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The effects of trazodone and putative sigma (sigma) receptor ligands were investigated on KCl-stimulated release of glutamate (Glu) and gamma-aminobutyric acid (GABA) from cerebellar mossy fibre synaptosomes. Both trazodone and serotonin (5-HT) inhibited the increase of Glu and GABA release evoked by 15 mM KCl. Trazodone increased the inhibition of Glu release caused by 0.01 microM 5-HT, while it antagonized the inhibition induced by higher 5-HT concentrations. Despite the low affinity of trazodone for both sigma(1) and sigma(2) binding sites, with a pK(i) of 5.9 and 6.0 respectively, two sigma receptor ligands, (+)-3-[3-hydroxypheny]-N-(1-propyl)piperidine ((+)-3-PPP) and N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(dimethylamino)ethylamine (BD 1047) antagonized the effects of trazodone. The putative sigma receptor ligand N-allylnormetazocine ((+)-SKF 10,047) mimicked the inhibitory effect of trazodone. As with trazodone, (+)-3-PPP and BD 1047 antagonized the activity of (+)-SKF 10,047 but not that of 5-HT. On the whole, these results suggest that trazodone shares a common molecular target with sigma compounds distinct from that of 5-HT and is involved in K(+)-stimulated Glu and GABA release from mossy fibre cerebellar synaptosomes.

Suramin, a symmetrical polysulfonated urea derivative, promotes the dissociation of trimeric human tumor necrosis factor-alpha (TNF-alpha) into biologically inactive subunits and prevents the interaction of TNF-alpha with its cellular receptors. The aim of this work was to identify compounds structurally related to suramin which inhibit the binding of TNF-alpha to its receptor. Molecular modeling studies were performed on suramin and TNF-alpha molecules and likely interaction sites were identified in the docked complex. On this basis, Evans blue, trypan blue, sulfonazo III, beryllon II, and 1,3,6-naphthalenetrisulfonic acid trisodium salt were identified as polysulfonated compounds endowed, to various extents, with the structural characteristics responsible for interaction with TNF-alpha. N,N-bis(3,5-di-tert-butylphenyl)-3,4,9,10-perylenedicarboximide was used as an unrelated structure. The capacity of these molecules to inhibit the binding of TNF-alpha with its receptor p55 was tested in vitro by means of a specific immunoenzymatic assay using suramin as reference compound. Evans blue and trypan blue inhibited TNF-alpha/p55 binding with an IC50 of 0.75 and 1.00 mM, respectively (suramin IC50: 0.65 mM); no effect was observed with the other molecules. Molecular modeling analyses on Evans blue and trypan blue docked into the TNF-alpha molecule support these experimental results by demonstrating that these compounds share with suramin a similar binding mode to TNF-alpha. The results of this work provide a new insight into and useful hints for the design of new chemical entities endowed with a potent and selective activity on TNF-alpha.

Deposition of beta-amyloid in the brain triggers an inflammatory response which accompanies the neuropathologic events of Alzheimer's disease and contributes to the destruction of brain tissue. The present study shows that beta-amyloid can stimulate human astrocytoma cells (T98G) to secrete the proinflammatory factors interleukin-6 and prostaglandins. Furthermore, prostaglandins can stimulate T98G to secrete interleukin-6, which in turn triggers the formation of additional prostaglandins. Prostaglandins are, therefore, a key element in the induction and maintenance of a state of chronic inflammation in the brain which may exacerbate the fundamental pathology in Alzheimer patients. Paracetamol (0.01-1000 microM), an unusual analgesic/antipyretic drug which acts preferentially by reducing prostaglandin production within the central nervous system, and indomethacin (0.001-10 microM) caused a clear dose-dependent reduction of prostaglandin E2 production by stimulated T98G cells whereas interleukin-6 release was not affected. These data provide further evidence of the involvement of non-steroidal anti-inflammatory drugs in the inflammatory processes that can be generated by glial cells in intact brain.

Melatonin is an antioxidant. Since other antioxidants inhibit the production of tumor necrosis factor (TNF) induced by lipopolysaccharide, we investigated its effect on TNF production in vivo and in vitro and on lethality associated with endotoxic shock. Administration of melatonin to mice (5 mg/kg, s.c., 30 min before or simultaneously with lipopolysaccharide) inhibited serum TNF levels by 50-80% and improved survival of mice treated with a lethal dose of lipopolysaccharide. By studying other, structurally related, indolamines (N-acetyl-5-hydroxytryptamine, 5-methoxytryptamine and 5-hydroxytryptamine) we found a good correlation between antioxidant activity (for which the 5-methoxy group is essential) and the inhibition of TNF production in vivo and in vitro in mononuclear cells. Melatonin did not increase serum corticosterone and did not modify the elevation of serum corticosterone levels by lipopolysaccharide or by interleukin-1. Furthermore, it exerted its inhibitory effect in adrenalectomized or hypophysectomized mice also, indicating that its effect is independent of the hypothalamus-pituitary-adrenal axis.

The activity of a novel calcitonin SB 205614 was compared with salmon calcitonin (sCT) and (Asu1,7)-eel calcitonin (ELC) in six different models of osteoclastic bone resorption in vitro and in vivo. SB 205614 is an ELC analogue that has an acetylenic bridge instead of the natural disulphide bridge, rendering the molecule more stable biologically than sCT and equally stable to ELC. Our aim was to determine whether this structural change compromised biologic activity, and if not, whether the increased stability could be used to exploit novel modes of administration. In the in vitro assays of pit formation by disaggregated rat osteoclasts on cortical bone slices (DROcA) and PTH stimulation of 45Ca-release from prelabeled fetal rat bone, no significant differences in activity were observed between the three calcitonins. In the DROcA, IC50s of 0.003, 0.015 and 0.064 pg/ml for sCT, ELC, and SB 205614, respectively, were determined, with total or near complete inhibition observed at 1 pg/ml (0.3 pM). In the assay of PTH-stimulation of 45Ca release, IC50s were measured of 5.5, 4.8, and 12.9 pM for sCT, ELC, and SB 205614, respectively; in every case maximal inhibition (ca. 80%) was observed at 30 and 100 pM. The internationally approved U.S. Pharmacopoeia bioassay of hypocalcemia in the rat following intravenous (IV) administration indicated that SB 205614 had a greater potency than ELC or sCT. More important, a full dose-hypocalcemic response curve demonstrated significantly increased potency compared to sCT or ELC, as the doses causing 15% lowering of serum calcium (approximately 50% of the maximum effect) were 33.9, 25.2, and 12.9 mg/kg for sCT, ELC, and SB 205614, respectively. As a preliminary means of investigating alternative delivery forms of calcitonin, the time course of the hypocalcemic effect was investigated in the rat and rabbit following IV administration, and was compared with that following intranasal (IN) administration (rat and rabbit), and following intracolonic administration (rat only). Maximal effects were similar, whereas in general the hypocalcemic effect of SB 205614 was of a longer duration than the other two calcitonins; this was reflected in a larger area over the curve (AOC). However, following IN administration in the rabbit, where an aerosol delivery device similar to that used in the clinic was used to administer the calcitonins, SB 205614 (100 IU/kg) induced a highly significant two-fold increase in the AOC compared to ELC or sCT. The calcitonins were also compared in assays designed to measure therapeutic efficacy in the rat.(ABSTRACT TRUNCATED AT 400 WORDS)