Lack of effect of interleukins 1α and 1β, during in vitro perifusion, on anterior pituitary release of adrenocorticotropic hormone and β endorphin in the male rat

It has been demonstrated that interleukin 1 (IL1) injection provokes a great variety of biological effects, notably an activation of the corticotropic axis, increasing plasma adrenocorticotropic hormone (ACTH) and corticosterone. However, the primary site of action of IL1 is still controversial. In the present study, we first verified the in vivo capability of human interleukins 1 alpha (hIL1 alpha) and 1 beta (hIL1 beta) to release ACTH and beta endorphin (beta EP) in the normal male rat, before investigating, through an anterior pituitary (AP) perifusion system, the hIL1 alpha and hIL1 beta effects on basal and corticotropin-releasing factor (CRF)-induced ACTH and beta EP secretions. This system enabled the examination of a dynamic profile of hormones secretion, avoiding the possibility of feedback mechanisms, as is the case with the use of regular but very often longtime incubations. The results showed that in a perifusion system, with a short duration treatment (below 2 hr) compatible with the kinetics of action observed in vivo, basal and CRF-induced ACTH and beta EP release were not modified in the presence of a broad range of concentrations (from 10(-12) to 10(-9) M) of hIL1 alpha or hIL1 beta. Taken together, these results clearly show that in an in vitro situation close to physiological conditions, the primary site of action of hIL1 alpha and hIL1 beta on ACTH and beta EP release is not located at the AP level in the male rat.