Lower ΔFosB expression in the dopaminergic system after stevia consumption in rats housed under environmental enrichment conditions.

Environmental enrichment (EE) has been proven to reduce drug seeking and the development of addiction-related behaviors in rodent models, but the effects of EE on natural reward acquisition in the form of sweet beverages are poorly understood. Accumulating evidence shows that the intake of sugar, the main ingredient of sweet beverages, alters the dopaminergic system, leading to addiction-related physiological and molecular changes. Sugar in sweet beverages has been replaced with natural sweeteners, such as stevia extract, which has greater sweetener potential but no energy content. Our research group found that sucralose consumption increased the expression of ΔFosB in reward-related nuclei, suggesting activation of the dopaminergic system. The present study assessed the effects of EE on stevia consumption and the expression of ΔFosB in the nucleus accumbens, caudate putamen, and prefrontal cortex. Sixteen male Wistar rats, 21 days old, were randomly assigned to an EE group (n = 8) or standard environment (SE) group (n = 8) and reared for 30 days. On postnatal day 52 (PND52), the brains of four animals in each housing condition were extracted to determine basal ΔFosB levels. Stevia consumption with intermittent access and ΔFosB immunoreactivity were measured for 21 days in the remainder of the rats. Compared with SE animals, EE animals exhibited a reduction of stevia consumption and alterations of ΔFosB immunoreactivity in the reward system. These results indicate that EE reduces stevia consumption and the stevia-induced ΔFosB expression, suggesting addiction-related changes in dopaminergic nuclei, which may be interpreted as a neuroprotective effect.

Creencias sobre la violencia y sus efectos en la prevalencia de la violencia en el noviazgo / Beliefs about violence and its effects on the prevalence of dating violence

Resumen La violencia en el noviazgo es un fenómeno multifactorial que requiere de estudios que profundicen respecto a los efectos que tienen las creencias culturales en el comportamiento tanto del agresor como de la víctima. Teniendo esto en cuenta, el objetivo de la presente investigación fue determinar la relación entre las creencias acerca de la violencia y la prevalencia de la violencia en el noviazgo. Para ello, se contó con una muestra de 420 estudiantes de dos universidades públicas mexicanas que respondieron el Inventario de creencias acerca de la violencia hacia la esposa, el Inventario de conflictos en las relaciones de noviazgo, y un cuestionario de información sociodemográfica. Los datos recolectados fueron examinados por medio de un análisis de correlación canónica, y los resultados mostraron que el modelo en general fue estadísticamente significativo (Wilks X = .654, F(20, 677.54) = 4.626,p < .05); que el tamaño del efecto del modelo general fue de .346, lo que indica que este explicó el 34.6 % de la varianza compartida por los dos conjuntos de variables; y que, específicamente en la primera función, el coeficiente de mayor magnitud fue el de la variable de justificación de la violencia (r2 s = 76.2; h 2 = 90.0), seguido por la del apoyo que se le puede brindar a la víctima (r2 s = 57.1; h2 = 94.5).

Abstract Dating violence is a multifactorial phenomenon that requires in-depth studies regarding the effects that cultural beliefs have on the behavior of both the aggressor and the victim. With this in mind, the objective of this research was to determine the relationship between beliefs about violence and the prevalence of dating violence. To this end, a sample of 420 students from two Mexican public universities answered the Inventory of Beliefs about Wife Violence, the Inventory of Conflicts in Dating Relationships, and a sociodemographic information questionnaire. The data collected were examined through a canonical correlation analysis, and the results showed that the overall model was statistically significant (Wilks X = .654, F (20, 677.54) = 4.626, p < .05); that the effect size of the overall model was .346, indicating that it explained 34. 6 % of the variance shared by the two sets of variables; and that, specifically in the first function, the coefficient of greatest magnitude was that of the variable of justification of the violence (r2 s = 76.2; h2 = 90.0), followed by that of the support that can be given to the victim (r2 s = 57.1; h2 = 94.5).

The mediating role of emotion regulation strategies in the relationship between family of origin violence and intimate partner violence

Abstract The effects of family of origin violence and intimate partner violence have been extensively documented; however, very few studies have examined the interaction with emotion regulation strategies. Thus, the objective of this research was to analyze whether different types of emotion regulation strategies, both adaptive and maladaptive, mediate the relationship between family of origin violence and intimate partner violence in the Mexican population. A total of 838 participants (45.9% men and 54.1% women) responded to instruments addressing family of origin violence, emotion regulation strategies, and intimate partner violence. The results revealed that both structural models were significant. For women, the model showed an adequate fit X 2 (11, N = 838) = 22.75, p = .288, GFI = .95, AGFI = .91, NFI = .98, CFI = .97, RMSEA = .05. Likewise, we found similar indexes for men X2 (11, N = 838) = 28.20, p = .348, GFI = .97, AGFI = .93, NFI = .97, CFI = .95, RMSEA = .04. Specifically, the direct effects of adaptive strategies on intimate partner violence were statistically significant. Meanwhile, the direct effects of family of origin violence on maladaptive emotion regulation strategies were significant, as were the direct effects of maladaptive strategies on intimate partner violence. In turn, the indirect effects of family of-origin violence were significantly related to intimate partner violence via maladaptive emotion regulation strategies. In addition, the results clearly showed that men reported higher levels of aggression against women. Finally, regarding the selection of emotion regulation strategies, while women employed more adaptive emotion regulation, men showed a more definite tendency to use maladaptive emotion regulation.

