Juan Manuel Mancilla-Díaz

Imagen Corporal y Trastornos de la Conducta Alimentaria

Objetivo Evaluar la asociacion de la edad y el peso corporal con la interiorizacion del ideal de delgadez, la insatisfaccion corporal y los sintomas de trastorno de la conducta alimentaria entre mujeres adolescentes, jovenes y adultas. Material y Metodos Participaron 145 mujeres de entre 12 y 46 anos, quienes contestaron cuatro instrumentos de autoreporte para evaluar: sintomas de anorexia nerviosa, sintomas de bulimia nerviosa, interiorizacion del ideal corporal de delgadez e insatisfaccion corporal; ademas fue registrado su peso y estatura para calcular el indice de masa corporal. Para analizar los datos, se utilizo estadistica descriptiva e inferencial, especificamente correlacion de Spearman y prueba de Kruskal-Wallis. Resultados Una mayor edad se asocio con incremento en la interiorizacion de ideal de delgadez y en la insatisfaccion corporal, pero no asi en cuanto a los sintomas de trastorno de la conducta alimentaria, los cuales no mostraron correlacion con la edad. La comparacion entre los grupos no solo confirmo que las mujeres adultas reportaron mayor insatisfaccion e interiorizacion, sino que sus actitudes y conductas alimentarias anomalas fueron practicamente equiparables a las presentes en las adolescentes. Conclusiones Los resultados de este estudio sustentan la necesidad de profundizar en el conocimiento de las actitudes y conductas alimentarias anomalas en las mujeres adultas, debido a que es en esta etapa de la vida cuando la recurrencia en la realizacion de metodos extremos para el control del peso corporal, puede significar un mayor riesgo sobre el estado de salud.

The effects of 5-HT1A and 5-HT2C receptor agonists on behavioral satiety sequence in rats

The present study examined the effects of 5-HT1A and 5-HT2C receptor agonists on behavioral satiety sequence (BSS) in rats. The 5-HT1A receptor agonist, 8-OH-DPAT (0.5 microg), and the 5-HT2C receptor agonist, Ro-60-0175 (3.0 microg), were injected into the paraventricular nucleus (PVN) of rats. The animals were maintained on an ad libitum feeding paradigm with access to water and individual sources of protein, carbohydrate, and fat. Intra-PVN administration of each agonist was associated with decreased carbohydrate consumption. The effect was enhanced by the administration of both agonists together. Behavioral analysis indicated that co-administration of 8-OH-DPAT and Ro-60-0175 interrupted the natural BSS with an increase in non-feeding behavior, whereas the 8-OH-DPAT alone promoted early development of the natural BSS. In conclusion, the 5-HT receptor agonists affected serotonergic modulation of feeding behavior in a functionally selective way.

Validity of the Eating Attitudes Test: A study of Mexican eating disorders patients

Objective: To evaluate the psychometric properties of the Mexican version of the Eating Attitudes Test (EAT-40) in clinical and control populations in Mexico City. Method: 276 female patients with eating disorders [52 with anorexia nervosa (AN), 102 with bulimia nervosa (BN) and 122 with eating disorders not otherwise specified (EDNOS)] and a comparison group of 280 normal control female subjects completed the EAT. Results: The EAT had an adequate level of internal consistency in the clinical sample (Cronbach’s alpha=0.90). Total score was significantly correlated with criterion group membership (r=0.77, p≤0.0001), suggesting a high level of concurrent validity. There was a small overlap in the frequency distribution of the 2 groups (eating disorders and control) and only 6% of the normal controls scored as high as lowest anorexic and bulimic patients. The factorial analysis yielded five factors accounting for 46.6% of total variance: 1) Dietary restraint, 2) Bulimia, 3) Drive of thinness, 4) Food preoccupation and 5) Perceived social pressure. Conclusions: This study provides evidence that the Mexican version of the EAT is an economical, reliable and potentially useful instrument for research in this field.

