Dietas ricas en grasa y composición corporal a lo largo de dos generaciones. Estudio experimental / High-fat diets and body composition over two generations. An experimental study

Antecedentes y objetivo A pesar de los últimos avances acerca de los factores nutricionales que inducen modificaciones epigenéticas, la información en edades tempranas es escasa. El presente trabajo estudió en un modelo experimental a lo largo de dos generaciones las posibles modificaciones en la composición corporal, la posible expresión de cambios epigenéticos, y el resultado del consumo de dietas isocalóricas con niveles de grasa diferentes. Materiales y métodos Ratas Wistar hembras al destete se dividieron en dos grupos que recibieron una dieta con 7 y 15% de grasa (rica en grasa). A los 70 días se aparearon (M1) y sus crías (C1) constituyeron la primera generación; C1 a los 70 días fueron apareadas (M2) y sus crías (C2) constituyeron la segunda generación. Al destete, se evaluaron tanto las madres como las crías (M1, M2 y C1, C2), el peso (P) y composición corporales % de grasa (% Gra), por método químico y contenido mineral óseo de esqueleto total (CMO) por densitometría, expresado como %CMO. Resultados Al destete, en los grupos con dieta rica en grasa M2 y C2 (15% Gra) se observó un incremento significativo del P y % Gra (p<0,05), mientras que el aumento en el % Gra ya se observó en C1 y M1 (p<0,001). Por el contrario, el % CMO de M2 y C2 disminuyó significativamente (p<0,001).Conclusión este estudio pone de manifiesto la potencial necesidad de modificar ciertos hábitos alimentarios que eviten repetir patrones distorsionados de generación en generación (AU)

Introduction and objective Despite recent findings reported on the nutritional factors that induce epigenetic changes, little information is available at early ages. This study analyzed in an experimental model, over two generations, potential changes in body composition and potential expression of epigenetic changes as the result of the intake of isoenergetic diets with different fat levels. Materials and methods At weaning, Wistar female rats were divided into two groups that were fed either a control diet (fat=7% w/w) or a high-fat diet (15% w/w). Rats were mated at 70 days (M1) and their pups (P1) were the first generation; P1 rats were mated at 70 days (M2) and their pups (P2) represented the second generation. At weaning, mothers and pups (M1, M2 and P1, P2) were measured body weight (W) and composition (% body fat, %BF), and total skeleton bone mineral content (BMC), expressed as %BMC, using chemical and DXA methods respectively. Results At weaning, high-fat diet groups M2 and P2 showed significant increases in W and %BF (p<0.05); increased %BF values were already found in the M1 and P1 groups (p<0.001). By contrast, %BMC significantly decreased in M2 and P2 rats (p<0.001).Conclusion This study demonstrates the need to review certain eating habits to avoid perpetuation of unhealthy patterns generation after generation (AU)

[High-fat diets and body composition over two generations. An experimental study]. / Dietas ricas en grasa y composición corporal a lo largo de dos generaciones. Estudio experimental.

INTRODUCTION AND OBJECTIVE: Despite recent findings reported on the nutritional factors that induce epigenetic changes, little information is available at early ages. This study analyzed in an experimental model, over two generations, potential changes in body composition and potential expression of epigenetic changes as the result of the intake of isoenergetic diets with different fat levels. MATERIALS AND METHODS: At weaning, Wistar female rats were divided into two groups that were fed either a control diet (fat=7% w/w) or a high-fat diet (15% w/w). Rats were mated at 70 days (M(1)) and their pups (P(1)) were the first generation; P(1) rats were mated at 70 days (M(2)) and their pups (P(2)) represented the second generation. At weaning, mothers and pups (M(1), M(2) and P(1), P(2)) were measured body weight (W) and composition (% body fat, %BF), and total skeleton bone mineral content (BMC), expressed as %BMC, using chemical and DXA methods respectively. RESULTS: At weaning, high-fat diet groups M(2) and P(2) showed significant increases in W and %BF (p<0.05); increased %BF values were already found in the M(1) and P(1) groups (p<0.001). By contrast, %BMC significantly decreased in M(2) and P(2) rats (p<0.001). CONCLUSION: This study demonstrates the need to review certain eating habits to avoid perpetuation of unhealthy patterns generation after generation.

Reduced methacholine-induced submandibular salivary secretion in rats with experimental periodontitis.