Anandamide and sucralose change ΔFosB expression in the reward system.

Food reward has been studied with highly palatable stimuli that come from natural additives such as sucrose. The most common food additive is sucralose, a noncaloric sweetener present in many food products of daily intake. The role of anandamide [N-arachidonylethanolamide (AEA)], an endogenous cannabinoid, has been widely studied in food behavior. Studies have shown that cannabinoids, such as AEA, 2-Arachidonilglycerol, and Tetrahydrocannabinol, can provoke hyperphagia, because they enhance the preference and intake of sweet and high-fat food. Taste perception is mediated by receptors taste type 1 receptor 3 (T1R3); therefore, there could be a synergistic effect between receptors CB1 and T1R3. This could explain why cannabinoids could change sweet taste perception and therefore the activity of neural nuclei involved in taste and reward. In this study, we evaluated the activity of dopaminergic nuclei implicated in food reward after the chronic administration of AEA (0.5 mg/kg bw) and sucralose intake (0.02%). We analyzed the expression of ΔFosB by immunohistochemistry. Our results show that the chronic administration of AEA and sucralose intake induces an overexpression of ΔFosB in the infralimbic cortex (Cx), nucleus accumbens (NAc) core, shell, and central nucleus of amygdala (Amy). These results suggest that the possible interaction between receptors CB1 and T1R3 has consequences not only in taste perception but also that AEA intervenes in the activity of dopaminergic nuclei such as the NAc, and that the chronic administration AEA and sucralose intake induce long-term changes in the reward system.

c-Fos immunoreactivity in the hypothalamus and reward system of young rats after social novelty exposure.

Socialization is an adaptive behavior during the early stages of life because it helps young animals become independent and determines healthy adult social behavior. Therefore, it is probable that the brain areas involved in the processing of social stimuli are more sensitive to social novelty during early life stages. To test this hypothesis, four groups of young male rats were exposed to different socioenvironmental stimuli; nonsocial physical novelty, social familiarity, social novelty, and a control group which received no stimulation. After stimuli exposure, brains were fixed and cut in coronal sections for c-Fos immunohistochemistry. The number of c-Fos-immunoreactive (c-Fos-ir) neurons in the paraventricular nucleus and supraoptic nucleus, the main producers of oxytocin and vasopressin, was compared, as well as in the nucleus accumbens and ventral pallidum, the main areas involved in reinforced behavior. A significantly higher number of c-Fos-ir neurons were found in animals exposed to social novelty in all areas, except in the supraoptic nucleus. In particular, the increase in c-Fos-ir in the paraventricular nucleus seems to be selective in response to social novelty, while the increase of c-Fos-ir in the nucleus accumbens and ventral pallidum suggests that social novelty during youth is a highly rewarding stimulus compared with social familiarity and nonsocial physical novelty.

Enriched environment attenuates nicotine self-administration and induces changes in ΔFosB expression in the rat prefrontal cortex and nucleus accumbens.

Environment enrichment conditions have important consequences on subsequent vulnerability to drugs of abuse. The present work examined whether exposure to an enriched environment (EE) decreases oral self-consumption of nicotine. Wistar rats were housed either in a standard environment (SE, four rats per standard cage) or in an EE during 60 days after weaning. EE consisted of eight animals housed in larger cages containing a variety of objects such as boxes, toys, and burrowing material that were changed three times a week. After this period, animals were exposed to nicotine for 3 weeks, where animals chose freely between water and a nicotine solution (0.006% in water). Fluid consumption was evaluated on a daily basis. ΔFosB immunohistochemistry in the prefrontal cortex and nucleus accumbens was also performed. Rats of the EE group consumed less nicotine solution (0.25±0.04 mg/kg/day) than SE rats (0.54±0.05 mg/kg/day). EE increased the number of ΔFos-immunoreactive (ΔFos-ir) cells in the nucleus accumbens core and shell and in the prefrontal cortex, compared with animals in the standard condition. However, rats exposed to nicotine in the SE showed higher ΔFos-ir cells in the nucleus accumbens core and shell than nonexposed rats. Nicotine consumption did not modify ΔFos-ir cells in these brain areas in EE animals. These results support the idea of a possible protective effect of the EE on reward sensitivity and the development of an addictive behavior to nicotine.

Sleep-inducing factors.

Kuniomi Ishimori and Henri Piéron were the first researchers to introduce the concept and experimental evidence for a chemical factor that would presumably accumulate in the brain during waking and eventually induce sleep. This substance was named hypnotoxin. Currently, the variety of substances which have been shown to alter sleep includes peptides, cytokines, neurotransmitters and some substances of lipidic nature, many of which are well known for their involvement in other biological activities. In this chapter, we describe the sleep-inducing properties of the vasoactive intestinal peptide, prolactin, adenosine and anandamide.