Effects of Chronic Stress on Hypothalamic lnterleukin‐1β, Interleukin‐2, and Gonadotrophin‐Releasing Hormone Gene Expression in Ovariectomized Rats

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Abstract
The influence of chronic stress on the expression of interleukin (IL)-1β and IL-2 mRNAs in ovariectomized rat brains, and the physiological consequences of the expression of these cytokines on hypothalamic-pituitary-gonadal (HPG) activity were investigated. Using polymerase chain reaction (PCR)-assisted semiquantitative analysis, we demonstrated alterated expression of IL-1β and IL-2 mRNA during repeated cold stress; the expression of both IL-β and IL-2 mRNA increased in the medial preoptic area and ventromedial hypothalamus, and decreased in the lateral hypothalamic area. In the arcuate nucleus/median eminence, IL-2 mRNA expression was dramatically decreased, in contrast to the increase in IL-1β mRNA expression. Concomitant analysis of GnRH mRNA expression indicated significant suppression of GnRH synthesis in the chronic phase, and a strong negative correlation with cytokine expression in the medial preoptic area. Similar results were obtained in intact females exposed to this stress. These results, together with previous pharmacological studies, suggest that chronic stress may induce reproductive dysfunction through the effects of stress-induced expression of endogenous cytokines.