Interleukin-1 beta stimulates adrenocorticotropin and corticosterone release in 10-day-old rat pups.

Interleukin-1 (IL-1) is a cytokine secreted in response to immunological challenge which has effects in many physiological systems in adult models. Among the central nervous system effects of IL-1 are its ability to alter sleep patterns, body temperature, and certain neuroendocrine parameters including the release of ACTH and corticosterone (B) in vivo. This study investigated the ability of IL-1 to induce ACTH and B release in 10-day-old rats. This age was chosen due to a well documented phenomenon, the stress hyporesponsive period (SHRP), in which rodents display a blunted pituitary-adrenal response to stressors during the first 2 postnatal weeks (postnatal days 3-14). Administration of IL-1 to rat pups during the SHRP resulted in robust ACTH and B increases. Data are discussed in terms of the site of action and ontogeny of negative feedback mechanisms in the hypothalamic-pituitary-adrenal axis.