Dietary-Induced Chronic Hypothyroidism Negatively Affects Rat Follicular Development and Ovulation Rate and Is Associated with Oxidative Stress
BIOLOGY OF REPRODUCTION
Authors: Meng, Li; Rijntjes, Eddy; Swarts, Hans; Bunschoten, Annelies; van der Stelt, Inge; Keijer, Jaap; Teerds, Katja
Abstract
The long-term effects of chronic hypothyroidism on ovarian follicular development in adulthood are not well known. Using a rat model of chronic diet-induced hypothyroidism initiated in the fetal period, we investigated the effects of prolonged reduced plasma thyroid hormone concentrations on the ovarian follicular reserve and ovulation rate in prepubertal (12-day-old) and adult (64-day-old and 120-day-old) rats. Besides, antioxidant gene expression, mitochondrial density and the occurrence of oxidative stress were analyzed. Our results show that continuous hypothyroidism results in lower preantral and antral follicle numbers in adulthood, accompanied by a higher percentage of atretic follicles, when compared to euthyroid age-matched controls. Not surprisingly, ovulation rate was lower in the hypothyroid rats. At the age of 120 days, the mRNA and protein content of superoxide dismutase 1 (SOD1) were significantly increased while catalase (CAT) mRNA and protein content was significantly decreased, suggesting a disturbed antioxidant defense capacity of ovarian cells in the hypothyroid animals. This was supported by a significant reduction in the expression of peroxiredoxin 3 (Prdx3), thioredoxin reductase 1 (Txnrd1), and uncoupling protein 2 (Ucp2) and a downward trend in glutathione peroxidase 3 (Gpx3) and glutathione S-transferase mu 2 (Gstm2) expression. These changes in gene expression were likely responsible for the increased immunostaining of the oxidative stress marker 4-hydroxynonenal. Together these results suggest that chronic hypothyroidism initiated in the fetal/neonatal period results in a decreased ovulation rate associated with a disturbance of the antioxidant defense system in the ovary.
Enhanced anti-obesity effects of complex of resistant starch and chitosan in high fat diet fed rats
CARBOHYDRATE POLYMERS
Authors: Si, Xu; Strappe, Padraig; Blanchard, Chris; Zhou, Zhongkai
Abstract
This study investigated the interventional effect of resistant starch (RS), chitosan (CS) and chitosan-starch complexes (CL) on blood glucose, lipid composition and oxidative stress in high-fat diet fed rats. Compared with RS or CS alone, CL administration performed more efficiently in controlling body weight and adipose tissue mass, together with an increase in HDL-C concentration, oxidative stress suppression by increasing body antioxidant capacity. Gene expression analysis demonstrated the fatty acid and triglyceride synthesis and metabolism gene SREBP-1, adipocyte differentiation gene PPAR gamma, cholesterol synthesis gene HMGCR, gluconeogenesis gene GAPDH, were significantly down-regulated, whilst lipid oxidation gene Acoxl and liver functional genes Gstm2, Gcic were up-regulated following CL consumption compared with single RS or CS treatment. Hypolipidemic effects were observed by CL administration and oxidative stress suppression by CL appeared to be associated with elevated antioxidant enzyme activity, increased lipid oxidation, as well as improved fatty acid and cholesterol homeostasis. (C) 2016 Published by Elsevier Ltd.