Persona: Pellón Suárez de Puga, Ricardo
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Pellón Suárez de Puga
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Publicación Environmental enrichment accelerates the acquisition of schedule-induced drinking in rats(Elsevier, 2023-09-15) Fuentes Verdugo, Esmeralda; López Tolsa Gómez, Gabriela Eugenia; García Pascual, Raquel; Pellón Suárez de Puga, RicardoEnvironmental enrichment (EE) provides an improvement in the housing conditions of experimental animals, such as laboratory rats, with greater physical and social stimulation through toys and company in the home cages. Its use is known to influence performance of experimental protocols, but these effects have not been well determined in the schedule-induced drinking (SID) procedure. The main goal of this study was to investigate the effects of EE on the acquisition of SID in 24 12-week-old male Wistar rats, divided into two groups, a group with EE housed with toys and companions, and a group without enrichment in individual housing conditions without toys (social isolation and no environmental enrichment, INEE). A total of 25 sessions, under a fixed time 30 s food reinforcement schedule and with access to water in the experimental chambers were carried out. Sessions lasted 30 min. The results showed that the EE group developed faster the excessive drinking pattern of SID, and drank to higher levels, than the INEE group. The greater development of SID in the EE group contradicts the view of schedule-induced behavior as linked to stress reduction and better suits with the conception of induction related to positive reinforcement.Publicación The irrelevancy of the inter-trial interval on delay-discounting experiments on an animal model of ADHD(Elsevier, 2021-06-25) SjØberg, Espen .A.; Johansen, Espen Borgå; Ramos Villaverde, Sergio; López Tolsa Gómez, Gabriela Eugenia; Pellón Suárez de Puga, RicardoDelay discounting involves choosing between a small, immediate reward, and a larger but delayed one. As the delay between choice and large reward gets longer, people with ADHD tend to become impulsive faster than controls, indicated by a switch in preference from the large to the smaller reward. Choosing the smaller reward when the larger is considered reward maximizing is labeled impulsive behaviour. It is well documented that increased delays between choice and reward affects choice preference in both humans and other animals. Other variables such as the inter-trial interval or trial length are observed to have an effect on human discounting, but their effect on discounting in other animals is largely assumed rather than tested. In the current experiment, we tested this assumption. One group of rats was exposed to increasing delays between choosing the large reward and receiving it, while another group experienced longer inter-trial intervals that were equal in length to the delays in the other group. This ensured that trial length was controlled for in delay discounting, but that the delay function and inter-trial intervals could be manipulated and measured separately. Results showed that while the delay between choice and reward caused impulsive behaviour in rats, the length of the inter-trial interval (and by extension trial length) had no impact on choice behaviour. A follow-up experiment found this to be the case even if the length of the inter-trial interval was signaled with audio cues. These results suggest that rats, and possibly animals in general, are insensitive to time between trials, and therefore cannot easily represent human counterparts on the task.Publicación Exercise, diet, and the reinforcing value of food in an animal model of anorexia nervosa(SAGE, 2019) Paz Regidor, Ana María de; Vidal García, Pedro; Pellón Suárez de Puga, Ricardo; SAGEActivity-based anorexia (ABA) develops when laboratory rats are subjected to a single meal per day and have access to an activity wheel for the remaining time. Here, we studied the contribution of exercise and diet to the reinforcing value of food during ABA development. Three groups of eight adult male Wistar rats were used: an ABA group with 21.5 hr (then 22 hr) of wheel access and 1 hr (then 30 min) of food access, a control group with the same time exposure to food but without exercise, and a yoked group to the ABA in terms of weight loss. Rats were daily tested on a progressiveratio schedule to measure their motivation for food. ABA rats gradually reduced their body weight more than the food control group. Animals steadily increased their breaking points in parallel to losses in body weight, but no significant differences were found between groups. Adult rats can develop ABA, but their loss in weight neither resulted in a decrease of food intake nor in the motivation to obtain it.Publicación Delay Gradients for Spout-Licking and Magazine-Entering Induced by a Periodic Food Schedule(Springer Nature, 2018-03-26) Killeen, Peter R.; Pellón Suárez de Puga, Ricardo; Ibias Martín, JavierThe present experiments studied impulsivity by manipulating the delay between target responses and presentation of a reinforcer. Food-deprived SHR, WKY, and Wistar rats were exposed