The Level of Sex Hormones and Corticosterone in Female Rats during Modeling of Visceral Obesity, Subsequent Physical Activity, and Normalization of the Diet.

The effects of diet-induced visceral obesity and non-drug options of its correction on the level of sex hormones and corticosterone were evaluated in 84 female Wistar rats. During stage I, the rats received either a standard diet (STD) or a high-calorie diet (HCD) for 8 weeks. During stage II, the animals were divided into subgroups depending on obesity correction: without correction (STD control and HCD), transition from HCD to STD (HCD/STD) and/or physical activity (treadmill exercise) for the next 8 weeks (HCD/STD+exercise, STD+exercise, and HCD+exercise). Diet-induced visceral obesity resulted in hyperandrogenization and increased blood corticosterone levels in females. Transition from HCD to STD regardless of physical activity led to normalization of testosterone level and, accordingly, to return to the functional norm of estrogen-androgen balance. The positive effect of moderate physical activity on hormonal status is realized only against the background of a balanced diet or during the transition from HCD to STD.

Effects of Diet-Induced Obesity and Programs for Body Weight Reduction on the Histostructure of the Triceps Surae Muscle in Male Rats.

We studied the effects of visceral obesity induced by a high-calorie diet and health-improving variants of its correction on morphological characteristics of the muscle tissue in male Wistar rats. At stage I, the rats received standard (StD) or high-calorie diet (HCD) for 8 weeks. At stage II, the animals were divided into the following subgroups: no correction (StD and HCD), switching from HCD to StD (HCD/StD) and/or connection of physical activity in the form of treadmill running (StD+running, HCD+running, and HCD/StD+running) for the next 8 weeks. Diet-induced visceral obesity was shown to result in a decrease in the weight of the triceps surae muscle, fatty infiltration, intracellular edema, partial lysis of contractile elements, weak inflammatory response, and decreased muscle fiber area on cross section. Treadmill running (HCD+running) exacerbates the morphological changes, but returns muscle fiber area to normal. Correction of visceral obesity and relative normalization of muscle tissue structure was noted when switching to a standard diet (HCD/StD and HCD/StD+running).

Reactivity of the Thyroid System to Short-Term Stress in Wistar Rats with Visceral Obesity and Restricted Social Activity.

The obesity problem requires a study of its pathophysiological consequences affecting hormonal regulation and organism's reactivity to extreme exposures. The study was aimed first to examine the effect of a high-calorie diet and social isolation, as well as their combination for 4 months, on the development of obesity, its metabolic and behavioral sequelae, features of the thyroid status, while at the second stage, to assess the reaction of hormonal indices of the thyroid status to short-term stress in rats. The experiments were carried out on male Wistar rats and at the first stage focused on the effects of a high-calorie diet and social isolation, as well as their combinations for 4 months. At the end of the experiment, behavioral reactions, metabolic syndrome indices, thyroid status, and cortisol levels were evaluated. At the second stage, the animals were exposed to short-term acute stress, and the shifts in the hormonal indices were recorded one hour later versus the initial background. A high-calorie diet led to the development of metabolic syndrome, signs of depression, increased thyroid-stimulating hormone (TSH), thyroxine and triiodothyronine serum levels, as well as iodothyronine deiodinase type 1 (D1) activity, in the rat liver. At the same time, there was a decrease in thyroperoxidase activity and an increase in thyroid levels of triglycerides and malondialdehyde. The physiological response to stress in the control rat group included an increase in cortisol and TSH serum levels, however, against the background of a high-calorie diet, no cortisol release into the bloodstream was recorded. Social isolation did not alter normal reactivity of the adrenal cortex, but reduced TSH release in response to acute stress, since the initial level of this hormone was slightly elevated against the background of chronic social isolation stress. Thus, excessive nutrition and the deficit of social activities in male Wistar rats led to significant changes in the organism's reactivity to acute stress.