Background: Gastric glands grow and cells reach differentiation at weaning in rats. By considering that early weaning (EW) can affect the timing of development, we aimed to compare molecular and cellular markers of differentiation in pups and adults. Methods: Wistar rats were separated into suckling-control (S) and EW groups at 15 days. Stomachs were collected at 15, 18, and 60 days for RNA and protein extraction, and morphology. Results: After EW, the expression of genes involved in differentiation (Atp4b, Bhlha15 and Pgc) augmented (18 days), and Atp4b and Gif were high at 60 days. EW increased the number of zymogenic cells (ZC) in pups and adults and augmented mucous neck cells only at 18 days, whereas parietal and transition cells (TC) were unchanged. Conclusions: EW affected the gastric mucosa mostly in a transient manner as the changes in gene expression and distribution of differentiated cells that were detected in pups were not fully maintained in adults, except for the size of ZC population. We concluded that though most of EW effects were immediate, such nutritional change in the infancy might affect part of gastric digestive functions in a permanent manner, as some markers were kept unbalanced in the adulthood.

The small intestine mucosa is lined by specialized cells that form the crypt-villus axis, which expands its surface. Among the six intestinal epithelial cell types, the Paneth cell is located at the base of the crypt, and it contains numerous granules in its cytoplasm, composed of antimicrobial peptides, such as defensins and lysozyme, and growth factors, such as epidermal growth factor, transforming growth factor-α, and Wnt ligands. Together, these elements act in the defense against microorganisms, regulation of intestinal microbiota, maintenance, and regulation of stem cell identity.Pathologies that target Paneth cells can disturb such defense activity, but they also affect the maintenance of the stem cell niche. In that way, Crohn's disease, necrotizing enterocolitis, and graft-versus-host disease promote a reduction of Paneth cell population, and, consequently, secretion of their products into the lumen of the crypts, making the affected organism predisposed to infections and dysbiosis. Additionally, the emergence of new intestinal cells is also decreased. This review aims to address the main characteristics of Paneth cells, highlighting their multiple functions and the importance of their preservation to ensure bowel homeostasis.

Neonatal- Maternal Separation (NMS) deprives mammals from breastfeeding and maternal care, influencing growth during suckling- weaning transition. In the gastric mucosa, Mist1 (encoded by Bhlha15 gene) and moesin organize the secretory apparatus for pepsinogen C in zymogenic cells. Our current hypothesis was that NMS would change corticosterone activity through receptors (GR), which would modify molecules involved in zymogenic cell differentiation in rats. We found that NMS increased corticosterone levels from 18 days onwards, as GR decreased in the gastric mucosa. However, as nuclear GR was detected, we investigated receptor binding to responsive elements (GRE) and observed an augment in NMS groups. Next, we demonstrated that NMS increased zymogenic population (18 and and 30 days), and targeted Mist1 and moesin. Finally, we searched for evolutionarily conserved sequences that contained GRE in genes involved in pepsinogen C secretion, and found that the genomic regions of Bhlha15 and PgC contained sites highly likely to be responsive to glucocorticoids. We suggest that NMS triggers GR- GRE to enhance the expression and to prime genes that organize cellular architecture in zymogenic population for PgC function. As pepsinogen C- pepsin is essential for digestion, disturbance of parenting through NMS might alter functions of gastric mucosa in a permanent manner.

The gastric mucosa is disturbed when breastfeeding is interrupted, and such early weaning (EW) condition permanently affects the differentiation of zymogenic cells. The aim of the study was to evaluate the immediate and long-term effects of EW on gastric cell proliferation, considering the molecular markers for cell cycle, inflammation, and metaplasia. Overall, we investigated the lifelong adaptation of gastric growth. Wistar rats were divided into suckling-control (S) and EW groups, and gastric samples were collected at 18, 30, and 60 days for morphology, RNA, and protein isolation. Inflammation and metaplasia were not identified, but we observed that EW promptly increased Ki-67-proliferative index (PI) and mucosa thickness (18 days). From 18 to 30 days, PI increased in S rats, whereas it was stable in EW animals, and such developmental change in S made its PI higher than in EW. At 60 days, the PI decreased in S, making the indices similar between groups. Spatially, during development, proliferative cells spread along the gland, whereas, in adults, they concentrate at the isthmus-neck area. EW pushed dividing cells to this compartment (18 days), increased PI at the gland base (60 days), but it did not interfere in expression of cell cycle molecules. At 18 days, EW reduced Tgfβ2, Tgfβ3, and Tgfbr2 and TβRII and p27 levels, which might regulate the proliferative increase at this age. We demonstrated that gastric cell proliferation is immediately upregulated by EW, corroborating previous results, but for the first time, we showed that such increased PI is stable during growth and aging. We suggest that suckling and early weaning might use TGFβs and p27 to trigger different proliferative profiles during life course.

Homeostasis of intestinal epithelial tissue is essential for the completion of digestion, absorption and barrier protection mediated by specialized epithelial cells. Growth and regeneration are controlled by stem cell niche located at the base of the crypts. The complete functional and morphological development of the intestine occurs during the weaning period, however, it is still unknown how this niche stem cells and the proliferative population behave in face of alterations in dietetic pattern. By considering that breastfeeding has important roles during the development of intestinal mucosa, we hypothesized that early weaning (EW) might induce changes in proliferation and differentiation processes. In order to determine the influence of EW in mucosal morphology and integrity, we studied the size of crypt–villus axis, cell proliferation, the distribution of goblet cells, and the expression of genes involved in intestinal functions and renewal. Wistar rats were separated into groups: suckling control (S) and early‐weaned (EW) at 15d (Ethical Committee 18/2015; 115/2017). Samples from middle jejunum were collected at 15, 18 and 60d for morphological analyses of cells stained with hematoxylin and eosin (HE); quantification of goblet cell after Periodic Acid‐Schiff (PAS) reaction; determination Ki‐67 proliferative index (PI), and RNA extraction for qPCR. We observed that the villus height was significantly decreased by EW at 18 d, showing an evident atrophy. However, at 60 d we did not detect differences between S and EW groups, suggesting a recovery of villus compartment during growth and ageing periods. The number of goblet cells in the villi was significantly reduced in EW group compared to S animals, without recovery at 60 days. In the crypt compartment, goblet cells were not altered by EW, increasing only as a function of villus growth. The PI (%) decreased in EW pups (18 d), and the effect was maintained in adults (60 d). The target genes for growth and functions were analyzed according to their immediate and late effect, and different responses were detected. Our preliminary findings suggest that EW affects cell proliferation, gene expression and the number of goblet cells immediately after interruption of suckling (18 d), but the effects are sustained to adulthood, indicating the priming of epithelial cells by EW.Support or Funding InformationThis study was financed in parts by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior Brazil (CAPES) – Finance Code 001; FAPESP grant 2018/07782‐8 and fellowship 2018/07409‐5.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.