Adriana Mirtella

Evidence for the neuronal origin of immunoreactive interleukin-1β released by rat hypothalamic explants

In this study, we have investigated the release of immunoreactive interleukin-1 beta (irIL-1 beta) from the rat hypothalamus in vitro. It was found that (1) tissue explants release sizable amounts of irIL-1 beta (ranging from 0.43 to 0.52 pg/mg of wet tissue) in 20 min incubations; (2) basal release in significantly increased by depolarization induced with 56 mM KCl; (3) K(+)-induced irIL-1 beta release is inhibited by the specific blocker of N-type calcium channels, omega-conotoxin, and by verapamil, but not by nifedipine; (4) K(+)-induced release is also inhibited by the Na+ channel blockers tetrodotoxin and lidocaine; (5) irIL-1 beta release is significantly increased by noradrenalin; such increase is antagonized by verapamil and the beta-blocker propranolol, but not by the alpha-blocker phentolamine. The present evidence suggests that irIL-1 beta released by rat hypothalamic explants following KCl depolarization is neuronal in origin.

Evidence that the interleukin-1β-induced prostaglandin E2 release from rat hypothalamus is mediated by type I and type II interleukin-1 receptors

Interleukin-1 beta (IL-1 beta) has been shown to specifically increase the release of prostaglandin (PG) E2 from rat hypothalamic explants in short-term experiments. In this study we attempted to characterize the receptor subtype(s) involved in this response. Rat hypothalamic explants were incubated with mouse monoclonal antibodies (mAbs) raised against human IL-1 type I or type II receptors, IL-1 receptor antagonist (IL-1ra) and alpha-melanocyte-stimulating hormone (alpha-MSH) (which appears to antagonize certain IL-1 induced inflammatory effects in vivo), alone and in the presence of IL-1 beta. PGE2 released into the incubation medium was measured by radioimmunoassay. The anti-type I mAb reduced both basal and IL-1 beta-stimulated PGE2 release at 10 micrograms/ml, but not at lower concentrations. The anti-type II mAb also produced a significant decrease in stimulated release but had no effect on basal release. IL-1ra mimicked the effects of the anti-type I mAb, while alpha-MSH failed to alter either basal or stimulated PGE2 release. These findings suggest that IL-1 beta controls production and release of PGE2 by the rat hypothalamus via both type I and type II receptors, although the latter appear to be involved only in the response to high levels of IL-1.

Increased production and release of prostaglandin-E2 by human granulosa cells from polycystic ovaries

This study was conducted to compare the levels of prostaglandin E2 (PGE2) released by cultured granulosa cells collected from normally-ovulating women (normal cells, NC) and those with polycystic ovaries (polycystic ovary granulosa cells, POGC). Granulosa cells were collected from 7 normal women and 7 anovulatory women with polycystic ovaries. Both groups underwent laparoscopic oocyte retrieval for gamete intra-fallopian transfer. Cell cultures were carried out under basal conditions and in the presence of various substances known to influence PGE2 biosynthesis. Prostaglandin E2 concentrations in the incubation media were taken as a marker of cyclo-oxygenase activity. Unexpectedly, POGC appeared to release greater amounts of PGE2 compared to the NC. There was no difference between the levels of PGE2 produced by the two types of cells during the first 3 hours after cell explants, whereas a difference (P < 0.01) was observed after 24 and 48 hours of incubation. Interleukin-1 beta enhanced PGE2 secretion (P < 0.01) in both POGC and NC, while lipopolysaccharide increased prostaglandin release only by the NC cells. Indomethacin inhibited PGE2 production to a greater extent in POGC (from -70 to -90% with respect to basal release, P < 0.01) than NC (approximately -50%, P < 0.01). Blockade by indomethacin and the weak inhibitory effect of the glucocorticoid, dexamethasone (P < 0.05 only in NC, and only at 24 hours), provided pharmacological evidence that PG production by granulosa cells in vitro might depend primarily on constitutive cyclo-oxygenase activity.

Release of Immunoreactive lnterleukin-1 -Alpha from Rat Hypothalamic Explants Is Increased by Bacterial Lipopolysaccharide and High KCI Concentrations

It has previously been shown that interleukin (IL)-1-like bioactivity is released from rat hypothalamic explants in short-term incubations. Experiments conducted with antiserum against IL-1Α or I

Interleukin-1 receptor antagonist displays intrinsic agonist activity on rat gastric fundus motility in vitro

It has been shown previously that both forms of interleukin-1, 1 alpha and 1 beta, produce dose-dependent relaxation of the rat gastric fundus in vitro, accompanied by an increased production and release of eicosanoids. This effect appears to be mediated, at least in part, by leukotrienes, since the inhibition of 5-lipoxygenase by specific drugs counteracts interleukin-1-induced gastric relaxation. In the present study, we attempted to antagonize interleukin-1-induced inhibition of gastric fundus motility with a interleukin-1 receptor antagonist. Surprisingly, the interleukin-1 receptor antagonist itself possessed interleukin-1-like agonist activity, since: (a) it produced rapid, dose-dependent relaxation of the rat gastric fundus, with an estimated EC50 of 70 pg/ml and a maximal effect at 10 ng/ml; (b) interleukin-1 receptor antagonist-induced relaxation was dose dependently inhibited by N-(3-phenoxycinnamyl)acetohydroxamic acid (BW A4c), a specific inhibitor of 5-lipoxygenase; (c) in the first 5 min after its addition to the bath solution, interleukin-1 receptor antagonist produced a significant increase in prostaglandin E2 release from the gastric strips. This evidence suggests that, shortly after receptor occupancy, in this experimental model interleukin-1 and interleukin-1 receptor antagonist share the same pattern of mechanical and biochemical activities.

Corrigendum to ‘Interleukin-1 receptor antagonist displays intrinsic agonist activity on rat gastric fundus motility in vitro’ [Eur. J. Pharmacol. 275 (1995) 31–37]

Abstract It has been shown previously that both forms of interleukin-1, 1α and 1β, produce dose-dependent relaxation of the rat gastric fundus in vitro, accompanied by an increased production and release of eicosanoids. This effect appears to be mediated, at least in part, by leukotrienes, since the inhibition of 5-lipoxygenase by specific drugs counteracts interleukin-1-induced gastric relaxation. In the present study, we attempted to antagonize interleukin-1-induced inhibition of gastric fundus motility with a interleukin-1 receptor antagonist. Surprisingly, the interleukin-1 receptor antagonist itself possessed interleukin-1-like agonist activity, since: (a) it produced rapid, dose-dependent relaxation of the rat gastric fundus, with an estimated EC 50 of 70 pg/ml and a maximal effect at 10 ng/ml; (b) interleukin-1 receptor antagonist-induced relaxation was dose dependently inhibited by N -(3-phenoxycinnamyl)acetohydroxamic acid (BW A4c), a specific inhibitor of 5-lipoxygenase; (c) in the first 5 min after its addition to the bath solution, interleukin-1 receptor antagonist produced a significant increase in prostaglandin E 2 release from the gastric strips. This evidence suggests that, shortly after receptor occupancy, in this experimental model interleukin-1 and interleukin-1 receptor antagonist share the same pattern of mechanical and biochemical activities.