Role of cannabinoid CB1 receptors on macronutrient selection and satiety in rats

It has been shown that endogenous and exogenous cannabinoids substantially increase feeding. Despite evidence for a role of endocannabinoids in mediating food ingestion, the mechanisms by which CB1 receptor agonists and antagonists have an effect on motivational processes (hunger, satiety) as well as on specific food preference are not entirely understood. The purpose of this study was to investigate the effects of systemic injection of the CB1 receptor agonist, ACEA, on protein, carbohydrates and fat intake as well as on the behavioural satiety sequence (BSS) in pre-satiated rats. Following a 120-min access to a three pure nutrient diet (protein, carbohydrates and fat) at dark onset, male Wistar rats were injected intraperitoneally with ACEA (0.1, 0.25, 0.5 and 1.0 mg/kg). Immediately after the injection, animals were placed into separate experimental cages with free access to food and a single 60-min period was video recorded to evaluate the BSS; protein, carbohydrates and fat intake (g) was measured at the same period of time. Intake of carbohydrates was significantly increased and this effect was prevented by the pre-treatment with AM 251. Analysis of BSS showed that administration of 0.5 mg/kg of ACEA reversed the satiation induced by food ingestion by increasing the time spent eating and decreasing the time resting without altering the overall activity. The present results suggest that the stimulation of food intake induced by activation of CB1 receptors involves a specific dietary component and behavioural selective mechanisms (stimulating hunger and inhibiting satiety).

Effect of 5-HT in mianserin-pretreated rats on the structure of feeding behavior.

The present study examined the effects of intra-PVN serotonin injection in mianserin-pretreated rats at the onset of the dark phase of light cycle on the structure of feeding behavior. The drugs were injected into the paraventricular nucleus (PVN) of the hypothalamus. The animals were maintained in a self-selection feeding paradigm and provided with freely available and separate sources of protein, carbohydrate, fat and water. The suppressive effect of 5-HT on carbohydrate intake was attenuated by mianserin at the beginning of the active (dark) feeding period. Mianserin-pretreatment increased the duration of carbohydrate and protein intake, but it was unable to block the effect of 5-HT on meal frequency and local rate of carbohydrate consumption. The present data suggests that carbohydrate intake may be in part mediated by postsynaptic 5-HT(2A/2C) receptors. However, the temporal characteristics of carbohydrate ingestion are mediated by another subpopulation of 5-HT receptors in the PVN and indicates a possibly adrenergic influence.

Stimulation of dopamine D4 receptors in the paraventricular nucleus of the hypothalamus of male rats induces hyperphagia: involvement of glutamate.

Obesity is a serious worldwide health problem, affecting 20-40% of the population in several countries. According to animal models, obesity is related to changes in the expression of proteins that control energy homeostasis and in neurotransmission associated to regulation of food intake. For example, it has been reported that diet-induced obesity produces overexpression of dopamine D4 receptor (D4R) mRNA in the ventromedial hypothalamic nucleus (VMH) of mice. Neurons in the VMH send dense glutamatergic projections to other hypothalamic regions as the paraventricular nucleus (PVN), where multiple signals are integrated to finely regulate energy homeostasis and food intake. Although it is well established that dopaminergic transmission in the hypothalamus plays a key role in modulating feeding, the specific mechanisms involved in the activation of D4R in the PVN and its modulatory action on glutamate release and feeding behavior have remained unexplored. To fill this gap, we characterize the behavioral and neurochemical role of D4R in the PVN. In behavioral experiments, we examined the effects of activation of dopamine D4 receptors in the PVN on food intake and on the behavioral satiety sequence in rats exposed to a food-restricted feeding program. In vitro experiments were conducted to study the effects of activation of dopamine D4 receptors on [(3)H]glutamate release and on plasma corticosterone in explants of the PVN. We found that activation of D4R in the PVN induced inhibition of glutamate release and stimulated food intake by inhibiting satiety. Furthermore, activation of D4R in the PVN decreased plasma levels of corticosterone, and this effect was reverted by NMDA. According to our findings, D4R in the PVN may be a target for the pharmacotherapy for obesity as well as eating disorder patients who show restrictive patterns and overweight.

Effect of gender and school level on disordered eating behaviours and attitudes in Mexican adolescents

The aim of this study was to assess eating behaviours and attitudes in a community sample of 615 adolescent Mexican students recruited at a middle school (192 boys and 226 girls; mean age ± standard deviation 13.56±0.09) and high school (90 boys and 107 girls; mean age 16.04±0.12 years), who completed the Eating Attitudes Test (EAT), the Bulimia Test (BULIT) and the Body Shape Questionnaire (BSQ). Multiple analysis of variance revealed the significant effect of gender on the negative feelings, body dissatisfaction, drive of thinness and perceived social pressure subscales, and school level on the body dissatisfaction and food preoccupation subscales. Among the high school girls, the gender x school level interaction had a significant effect on negative feelings, body dissatisfaction, drive of thinness, food preoccupation and perceived social pressure subscales. These data support previous findings concerning gender, and also suggest that perceived social pressure in the case of girls and food preoccupation in the case of boys could be important factors in the natural development of eating disorders.

