PITUITARY AND OVARIAN INTERLEUKIN-1-ALPHA CONTENT CHANGES ACCORDING TO ESTROUS-CYCLE AND ACUTE STRESS EXPOSURE

A complex interaction between the immune and neuroendocrine systems ha s been established. In particular, cytokines are known to be one of th e mediators of the stress response, and modulate hormone secretion by acting in the brain, pituitary and gonads. The aim of the present stud y is to investigate whether pituitary and ovarian interleukin-1alpha ( IL-1alpha) content changes according to the estrous cycle. In addition , the possible pituitary and ovarian IL-1alpha changes in rats exposed to acute (5 min) or chronic intermittent (twice a day for 4 days) col d swimming stress were studied. The IL-1alpha content of ovarian and p ituitary homogenates was measured by a sensitive and specific radioimm unoassay. Immunoreactive IL-1alpha (irIL-1alpha) was detectable only i n ovaries collected in rats at proestrus and estrus while not in those collected at diestrus I and II. The highest values were found at proe strus. No significant changes were found in ovarian irIL-1alpha conten t in rats exposed to acute or chronic intermittent stress in compariso n to control rats. In the pituitary, no difference in IL-1alpha conten t was found throughout the estrous cycle. Acute stress induced a signi ficant increase in pituitary irIL-1alpha content only at proestrus (p < 0.01), however, no significant differences were found in comparison to control rats after chronic intermittent stress. The proestrus-relat ed changes of ovarian IL-1alpha may constitute a hormone-dependent sig nal within the ovary that is involved in the ovulatory process. Furthe rmore, it is possible that the stress-related pituitary IL-1alpha chan ges occurring at proestrus may represent an additional mediator in the complex paracrine phenomena modulating the neuroendocrine responses t o stressful stimuli.