Hypothyroidism modifies differentially the content of lipids and glycogen, lipid receptors, and intraepithelial lymphocytes among oviductal regions of rabbits

Abstract

Hypothyroidism affects the content of triacylglycerol (TAG), total cholesterol (TC), oxidized lipids, glycogen, and infiltration of immune cells into the ovary and uterus. This study aimed to analyze the impact of hypothyroidism on the lipid content of different regions of the oviduct. Control (n = 6) and hypothyroid (n = 6; 10 mg/kg/day of methimazole in the drinking water for 30 days) adult rabbits were used. In the fimbriae/infundibulum (FIM/INF), ampulla, (AMP), isthmus (IST), and utero-tubal junction (UTJ), the TAG and TC concentrations, presence of oxidized lipid, relative expressions of perilipin A (PLIN A), peroxisome proliferator-activated receptor γ (PPARγ), CAAT/enhancer-binding protein α (C/EBPα), and farnesoid X receptor (FXRα) were analyzed. The content of glycogen and glycans, as well as the infiltration of lymphocytes, were also quantified. In the FIM/INF, hypothyroidism reduced the content of TC, expression of C/EBPα, and presence of glycans while increased the number of intraepithelial lymphocytes. In the AMP and IST-UTJ regions, hypothyroidism increased the content of TAG, oxidized lipids, expression of PPARγ, and glycogen content but decreased the expression of PLIN-A. The FXRα expression in secretory cells of IST-UTJ was higher in the hypothyroid rabbits compared to controls. Additionally, hypothyroidism reduced the C/EBPα expression and the number of intraepithelial lymphocytes in the AMP and IST-UTJ regions, respectively. We demonstrated that the effect of hypothyroidism depends on the oviductal region, possibly associated with different physiological functions specific to each region. These alterations may be related to infertility, tubal disturbances, and ectopic pregnancy observed in hypothyroid women.

Keywords: C/EBPα; FXRα; Glycan; PPARγ; Triacylglycerol.