS to action,outcome learning. Rats with bilateral cannulae in the pDMS were first trained to perform two actions (left and right lever presses), for sucrose solution. After the pre-training phase, they were given an infusion of the NMDA antagonist 2-amino-5-phosphonopentanoic acid (APV, 1 mg/mL) or artificial cerebral spinal fluid (ACSF) before a 30-min session in which pressing one lever delivered food pellets and pressing the other delivered fruit punch. Learning during this session was tested the next day by sating the animals on either the pellets or fruit punch before assessing their performance on the two levers in extinction. The ACSF group selectively reduced responding on the lever that, in training, had earned the now devalued outcome, whereas the APV group did not. Experiment 2 replicated the effect of APV during the critical training session but found no effect of APV given after acquisition and before test. Furthermore, Experiment 3 showed that the effect of APV on instrumental learning was restricted to the pDMS; infusion into the dorsolateral striatum did not prevent learning. These experiments provide the first direct evidence that, in instrumental conditioning, NMDARs in the dorsomedial striatum are involved in encoding action,outcome associations. [source] Elevated ability to compete for limited food resources by ,all-fish' growth hormone transgenic common carp Cyprinus carpioJOURNAL OF FISH BIOLOGY, Issue 6 2009M. Duan Food consumption, number of movements and feeding hierarchy of juvenile transgenic common carp Cyprinus carpio and their size-matched non-transgenic conspecifics were measured under conditions of limited food supply. Transgenic fish exhibited 73·3% more movements as well as a higher feeding order, and consumed 1·86 times as many food pellets as their non-transgenic counterparts. After the 10 day experiment, transgenic C. carpio had still not realized their higher growth potential, which may be partly explained by the higher frequency of movements of transgenics and the ,sneaky' feeding strategy used by the non-transgenics. The results indicate that these transgenic fish possess an elevated ability to compete for limited food resources, which could be advantageous after an escape into the wild. It may be that other factors in the natural environment (i.e. predation risk and food distribution), however, would offset this advantage. Thus, these results need to be assessed with caution. [source] Oral vaccination with envelope protein VP28 against white spot syndrome virus in Procambarus clarkii using Bacillus subtilis as delivery vehiclesLETTERS IN APPLIED MICROBIOLOGY, Issue 5 2008L.L. Fu Abstract Aims:, To achieve high-level expression and secretion of active VP28 directed by a processing-efficient signal peptide in Bacillus subtilis WB600 and exploit the possibility of obtaining an oral vaccine against white spot syndrome virus (WSSV) using vegetative cells or spores as delivery vehicles. Methods and Results:, The polymerase chain reaction (PCR)-amplified vp28 gene was inserted into a shuttle expression vector with a novel signal peptide sequence. After electro-transformation, time-courses for recombinant VP28 (rVP28) secretion level in B. subtilis WB600 were analysed. Crayfish were divided into three groups subsequently challenged by 7-h immersion at different time points after vaccination. Subgroups including 20 inter-moult crayfish with an average weight of 15 g in triplicate were vaccinated by feeding coated food pellets with vegetative cells or spores for 20 days. Vaccination trials showed that rVP28 by spore delivery induced a higher resistance than using vegetative cells. Challenged at 14 days postvaccination, the relative per cent survival (RPS) values of groups of rVP28-bv and rVP28-bs was 51·7% and 78·3%, respectively. Conclusions:, The recombinant B. subtilis strain with the ability of high-level secretion of rVP28 can evoke protection of crayfish against WSSV by oral delivery. Significance and Impact of the Study:, Oral vaccination by the B. subtilis vehicle containing VP28 opens a new way for designing practical vaccines to control WSSV. [source] | ||||||||||