Bacterial lipopolysaccharide (LPS) and prostaglandins (PG) E2 and F(2α) are putative activators of the hypothalamo-pituitary-adrenal axis. Certain of the biological effects of LPS may be mediated by cytokines such as interleukin-1β (IL-1β), while IL-1β itself may operate via induction of the prostaglandins and/or nerve growth factor (NGF). As IL-1β stimulates the release of corticotrophin-releasing hormone (CRH) from acute rat hypothalamic explants directly, the effects of these substances on the release of CRH in vitro were investigated in short- and medium-term (20 and 60 min) incubations. The effect of LPS on the release of PGE2 and PGF(2α) from these explants, as well as from cortical astrocyte cultures, was also studied. LPS did not modify the release of CRH, PGE2 or PGF(2α) in 20-min incubations. In 60-min incubations, LPS stimulated the release of PGE2, whereas the release of CRH was weakly, but significantly, reduced; PGF(2α) was not altered. PGE2 significantly stimulated CRH release in the 60-min but not in the 20-min experiments. This effect appeared to be selective for PGE2, since PGF(2α) did not modify CRH release, alone or in combination. LPS also selectively released PGE2 but not PGF(2α) from cortical astrocyte cultures after 24-h incubation. NGF had no effect on the release of explant CRH, regardless of the length of incubation. It was concluded that neither LPS nor NGF acutely stimulate the hypothalamo-pituitary-adrenal axis by a direct action on hypothalamic CRH, while hypothalamic PGE2 may mediate, at least in part, certain of the neuroendocrine responses to LPS.
|Number of pages||7|
|Journal||Journal of Endocrinology|
|Publication status||Published - 1994|
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