Effect of Vitamin D3 supplementation in female mice with accelerated aging: Evaluation of the involvement of Angiotensin II converting enzyme in the modulation of the aryl hydrocarbon receptor.

• Grant number: 25/01591-0
• Support Opportunities: Regular Research Grants
• Start date: October 01, 2025
• End date: September 30, 2027
• Field of knowledge: Biological Sciences - Physiology - Physiology of Organs and Systems
• Principal Investigator: Luiz Guilherme de Siqueira Branco
• Grantee: Luiz Guilherme de Siqueira Branco
• Host Institution: Faculdade de Odontologia de Ribeirão Preto (FORP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil
• City of the host institution: Ribeirão Preto
• Associated researchers: Patrícia Passaglia

Abstract

SAMP8 (senescence-accelerated mouse prone - 8) mice, compared with SAMR1 (senescence-accelerated resistant 1 mouse), present deficits in the integrity of the intestinal barrier associated with changes in the intestinal microbiota. The angiotensin II-converting enzyme (ACE2) is capable of modifying the composition of the intestinal microbiota by regulating the levels of 5-hydroxyindoleacetic acid (5-HIAA), which acts as one of the endogenous ligands of the aryl hydrocarbon receptor (AhR). Recently, vitamin D supplementation has been pointed out as an important strategy for ACE2 activation. Thus, the project's objective is to evaluate the involvement of ACE2, via modulation of the AhR pathway, in the intestinal changes induced by aging in female SAMP8 and SAMR1 mice supplemented with vitamin D3. Two hundred female SAMP8 and SAMR1 mice (6 months old) will be used, which will receive: standard chow and/or chow supplemented with vitamin D3 (10,000 IU/kg, AIN-93M formulation). In the experimental groups that will receive the personalized diet: the standard diet will be offered for 4 months, followed by the diet supplemented with vitamin D3 for 2 months, while the other groups will receive the standard diet for 6 months. MLN4760 (5 mg/kg, drinking water, ACE2 inhibitor), and/or CH223191 (10 mg/kg, i.p., selective AhR antagonist) will be administered one hour before euthanasia of the animals. The fecal microbiota transplantation technique will be performed, in the presence or absence of MLN4760 and/or CH223191. The following will be analyzed: length, histochemistry, leukocyte infiltration, inflammatory mediators, gene and protein expression of ZO-1, claudin, occludin, ACE2 and AhR in the colon; intestinal permeability; intestinal microbiota in feces by PCR; aspartate aminotransferase (AST), alanine aminotransferase (ALT), inflammatory mediators, trimethylamine N-oxide (TMAO) and triglycerides (TAG) in the liver; serum levels of tryptophan, 5-HIAA, calcium, and vitamin D; brain immunofluorescence (Iba-1 and GFAP) and brain and serum dosage of C-C motif chemokine 11 (CC motif chemokine ligand 11 - CCL11). (AU)