Different stress modalities result in distinct steroid hormone responses by male rats

Abstract

Since both paradoxical sleep deprivation (PSD) and stress alter male reproductive function, the purpose of the present study was to examine the influence of PSD and other stressors (restraint, electrical footshock, cold and forced swimming, N = 10 per group) on steroid hormones in adult Wistar male rats. Rats were submitted to chronic stress for four days. The stressors (footshock, cold and forced swimming) were applied twice a day, for periods of 1 h at 9:00 and 16:00 h. Restrained animals were maintained in plastic cylinders for 22 h/day whereas PSD was continuous. Hormone determination was measured by chemiluminescent enzyme immunoassay (testosterone), competitive immunoassay (progesterone) and by radioimmunoassay (corticosterone, estradiol, estrone). The findings indicate that PSD (13.7 ng/ dl), footshock (31.7 ng/dl) and cold (35.2 ng/dl) led to lower testosterone levels compared to the swimming (370.4 ng/dl) and control (371.4 ng/dl) groups. However, progesterone levels were elevated in the footshock (4.5 ng/ml) and PSD (5.4 ng/ml) groups compared to control (1.6 ng/ml), swimming (1.1 ng/ml), cold (2.3 ng/ml), and restrained (1.2 ng/ml) animals. Estrone and estradiol levels were reduced in the PSD, footshock and restraint groups compared to the control, swimming and cold groups. A significant increase in corticosterone levels was found only in the PSD (299.8 ng/ml) and footshock (169.6 ng/ml) groups. These changes may be thought to be the full steroidal response to stress of significant intensity. Thus, the data suggest that different stress modalities result in distinct steroid hormone responses, with PSD and footshock being the most similar.

Mifepristone in the Central Nucleus of the Amygdala Reduces Yohimbine Stress-Induced Reinstatement of Ethanol-Seeking

“…Our group and others (Marinelli et al, 2007) have previously shown that yohimbine produces significant increases in circulating CORT levels and, in the present study, we show that yohimbine administration in ethanol-extinguished rats causes a nonsignificant increase in progesterone levels (Supplementary Figure 1). However, the levels in the male rats described here remain very low and are quite close to basal levels reported in the literature (Andersen et al, 2004(Andersen et al, , 2005Auger et al, 2006). Additional experiments with more selective ligands for GR and PR are necessary to fully determine the mechanism of action for mifepristone's effect on yohimbine-induced reinstatement of ethanol-seeking.…”

Biomarcadores de estresse em ratos exercitados por natação em intensidades igual e superior à máxima fase estável de lactato

“…The glucocorticoids are able to stimulate the glucogenesis by the liver, directly acting in the phosphoenolpyruvate carboxykinase enzyme (PEPCK) or indirectly through the augmented sensibility of the hormones responsible for the hepatic glycolysis, adrenaline and glucagon (38) . However, excessive HHA axis activation and consequent increases in the plasma concentrations of corticosterone, may lead to homeostasis rupture and undesirable effects to the body (3,34) .…”

“…Physical exercise is known to be a stressor stimulus both in humans and animals which leads to countless physiological alterations aiming to provide the augmentation of the energetic demand as well as the reach for a new situation of homeostasis (1)(2)(3) .…”

“…On the other hand, prolonged periods of high activity of glucocorticoids (in men, mainly cortisol, and in most rodents, corticosterone), may trigger undesirable responses to the body, such as: insulin resistance, suppression of the immune system and of the hypothalamic-hypophysis-adrenal axis (HHA) (3,(8)(9)(10) as well as increase in the incidence of cardiovascular diseases (11)(12)(13) .…”

“…Such fast mobilization of amino acids from muscle storages makes them available both as energetic source and synthesis of other compounds (3,(14)(15) . Such fact, although useful in the preservation of homeostasis, implies in harm for the muscle function.…”