Persona: Pellón Suárez de Puga, Ricardo
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Pellón Suárez de Puga
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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 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 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 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 Mutual facilitation between activity-based anorexia and schedule-induced polydipsia in rats(Springer, 2023-01-05) Labajos López, María José; Calcagni, Gianluca; Pellón Suárez de Puga, RicardoThe objective of this study was to evaluate the possible relationship between drinking (licks) in the schedule-induced polydipsia (SIP) phenomenon and running (turns in the wheel) in the activity-based anorexia (ABA) one. Within-subjects counterbalanced experiments were designed with male Wistar rats which underwent both behavioral procedures; half of them performed the ABA procedure frst and the other half the SIP procedure frst. In Experiment 1, the initial development of ABA facilitated the subsequent acquisition of SIP, whereas the frst acquisition of SIP retarded the subsequent development of ABA. Given that SIP exposure implied food restriction, it could be that adaptation to the food regime contributed to lowering ABA manifestation. Thus, Experiment 2 was carried out in exactly the same way as Experiment 1, with the exception that animals which frst went through SIP prior to undergoing the ABA procedure had no food restriction. In this case, both ABA and SIP as frst experiences facilitated the further development of SIP and ABA, respectively. This suggests that running in ABA may be functionally similar to drinking in SIP; therefore, both behaviors can be thought of as induced by the schedule/regime of intermittent food availability.Publicación Socialization, and its modulation by sex, on the development and recovery of activity-based anorexia in rats(Elsevier, 2023-07-17) Martínez Herrada, Antonio; Paz Regidor, Ana María de; Pellón Suárez de Puga, RicardoThe activity-based anorexia (ABA) animal model has been used in the laboratory to study the role of excessive physical activity in the manifestation of anorexia nervosa (AN) in humans. Factors of social context are crucial in human health and the emergence of many psychological disorders, which have also been observed in studies using different mammal species that, like human beings, set their lives in groups. In the present study, the animals’ social condition was manipulated to observe the effect of socialization in ABA development, and the possible different influence of the variable sex on the phenomenon. Eighty Wistar Han rats were distributed into four male and four female groups with 10 subjects each, manipulating social conditions (group housing or social isolation) and physical activity (access or not to a running wheel). Throughout the procedure, all groups had food restricted to 1 h/day during the light period. Furthermore, ABA experimental groups with access to the running wheel had two periods of access to the wheel of 2 h each, one before and the other after the food period. In this experiment, socialized rats were less vulnerable to weight loss during the procedure, although there were no differences between the ABA groups. Moreover, social enrichment was shown to be an enabling variable of the animals’ recovery after their withdrawal from the procedure, with this effect being more pronounced in females. The results in this study suggest the need to further in the analysis of the role of socialization in the development of ABA.Publicación Physical activity reduces alcohol consumption induced by reward downshift(American Psychological Association, 2023) Castejón, Elena; Fuentes Verdugo, Esmeralda; Torres, Carmen; Pellón Suárez de Puga, RicardoIncreased voluntary consumption of alcohol and other anxiolytics has been demonstrated in animals after experiencing frustrative reward devaluation (downshift) or omission. These results have been interpreted in terms of emotional self-medication. In the present study, we analyzed whether voluntary physical activity reduces alcohol intake induced by reward downshift. Sixty-four male Wistar rats were divided into eight groups (n = 8). Thirty-two (downshifted) animals received 32% sucrose during 10 preshift sessions (5 min), followed by 4% sucrose during five postshift sessions, whereas 32 (unshifted) controls were always exposed to 4% sucrose. Immediately after each consummatory session, animals were exposed to a 2-hr two-bottle preference test involving 32% alcohol versus water or water versus water. Half of the animals had also access to a wheel for voluntary running during the preference test. The results showed lower sucrose consumption in downshifted groups compared with unshifted controls (the frustrative reward downshift effect). Reward downshift significantly increased alcohol intake, this effect being absent in downshifted animals with access to the wheel. These findings suggest that physical exercise could be useful to prevent alcohol self-medication induced by frustrative nonreward. Public Health Significance Human and nonhuman studies suggest that consumption-dependent reduction in negative affect promotes alcohol intake. This “self-medication behavior” has been observed in frustrating situations involving reward loss. This study showed (in rats) that increased alcohol intake induced by a reward devaluation event was abolished by voluntary wheel running. Physical exercise could therefore be useful to prevent the maladaptive effects of frustration on drug use.