The effects of 5-HT on feeding behaviour in mianserin- or cyproheptadine-pretreated rats

We examined the effects of 5-HT on the feeding behaviour patterns of rats pretreated with mianserin (5-HT1B/2A/1D receptor antagonist) or cyproheptadine (a 5-HT2C receptor antagonist), injected into the pariventricular hypothalamus nucleus (PVN). The animals were kept at 21±1°C with a 12 h light and 12 h dark cycle on a self-selected feeding paradigm, and provided with freely available and separate sources of proteins, carbohydrates, fats and water. The results indicate that the suppressive effect of 5-HT on carbohydrate intake can be blocked by mianserin and cyproheptadine even at the onset of the natural (dark) feeding period; however, this is a distinct blockade in the paradigm of feeding behavior. All of the meal patterns of fat intake and rest remained unaffected.

Body dissatisfaction and socio-cultural factors in women with and without BED: Their relation with eating psychopathology

The goal of the present study was to assess the role of body dissatisfaction and socio-cultural factors on eating psychopathology in women with Binge Eating Disorder (BED) and women without BED. Seventy obese women consecutively evaluated participated: 35 with BED and 35 without BED who attended for the first time in a weight loss program. All participants completed a battery of questionnaires, including: Body Shape Questionnaire, Questionnaire of Influences on the Aesthetic Body Shape Model, Questionnaire on Eating and Weight Patterns, Three Factor Eating Questionnaire, and they were interviewed with the Interview for the Diagnosis of Eating Disorder-IV. The Body Mass Index, Waist-to-Hip Ratio and Body Fat were calculated. The results showed that 21% of obese women who participated in a weight reduction program met BED criteria. The scores of body dissatisfaction, influences of socio-cultural factors and eating psychopathology were higher in women with BED compared with women without BED. In the same way, significantly stronger correlations were found among influences of socio-cultural factors, specifically, influence of advertisement, social relations and eating psychopathology in women with BED than women without BED. It is concluded that the high body dissatisfaction as well as stronger associations among influence of socio-cultural factors and eating psychopathology could play an important role in women with BED.

Intra-accumbens Raclopride Administration Prevents Behavioral Changes Induced by Intermittent Access to Sucrose Solution

Overeating is one of the most relevant clinical features in Binge Eating Disorder and in some obesity patients. According to several studies, alterations in the mesolimbic dopaminergic transmission produced by non-homeostatic feeding behavior may be associated with changes in the reward system similar to those produced by drugs of abuse. Although it is known that binge-eating is related with changes in dopaminergic transmission mediated by D2 receptors in the nucleus accumbens shell (NAcS), it has not been determined whether these receptors may be a potential target for the treatment of eating pathology with binge-eating. Accordingly, the aim of the present study was to evaluate whether sugar binging induced by intermittent access to a sucrose solution produced changes in the structure of feeding behavior and whether blocking D2 receptors prevented these changes. We used the intermittent access model to a 10% sucrose solution (2 h/day for 4 weeks) to induce sugar binging in Sprague Dawley female rats. Experimental subjects consumed in a 2-h period more than 50% of the caloric intake consumed by the subjects with ad-lib access to the sweetened solution without any increase in body weight or fat accumulation. Furthermore, we evaluated whether sugar binging was associated to the estrous cycle and we did not find differences in caloric intake (estrous vs. diestrus). Subsequently, we characterized the structure of feeding behavior (microstructural analysis) and the motivation for palatable food (breakpoints) of the subjects with sugar binging and found that feeding episodes had short latencies, high frequencies, as well as short durations and inter-episode intervals. The intermittent access model did not increase breakpoints, as occurred in subjects with ad-lib access to the sucrose. Finally, we evaluated the effects of D2 receptor blockade in the NAcS, and found that raclopride (18 nM) prevented the observed changes in the frequency and duration of episodes induced by intermittent access to the sucrose solution. Our results suggest that alterations in behavioral patterns associated with binge-eating behavior depend in part on the dopaminergic transmission in the NAcS and that the antagonism of D2 receptors may be a therapeutic tool for feeding pathology with binge-eating.