Stress exposure alters brain mRNA expression of the genes involved in insulin signalling, an effect modified by a high fat/high fructose diet and cinnamon supplement

In occidental societies, high fat and high sugar diets often coincide with episodes of stress. The association is likely to modify brain energy control. Brain insulin signalling is rarely studied in stressed individuals consuming high fat diets. Furthermore the effects of cinnamon supplement are not known in these conditions. Therefore, we exposed rats, over a 12-week period, to a control (C) or a high fat/high fructose (HF/HFr) diet that induces peripheral insulin resistance. A cinnamon supplement (C+CN and HF/HFr +CN) was added or not. After diet exposure, one group of rats was exposed to a 30-min restraint followed by a 10-min open-field test, their combination featuring a moderate stressor, the other rats staying unstressed in their home cages. The insulin signalling in hippocampus and frontal cortex was studied through the mRNA expression of the following genes: insulin receptor (Ir), insulin receptor substrate (Irs1), glucose transporters (Glut1 and Glut3), glycogen synthase (Gys1) and their modulators, Akt1 and Pten. In C rats, stress enhanced the expression of Ir, Irs1, Glut1, Gys1 and Akt1 mRNA. In C+CN rats, stress induced an increase in Pten but a decrease in Gys1 mRNA expression. In HF/HFr rats, stress was associated with an increase in Pten mRNA expression. In HF/HFr+CN rats, stress increased Pten mRNA expression but also decreased Gys1 mRNA expression. This suggests that a single moderate stress favours energy refilling mechanisms, an effect blunted by a previous HF/HFr diet and cinnamon supplement

Excretion of electrolytes in Brown Norway and Fischer 344 rats : effects of adrenalectomy and of mineralocorticoid and glucocorticoid receptor ligands

International audienc

Effects of adrenalectomy and mineralocorticoid receptor/glucocorticoid receptor ligands in female brown norway and fischer 344 rats and F1 hybrids

International audienc

Strain differences in corticosteroid receptor efficiencies and regulation in Brown Norway and Fischer 344 rats

International audienc

Is the mineralocorticoid receptor in brown norway rats constitutively active?

International audienc

QTL mapping for traits associated with stress neuroendocrine reactivity in rats

In the present study we searched for quantitative trait loci (QTLs) that affect neuroendocrine stress responses in a 20-min restraint stress paradigm using Brown–Norway (BN) and Wistar–Kyoto–Hyperactive (WKHA) rats. These strains differed in their hypothalamic–pituitary–adrenal axis (plasma ACTH and corticosterone levels, thymus, and adrenal weights) and in their renin–angiotensin–aldosterone system reactivity (plasma renin activity, aldosterone concentration). We performed a whole-genome scan on a F2 progeny derived from a WKHA × BN intercross, which led to the identification of several QTLs linked to plasma renin activity (Sr6, Sr8, Sr11, and Sr12 on chromosomes RNO2, 3, 19, and 8, respectively), plasma aldosterone concentration (Sr7 and Sr9 on RNO2 and 5, respectively), and thymus weight (Sr10, Sr13, and Srl4 on RNO5, 10, and 16, respectively). The type 1b angiotensin II receptor gene (Agtrlb) maps within the confidence intervals of QTLs on RNO2 linked to plasma renin activity (Sr6, highly significant; LOD = 5.0) and to plasma aldosterone level (Sr7, suggestive; LOD = 2.0). In vitro studies of angiotensin II–induced release of aldosterone by adrenal glomerulosa cells revealed a lower receptor potency (log EC50 = −8.16 ± 0.11 M) and efficiency (Emax = 453.3 ± 25.9 pg/3 × 104 cells/24 h) in BN than in WKHA (log EC50 = −10.66 ± 0.18 M; Emax = 573.1 ± 15.3 pg/3 × 104 cells/24 h). Moreover, differences in Agtr1b mRNA abundance and sequence reinforce the putative role of the Agtr1b gene in the differential plasma renin stress reactivity between the two rat strains.Bastien Llamas, Vincent Contesse, Véronique Guyonnet–Duperat, Hubert Vaudry, Pierre Mormède and Marie-Pierre Moisa