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  • Effects of the estrous cycle and ovarian hormones on central expression of interleukin-1 evoked by stress in female rats.

Effects of the estrous cycle and ovarian hormones on central expression of interleukin-1 evoked by stress in female rats.

Neuroendocrinology (2014-10-11)
Keiko Arakawa, Hiroyuki Arakawa, Cara M Hueston, Terrence Deak
ABSTRACT

Exposure to stressors such as foot shock (FS) leads to increased expression of multiple inflammatory factors, including the proinflammatory cytokine interleukin-1 (IL-1) in the brain. Studies have indicated that there are sex differences in stress reactivity, suggesting that the fluctuations in gonadal steroid levels across the estrous cycle may play a regulatory role in the stress-induced cytokine expression. The present studies were designed to investigate the role of 17-β-estradiol (E2) and progesterone (Pg) in regulating the cytokine response within the paraventricular nucleus (PVN) of the hypothalamus through analysis of gene expression with real-time RT-PCR. Regularly cycling female rats showed a stress-induced increase in PVN IL-1 levels during the diestrous, proestrous, and estrous stages. During the metestrous stage, no change in IL-1 levels was seen following FS; however, estrogen receptor (ER)-β levels did increase. Ovariectomy resulted in an increase in PVN IL-1 levels, which was attenuated by treatment with estradiol benzoate (10 or 50 µg), indicating an E2-mediated anti-inflammatory effect. Ovariectomized rats treated with Pg (500 or 1,250 µg) showed no alteration in IL-1 levels, but Pg did up-regulate ER-β gene expression. The results from the current study implicate a potential mechanism through which high availability of endogenous Pg during the metestrous stage increases ER-β sensitivity, which in turn attenuates the PVN IL-1 response to stress. Thus, the interaction between gonadal steroid hormones and their central receptors may exert a powerful inhibitory effect on neuroimmune consequences of stress throughout the estrous cycle.

MATERIALS
Product Number
Brand
Product Description

Estradiol benzoate for system suitability, European Pharmacopoeia (EP) Reference Standard
Estradiol benzoate, European Pharmacopoeia (EP) Reference Standard
Sigma-Aldrich
β-Estradiol 3-benzoate, ≥97%