LIPOPOLYSACCHARIDE MODULATION OF EICOSANOID AND CORTICOTROPIN-RELEASING HORMONE-RELEASE FROM RAT HYPOTHALAMIC EXPLANTS AND ASTROCYTE CULTURES IN-VITRO - EVIDENCE FOR THE INVOLVEMENT OF PROSTAGLANDIN E(2) BUT NOT PROSTAGLANDIN-F2-ALPHA AND LACK OF EFFECT OF NERVE GROWTH-FACTOR
G. Pozzoli et al., LIPOPOLYSACCHARIDE MODULATION OF EICOSANOID AND CORTICOTROPIN-RELEASING HORMONE-RELEASE FROM RAT HYPOTHALAMIC EXPLANTS AND ASTROCYTE CULTURES IN-VITRO - EVIDENCE FOR THE INVOLVEMENT OF PROSTAGLANDIN E(2) BUT NOT PROSTAGLANDIN-F2-ALPHA AND LACK OF EFFECT OF NERVE GROWTH-FACTOR, Journal of Endocrinology, 140(1), 1994, pp. 103-109
Bacterial Lipopolysaccharide (LPS) and prostaglandins (PG) E(2) and F-
2 alpha, are putative activators of the hypothalamo-pituitary-adrenal
axis. Certain of the biological effects of LPS may be mediated by cyto
kines such as interleukin-1 beta (IL-1 beta), while IL-1 beta itself m
ay operate via induction of the prostaglandins and/or nerve growth fac
tor (NGF). As IL-1 beta stimulates the release of corticotrophin-relea
sing hormone (CRH) from acute rat hypothalamic explants directly, the
effects of these substances on the release of CRH in vitro were invest
igated in short- and medium-term (20 and 60 min) incubations. The effe
ct of LPS on the release of PGE(2) and PGF(2 alpha) from these explant
s, as well as from cortical astrocyte cultures, was also studied. LPS
did not modify the release of CRH, PGE(2) or PGF(2 alpha) in 20-min in
cubations. In 60-min incubations, LPS stimulated the release of PGE(2)
, whereas the release of CRH was weakly, but significantly, reduced; P
GF(2), was not altered. PGE(2) significantly stimulated CRH release in
the 60-min but not in the 20-min experiments. This effect appeared to
be selective for PGE(2), since PGF(2 alpha), did not modify CRH relea
se, alone or in combination. LPS also selectively released PGE(2) but
not PGF(2 alpha) from cortical astrocyte cultures after 24-h incubatio
n. NGF had no effect on the release of explant CRH, regardless of the
length of incubation. It was concluded that neither LPS nor NGF acutel
y stimulate the hypothalamo-pituitary-adrenal axis by a direct action
on hypothalamic CRH, while hypothalamic PGE(2) may mediate, at least i
n part, certain of the neuroendocrine responses to LPS.