OBJECTIVE: Saliva is the first barrier to the entry of bacteria and viruses into the body and is considered a necessary instrument in oral health. Intraperitoneal injection of lipopolysaccharide endotoxins results in submandibular gland (SMG) hyposalivation. The objective of present studies was to assess if periodontitis, a chronic inflammatory disease caused by oral bacteria, alters cholinergic-induced SMG salivary secretion. DESIGN: An experimental periodontitis model (EP) (cotton thread ligature around the neck of the first lower molars) was used. Male Wistar rats (300-380g) were randomly divided into 3 groups: control, 7 days-bilateral EP and 7 days-unilateral EP (to study if there were different effects at the ipsilateral and contralateral side). The following determinations were performed in SMG: (1) dose-response curves to the cholinergic agonist methacholine, (2) prostaglandin E (PGE) content, (3) inducible nitric oxide synthase (iNOS) activity and (4) histology of gland sections. RESULTS: The molars with EP, no matter the group, exhibited significant and similar bone loss (p<0.001). Bilateral EP reduced methacholine-induced salivary secretion (p<0.05, dose 1µg/kg; p<0.001, dose 3-30µg/kg), increased PGE content (p<0.01), stimulated iNOS activity (p<0.05). Ipsilateral glands of unilateral EP animals presented lower methacholine-induced salivary secretion (p<0.05, dose 3µg/kg; p<0.001, dose 10-30µg/kg), and higher PGE content than contralaterals (p<0.001). In turn, at 3 and 10µg/kg of methacholine, contralateral glands showed significantly lower secretion than control animals (p<0.001). Histological studies of glands revealed partial loss of secretor granular material and periductal oedema in the bilateral and unilateral EP groups as compared to controls. CONCLUSIONS: As far as we know, the present results demonstrate for the first time that EP reduces methacholine-induced SMG salivary secretion.

[Neuronal LHRH system activity in an animal model of growth retardation]. / Actividad del sistema neuronal LHRH en un modelo animal de retraso del crecimiento.

OBJECTIVE: Mild and chronic energy restriction results in growth retardation with puberal delay, a nutritional disease known as nutritional dwarfing (ND). The aim of the present study was to assess the profile of hypothalamic luteinizing hormone-releasing hormone (LHRH) release, at baseline and under glutamate stimulation, in ND rats to elucidate gonadotrophic dysfunction. Reproductive ability during refeeding was also studied. MATERIAL AND METHODS: At weaning, 60 male rats were assigned to two groups of 30 animals each: a control and an experimental group. Control rats were fed ad libitum with a balanced rodent diet. The experimental group received 80% of the diet consumed by the control group for 4 weeks. After 4 weeks of food restriction, the ND group was fed freely for 8 weeks. Ten rats from each group were sacrificed every 4 weeks for assays. RESULTS: At week 4, body weight and length were significantly diminished in the experimental group vs. the control group (p<0.001). No changes were observed in LHRH baseline release, pulse frequency or amplitude in the experimental group compared with the control group at any time. However, under glutamate stimulation, LHRH release was significantly higher in ND rats than in control rats at week 4 (p<0.05). Refeeding the ND group allowed the rats to reach overall growth and reproductive ability. CONCLUSIONS: The results of the present study suggest that the response to the facilitatory effect of glutamate on LHRH release in post-restricted ND rats is probably related to a lesser central nervous system maturation in relation to their chronological age. The adequate somatic growth and normal reproductive ability attained with refeeding suggest the reversibility of the two energetically costly processes compromised by global, mild and chronic food restriction.

Actividad del sistema neuronal LHRH en un modelo animal de retraso del crecimiento / Neuronal LHRH system activity in an animal model of growth retardation

Objetivo La restricción energética leve y crónica resulta en una enfermedad de origen nutricional, enanismo por desnutrición (ED), con retraso del crecimiento y del desarrollo puberal. Se evaluó el perfil de secreción hipotalámica de hormona liberadora de la hormona luteinizante, basal y por estimulación con glutamato en ratas ED a fin de dilucidar la disfunción gonadotrófica. Asimismo, se evaluó la capacidad reproductiva de dichos animales durante la realimentación. Materiales y métodos60 ratas de destete se dividieron en 2 grupos: Control (C) y experimental (ED). C fueron alimentadas a demanda libre con una dieta balanceada para roedores. ED recibió el 80% de la dieta consumida por C, durante 4 semanas (T4); A T4, ED fue alimentado a demanda libre por 8 semanas. Diez ratas de cada grupo fueron sacrificadas cada 4 semanas para los ensayos. Resultados A T4, peso y longitud corporal de ED frente a C disminuyeron significativamente (p<0,001). No se observaron cambios en la secreción basal, la frecuencia y la amplitud de pulsos de hormona liberadora de la hormona luteinizante de ED frente a C en ninguno de los tiempos estudiados. Por estimulación con glutamato, la secreción de hormona liberadora de la hormona luteinizante de ED frente a C fue significativamente mayor a T4 (p<0,05). Durante la realimentación, los ED alcanzaron el crecimiento compensador y la capacidad reproductiva. Conclusiones Los resultados sugieren una menor madurez del SNC en los animales ED después de la restricción en relación a su edad cronológica. El crecimiento somático adecuado y la capacidad reproductiva normal en las ratas ED realimentadas sugieren la reversibilidad de dichos procesos comprometidos por la restricción global, leve y crónica (AU)

