Sex differences in adult Wistar rats in the voluntary consumption of ethanol after pre-exposure to ethanol-induced flavor avoidance learning.

Vulnerability to ethanol abuse may be a function of the balance between the opposing (aversive and rewarding) motivational effects of the drug. The study of these effects is particularly important for understanding alcohol addiction. Research in this field seems to point out that ethanol effects are determined by a set of internal factors (sex, ethanol intake history, etc.), as well as by environmental conditions surrounding the individual (i.e., stress) and, of course, the interactions between all these factors. This work explores sex differences in sensitivity to aversive effects of ethanol using the procedure of flavor avoidance learning (FAL), as well as the effect of this learning experience on subsequent voluntary ethanol consumption, in adult rats. The results obtained indicated a slight sex based difference in the amount of FAL acquired in that females acquisition was weaker (experiment 1), and a differing influence of previous experience with the aversive effects of ethanol on the voluntary consumption of the drug for each sex (experiment 2). In particular, it was observed that female ethanol-naive rats showed a higher intake level and preference for ethanol than both ethanol-experienced female rats and ethanol-naive male rats. In contrast, the ethanol-experienced male rats showed a greater consumption of and preference for ethanol than ethanol-naive male rats and ethanol-experienced female rats. These data are discussed noting a range of possible explicative factors (sex hormones, hedonic processing, etc.), but further studies are warranted to elucidate the mechanisms by which ethanol pre-exposure influences the subsequent intake of ethanol differently by sex.

Una revisión de la literatura experimental sobre los efectos motivacionales del alcohol y su modulación por factores biológicos y ambientales / A review of experimental literature on alcohol´s motivational effects and its modulation by biological and environmental factors

El alcohol es posiblemente la droga psicoactiva más consumida en el mundo. La ingesta moderada es común, pero para algunos individuos el consumo de alcohol se convierte en un trastorno adictivo. La progresión desde un consumo moderado de alcohol hasta el abuso podría deberse a la existencia de una sensibilidad diferencial, genéticamente determinada, a los efectos reforzantes y aversivos del alcohol. Así mismo, se sugiere que factores ambientales, como el estrés, podrían intervenir en el inicio del alcoholismo, influyendo sobre dicha sensibilidad diferencial y, en última instancia, sobre el consumo de alcohol. En el presente trabajo se revisa la literatura experimental existente acerca de los elementos protagonistas en la relación entre estrés y etanol. Por una parte se revisan los principales modelos de estrés existentes y, por otra, se aborda el estudio de las propiedades reforzantes y aversivas de esta droga, incluyendo datos sobre la influencia de variables como la edad, el sexo, y la experiencia previa con la droga. Finalmente, se expone un resumen de los datos existentes sobre la investigación con animales sobre la influencia del estrés en la percepción de las propiedades motivacionales opuestas del etanol. Nuestro objetivo es contribuir a clarificar el conocimiento existente acerca de las relaciones entre determinados factores biológicos (como el sexo o la edad) y ambientales (experiencia previa y estrés), y la conducta de ingesta de alcohol, poniendo de manifiesto la importancia de algunos factores de riesgo para el desarrollo del alcoholismo (AU)

Alcohol is probably the most consumed psychoactive drug in the world. Controlled consumption of alcohol is common, but for many individuals this consumption becomes an addiction. The progression from an habitual consumption of alcohol to abuse of the substance could be due to the existence of a differential sensitivity, which would be genetically determined, to the reinforcing and aversive effects of alcohol. Likewise, it has been suggested that environmental factors such as stress might be involved in the onset of alcoholism, influencing on such a differential sensitivity and, ultimately, on the consumption of alcohol. In this paper it is reviewed the experimental published data on each of the elements of the relationship between stress and ethanol. Thus, on the one hand they are reviewed the main animals models of stress and, on the other hand, we approached the study of the reinforcing and aversive properties of ethanol, including data on the influence of variables such as age, sex, and previous experience with the drug. And, finally, we present a resume of data collected from animal research on the influence of stress on the perception of the motivational opposing properties of ethanol. Our purpose is help to clarify the existing knowledge about the relations between biological factors (such as sex or age) and environmental factors (previous experience and stress), and the behavior of alcohol intake, thus highlighting the importance of some factors of risk for developing alcoholism (AU)

Differences in Extinction of an Appetitive InstrumentalResponse in Female Inbred Roman High- (RHA-I) and Low- (RLA-I) Avoidance Rats

An experiment was conducted with the goal of exploring strain differences between female inbred Roman High and Low Avoidance rats (RHA-I, and RLA-I, respectively) on acquisition and extinction of a food-rewarded running response in a straight alley. Acquisition proceeded faster in the less emotional RHA-I and Wistar rats (used as controls) than in the more emotional RLA-I rats. However, extinction proceeded slower in RHA-I ratsthan in RLA-I and Wistar rats. This strain-based asymmetry on instrumental performance between acquisition and extinction is discussed in terms of strain differences in locomotor activity, associative flexibility and emotional reactivity (AU)

Se realizó un experimento con el objetivo de explorar las diferencias de ejecución entre ratas Romanas consanguíneas de Alta y Baja Evitación(RHA-I y RLA-I, respectivamente) en la adquisición y la extinción de una respuesta de carrera recompensada con comida en un laberinto recto. La adquisición fue más rápida en las ratas menos emocionales RHA-I y Wistar (utilizadas como controles) que en las ratas más emocionales RLA-I. Sin embargo, la extinción fue más lenta en las ratas RHA-I que en las ratasRLA-I y Wistar. Esta asimetría en la actuación instrumental en función de la cepa entre la adquisición y la extinción se discute en términos de diferencias de cepa en la actividad locomotora, en la flexibilidad asociativa y en la reactividad emocional (AU)

