The model of litter size reduction induces long-term disruption of the gut-brain axis: An explanation for the hyperphagia of Wistar rats of both sexes.

The gut microbiota affects the host's metabolic phenotype, impacting health and disease. The gut-brain axis unites the intestine with the centers of hunger and satiety, affecting the eating behavior. Deregulation of this axis can lead to obesity onset. Litter size reduction is a well-studied model for infant obesity because it causes overnutrition and programs for obesity. We hypothesize that animals raised in small litters (SL) have altered circuitry between the intestine and brain, causing hyperphagia. We investigated vagus nerve activity, the expression of c-Fos, brain-derived neurotrophic factor (BDNF), gastrointestinal (GI) hormone receptors, and content of bacterial phyla and short-chain fatty acids (SCFAs) in the feces of adult male and female Wistar rats overfed during lactation. On the 3rd day after birth, litter size was reduced to 3 pups/litter (SL males or SL females) until weaning. Controls had normal litter size (10 pups/litter: 5 males and 5 females). The rats were killed at 5 months of age. The male and female offspring were analyzed separately. The SL group of both sexes showed higher food consumption and body adiposity than the respective controls. SL animals presented dysbiosis (increased Firmicutes, decreased Bacteroidetes) and had increased vagus nerve activity. Only the SL males had decreased hypothalamic GLP-1 receptor expression, while only the SL females had lower acetate and propionate in the feces and higher CCK receptor expression in the hypothalamus. Thus, overfeeding during lactation differentially changes the gut-brain axis, contributing to hyperphagia of the offspring of both sexes.

Changes in gut-brain axis parameters in adult rats of both sexes with different feeding pattern that were early nicotine-exposed.

Nicotine is an endocrine disruptor and imprinting factor during breastfeeding that can cause food intake imbalance in the adulthood. As nicotine affects the intestinal microbiota, altering the composition of the bacterial communities and short-chain fatty acids (SCFAs) synthesis in a sex-dependent manner, we hypothesized that nicotine could program the gut-brain axis, consequently modifying the eating pattern of adult male and female rats in a model of maternal nicotine exposure (MNE) during breastfeeding. Lactating Wistar rat dams received minipumps that release 6 mg/kg/day of nicotine (MNE group) or saline for 14 days. The progeny received standard diet from weaning until euthanasia (26 weeks of age). We measured: in vivo electrical activity of the vagus nerve; c-Fos expression in the nucleus tractus solitarius, gastrointestinal peptides receptors, intestinal brain-derived neurotrophic factor (BDNF), SCFAs and microbiota. MNE females showed hyperphagia despite normal adiposity, while MNE males had unchanged food intake, despite obesity. Adult MNE offspring showed decreased Bacteroidetes and increased Firmicutes, Actinobacteria and Proteobacteria. MNE females had lower fecal acetate while MNE males showed higher vagus nerve activity. In summary nicotine exposure through the milk induces long-term intestinal dysbiosis, which may affect eating patterns of adult offspring in a sex-dependent manner.

Effects of transgenic soybean and organic soybean on rat penis morphology during the aging process / Efectos de los frijoles de soja transgénica y de soja orgánica en la morfología del pene de rata durante el proceso de envejecimiento

The contents of soybean can modify the structure of the reproductive system, especially, when consumed for prolonged periods. In this study, we evaluated the effects of the consumption of transgenic soybean on rat penis morphology after prolonged use. Wistar rats (n = 30) were divided into three groups according to diet: Transgenic Soybean (TS) group, Organic Soybean (OS) group and Control (C) group. After 455 days of intake, the rats were sacrificed and the penises were excised and fixed in formalin for subsequent histological processing. The samples were stained with hematoxylin and eosin, Weigert’s resorcin-fuchsin stain, and picrosirius red with polarization. The images were scanned for the histomorphometric analyses of the corpora cavernosa, corpus spongiosum, erectile tissue, and tunica albuginea as well as the measurement of the thickness of the tunica albuginea. The diameter and areas of the penile arteries with the intima and media tunica were also measured. The elastic fibers of the tunica albuginea, corpora cavernosa and corpus spongiosum were quantified using stereological methods. No significant differences were observed in the collagen and elastic components among the groups. We concluded that no statistically significant differences were found among the groups, demonstrating that the prolonged consumption of OS and TS does not affect the penile structure.

El contenido de frijoles de soja puede modificar la estructura del sistema reproductivo, especialmente, cuando se consume durante períodos prolongados. En este estudio, se evaluaron los efectos del consumo de frijoles de soja transgénica en la morfología del pene de rata después de un uso prolongado. Las ratas Wistar (n = 30) se dividieron en tres grupos según la dieta: grupo de frijoles de soja transgénica (TS), grupo de frijoles de soja orgánica (OS) y grupo control (C). Después de 455 días de ingesta, se sacrificaron las ratas y se extirparon los penes y se fijaron en formalina para posterior procesamiento histológico. Las muestras se tiñeron con hematoxilina y eosina, tinción de resorcina-fucsina de Weigert y rojo de picrosirius con polarización. Las imágenes fueron escaneadas para análisis histomorfométrico de los cuerpos cavernosos, cuerpo esponjoso, tejido eréctil y túnica albugínea, así como para la medición del espesor de la túnica albugínea. También se midieron el diámetro y las áreas de las arterias penianas con las túnicas íntima y media. Se cuantificaron las fibras elásticas de la túnica albugínea, cuerpos cavernosos y cuerpos esponjosos utilizando métodos estereológicos. No se observaron diferencias significativas en los componentes colágenos y elásticos entre los grupos. Se concluyó que no se encontraron diferencias estadísticamente significativas entre los grupos, lo que demuestra que el consumo prolongado de OS y TS no afecta a la estructura del pene.