Objective Mild and chronic energy restriction results in growth retardation with puberal delay, a nutritional disease known as nutritional dwarfing (ND). The aim of the present study was to assess the profile of hypothalamic luteinizing hormone-releasing hormone (LHRH) release, at baseline and under glutamate stimulation, in ND rats to elucidate gonadotrophic dysfunction. Reproductive ability during refeeding was also studied. Material and methods At weaning, 60 male rats were assigned to two groups of 30 animals each: a control and an experimental group. Control rats were fed ad libitum with a balanced rodent diet. The experimental group received 80% of the diet consumed by the control group for 4 weeks. After 4 weeks of food restriction, the ND group was fed freely for 8 weeks. Ten rats from each group were sacrificed every 4 weeks for assays. Results At week 4, body weight and length were significantly diminished in the experimental group vs. the control group (p<0.001). No changes were observed in LHRH baseline release, pulse frequency or amplitude in the experimental group compared with the control group at any time. However, under glutamate stimulation, LHRH release was significantly higher in ND rats than in control rats at week 4 (p<0.05). Refeeding the ND group allowed the rats to reach overall growth and reproductive ability. Conclusions The results of the present study suggest that the response to the facilitatory effect of glutamate on LHRH release in post-restricted ND rats is probably related to a lesser central nervous system maturation in relation to their chronological age. The adequate somatic growth and normal reproductive ability attained with refeeding suggest the reversibility of the two energetically costly processes compromised by global, mild and chronic food restriction (AU)

Influence of submandibulectomy on alveolar bone loss in rats.

BACKGROUND: The incidence of dry mouth and its public health impact are increasing as the result of a progressively larger, medicated older population and because chronic diseases, like periodontitis, are prevalent pathologies among elderly patients. Periodontitis and continuous remodeling and rebuilding alveolar processes greatly affect the margin of the alveolar bone, and there is evidence indicating the role of submandibular glands in the regulation of immune/inflammatory reactions. The purpose of this study was to assess the effect of submandibular-sublingual complex ablation (Sx) on alveolar bone loss in rats submitted or not to ligature-induced experimental periodontal disease (EP). METHODS: Wistar male rats were submitted to Sx or sham operations (day 0). Two weeks later, unilateral EP was induced on the right mandibular first molars for 7 days with the contralateral side serving as control. Bone loss at the level of the dental pieces was estimated by bone histomorphometry on mesio-distally oriented sections of the molars and by the determination on lingual and vestibular mandibular surfaces of the distances from the cemento-enamel junction to the alveolar crest. RESULTS: Sx and EP significantly increased lingual and vestibular alveolar bone loss. Molars with EP exhibited greater lingual loss in Sx animals compared to those with the sham operation. EP induced similar interradicular bone loss in sham and Sx rats. CONCLUSION: Sx has a deleterious effect on the periodontal tissues, particularly marginal alveolar bone, indicating the importance of the submandibular/sublingual glands in maintaining healthy periodontal conditions.

Decrease in salivary secretion by radiation mediated by nitric oxide and prostaglandins.

OBJECTIVE: In the present work, we evaluated the effect of exposing the submandibular glands (SMG) to radiation, studying different functional parameters such as salivary secretion, nitric oxide (NO) production, reactive oxygen species formation, prostaglandin (PGE) content and apoptosis. METHODS: We irradiated rats in the head and neck region with a single dose of gamma-ray radiation of 15 Gy. Two hours after radiation, we measured norepinephrine-induced salivary secretion. After that, the SMG were dissected, and in this tissue, we measured the activity of NO synthase (NOS), the PGE content, the amount of reactive oxygen species, apoptotic cells and mitochondrial inducible NOS (iNOS) expression. RESULTS: We found that radiation decreased salivary secretion when 10 and 30 microg/kg of norepinephrine was administered via the right femoral vein. We observed that iNOS activity was reduced and PGE content increased after radiation in SMG, indicating that NO and PGEs may participate in salivary secretion. The expression of mitochondrial NOS was increased after radiation leading to the formation of large amounts of NO that acts as a proapoptotic signal. In fact, we observed an augmentation in apoptotic cells. In this study, we also observed an increase in lipid peroxidation induced by radiation that may contribute to tissue damage. CONCLUSIONS: Our results indicate that radiation induced a decrease in salivary secretion and SMG iNOS activity, meanwhile the PGE content, the lipid peroxidation and apoptosis increased in the tissue. These modifications decrease salivary secretion.