Differences in Extinction of an Appetitive Instrumental Response in Female Inbred Roman High- (RHA-I) and Low- (RLA-I) Avoidance Rats

Se realizó un experimento con el objetivo de explorar las diferencias de ejecución entre ratas Romanas consanguíneas de Alta y Baja Evitación (RHA-I y RLA-I, respectivamente) en la adquisición y la extinción de una respuesta de carrera recompensada con comida en un laberinto recto. La adquisición fue más rápida en las ratas menos emocionales RHA-I y Wistar (utilizadas como controles) que en las ratas más emocionales RLA-I. Sin embargo, la extinción fue más lenta en las ratas RHA-I que en las ratas RLA-I y Wistar. Esta asimetría en la actuación instrumental en función de la cepa entre la adquisición y la extinción se discute en términos de diferencias de cepa en la actividad locomotora, en la flexibilidad asociativa y en la reactividad emocional (AU)

An experiment was conducted with the goal of exploring strain differences between female in bred Roman High and Low Avoidance rats (RHA-I, and RLA-I, respectively) on acquisition and extinction of a food-rewarded running response in a straight alley. Acquisition proceeded faster in the less emotional RHA-I and Wistar rats (used as controls) than in the more emotional RLA-I rats. However, extinction proceeded slower in RHA-I rats than in RLA-I and Wistar rats. This strain-based asymmetry on instrumental performance between acquisition and extinction is discussed in terms of strain differences in locomotor activity, associative flexibility and emotional reactivity (AU)

The role of the medial-external subnucleus of the medial parabrachial nucleus in hypertonic NaCl-induced concurrent and delayed-sequential flavor avoidance learning.

In behavioral as well as neuroanatomical studies, the medial area of the parabrachial complex has been associated with flavor avoidance learning (FAL). Within this medial area the medial external subnucleus (PBNme) has been linked to gustatory-visceral convergence or integration, which is apparently required for flavor-illness learning. Therefore, this area may play an important role in sensorial (gustatory and/or visceral) processing and/or in the gustatory-visceral integrative processes implicated in FAL. The present study used a lesion approach in rats to explore the effects of damage to the medial-external medial parabrachial nucleus (PBNme) in FAL using different FAL paradigms and hypertonic NaCl as the aversive agent. In the first of two experiments, PBNme-lesioned rats were subjected to a hypertonic NaCl-induced concurrent FAL. In this modality, both the gustatory and the visceral stimulation take place simultaneously. In the second experiment, rats with lesions similarly located (see above) and rats with lesions in the external area of the lateral parabrachial nucleus (PBNle) were subjected to a delayed-sequential FAL induced by the same chemical agent. The results show a clear disruptive effect of the hypertonic NaCl-induced concurrent FAL (experiment 1), as well as of NaCl-induced delayed-sequential FAL in animals lesioned in the PBNme (experiment 2). However, animals lesioned in the PBNle do learn the delayed-sequential task. The underlying nature, sensorial or associative, of the deficits showed by PBNme-lesioned animals in the acquisition of each modality of FAL is discussed.

The partial reinforcement extinction effect (PREE) in female Roman high- (RHA-I) and low-avoidance (RLA-I) rats.

The present experiment was designed with the goal of studying the partial reinforcement extinction effect (PREE) in female inbred Roman high- (RHA-I) and low-avoidance (RLA-I) rats. Two groups of RHA-I and two of RLA-I food-deprived animals were placed in a straight alley where they were partially or continuously reinforced. Once the animals reached the acquisition criterion, they were exposed to an extinction phase where the reinforcement was omitted. During the extinction phase RHA-I animals continuously reinforced during acquisition exhibited more resistance to extinction than their RLA-I counterparts, whereas only RLA-I rats partially reinforced during acquisition showed an increased resistance to extinction in comparison to continuously reinforced control RLA-I rats, this PREE being absent in RHA-I animals. These results are discussed within the framework of PREE theories that account for this effect by using emotional mechanisms, as pertains to the repeatedly observed RHA-RLA differences in emotional reactivity.

Successive negative contrast effect in instrumental runway behaviour: a study with Roman high- (RHA) and Roman low- (RLA) avoidance rats.

It has been recently shown that Roman high- (RHA) and low- (RLA) avoidance rats show behavioural divergence in successive negative contrast (SNC) induced in one-way avoidance learning [Torres C, Cándido A, Escarabajal MD, de la Torre L, Maldonado A, Tobeña A, et al. Successive negative contrast effect in one-way avoidance learning in female roman rats. Physiol Behav 2005;85:377-82]. A 2-experiment study was conducted with the goal of analyzing whether these differences in SNC can also be extended to a different experimental paradigm. Food-deprived RHA and RLA female rats were exposed to a straight alley, recording the latency (DV) between leaving the start box and reaching the food available in the goal box at the end of the alley. To induce the SNC effect the amount of reinforcement received went from 12 pellets in the pre-shift phase to 1 pellet (Experiment 1) or 2 pellets (Experiment 2) in the postshift phase. The SNC effect appeared in both strains in Experiment 1, but only in RLA rats in Experiment 2. These results are discussed within the framework of SNC theories that account for this effect by using emotional mechanisms, as related to the differences in emotional reactivity seen between the RHA and RLA strains in a number of behavioural tests of fear/anxiety.