to a fixed-time 30-s schedule of food pellet presentation until they developed stable patterns of water spout-licking and magazine-entering. In successive phases of the study, a resetting delay contingency postponed food delivery if target responses (licks or entries) occurred within the last 1, 2, 5, 10, 20, 25, or 28 s of the inter-food interval. Response-food delays were applied independently for the two behaviors during separate experimental phases, and order of presentation and the behavior that was punished first were counterbalanced. Licking was induced in the order of Wistar > SHR > WKY, and magazine entries were in the order of SHR > WKY > Wistar. Magazine entries showed steeper delay gradients than licking in SHR and Wistar rats but were of similar great inclination in the WKY rats. The different responses were differentially sensitive to delays. This suggests a different ordering of them in the interval between reinforcers. It also has implications for attempts to change impulsive behavior, both in terms of the nature of the response and its removal from reinforcing consequences.Publicación Influence of early maternal separation on susceptibility to the activity-based anorexia model in male and female Sprague Dawley rats(Elsevier, 2022-11) Kojo Morgan, Godstime Stephen; Mata, Yolanda; Carrillo Urbano, Beatriz; Pellón Suárez de Puga, Ricardo; Collado Guirao, Paloma; Gotti, Stefano; Pinos Sánchez, María ElenaA principal animal paradigm employed in Anorexia Nervosa (AN) study is the activity-based anorexia (ABA) model. The model's efficacy in recapitulating the core features of AN in humans allows for the study of the parameters involved in the disorder. The current study examined the susceptibility to the ABA protocol in the presence of a significant stressor (maternal separation) in male and female Sprague Dawley rats. More importantly, we analysed the sex-differences on activity levels during different periods of the ABA protocol to determine the period(s) influencing the most pathological weight loss. Both components of the ABA protocol contributed to the subjects’ bodyweight loss. Stress in the first two weeks of development conferred a protective effect in males. Time spent and activity levels on the running wheel were higher in females compared to males. Hyperactivity in ABA subjects was observed during the food-anticipatory activity (FAA) and postprandial activity in males and during the FAA and nocturnal activity periods in females. This study aids in understanding the effect of intensity of activity during specific periods on the pathological weight loss in ABA rats. These observations are informative for therapies aimed at ameliorating body mass index in AN patients.Publicación The Effect of Methylphenidate on the Microstructure of Schedule-Induced Polydipsia in an animal model of ADHD(Elsevier, 2017-08-30) Daniels, Carter W.; Sanabria, Federico; Ibias Martín, Javier; Miguens Vázquez, Miguel; Pellón Suárez de Puga, RicardoSchedule-induced polydipsia (SIP) was established in spontaneously hypertensive rats (SHR), Wistar Kyoto rats (WKY), and Wistar rats, using a multiple fixed-time (FT) schedule of food delivery, with 30- and 90-s components. Thereafter, animals were exposed to methylphenidate (MPH; 2.5 mg/kg/d) for six consecutive SIP sessions. A test to assess possible sensitization effects was also conducted four days after termination of the drug treatment. At baseline, FT 90-s produced longer and more frequent drinking episodes in SHR than in WKY. An analysis of the distribution of inter-lick intervals revealed that drinking was organized in bouts, which were shorter in SHR than in WKY. Across strains and schedules, MPH shifted drinking episodes towards the beginning of inter-food intervals, which may reflect a stimulant effect on SIP. MPH transiently reduced the frequency of drinking episodes in WKY in FT 30-s, and more permanently reduced the frequency of licking bouts in Wistar rats. MPH also increased the length of licking bouts in Wistar rats. Overall, SHR displayed a hyperactive-like pattern of drinking (frequent but short bouts), which 2.5 mg/kg MPH appears to reduce in WKY and Wistar but not in SHR rats. It appears that therapeutic effects of MPH on hyperactive-like SIP require higher doses in SHR relative to control strains.Publicación Chronic ∆-9-Tetrahydrocannabinol administration delays acquisition of schedule-induced drinking in rats and retains long-lasting effects(Springer, 2021-08-26) Fuentes Verdugo, Esmeralda; López Tolsa Gómez, Gabriela Eugenia; Pellón Suárez de Puga, Ricardo; Miguens Vázquez, MiguelRationale: Schedule-induced drinking (SID) is a behavioural phenomenon characterized by an excessive and repetitive drinking pattern with a distinctive temporal distribution that has been proposed as a robust and replicable animal model of compulsivity. Despite cannabis currently being the most widely consumed illicit drug, with growing interest in its clinical applications, little is known about the effects of ∆-9-Tetrahydrocannabinol (THC) on SID. Objectives: The effects of chronic and acute THC administration on SID acquisition, maintenance and extinction were studied, as