|[Frontiers in Bioscience 2, d88-125, March 1, 1997]|
CROSS-TALK SIGNALS IN THE CNS: ROLE OF NEUROTROPHIC AND HORMONAL FACTORS, ADHESION MOLECULES AND INTERCELLULAR SIGNALING AGENTS IN LUTEINIZING HORMONE-RELEASING HORMONE (LHRH)-ASTROGLIAL INTERACTIVE NETWORK|
Department of Pharmacology, Medical School, University of Catania, 95125 Catania, Laboratory of Biotech. Neuropharmacology, OASI Institute for Research and Care (IRCCS) on Mental Retardation and Brain Aging (IRCCS) Troina, (EN), Italy.
Received 8/2/96; Accepted 2/20/97; On-line 3/1/97
In order to establish the ability of astroglial-derived cytokines to modulate LHRH release from the GT cell line, the potent inducer of immune soluble mediators, lipopolysaccharide (LPS) was studied in both co-culture and mixed culture conditions. While in absence of physical contacts (co-culture), LPS treated glia, sharply stimulated LHRH release, a marked inhibition of spontaneous LHRH production followed addition of LPS in the mixed culture condition (Fig. 16). Since LPS is known to stimulate NO production, a possible intermediacy of the nitroxidergic pathway in LPS-induced LHRH release cannot be discounted. On the other hand, the marked inhibition of LHRH in the mixed culture condition in the presence of cell-to-cell contacts may suggest a. the prevalence of inhibitory signals and/or b. the saturation of intracellular transducing pathways leading to the release of LHRH.
Figure 16. Effect of lipopolysaccharide stimulation in LHRH-glia interactions. To test the ability of astroglial-derived cytokines to modulate LHRH output from the GT1 cell line, the potent cytokine inducer, lipopolysaccharide (LPS, 10-100 ng/ml) was added to either the co-culture or mixed culture models. Astroglia proliferation was monitored by DNA labeling. Note the sharp stimulation of LHRH release following 10 and 50 ng/ml LPS and the parallel increase in astroglia proliferation during co-culture. In mixed culture, however, an almost 60 to 70% decrease of LHRH release was measured.