Pituitary and ovarian interleukin-1α content changes according to estrous cycle and acute stress exposure

A complex interaction between the immune and neuroendocrine systems has been established. In particular, cytokines are known to be one of the mediators of the stress response, and modulate hormone secretion by acting in the brain, pituitary and gonads. The aim of the present study is to investigate whether pituitary and ovarian inter-leukin-1α (IL-1α content changes according to the estrous cycle. In addition, the possible pituitary and ovarian IL- 1α changes in rats exposed to acute (5 min) or chronic intermittent (twice a day for 4 days) cold swimming stress were studied. The IL-1α content of ovarian and pituitary homogenates was measured by a sensitive and specific radioimmunoassay. Immunoreactive IL- 1α (irIL- 1α was detectable only in ovaries collected in rats at proestrus and estrus while not in those collected at diestrus I and II. The highest values were found at proestrus. No significant changes were found in ovarian irIL- 1α content in rats exposed to acute or chronic intermittent stress in comparison to control rats. In the pituitary, no difference in IL- 1α content was found throughout the estrous cycle. Acute stress induced a significant increase in pituitary irIL- 1α content only at proestrus (p <0.01), however, no significant differences were found in comparison to control rats after chronic intermittent stress. The proestrus-related changes of ovarian IL-1α may constitute a hormone-dependent signal within the ovary that is involved in the ovulatory process. Furthermore, it is possible that the stress-related pituitary IL-1α changes occurring at proestrus may represent an additional mediator in the complex paracrine phenomena modulating the neuroendocrine responses to stressful stimuli.