were the effects of such administrations on the distinctive temporal distribution pattern of SID. Methods: THC (5 mg/kg i.p.), or the corresponding vehicle, was administered to adult Wistar rats for 14 days in a row. Subsequently, THC effects on SID acquisition were tested during 21 sessions using a 1h fixed-time 60-s food delivery schedule. Acute effects of THC were also evaluated after SID development. Finally, two extinction sessions were conducted to assess behavioural persistence. Results: The results showed that previous chronic THC treatment delayed SID acquisition and altered the distinctive behavioural temporal distribution pattern during sessions. Moreover, acute THC administration after SID development decreased SID performance in animals chronically pre-treated with the drug. No great persistence effects were observed during extinction in animals pre-treated with THC. Conclusions: These results suggest that chronic THC affects SID development, confirming that it can disrupt learning, possibly causing alterations in time estimation, and also leads to animals being sensitized when they are re-exposed to the drug after long periods without drug exposure.Publicación Activity-Based Anorexia(Springer, 2020) Paz Regidor, Ana María de; Vidal García, Pedro; Pellón Suárez de Puga, Ricardo; SpringerPublicación Assessment of the “timing” function of schedule-induced behavior on fixed-interval performance.(American Psychological Association, 2021) López Tolsa Gómez, Gabriela Eugenia; Pellón Suárez de Puga, RicardoIt has been suggested that schedule-induced behaviors allow organisms to adapt better to temporal regularities of the environment. The main goal of the present study was to observe the effect of scheduleinduced drinking (SID) on the performance in fixed-interval (FI) schedules. Rats were exposed to a FI 15-, 30-, or 60-s food reinforcement schedule, and only half of them had access to water in the experimental chamber. Rats with access to water developed SID, which occurred in the first part of the interval, regardless of the FI value, and was followed by an increase in lever pressing rate. There were no substantial differences in the quantitative measures of timing between groups that had or did not have access to water, except for the rats in the FI 15-s group with access to water, who showed longer postreinforcement pauses, possibly attributable to competition between SID and lever pressing. SID did not manifest the scalar property, contrary to lever pressing, but it is proposed that behaviors are displayed serially until the last behavior before the target operant response becomes a discriminative stimulus for that behavior. It is not assumed that the purpose of schedule-induced behaviors is to aid timing, but the development of behavioral patterns might determine the performance of organisms on temporal tasks. Additionally, in some cases competition between responses might exert more control on when the operant behavior occurs than timing. Timing seems to consist in the temporal organization of available behaviors that leads to a specific behavior occurring at a specified time, a single characteristic that typically had come to indicate accurate timing.Publicación Activity-based anorexia alters hypothalamic POMC and orexin populations in male rats(Elsevier, 2022-08-11) Sánchez Serrano, Ricardo; Carrillo Urbano, Beatriz; Fernández García, José Manuel; García Úbeda, Rocío; Paz Regidor, Ana María de; López Tolsa Gómez, Gabriela Eugenia; Vidal García, Pedro; Gutiérrez Ferre, Valeria Edith; Pellón Suárez de Puga, Ricardo; Collado Guirao, Paloma; Pinos Sánchez, María ElenaThe objective of this study was to investigate the orexin and POMC populations in the hypothalamic nuclei of male Wistar rats after the activity-based anorexia (ABA) procedure. Four groups were established based on food restriction and activity: activity (A), ABA, diet (D) and control (C). The ABA protocol consisted of free access to a running wheel for a period of 22 h and access to food for 1 h. When the animals in the ABA group reached the ABA criterion, were sacrificed, and their brains were collected and serially sectioned. The free-floating sections were processed for orexin and POMC immunostaining. The number of orexin A-ir cells in the perifornical-dorsomedial-hypothalamus continuum (PFD) and lateral hypothalamus (LH) and the number of POMC-ir cells in the arcuate nucleus (Arc) were estimated. Data on food intake, body weight and wheel turns were also analyzed. The ABA procedure caused a significant decrease in body weight along with a significant increase in activity. Moreover, at the end of the ABA procedure, the number of POMC-ir cells decreased in the Arc in the A group, and significantly more in the ABA group, and the number of orexin A-ir positive cells decreased in the LH in D and ABA groups. The differential decrease in POMC in the ABA group emphasizes the importance of the melanocortin system in the maintenance of ABA, but more research is needed to elucidate the involvement of this peptide in the mechanism that promotes and maintains anorexia nervosa and how increased activity may interact with all these processes.